论文资料：登革热和黄热病的共存现象DEN and YF coexistence
BioSystems106 (2011) 111–120
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BioSystems
j o u r n a l h o m e p a g e:w w w.e l s e v i e r.c o m/l o c a t e/b i o s y s t e m
s
Why dengue and yellow fever coexist in some areas of the world and not in others?
Marcos Amaku a,Francisco Antonio Bezerra Coutinho b,Eduardo Massad b,c,?
a School of Veterinary Medicine,The University of S?o Paulo,Brazil
b School of Medicine,The University of S?o Paulo,and LIM01HCFMUSP,Brazil
c London School of Hygiene an
d Tropical Medicine,UK
a r t i c l e i n f o
Article history:
Received31January2011
Received in revised form17June2011 Accepted22July2011
Keywords:
Yellow fever
Dengue
Cross-immunity
Competitive exclusion principle Mathematical models a b s t r a c t
Urban yellow fever and dengue coexist in Africa but not in Asia and South America.In this paper,we examine four hypotheses(and various combinations thereof)to explain the absence of yellow fever in urban areas of Asia and South America.In addition,we examine an additional hypothesis that offers an explanation of the coexistence of the infections in Africa while at the same time explaining their lack of coexistence in Asia.The hypotheses we tested to explain the nonexistence of yellow fever in Asia are the following:(1)the Asian Aedes aegypti is relatively incompetent to transmit yellow fever;(2)there would exist a competition between dengue and yellow fever viruses within the mosquitoes,as suggested by in vitro studies in which the dengue virus always wins;(3)when an A.aegypti mosquito that is infected by or latent for yellow fever acquires dengue,it becomes latent for dengue due to internal competition within the mosquito between the two viruses;(4)there is an important cross-immunity between yellow fever and other?aviviruses,dengue in particular,such that a person recovered from a bout of dengue exhibits a diminished susceptibility to yellow fever.This latter hypothesis is referred to below as the “Asian hypothesis.”Finally,we hypothesize that:(5)the coexistence of the infections in Africa is due to the low prevalence of the mosquito Aedes albopictus in Africa,as it competes with A.aegypti.We will refer to this latter hypothesis as the“African hypothesis.”
We construct a model of transmission that allows all of the above hypotheses to be tested.We con-clude that the Asian and the African hypotheses can explain the observed phenomena,whereas other hypotheses fail to do so.
? 2011 Elsevier Ireland Ltd. All rights reserved.
1.Introduction
Yellow fever and dengue fever/dengue hemorrhagic fever are diseases caused by mosquito-borne viruses belonging to the fam-ily Flaviridae,genus Flavivirus(Monath and Heinz,1996;Gubler, 2004).The urban form of yellow fever,the object of this paper,is transmitted by Aedes aegypti mosquitoes.Dengue,the other?a-vivirus infection of interest,is also transmitted by A.aegypti and additionally by another mosquito,Aedes albopictus,although with less competence(Marques et al.,1994;Gubler and Kuno,1997).
Urban yellow fever epidemics continue to occur in Africa(WHO, 1991)with180000new cases per year(WHO,2003),where A. aegypti has never been controlled(Monath,1994),and the disease coexists with dengue in African urban centers(500000cases per year,WHO,2010).In addition,it is known that there are other species of insects that could add to the transmission of yellow ?Corresponding author at:School of Medicine,The University of S?o Paulo,and LIM01HCFMUSP,Brazil.Tel.:+551130617435;fax:+551130617382.
E-mail address:edmassad@usp.br(E.Massad).fever in Africa.However,in Asia,dengue is extremely prevalent (200000cases per year,WHO,2010),but yellow fever has never been reported(Monath,1989).This absence has been the subject of a great deal of speculation,and a number of hypotheses have been proposed in the literature to explain it.Among these hypothe-ses,we identi?ed three main hypotheses to explain the absence of yellow fever in Asia(Monath,1988),listed below and ordered according to the importance attributed to them:
(a)the risk of importation of a yellow fever viremic person to Asia
is very low;
(b)there is a cross-immunity between yellow fever and other
?aviviruses,particularly dengue,that would diminish one’s sus-ceptibility to yellow fever;and
(c)a relatively incompetent vector is present in the region. Hypothesis“a”above will not be tested in this paper because the risk of importation,known to be low,it is not zero.Therefore, the deterministic nature of our model is not appropriate for this kind of calculation.The low risk of importation of viraemic persons
0303-2647/$–see front matter? 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.biosystems.2011.07.004
112M.Amaku et al./BioSystems106 (2011) 111–120
infected with yellow fever to Asia is currently due to a demand of yellow fever vaccination certi?cate to travelers to all countries in the region.However,even before the discovery of the yellow fever vaccine there was no case of the disease in Asia.
In addition,a fourth hypothesis has been suggested by in vitro studies indicating interference between dengue and yellow fever viruses within Aedes mosquitoes cells,in which dengue always wins the competition(Abr?o and Fonseca,2006,2007;Costa and Fonseca,2006).However,the most accepted hypothesis to explain the absence of yellow fever in Southeast Asia is the cross-immunity among?avivirus(hypothesis b above),such that an individual who has recovered from a dengue bout is protected against yellow fever.We call this theory the“Asian hypothesis.”A classical exper-iment indicated that dengue-immune rhesus monkeys,when challenged with the yellow fever virus,exhibit reduced levels of viremia relative to nonimmunized control monkeys(Theiller and Anderson,1975).
But if there are several hypotheses to explain the absence of yel-low fever in Asia,where A.aegypti is extremely prevalent,it remains to be explained why dengue and(urban)yellow fever coexist in Africa.Here we hypothesize that the virtual absence of A.albopic-tus(introduced in Africa only in2003(Toto et al.,2003))explains this coexistence.We call this theory the“African hypothesis.”
The Asian hypothesis is strongly suggested by the following generalization of the so-called Competitive Exclusion Principle (Bremermann and Thieme,1988;Burattini et al.,2008;Amaku et al., 2010).If a mosquito that is infected with dengue cannot be infected by yellow fever,and vice versa,and if a person recovered from dengue cannot acquire yellow fever,and vice versa,then one of the diseases is excluded.The disease with the lower basic repro-duction number will be excluded.This result is demonstrated in Appendix A.
Of course,the hypotheses implied by the Competitive Exclu-sion Principle(complete cross-immunity in both mosquitoes and humans)are extreme,and the purpose of this paper is to explore the extent to which this complete cross-immunity can be relaxed and still explain the exclusion of yellow fever from some dengue areas but not others.
It should be mentioned that yellow fever vaccination was not considered in our model in none of the regions of the world ana-lyzed.The fact that all countries of Southeast Asia demand the certi?cate of yellow fever vaccination to all visitors from endemic countries certainly is a contributing factor for the effective control of yellow fever in those regions.However,in spite of this the role of vaccination to control yellow fever was not tested in our model. This was not done because vaccination is not used in the local pop-ulation of Southeast Asia.In addition,the coverage of yellow fever vaccination in Africa is relatively low.In South America the cover-age of the vaccine is relatively high but,in spite of this,the sylvatic cycle of yellow fever is prevalent.The coverage in South America is such that a belt of vaccinated people prevent the introduction of the urban cycle of the disease.Therefore,we can consider that without vaccination the urban yellow fever could coexist in South America.However,there are regions of South America without any routine vaccination program in which urban yellow fever is absent. Finally,it should be remembered that there was no yellow fever in Southeast Asia before the discovery of the vaccine.Therefore,it seems that the absence of yellow fever in Asia precedes the vaccine.
This paper is organized as follows.In the next section,we enumerate the hypotheses that are going to be explored in the remainder of the paper.In the third section,we present the mathe-matical model that will be used to test the hypotheses.In the fourth section,we test the hypotheses using numerical and analytical methods.Finally,in the last section,we summarize our?ndings.
This paper has three appendices.In Appendix A we discuss a generalized Competitive Exclusion Principle showing that in an extreme case(not realized in nature)dengue could exclude yel-low fever.In Appendix B we present the steady-state equilibrium solutions of our model considering,for simplicity,only one disease transmitted by only one mosquito.Finally,Appendix C brie?y dis-cusses the evolutionary dynamics of dengue and yellow fever and its possible implications.
2.The Hypotheses to be Tested
We present below5hypotheses that will be treated in this paper.Note that among those hypotheses we included two of the hypotheses that are commonly mentioned in the literature,namely hypotheses“b”and“c”above.
1.The mosquito A.aegypti can only be infected by yellow fever or
dengue but not by both simultaneously(see Abr?o and Fonseca, 2006,2007;Costa and Fonseca,2006).
2.When an A.aegypti mosquito that is infected by or latent for
yellow fever acquires dengue,it becomes latent for dengue due to internal competition within the mosquito between the two viruses.Mosquitoes are in a latent state when they are infected but are not infectious.The latent period in the mosquitoes is usually called the“extrinsic incubation period”.
3.The Asian A.aegypti mosquito is relatively less competent at
transmitting yellow fever,either because it is more resistant to the infection or because it is less able to transmit the infection to humans.
4.Individuals who have recovered from dengue are partially
immune to yellow fever.To formulate this hypothesis in math-ematical terms,let p be the probability of an individual who never acquired dengue to get yellow fever when bitten by an infected mosquito.The probability of an individual recov-ered from dengue—and,according to this hypothesis,partially immune to yellow fever—to acquire yellow fever is denoted ?p(0≤?<1).Hence,when?=0,individuals recovered from dengue are completely immune to yellow fever and when?=1, they are completely susceptible.The parameter(1??)is there-fore a measure of cross-immunity.Cross-immunity introduces a threshold below which coexistence is not possible.
5.The low prevalence of the oriental mosquito A.albopictus in
Africa,combined with a high density of A.aegypti,would explain the coexistence of dengue and(urban)yellow fever in that con-tinent by reducing the cross-immunity threshold mentioned above.
It is known that A.albopictus competes with A.aegypti.It is also known that while there are several regions within Africa where the former species has established itself,it is not as widespread as A.aegypti.Because of the competition mentioned above,this may result in a much higher abundance of A.aegypti.This factor is also helped by the general conditions of urban Africa.
2.1.The Model
The model includes humans and two mosquitoes species,A. aegypti(which transmits both infections:yellow fever and dengue) and A.albopictus(which transmits only dengue).
The variables of the model are described in Table1.
The proposed model belongs to the classical Ross–Macdonald class(Lopez et al.,2002;Ruan et al.,2008).The dynamics of the model is described by the set of equations below,whereas the parameters,their biological signi?cance and their values are indi-cated in Table2.The physical meaning of the terms in the system of Eqs.(1)–(29)is explained brie?y below.
Most of the parameters in Table2were taken from the lit-erature(Lopez et al.,2002;Massad et al.,2003;Coutinho et al.,
M.Amaku et al./BioSystems106 (2011) 111–120113 Table1
Variables.
Variable Biological meaning
M1Susceptible A.aegypti mosquitoes
M1LD A.aegypti mosquitoes latent for dengue
M1LDLY A.aegypti mosquitoes latent for dengue and yellow fever
M1IDIY A.aegypti mosquitoes infected with dengue and yellow fever
M1ID A.aegypti mosquitoes infected with dengue
M1IDLY A.aegypti mosquitoes infected with dengue and latent for yellow fever
M1LY A.aegypti mosquitoes latent for yellow fever
M1LYLD A.aegypti mosquitoes latent for yellow fever and dengue
M1IYID A.aegypti mosquitoes latent for yellow fever and infected with dengue
M1IY A.aegypti mosquitoes infected with yellow fever
M1LYID A.aegypti mosquitoes infected with yellow fever and latent for dengue
M1L2 A.aegypti mosquitoes simultaneously latent for both yellow fever and
dengue
M1I2 A.aegypti mosquitoes simultaneously infected with both yellow fever
and dengue
M2Susceptible A.albopictus mosquitoes
M2LD A.albopictus mosquitoes latent for dengue
M2ID A.albopictus mosquitoes infected with dengue
H Humans susceptible to both infections
H ID Humans infected with dengue
H RD Humans recovered from dengue
H RDIY Humans recovered from dengue and then infected with yellow fever
H IDIY Humans?rst infected with dengue and then infected with yellow
fever
H RDRY Humans?rst recovered from dengue and then recovered from yellow
fever
H IY Humans infected with yellow fever
H IYID Humans?rst infected with yellow fever and then infected with
dengue
H RY Humans recovered from yellow fever
H RYID Humans recovered from yellow fever and then infected with dengue
H RYRD Humans recovered from yellow fever and then recovered with dengue
H I2Humans simultaneously infected with both infections
H R2Humans simultaneously recovered from both infections
2006).However,the values for some of the parameters are essen-
tially unknown.For example,the parameter 1LDLY denotes the
inverse of the average period of time a mosquito(Aedes)infected
with both viruses spends in the latent condition.Its value was esti-
mated as the inverse of the longest latent period(dengue,7days)
plus half of the shortest latent period(yellow fever,5days).So,
1LDLY=1/(7+2.5)=0.11days?1.All of the other composite param-
eters were estimated in a similar fashion.These estimates are
obviously not entirely correct,but they offer good approxima-
tions and do not qualitatively interfere with our results.The exact
answers should consider the history of the infection within each
host.
The equations of the model are the following:
dM1 dt =?a1c1D M1(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
?a1c1Y M1(H IY
+H IYID+H IDIY+H RDIY+H I2)
N H
?a1(c1D c1Y)M1(H IYID
+H IYID+H I2)
N H
ε? 1M1+ M
1
(1)
dM1LD dt =a1c1D M1(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
?( 1LD+ M
1
)M1LD+a1c1D M1LY
×(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
+a1c1D M1IY(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
?a1c1Y M1LD(H IY
+H IYID+H IDIY+H RDIY+H I2)
N H
ε (2)
dM1LDLY
dt
=a1c1Y M1LD(H IY
+H IYID+H IDIY+H RDIY+H I2)
N H
ε
?( 1LDLY+ M
1
)M1LDLY(3)
dM1IDIY
dt
= 1LDLY M1LDLY+ 1IDLY M1IDLY? M
1
M1IDIY(4)
dM1ID
dt
= 1LD M1LD? M
1
M1ID
?a1c1Y M1ID(H IY
+H IYID+H IDIY+H RDIY+H I2)
N H
ε (5)
dM1IDLY
dt
=a1c1Y M1ID(H IY
+H IYID+H IDIY+H RDIY+H I2)
N H
ε
?( 1IDLY+ M
1
)M1IDLY(6)
dM1LY
dt
=a1c1Y M1(H IY
+H IYID+H IDIY+H RDIY+H I2)
N H
?( 1LY+ M
1
)M1LY?a1c1D M1LY
×(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
?a1c1D M1LY(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
ε (7)
dM1LYLD
dt
=a1c1D M1LY(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
ε
?( 1LYLD+ M
1
)M1LYLD(8)
dM1IYID
dt
= 1LYLD M1LYLD+ 1IYLD M1IYLD? M
1
M1IDIY(9)
dM1IY
dt
= 1LY M1LY? M
1
M1IY?a1c1D M1IY
×(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
?a1c1D M1IY(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
ε (10)
dM1IYLD
dt
=a1c1D M1IY(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
ε
?( 1IYLD+ M
1
)M1IYLD(11)
dM1L2
dt
=a1(c1D c1Y)M1(H IYID
+H IYID+H I2)
N H
ε?( 1L2+ M
1
)M1L2
(12)
dM1I2
dt
= 1L2M1L2? M
1
M1I2(13)
dM2
dt
=?a2c2D M2(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
? 2M2+ M
2
(14)
dM2LD
dt
=?a2c2D M2(H ID
+H RYID+H IYID+H IDIY+H I2)
N H
? 2LD M2LD? 2M2LD(15)
114M.Amaku et al./BioSystems106 (2011) 111–120
Table2
Parameters,their biological signi?cance and values.
Parameter Biological signi?cance Value[16,18,19]
a1Daily biting rate of Aedes aegypti mosquitoes1days?1
a2Daily biting rate of Aedes albopictus mosquitoes0.8days?1
c1D Probability of dengue infection for Aedes aegypti mosquitoes0.8
c2D Probability of dengue infection for Aedes albopictus mosquitoes0.5
c1Y Probability of yellow fever infection for Aedes aegypti mosquitoes Variable
M1Mortality rate of Aedes aegypti mosquitoes0.1days?1
M2Mortality rate of Aedes albopictus mosquitoes0.1days?1
Y1LD Inverse of the latent period of Aedes aegypti infected with dengue0.14days?1
Y1LDLY Inverse of the latent period of Aedes aegypti infected with dengue and yellow fever0.11days?1
Y1LY Inverse of the latent period of Aedes aegypti infected with yellow fever0.2days?1
Y1LYLD Inverse of the latent period of Aedes aegypti infected with yellow fever and dengue0.11days?1
Y1IYLD Inverse of the latent period of Aedes aegypti infectious with yellow fever and infected with dengue0.11days?1
Y1IDLY Inverse of the latent period of Aedes aegypti infectious with dengue and infected with yellow fever0.11days?1
Y1L2Inverse of the latent period of Aedes aegypti infected with dengue and yellow fever simultaneously0.07days?1
Y2L2Inverse of the latent period of Aedes albopictus infected with dengue and yellow fever simultaneously0.07days?1
b1D Human susceptibility to dengue from Aedes aegypti0.15
b2D Human susceptibility to dengue from Aedes albopictus0.04
b1Y Human susceptibility to yellow fever from Aedes aegypti Variable
H Human mortality rate0.0000457days?1 ID Inverse of the infectious period of dengue0.14days?1
RDIY Inverse of the infectious period of yellow fever for patients recovered from dengue0.14days?1
IDIY Inverse of the infectious period of dengue and yellow fever0.1days?1
IYID Inverse of the infectious period of yellow fever and dengue0.1days?1
RYID Inverse of the infectious period of dengue for patients recovered from yellow fever0.14days?1
IY Inverse of the infectious period of yellow fever0.14days?1
I2Inverse of the infectious period of dengue and yellow fever simultaneously0.1days?1
?ID Mortality rate of dengue0.001days?1
?IY Mortality rate of yellow fever0.018days?1
?IDIY Mortality rate of dengue and yellow fever0.018days?1
?IYID Mortality rate of yellow fever and dengue0.018days?1
?I2Mortality rate of both infections simultaneously0.018days?1
εControls the intensity of simultaneous infection by dengue and yellow fever in the mosquito0≤ε≤1
ε Controls the possibility that the latent and the infectious mosquitoes with dengue will acquire yellow fever.0≤ε ≤1
ε Controls the possibility that the latent and the infected mosquitoes with yellow fever will acquire dengue.0≤ε ≤1
Controls the possibility that a latent or infected mosquito with yellow fever will catch dengue and become
latent with dengue loosing the yellow fever virus.
(0or1)
ωControls the possibility that a human infected with dengue will acquire yellow fever.0≤ω≤1
ω Controls the possibility that a human who has been infected with yellow fever will acquire dengue.0≤ω ≤1
ω The human equivalent toεfor the mosquitoes0≤ω ≤1
?Controls the possibility that a human who has recovered from dengue will acquire yellow fever.0≤?≤1
? Controls the possibility that a human who has recovered from yellow fever will acquire dengue0≤? ≤1
dM2ID
dt
= 2LD M2LD? 2M2ID(16)
dH dt =?a1b1D H(M1ID
+M1IDIY+M1IDLY+M1IYID+M1I2)
N H
?a1b1Y H(M1IY
+M1IDIY+M1IYID+M1IYLD+M1I2)
N H
?a2b2D H M2ID
N H
? H H+ H?a1b1Y b1D H
×(M1IDIY
+M1IYID+M1I2)
N H
ω (17)
dH ID dt =a1b1D H(M1ID
+M1IDIY+M1IDLY+M1IYID+M1I2)
N H
+a2b2D H M2ID
N H
?( H+ ID+?ID)H ID?a1b1Y H ID
×(M1IY
+M1IDIY+M1IYID+M1IYLD+M1I2)
N H
ω(18)
dH RD
dt
= ID H ID? H H RD?a1b1Y H RD
×(M1IDIY +M1IYID+M1IY+M1IYLD+M1I2)
N H
?(19)
dH RDIY
dt
=a1b1Y H RD(M1IDIY
+M1IYID+M1IY+M1IYLD+M1I2)
N H
?
?( H+ RDIY+?IY)H RDIY(20)
dH RDRY
dt
= IDIY H IDIY+ RDIY H RDIY? H H RDRY(21)
dH IDIY
dt
=a1b1Y H ID(M1IY
+M1IDIY+M1IYID+M1IYLD+M1I2)
N H
ω
? IDIY H IDIY?( H+?IDIY)H IDIY(22)
dH IY
dt
=a1b1Y H(M1IY
+M1IDIY+M1IYID+M1IYLD+M1I2)
N H
?( H+ IY+?IY)H IY?a2b2D H IY M2ID
N H
?a1b1D H IY
×(M1ID
+M1IDIY+M1IYID+M1IDLY+M1I2)
N H
ω (23)
dH IYID
dt
=a1b1D H IY(M1ID
+M1IDIY+M1IYID+M1IDLY+M1I2)
N H
ω
+a2b2D H IY M2ID
N H
?( H+ IYID+?IYID)H IYID(24)
M.Amaku et al./BioSystems106 (2011) 111–120115
dH RYRD
dt
= IYID H IYID+ RYID H RYID? H H RYRD(25)
dH RY dt = IY H IY? H H RY?a2b2D H RY M2ID
N H
?a1b1D H RY
×(M1ID
+M1IDIY+M1IYID+M1IDLY+M1I2)
N H
? (26)
dH RYID dt =a1b1D H RY(M1ID
+M1IDIY+M1IYID+M1IDLY+M1I2)
N H
?
+a2b2D H RY M2ID
N H
?( H+ RYID+?ID)H RYID(27)
dH I2 dt =a1b1Y b1D H(M1IDIY
+M1IYID+M1I2)
N H
ω
?( H+ I2+?I2)H I2(28)
dH R2
dt
= I2H I2? H H R2(29) The physical signi?cance of the terms of the system((1)–(29)) is classical(Lopez et al.,2002;Ruan et al.,2008).Take,for instance, the?rst term of the right hand side of equation(1):
a1c1D M1(H ID+H RYID+H IYID+H IDIY+H I2)
N H
The product a1M1is the number of bites in?icted by sus-ceptible mosquitoes per unit time.Of these,a fraction (H ID+H RYID+H IYID+H IDIY+H I2)/N H involves infected humans with dengue,and c1D is the probability that these bites will generate new infected mosquitoes.The other terms in the system that are not of this type include the removal rates internal or external to the model(deaths).The parameters M1, M2and H are adjusted to be equal to the total death rates of their respective populations,such that the populations are kept constant.Note that seasonality(Coutinho et al.,2006)was not considered because it does not interfere with the objectives of this paper.
The model contains40parameters which signi?cance we now explain.
The parameters involved in the equations describing the mosquitoes’populations dynamics are:
?Biting rates(a1and a2)for the two mosquitoes involved.?Probability that a mosquito get infected by dengue(c1D and c2D) or yellow fever(c1Y)when biting an infectious human for each viruses.
?Mortality rates of the mosquitoes( M1and M2).
?Eight parameters labeled that represent the rate at which latent mosquitoes become infectious.The subscripts in these param-eters indicate the process which is occurring.For example,in the parameters 1LDLY the number1indicates A.aegypti,the ID indicates infectious with dengue and the LY indicates latent with yellow fever.Other parameters labeled are indicated and explained in Table2;
The parameters involved in the equations describing the human populations dynamics are:
?Probability that a human acquires dengue(b1D and b2D)or yellow fever(b1Y)when bitten by an infectious A.aegypti(subscript1) or A.albopictus(subscript2).
?Human natural mortality rate( H).
?Six parameters labeled that represent the transition rate from latent to infectious humans.The subscripts in these
parameters indicate the process which is occurring.For example RYLD represents the rate at which individuals recovered from yellow fever(RY)and latent with dengue(LD)become infec-tious with dengue.Other parameters labeled are indicated and explained in Table2.
?Four parameters labeled?representing the disease-induced mortality rates.The subscripts in these parameters indicate the process that is occurring.For example?IDIY represents the addi-tional mortality of individuals who were?rst infected with dengue and then(before recovering from the disease)with yellow fever and become infectious with both viruses.Another exam-ple?12represents the additional mortality of individuals who acquired dengue and yellow fever simultaneously.Other param-eters labeled?are indicated and explained in Table2.
The control parametersε,ε ,ε ,T,ω,ω ,ω ,?and?are described below and in Table2.
The system of Eqs.(1)–(29)can represent several models in the sense that different parameters combinations result in different biological situations.Indeed,as described below,there are several parameters that were introduced so that making different com-binations of them zero the model can simulate distinct biological assumptions.
The parameters that change the model,related to the part of the model that describes the dynamics of the infection in Aedes mosquitoes are as follows:
(1)The parameterε(0≤ε≤1)controls the intensity of simulta-
neous infection by dengue and yellow fever in the mosquito.
Whenε=0,double infection is not allowed,and whenε=1, double infection is completely allowed and the mosquitoes are moved from the susceptible condition,M1,to the double latent condition,M1L2.
(2)The parameterε (0≤ε ≤1)controls the possibility that the
latent and the infectious mosquitoes with dengue will acquire yellow fever.Thus,whenε =0,latent or infected mosquitoes with dengue are protected against yellow fever.However,when ε =1,the latent and the infectious mosquitoes acquire yellow fever but do not lose the dengue virus.
(3)The parameterε (0≤ε ≤1)controls the possibility that
the latent and the infected mosquitoes with yellow fever will acquire dengue.Thus,whenε =0,latent or infected mosquitoes with yellow fever are protected against dengue.
However,whenε =1,the latent and the infectious mosquitoes with dengue acquire yellow fever but do not lose the dengue virus.
(4)The parameter (0or1)controls the possibility that a latent
or infected mosquito with yellow fever will catch dengue and become latent with dengue loosing the yellow fever virus.
Thus this parameter controls the competition between the two viruses[14,20]within the mosquito.In particular,when =1,
a mosquito that is latent or infected with yellow fever becomes
instantaneously latent with dengue when infected by dengue.
This is an extreme case,where it is assumed that the competi-tion within the mosquito between the yellow fever and dengue viruses is won very quickly by the dengue virus.A mosquito that is latent or infected with dengue can be assumed to be protected against yellow fever.Note that when =0,this competition is absent,that is,the mosquito can acquire both infections at the same time.It is very important to note that,if =1,the param-etersε,ε andε must be zero.However,when =0,ε,ε andε can assume any value between0and1.
The parameters(which can change the model)related to the human dynamics of the model are as follows:
116M.Amaku et al./BioSystems106 (2011) 111–120
(1)The parameterω (0≤ω ≤1)is the human equivalent toεfor
the mosquitoes.Whenω =0,no double infections in humans are allowed.
(2)Parameterω(0≤ω≤1)controls the possibility that a human
infected with dengue will acquire yellow fever.Note that when ω=0,ω must be zero for biological consistency.
(3)The parameter?(0≤?≤1)controls the possibility that a human
who has recovered from dengue will acquire yellow fever.
Thus,when?=0,humans who have been previously infected with dengue are completely protected against yellow fever(the Asian hypothesis).
(4)The parameterω (0≤ω ≤1)controls the possibility that a
human who has been infected with yellow fever will acquire dengue.Thus,whenω =0,humans who have been previously infected with yellow fever cannot become infected by dengue.
(5)Finally,the parameter? (0≤? ≤1)controls the possibility that
a human who has recovered from yellow fever will acquire
dengue.
2.2.Testing the Hypotheses
Although it is possible to analytically solve for the equilibrium prevalences of the diseases,the resulting expressions are compli-cated and will not be reported here.However,a simpler model (with one mosquito,one virus and one human host)will be exam-ined analytically to explore the equilibrium prevalences and to interpret the results.
2.3.Hypothesis0
We begin with a simulation in which everything is possible,that is,mosquitoes and humans can acquire dengue,yellow fever or both.For this situation,the only parameter set to zero is (remem-ber that when =1,mosquitoes infected and latent with yellow fever become latent with dengue following dengue infection,due to internal competition within the mosquitoes).Note that,in this model,the two diseases are practically independent.The presence of dengue does not affect yellow fever and vice versa.The preva-lences obtained under these conditions are called the‘baseline’case,against which all of the other simulations will be compared.
2.4.Hypothesis1
To test Hypothesis1,that is,that mosquitoes can be infected by either dengue or yellow fever but not by both,we set ε=ε =ε = =0andω=ω =ω =?=? =1.The numerical simulation of the model indicates that both dengue and yellow fever settle to a nonzero equilibrium.We observe a very small reduction in both dengue(0.25%)and yellow fever(0.37%)equilibrium prevalences in humans,compared to the baseline case(see Table3).Therefore, the absence of yellow fever in Asia cannot solely be explained by Hypothesis1.
It is easy to understand why this hypothesis does not work. In Appendix B,we deduce(in a simpli?ed version of the model) the equilibrium proportions of infected and recovered humans (Eqs.(A9)and(A10))and the equilibrium proportions of both latent and infected mosquitoes(Eqs.(A14)and(A15)).The val-ues of the parameters are?xed at their physical values.So,the only magnitude that can vary from place to place is the density of mosquitoes with respect to humans,given by m=N M1/N H.The values obtained by varying m from zero(the threshold)to the limit(as m→∞)are given by Eqs.(A12),(A13),(A17)and(A18). It should be noted that the equilibrium proportion of humans and the equilibrium proportions of latent and infected mosquitoes remain very low as m increases.So,the proportion of mosquitoes affected by both infections(the product of the individual propor-tions)is even smaller.Therefore,suppressing double infections of the mosquitoes produces almost no effect on the incidence of disease.
However,if we arti?cially increase the biting rate of the mosquitoes,we see that m?
I
and m?
L
increase,but the proportion of humans infected remains constant.This result occurs because, although the mosquitoes are biting the host repeatedly,they are causing this low proportion of infected humans.The limiting pro-portions of infected humans and recovered humans,as well as latent and infected mosquitoes are given by Eqs.(A17)(which is the same as(A7)),(A18),(A19)and(A20).So,in this case(with an arti?cially increased a1),suppressing double infections in the mosquitoes has an impact on the proportion of infected mosquitoes but not on the human proportion of infection.
2.5.Hypothesis2
To test Hypothesis2,that when a A.aegypti mosquito that is infected or latent by yellow fever acquires dengue,it becomes latent for dengue due to internal competition within the mosquito between the two viruses,we setε=ε =ε =0, =1and ω=ω =ω =?=? =1.
The numerical simulation of the model indicates that both dengue and yellow fever settle to a nonzero equilibrium.Again,we observe a very small reduction in both the dengue(0.22%)and yel-low fever(0.36%)equilibrium prevalences in humans,compared to the baseline case(see Table3).Therefore,the absence of urban yel-low fever in Asia cannot be explained solely by Hypothesis2either. The above observations on the proportions of latent and infected mosquitoes apply to this case as well.
2.6.Hypothesis3
To test Hypothesis3,that the Asian A.aegypti mosquito is rel-atively less competent to transmit yellow fever,either because it is more resistant to the infection or because it is less able to pass the infection to humans,we setε=ε =ε =1, =0,ω=ω =ω =1,?=1,? =1and varied c1Y or b1Y to test the effect of mosquitoes competence in transmitting yellow fever to humans.The result of this simulation is indicated in Fig.1,in which the equilibrium prevalence of yellow fever is plotted against c1Y and b1Y.
Note that even low values of c1Y or b1Y results in a relatively high prevalence of yellow fever(that is,80%of the prevalences obtained with the accepted values for c1Y and b1Y which are0.7and0.8, respectively).For instance,for c1Y and b1Y of the order of0.2(which represents very incompetent vectors since the accepted values are of the order of0.7and0.8,respectively)the prevalence of yellow fever is reduced by an amount of the order of20%.Therefore,this hypothesis is not enough to explain the absence of yellow fever in Asia.
Table3
Testing Hypotheses1and2on the equilibrium prevalences of both infections.
Hypothesis Control parameters Equilibrium prevalence of dengue Equilibrium prevalence of yellow fever
H0ε=ε =ε =1, =0andω=ω =ω =?=? =1 2.70×10?5 2.35×10?5
H1ε=ε =ε = =0andω=ω =ω =?=? =1 2.69×10?5 2.34×10?5
H2ε=ε =ε =0, =1andω=ω =ω =?=? =1 2.69×10?5 2.34×10?5
M.Amaku et al./BioSystems 106 (2011) 111–120
117
Vector compete nce
E q u i l i b r i u m p r e v a l e n c e o f y e l l o w f e v e r (r e l a t i v e s c a l e )
Fig.1.Equilibrium prevalence of yellow fever (relative scale)as a function of vector
competence.The dotted line represents the variation in b 1Y ,and the continuous line represents the variation in c 1Y .
2.7.Hypothesis 4(the Asian Hypothesis)
To test Hypothesis 4,that individuals recovered from dengue are partially immune to yellow fever,we set ε=ε =ε =1, =0and ω=ω =ω =1,?=variable,? =1.Therefore,humans recovered from yellow fever can get dengue but humans recovered from dengue are partially protected against yellow fever (they are totally immune if ?=0).
In this case,called the Asian hypothesis,only dengue survives when the cross-immunity (1??)is above a given threshold (see below).We also simulated the model by varying parameter ?to check the effect of a hypothetical partial immunity conferred by dengue against yellow fever.The result is indicated in Fig.2.
It should be noted that there is a threshold in the intensity of cross-immunity (1??).When the cross-immunity is greater than 78%,yellow fever is excluded.Therefore,the Asian hypoth-esis explains the absence of yellow fever in Asia.However,the coexistence of both infections in Africa remains to be explained.
2.8.Hypothesis 5(the African Hypothesis)
It is known that A.albopictus competes with A.aegypti .It is also known that while there are several regions within Africa where the former species has established itself,it is not as widespread as A.aegypti .Because of the competition mentioned above,this may result in a much higher abundance of A.aegypti .This factor is also helped by the general conditions of urban Africa.In addition,it is known that there are other species of insects that could add to the transmission of yellow fever in Africa.
To test Hypothesis 5,that the low prevalence of the oriental mosquito A.albopictus in Africa explains the coexistence of dengue
00.10.20.30.40.50.60.70.80.911
0.95
0.9
0.85
0.8
0.75
0.7
0.65
0.6
Cross -immun ity (1 - δ)
E q u i l i b r i u m p r e v a l e n c e o f y e l l o w f e v e r (r e l a t i v e s c a l e )
Fig.2.Model simulation varying parameter ?to determine the effect of a hypothet-ical partial immunity conferred by dengue against yellow
fever.
Cross -immun ity (1 - δ)
e q u i l i b r i u m p r e v a l e n c e o
f y e l l o w f e v e r (r e l a t i v e s c a l e )
Fig.3.Equilibrium prevalence of yellow fever in the presence (continuous line)and absence (dotted line)of Aedes albopictus .
and urban yellow fever in that continent,we set ε=ε =ε = =0and ω=ω =ω =?=? =1and set the population of A.albopictus to zero.In addition,we increased the population of mosquitoes by adding in the same amount of A.albopictus that was removed from the A.aegypti population in the simulation.We then compared the equi-librium prevalence of yellow fever in the presence and absence of A.albopictus .The numerical simulation of the model (Fig.3)indicates that both dengue and yellow fever settle to a nonzero equilibrium.
In the absence of A.albopictus and the high density of A.aegypti ,the threshold in the intensity of cross-immunity (1??)is shifted upward,that is,less cross-immunity is required for the extinction of yellow fever in the presence of A.albopictus .This result can be understood by considering Eqs.(A9)and (A10).By increasing the ratio m =N M 1/N H ,the prevalence of infected and recovered humans from a given infection increases.So,higher levels of cross-immunity are required for the extinction of urban yellow fever.
We found that,if the cross-immunity is below 93%in Africa,then both diseases coexist.Thus,the African hypothesis explains the coexistence of dengue and urban yellow fever in Africa.
3.Discussion
Yellow fever and dengue are the two most important arthropod-borne virus diseases that affect humans (Monath,1994).As both
infections are transmitted in urban areas by the same Aedes mosquitoes,one would expect that dengue-infested cities would be prone to the introduction of yellow fever (Massad et al.,2003).However,as mentioned above,the dengue affected area of Asia,in spite of multiple opportunities for the introduction and spread of yellow fever,have never experienced this phenomenon.In this paper,we explored four possible hypotheses to explain the absence of yellow fever in Asia.
The ?rst hypothesis,that mosquitoes can be infected by dengue or yellow fever but not by both,failed to explain the exclusion of yellow fever from dengue affected areas of Asia,although we observed a very small reduction in both dengue and yellow fever compared to the baseline case.The next hypothesis,also related to the competition within the mosquitoes,was stronger than Hypothesis 1and involved the idea that yellow fever is completely excluded by dengue within the mosquito,as explained below.
Hypothesis 2,that when an A.aegypti mosquito that is infected by or latent for yellow fever acquires dengue,it becomes latent for dengue due to internal competition between the two viruses within the mosquito,also failed to explain the exclusion of yel-low fever from dengue-affected areas of Asia.Notwithstanding,we again observed a very small reduction in both dengue and yel-low fever compared to the baseline case.This observed reduction was more pronounced in the yellow fever equilibrium prevalence,as expected.Because the average prevalence of dengue-infected
118M.Amaku et al./BioSystems106 (2011) 111–120
mosquitoes is low in Asia,one might assume that this hypothesis should be excluded a priori.However,the geographical distribution of infected mosquitoes is not homogeneous.Thus,it was necessary to investigate this hypothesis with a high percentage of infected mosquitoes.Also,it should be noted that mosquitoes in the latent state should be considered and were included in our calculations.
Hypothesis3,that the Asian A.aegypti mosquito is relatively less competent to transmit yellow fever,either because it is more resis-tant to the infection or because it is less able to pass the infection to humans,was plausible from the biological point of view but was not suf?cient to support the absence of yellow fever in Asia.We observed that very low values of c1Y or b1Y resulted in a relatively high prevalence of yellow fever.It is very unlike that the Asian A. aegypti is suf?ciently incompetent at transmitting yellow fever to explain the real world observations.
Hypothesis4,that individuals recovered from dengue are par-tially immune to yellow fever,is able to explain the absence of yellow fever in Asia.However,we observed that a high level of cross-immunity is necessary to completely exclude yellow fever, although its prevalence is strongly affected by cross-immunity. Technically,this factor means that the cross-immunity threshold for the elimination of yellow fever is very high.It should be men-tioned that,in spite of cross-immunity,dengue coexists with other ?aviviruses in Asia.The exclusion of yellow fever from that region is due,as explained above,to its relatively low basic reproduction number.Note that the partial protection against yellow fever con-ferred by previous dengue infection cannot substitute the yellow fever vaccine:as mentioned above this partial cross-immunity is weak.Therefore the requirement of a yellow fever vaccination cer-ti?cate to get entrance in many Asian countries is a wise measure, in spite of the fact that yellow fever is not totally harmless.
All of the four hypotheses above might have an additive effect on reducing the prevalence of yellow fever in Asia,although the effect of cross-immunity predominates.
Hypothesis5is that the absence of the oriental mosquito A. albopictus in Africa,combined with a high density of A.aegypti can explain the coexistence of dengue and(urban)yellow fever on that continent,by reducing the cross-immunity threshold mentioned above.Indeed,it has been suggested(Gubler,2003)that the intro-duction and spread of A.albopictus(thanks to its inef?ciency as an epidemic vector and its ecological competition with A.aegypti (Fang,2010)in urban and peri-urban areas might exert a bene?cial effect on public-health by decreasing the risk of major epidemics of urban diseases such as dengue and yellow fever.In support of the ecological competition mentioned above,experiments on larval competition between North American populations of the two species have indicated that A.albopictus has the competitive advantage under local?eld conditions,which offers an explanation for the displacement of A.aegypti from much of the United States after the invasion of A.albopictus(Braks et al.,2004).It is not know whether A.albopictus outcompete the other species of mosquitoes that transmit yellow fever.However,since these species are poor transmitters of yellow fever,this competition with A.albopictus was not considered in our analysis.We should also mention that the low coverage of yellow fever vaccination could contribute to the maintenance of the disease in Africa.
In South America widespread vaccination is probably avoiding the urbanization of yellow fever.Since our model does not include vaccination,it cannot be applied to this region.However,we can speculate that in the absence of vaccination South America could be very similar to Africa.However,the recent invasion of A.albopic-tus(the African hypotheses)could help to explain,in addition to widespread vaccination the lack of urban cases of yellow fever in the past few decades.Although it remains prevalent in its sylvatic form,the cross-immunity between yellow fever with dengue in city-dwellers,as well as the relative abundance of the mosquito A.albopictus in urban areas,may have been enough to avoid the reintroduction of urban yellow fever in South American cities.In addition,the density of A.aegypti was very low from the early1930s until1970.From this moment onwards,A.aegypti re-infested the Americas,resulting from both a relaxation of the control routine and also growth of the cities,which made control more dif?cult. However,the density of A.aegypti in South America at present is much lower than that observed in Africa(Braga and Valle,2007).In addition,human settlement patterns also in?uence disease trends. In South America,more than70%of the population lives in urban areas,whereas in Africa,more than70%of the population lives in rural areas,where it is often more dif?cult to control mosquitoes (Githeko et al.,2000).
It should be mentioned here that vertical transmission of dengue in the vectors(Mitchell et al.,1990;Arunachalam et al.,2008) is important for the phenomenon of overwintering of dengue (Coutinho et al.,2006).Since seasonality was not considered because it does not interfere with the objectives of this paper,the phenomenon of vertical transmission can be also be neglected from our analysis.
Among the competing hypotheses listed in this paper,cross-immunity best explains the absence of yellow fever in Asia,and a particularly high ratio of A.aegypti mosquitoes over A.albopictus mosquitoes helps to explain the coexistence of both infections in Africa.Therefore,it is important to experimentally test the preva-lence of anti-?avivirus antibodies in Asian populations and the relative densities of A.aegypti and A.albopictus in Asia and in Africa.
Finally,we should comment on the role of vaccination in the regions analyzed in this paper.In Asia,vaccination of the local community is virtually absent but travelers from endemic areas are demanded to produce a vaccination certi?cate at entrance of the countries of this region.This indeed reduces the probability of importation of the disease.In Africa vaccination coverage is rather low and,therefore,vaccination plays no signi?cant role.In South America there is widespread vaccination of certain endemic areas. This,along with the recent invasion of A.albopictus could explain the absence of urban yellow fever in this region.
Con?ict of Interest
None.
Acknowledgments
The authors thank the support of LIM01-HCFMUSP,CNPq and FAPESP.
Appendix A.A competitive Exclusion Principle
If we assume that mosquitoes can be infected by dengue or yel-low fever but not by both,and similarly,that individuals can be infected by dengue or yellow fever but not by both,the system of Eqs.(1)–(29)can be greatly simpli?ed.The compartments that represent humans and mosquitoes that/who are infected?rst with dengue and then with yellow fever(or vice versa)or simultaneously with both infections disappear.We can also assume the presence of only one type of mosquito(say,type1)to represent A.aegypti.
So,in this appendix we assume that each infection severs as a perfect vaccine for the other infection in both human hosts and in mosquitoes.This is not,of course,what it is seen in practice but it is an essential assumption for the competitive exclusion princi-ple,explained below,to hold.As explained in the introduction,the Competitive Exclusion Principle represents an extreme idealized situation in which only one disease prevails.
M.Amaku et al./BioSystems106 (2011) 111–120119 Assuming equilibrium,we get:
from Eqs.(2)and(5)withε = =0,we get
a1c1D M1H ID
N H
?( 1LD+ M
1
)
M
1
M1ID
1LD
=0(A1)
from Eqs.(7)and(10)withε = =0,we get
a1c1Y M1H IY
N H
?( 1LY+ M
1
)
M
1
M1IY
1LY
=0(A2)
from Eq.(18)andω=0,we get
a1b1D H M1ID
N H
?( H+ ID+?ID)H ID=0;(A3)
and from Eq.(23)withω =0,we get
a1b1Y H M1IY
N H
?( H+ IY+?IY)H IY=0(A4)
These equations are of the form:
AM1H ID?BM1ID=0(A5) CM1H IY?DM1IY=0(A6) EM1ID H?FH ID=0(A7) GM1IF H?JH IY=0(A8) where A–G and J are constants.Therefore,we have four equations for four unknowns(H1D,M1ID,H1F and M1IY)that have a nonzero solution only if
HM=DJ
CG and HM1=BF AE which are incompatible unless
DJ=BF and CG=AE.Therefore,one of the equilibrium must be zero. It is easy to deduce that the equilibrium different from zero is the one with the greatest basic reproduction number.This result characterizes the Competitive Exclusion Principle(Bremermann and Thieme,1988).
Appendix B.The Equilibrium Solution for a Simple Case In this appendix,we consider only one infection that is trans-mitted by one mosquito to human hosts.It is possible to solve the equilibrium by considering the full model given by equations ((1)–(29)).However,the resulting expressions would complicate and would not contribute to the points we want to make.The com-plete equilibrium expressions are rather opaque,so to analyze the complete system it is better to proceed numerically.We shall,how-ever,forward the complete expression to any reader that may ask us.
The equilibrium can be calculated setting Eqs.(2)toε = =0,(5) toε =0,(18)toω=0.Then,dropping the subscripts D and solving for H I and H R,we get:
h?I =
H?
I
N H
=
ma12b1c1 H 1L?( H+?I+ I)( 1L+ M
1
) M
1
H
ma12b1c1 1L( H+ I)+( H+?I+ I)a1c1( 1L+ M
1
) H
(A9)
and
h?R =
H?
R
N H
= I
H
ma12b1c1 H 1L?( H+?I+ I)( 1L+ M
1
) M
1
H
ma12b1c1 1L( H+ I)+( H+?I+ I)a1c1( 1L+ M
1
) H
(A10)
where m=N M1/N H.
When the numerator is set to zero,we get the basic reproductive number:
R0=
a12b1c1m IL
( H+?I+ I)( IL+ M
l
) M
1
(A11)
On the other hand,as m→∞,we get:
h?I H I
N H
→ H
H+ I
(A12)
and
h?R H R
N H
→ 1
H
H
H+ I
(A13)
which is the maximum proportion of infected and recovered
humans as m→∞.This value is the maximum equilibrium preva-
lence that is obtained when the number of mosquitoes is much
greater than the number of human hosts.
Similarly,m?
L
,and m?
I
the equilibrium proportion of latent and
infected mosquitoes can be written as a function of h?
I
m?
I
=M I
N M
=
a1c1h?
I
a1c1(1+( M1/ 1L))h?
I
?+( M1+ 1L) M1/ 1L(A14)
and
m?
L
= M1
1L
m?
I
(A15)
as m→∞,
m?
I
→a1c1 H 1L
( M1+ 1L)(a1c1 H+( H+ I) M1)
(A16)
The limiting values of the relevant proportions as a1→∞are
h?
I
H I
N H
→ H
H I
(A17)
and
h?
R
H R
N H
→ 1
H
H
H+ I
(A18)
The mosquito’s proportions become
m I(a→∞)=
1L
( M1+ 1L)
(A19)
and
m L(a→∞)=
M1
( M1+ 1L)
(A20)
Appendix C.Evolutionary Dynamics
In this appendix,we brie?y address the question on how differ-
ent evolutionary dynamics between dengue and yellow fever could
explain the coexistence or not of those infections.
It is believed that evolution of pathogens is such that the basic
reproduction number increases with time(Anderson and May,
1991).The basic reproduction number of yellow fever is lower than
that of dengue(Massad et al.,2001)and this fact is puzzling because
yellow fever is older among humans than dengue(Fields et al.,
1966).
The difference between the two basic reproduction numbers
can be understood from Eq.(A11),and is due to differences
in lethality,?I(I=dengue or yellow fever),recovery rate, I(I=
dengue or yellow fever)and the probabilities of infection from
humans to mosquitoes,c I(I=dengue or yellow fever)and from
mosquitoes to humans,b I(I=dengue or yellow fever).In the non-
vaccinated areas of the state of S?o Paulo,Brazil,the basic
reproduction number of yellow fever is about35%less than that for
dengue(Massad et al.,2001).Therefore,the evolutionary dynam-
ics of dengue was faster than that of yellow fever and could explain
why yellow fever is less spread than dengue.
In general,for two different strains of the same virus we have to
consider two types of competition,namely the competition within
the host and the competition between hosts.In the case of diseases
without recovery from infection and without immune reaction
against the virus,we have shown(Burattini et al.,2008;Amaku
et al.,2010)that the strains can coexist only if the one with the
highest basic reproduction number within the host has the lowest
basic reproduction number between the hosts.However,when we
have recovery from infection and reaction of the immune system,
one cannot say whether or not both strains will coexist.
Since yellow fever and dengue are different species of virus their
eventual competition would be ecological rather than evolution-
ary,as the one that may occur inside A.aegypti.Then,assuming
120M.Amaku et al./BioSystems106 (2011) 111–120
that yellow fever and dengue compete within their host,we could extend the above analysis to them.However,the physiopathology of both viruses is remarkably different,that is,they affect distinct organs of the individual hosts.Thus,it is not possible to conclude that coexistence or not of yellow fever and dengue basing only on the relative values of their basic reproduction numbers,that is,on their different evolutionary dynamics.Note that there are other examples of two similarly transmitted viruses with different basic reproduction numbers like measles and rubella,in which the old-est(measles)has the higher basic reproduction number and the youngest(rubella)has the lower basic reproduction number and both coexist everywhere in the world.
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Gubler,D.J.,2003.Aedes albopictus in Africa.The Lancet Infectious Diseases3, 751–752.
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预防登革热宣传
预防登革热宣传 Modified by JEEP on December 26th, 2020.
预防登革热宣传资料 一、登革热病媒是什么 登革热通过带有登革热病毒的雌性伊蚊叮咬而传染给人类。主要传播媒介为埃及伊蚊、白纹伊蚊。其中白纹伊蚊（俗称“花斑蚊”）在我省分布广泛，主要在清水容器中孳生，大多数在屋外或野外阴暗处流连，但亦会在户内活动。雌蚊嗜吸人血，吸血高峰在日落前两小时(约为下午五、六时)，及早上八、九时。室外及室内皆可叮咬人。 二、典型登革热的病征是什么 感染登革热病毒后，经过3至15天的潜伏期（通常为5至8日），患者多以突然发热为首发症状，持续发热3～5天，严重头痛，四肢酸痛、关节痛、肌肉痛、背痛、后眼窝痛。发病后3、4日出现红疹，恶心、呕吐，轻微的流牙血和流鼻血。病后有可能出现极度疲倦及抑郁症状，极少数病者会恶化至出血性登革热，并进一步出血、休克，严重时可引致死亡。 三、个人如何做好登革热防护 现时并没有一种有效疫苗来预防登革热。预防登革热的最佳方法就是清除积水，防止伊蚊孳生，以避免给蚊子叮咬，有关预防蚊咬的措施如下： （一）、避免在“花斑蚊”出没频繁时段在树荫、草丛、凉亭等户外阴暗处逗留。 （二）、防止积水，清除伊蚊孳生地： 1、尽量避免用清水养殖植物。
2、对于花瓶等容器，每星期至少清洗、换水一次，勿让花盆底盘留有积水。 3、把室外露天的盆、罐及瓶子倒置或放进有盖的垃圾桶内，防止积水。 4、将贮水容器、水井及贮水池加盖。 5、保持所有渠道畅通。 6、将地面凹陷的地方全部填平，以防积水。 （三）、怀疑自己感染登革热时要及时就诊。
登革热防控工作方案
登革热防控工作方案(总3页) -CAL-FENGHAI.-(YICAI)-Company One1 -CAL-本页仅作为文档封面，使用请直接删除
生产厂房项目 登革热防控工作方案 由于近期内广东地区出现登革热现象，较多的人员感染，事态比较严重。为了加强生产厂房工程的安全生产工作，提高公司在施工生产过程中突发事件的应变能力，尽快控制事态，尽量减少损失，尽早恢复正常施工秩序。为了有效防止登革热疫情的发生和扩散，采取科学、有力的防控措施，落实做好切断登革热传播途径和根治疫情。根据传染病防治法和突发公共卫生事件应急条例等有关法律法规，结合本项目管理工作的实际情况，特制定本项目部登革热防控工作方案。 一、出现登革热的原因和传播 登革热是由伊蚊（俗称花蚊或花斑蚊）传播，人与人之间是不会传播的。伊蚊吸食了登革热病人的血后，会把登革热病毒传染给下一个被叮咬的健康人。人感染了登革热病毒后大约一周左右开始发病，会出现发热、头痛、全身肌肉关节酸痛等症状；发病第3-6天全身出现发疹，有的病人会出现皮肤粘膜出血症状，少数病人会突然病情加重出现登革热休克综合症，病情凶险，如不及时抢救，可于4-6小时死亡。目前还没有治疗和预防登革热的特效药物，但是只要消灭传播登革热的伊蚊，就可以防止登革热的流行 二、工作目标 按照科学防控措施，坚持预防为主的原则，切实加大灭蚊、环境整治、疫情监测等综合防控工作力度，彻底扑灭登革热疫情，切实保障职工的身体健康和生命安全，保障本工程项目的顺利进行。 三、工作内容及防控措施 强化环境卫生整治管理，积极消杀蚊虫，做好登革热防控。
1、加强对登革热防控工作的组织领导，建立防控工作督导小组，小组人员名单如下： 项目部安全领导小组其人员组成 2、对工地办公区、生活区、施工区实施全面防控，生活区作为重点区域进行防控，防控工作分三个部分： ⑴做好食堂、厨房、宿舍、垃圾池等地方的生活垃圾及废物进行及时清理，不留卫生死角，保持良好的生活环境和工作环境，有效防治蚊虫的孳生、繁殖。 ⑵定期对卫生间、冲凉房、食堂、厨房、宿舍、仓库、垃圾池、排水沟、积水池、绿化带等地方进行灭蚊、杀虫、打药、消毒等科学方法来处理，有效防止蚊虫的滋生、繁殖从而把病源体传染至人体。 ⑶做好工地现场环境卫生的清理工作。对一些正在施工的场地，注重施工材料堆放和现场环境卫生。对一些已完成的工程，做到工完场清，保持整洁的施工场地，也是消除蚊蝇孳生场所的有效措施。 3、积极宣传引导。充分利用板报、宣传栏等形式，进行全面的宣传，普及登革热防控知识，提高防控意识，切实增强职工自我防范意识、公共卫生意识，形成良好的卫生习惯，做到人人皆知、人人参与、人人动手。 4、强化督查考核，严格落实防控责任制，做到任务到人、工作到人、责任到人。要求每星期开展至少1次的检查工作，并在每次防控工作后由项目督导小组进行一次检查考评。
登革热的防控措施审批稿
登革热的防控措施 YKK standardization office【 YKK5AB- YKK08- YKK2C- YKK18】
登革热的防控措施及健康教育 登革热(Dengue Fever)是由登革病毒(DV)引起的急性传染病，主要通过埃及伊蚊或白纹伊蚊为媒介进行传播。本病具有传播迅猛、发病率高、登革出血热和登革休克综合征 （DHF/DSS）病死率较高等特点。 登革热患者和感染者是本病城市型的传染源，病人一般在发病前一天至发病后5天内传染性较强。在流行期间，非典型病例及亚临床感染者比典型病例多几十倍，具有更重要的传染源作用。在东南亚存在丛林型自然疫源地，猴子是自然储存宿主，人仅在偶然机会进入循环圈才可能受染。 登革热广泛分布于有媒介伊蚊存在的热带、亚热带地域，有时侵入温带地区引起流行。我国主要流行于海南、广东、广西、台湾等地，云南也曾发现病例，在丛林猴、蚊中分离到登革病毒。 登革热在热带、亚热带地域可常年发病，一般流行于夏秋季，但地理性质不同的地区流行高峰时间不同。如为输入性传播则发病高峰依输入时间而转移。 在登革热呈地方性流行的地区，存在着蚊媒孳生的自然条件和高人口出生率，疫情年年不断，可分离出多型登革病毒，主要在儿童中发病，且常发生DHF/DSS，成为儿童住院和死亡的主要原因；外来人群发病则为多表现典型登革热。流行季节与雨季相一致。尚无证据表明我国存在登革热地方性流行区，但有人认为我国海南岛、云南省也面临威胁。 登革热地域分布特点与埃及伊蚊、白纹伊蚊的生物区带有极密切关系，流行季节性表现和气温、降雨及伊蚊密度相关，海南省由于长年气温高，冬季伊蚊吸血活动依然，则全年均可发病。 社会因素方面如人口密度高、不良居住卫生条件、卫生知识水平和习惯，较高的人口出生率及人口流动等都对发病率有重要影响。沿海或缺水地区家家户户有贮水容器，易形成伊蚊
从哪些方面预防登革热
从哪些方面预防登革热 患者和隐性感染者为主要传染源，未发现健康带病毒者。以发病前1天至发病后5天传染性最强，轻型和隐性感染者可能是重要的传染源。主要传播媒介为埃及伊蚊，其次为白纹伊蚊。蚊虫吸血受染后8~14天才有传染性，再次叮人即可传播疾病。伊蚊受染后终身具传染性，登革热病毒在白纹伊蚊的唾液腺及神经细胞中可大量复制。病毒在蚊体内可经卵传代，所以伊蚊又是本病毒的储存宿主。感染后对同型病毒有巩固的免疫力，并可维持多年，对异型病毒也有1年以上的免疫力。流行季节与各地气候、蚊虫繁殖情况有关，广东省为5~10月，海南省为3~10月。 下面就是预防的几种方法： 一、处理孳生地、消灭蚊蚴： 1、疏通沟渠、下水道，防止积水，填平洼地、翻盆倒罐清除积水。 2、尽量避免用清水养植植物，对于花瓶等容器，每星期至少清洗、换水一次，勿让花盆底盘留有积水。把所有用过的罐子及瓶子放进有盖的垃圾桶内，摧毁白纹伊蚊孳生地。 二、杀灭成蚊： 在住宅、办公室、医院等及其他公共场所可采用药物杀灭成蚊。目前可采用下列几种： 1、敌敌畏：可采用药物稀释喷洒及烟薰，特点是速效，迅速杀死成蚊。对人畜有毒性。使用时须小心，注意安全。 2、三氯杀虫酯(7504)：对人畜毒性低，可采用药物稀释喷洒及烟薰，特点是见效慢，但保持时间长，7～10天仍有效。可与敌敌畏混合使用，比例为4:1或3:1,其优点是速效且持续时间长。 3、人工合成除虫菊酯类：其制剂有二氯苯醚菊酯，胺菊酯等，可采用药物稀释喷洒，特点是杀虫效果强，对人畜毒性低。 4、溴氰菊酯：属于触杀药(即接触中毒)可采用药物稀释喷洒，杀虫作用强，对人畜毒性低。 三、认真做好个人防护： 1、养成睡觉时放蚊帐的习惯。亦可用防蚊油涂搽暴露皮肤，室内可点燃蚊香。 2、到登革热流行区旅游或生活，应穿着长袖衣服及长裤，并在外露的皮肤及衣服上涂蚊虫驱避药物。
防蚊灭蚊预防登革热工作方案(修订版)
目录 一、工作目标 (2) 二、主要任务 (2) 三、工作标准 (2) 四、检查工作时间 (3) 五、防蚊灭蚊人员组织架构 (3) 六、工作方式 (3) 七、灭蚊工作措施 (4) 八、环境卫生管理办法 (5)
防蚊灭蚊预防登革热工作方案 登革热是一种通过蚊子叮咬传播的急性传染病，人被感染登革热病毒的“花斑蚊”叮咬，经过5-8天后，突发高热、头痛、全身酸痛（周身骨痛）、脸面潮红，结膜充血（如醉酒状）、有时出现皮疹等。 传播登革热的蚊子生长在室内外种养水生植物的花瓶、花盆托盘，及其他水缸、水盆、罐等小积水容器中；孳生地大概可分为两类：人造容器（容器、轮胎、排水明渠），天然环境（树洞、竹节、叶腋）。清除积水，可以控制蚊子，预防登革热。 为加强工地病媒生物防制工作，预防登革热疫情的发生及传播，制定本方案。 工作目标 根据《病媒生物预防控制管理规定》和《广东省病媒生物预防控制管理规定》、《深圳市爱国卫生工作规定》和《深圳市人民政府关于开展爱国卫生运动防控登革热的通告》、《深圳市爱国卫生运动委员会办公室关于国庆节前开展全市灭蚊统一行动的通知》和《深圳市2017年病媒生物防制工作方案》，建立工地防蚊灭蚊工作体系，广泛发动工地人员，大力开展环境。综合整治，清除蚊虫孳生地，开展消杀灭蚊工作，大力清除蚊媒传播，预防登革热发生和传播。 主要任务 加强灭蚊预防登革热的宣传工作。充分利用各种宣传工具，广泛开展灭蚊预防登革热的宣传教育活动，提高施工人员对灭蚊知识的认知度，进一步增强施工人员防控登革热病的意识。 发动施工人员做好宿舍、厕所、办公室、工地清除积水工作。清除积水是降低蚊虫密度、预防登革热病传播的关键。广泛发动施工人员清理宿舍、水池、沟渠等各类小型积水和生活垃圾，从源头上清除蚊虫的孳生地。 工地每周对施工范围内各种有可能孳生白纹伊蚊的容器积水或小型积水进行检查，并及时进行处理。将每周检查和控制情况填于《防蚊灭蚊预防登革热周记》。 工作标准 具体灭蚊行动，参照深爱卫【2017】12号文件-2017年夏秋季深圳市灭蚊预
施工现场预防登革热专项方案
预防登革热专项方案 编制人： 审核人： 批准人： 广州XXX集团有限公司 广州XXX安置房工程项目部 2018年8月10日
预防登革热专项方案 广州地区过往年份出现登革热疫情，现在的季节正处于暴发期，广州市每年有较多的人员感染，一旦发生，事态比较严重。为了有效防止登革热疫情的发生和扩散，采取科学、有力的防控措施，落实做好切断登革热传播途径和根治疫情。根据传染病防治法和突发公共卫生事件应急条例等有关法律法规，结合本项目管理工作的实际情况，特制定本项目部登革热防控工作方案。 一、登革热防治基本知识、出现登革热的原因和传播 （一）传染源。 登革热患者、隐性感染者、带病毒动物是本病主要传染源和宿主。 1、患者。 患者是登革热主要传染源。在发病前3天至发病后10天内具有病毒血症的患者是至关重要的传染源；轻型患者不易被发现，且数量远大于典型患者，是更为危险的传染源。 病例诊断原则：依据患者流行病学史、临床表现及实验室检查结果综合进行诊断。确诊须有血清学或病原学检查结果。病例分为三种类型：疑似病例、临床诊断病例和实验室确诊病例。这三种病例均作为传染源对待。 2、隐性感染者。 登革热流行后，当年人群中抗体水平较高，表明很多人可通过隐性感染获得免疫，这些人在其病毒血症期也可以作为传染源。 3、带病毒动物。 有实验证明，非人灵长类等动物能携带登革热病毒，有可能成为人类登革
热的传染源。登革热在我国的主要传播媒介为埃及伊蚊和白纹伊蚊。伊蚊雌蚊吸血感染病毒后，观察不到任何病变，但病毒在蚊体内繁殖，至少可存活30天甚至终生，再经蚊叮咬传染给人。人类对登革热不分种族、年龄、性别普遍易感，但感染后仅有部分人发病。人初次感染登革病毒后对同型病毒有较巩固的免疫力，可持续数年，但对异型登革病毒免疫力只能维持很短时间。 4、登革热是由伊蚊（俗称花蚊或花斑蚊）传播，人与人之间是不会传播的。伊蚊吸食了登革热病人的血后，会把登革热病毒传染给下一个被叮咬的健康人。人感染了登革热病毒后大约一周左右开始发病，会出现发热、头痛、全身肌肉关节酸痛等症状；发病第3-6天全身出现发疹，有的病人会出现皮肤粘膜出血症状，少数病人会突然病情加重出现登革热休克综合症，病情凶险，如不及时抢救，可于4-6小时死亡。目前还没有治疗和预防登革热的特效药物，但是只要消灭传播登革热的伊蚊，就可以防止登革热的流行。 5、要消灭伊蚊就要了解伊蚊的生活习性。伊蚊无论白天和晚上都会叮咬人，要切实做好防蚊叮咬的措施很困难，最有效消灭伊蚊的方法是消除伊蚊的孳生地。伊蚊繁殖的孳生地主要是工地积水坑、排水沟不畅通处、板房与围墙交界处的不易清理，容易积水的地方，小型盆罐、旧轮胎、塑料袋等积水也是伊蚊的孳生地，必须采取每星期翻盆倒罐消除积水，养鱼或放农药、清理弃置容器等综合措施。伊蚊孳生地附近的居民危害最大，伊蚊飞行活动的半径为100米，所以需要大家互相督促齐齐动手，你我齐参与共同开展消灭伊蚊的活动，防止登革热发生与流行。 二、工作目标 按照科学防控措施，坚持预防为主的原则，切实加大灭蚊、环境整治、疫情监测等综合防控工作力度，彻底扑灭登革热疫情，切实保障职工的身体健康
登革热登记表
依申请公开 特急 佛山市防控登革热应急指挥部办公室文件 佛登革热防办〔2016〕10号 佛山市防控登革热应急指挥部办公室关于开展2016年登革热流行期统一灭蚊行动 （第一轮）的紧急通知 各区防控登革热应急指挥部，市有关单位： 当前，我市已进入登革热高发期，防控形势十分复杂、严峻。 为切实有效阻断登革热疫情的进一步流行蔓延，实施科学、精准防控，现将《2016年登革热流行期全市统一灭蚊行动方案（第一轮）》下发给你们，请各区、各单位按照方案内容要求，在规定时间认真组织落实相关工作，并做好工作情况总结和记录登 — 1 —
记。 附件：2016年登革热流行期统一灭蚊行动方案（第一轮） 佛山市防控登革热应急指挥部办公室 （代章） 2016年8月8日 （联系人：麦立群、龚小明，联系电话：83389609，邮箱：fssfsb@https://www.wendangku.net/doc/4312662503.html,） — 2 —
附件 2016年登革热流行期统一灭蚊行动方案 （第一轮） 当前，我市已进入登革热高发期，防控形势十分复杂、严峻。目前掌握的全市各区本地病例均为Ⅱ型同源登革病毒感染，病例呈多点散发、局部聚集、主要沿“325国道”及周边交通物流通道跨区域传播、扩散的分布特点。一旦失控，并与周边地区Ⅰ型登革病毒混合流行，重症、乃至死亡病例发生的风险将显著增加。为切实有效阻断登革热疫情的进一步流行蔓延，实施科学、精准防控，按照省、市专家的研判建议，须立即在全市范围内开展登革热流行期全市统一灭蚊爱国卫生行动。为顺利开展工作，特制订本方案。 一、行动目标 统一组织开展以清理外环境垃圾及卫生死角，杀灭成蚊、清除蚊媒孳生地为重点的灭蚊行动，控制蚊媒密度，阻断登革热等蚊媒传染病的传播途径。 二、行动时间 2016年8月10日、13日、19日统一开展登革热流行期第一轮灭蚊行动。 三、行动范围 — 3 —
启慧学校登革热防控工作方案
天河区启慧学校登革热防控工作方案 为进一步加强登革热防控工作，强化每个人的责任意识。根据上级有关文件精神，按照“属地管理”和“谁主管、谁负责”的原则，现结合我校实际，特制定登革热防控工作责任方案。 一、组织领导： 学校成立由校长任组长的登革热防控工作领导小组，具体负责落实防控工作。 组长：李娜 副组长：惠琳、周静 组员：郑伶俐、王偶偶、周志强、李淑贤、胡绩南 二、防控工作网络化责任人及其职责： 为明确每个责任区的责任人，切实做到职责到人，责任到人，工作到人，形成一条“一级抓一级，一级对一级负责”的登革热防控责任“链”，形成一张“横向到边、纵向到底”的登革热防控工作网络。具体如下： 1、校长为我校登革热防控工作第一责任人。全程指导、组织、督促各线人员积极做好登革热的防控工作，使防控工作达到区政府及卫生部门提出的要求。 2、总务处周静全面负责全校的登革热防控工作，经常组织人员对各线及各幢楼的防控工作进行督促、检查，并将检查结果向第一责任人汇报。负责组织安排全校卫生大扫除，翻盆倒罐，清理积水，消杀灭蚊。
3、教导处王偶偶负责对全校师生进行登革热防控知识宣传教育，组织、发动全校各班开展“登革热防控”主题班队会课，并鼓励学生开展“小手牵大手”活动，对家长进行登革热防控的知识宣传。 4、各班主任、各办公室负责人具体负责自己班级或办公室的卫生、灭蚊防控。 三、防控工作小组及其职责： 1、宣传教育组（由教导处负责） （1）通过宣传窗、广播、多媒体等宣传工具，广泛宣传讲解有关登革热的防控基本知识和预防措施。 （2）向全校各班下发有关登革热的预防知识材料，由班主任利用点名课统一组织学生学习。 （3）学校办公室订做有关登革热预防知识的展板，供学生观看。 （4）在升旗仪式时，开展“国旗下讲话”，进行登革热预防宣传。通过以上各种形式的宣传教育，既避免学校师生产生不必要的恐慌情绪，又普及科学防范知识。让师生了解预防登革热就是要讲究卫生，不让蚊子有孳生场所，并积极开展灭蚊工作。 2、卫生保洁、督查组（总务处负责） （1）校园环境卫生、绿化场地卫生、教学楼公共区域卫生由总务处负责； （2）教室：由班主任负责； （3）各办公室、功能室卫生：由各办公室、功能室负责人负责； （4）学生个人卫生：由班主任负责。
登革热的防控措施
登革热的防控措施及健康教育 登革热(Dengue Fever)是由登革病毒(DV)引起的急性传染病，主要通过埃及伊蚊或白纹伊蚊为媒介进行传播。本病具有传播迅猛、发病率高、登革出血热和登革休克综合征（DHF/DSS）病死率较高等特点。 登革热患者和感染者是本病城市型的传染源，病人一般在发病前一天至发病后5天内传染性较强。在流行期间，非典型病例及亚临床感染者比典型病例多几十倍，具有更重要的传染源作用。在东南亚存在丛林型自然疫源地，猴子是自然储存宿主，人仅在偶然机会进入循环圈才可能受染。 登革热广泛分布于有媒介伊蚊存在的热带、亚热带地域，有时侵入温带地区引起流行。我国主要流行于海南、广东、广西、台湾等地，云南也曾发现病例，在丛林猴、蚊中分离到登革病毒。 登革热在热带、亚热带地域可常年发病，一般流行于夏秋季，但地理性质不同的地区流行高峰时间不同。如为输入性传播则发病高峰依输入时间而转移。 在登革热呈地方性流行的地区，存在着蚊媒孳生的自然条件和高人口出生率，疫情年年不断，可分离出多型登革病毒，主要在儿童中发病，且常发生DHF/DSS，成为儿童住院和死亡的主要原因；外来人群发病则为多表现典型登革热。流行季节与雨季相一致。尚无证据表明我国存在登革热地方性流行区，但有人认为我国海南岛、云南省也面临威胁。 登革热地域分布特点与埃及伊蚊、白纹伊蚊的生物区带有极密切关系，流行季节性表现和气温、降雨及伊蚊密度相关，海南省由于长年气温高，冬季伊蚊吸血活动依然，则全年均可发病。 社会因素方面如人口密度高、不良居住卫生条件、卫生知识水平和习惯，较高的人口出生率及人口流动等都对发病率有重要影响。沿海或缺水地区家家户户有贮水容器，易形成伊蚊孳生场所。，随着经济文化提高，户内绿化盆栽水养植物花卉增多，积水容器利于伊蚊孳生而引起登革热流行。基建较多的城市，建筑工地积水可以是伊蚊的主要孳生地，是城市型登革热流行的危险因素。 目前尚没有特效的治疗药物，也无疫苗，预防是防制登革热的关键措施。控制传染源、切断传播途径和保护易感人群。主要措施如下： 个人防护措施： 1．睡觉的时候要挂蚊帐，注意个人卫生。 2. 出门郊游要穿长袖衣裤、涂防蚊水。 3.不在树林、草丛及水潭逗留。 4. 在平时多锻炼，注意休息，提高自身的免疫力。 5．所处区域疫情发生时，尽量不要剧烈运动，以防止身体过多分泌乳酸而招蚊子，而且要少喝酒。 6. 在疫情发生时，避免进入疫区，发现感染者必须及时报告。 7. 当自己出现登革热的症状时，及时检查、就诊。 环境控制措施： 1. 清除蚊子滋生的容器、水潭、树穴、轮胎积水等 2．垃圾统一回收处理，保持生活区环境清洁卫生。 3. 在蚊子活动密度较高的地方适当地使用学药剂进行杀灭。如厕所、水沟、污水处理池等。 4. 宿舍应整洁卫生，定期灭蚊，睡觉时必须挂蚊帐。 5.加强登革热知识的宣传教育，提高职工的防控意识。 6、若出现发烧的病例须立即送往医院进行检查和治疗，如确诊患登革热必须隔离治疗。
预防登革热宣传知识
预防登革热宣传知识标准化管理处编码[BBX968T-XBB8968-NNJ668-MM9N]
预防登革热宣传知识 登革热是由花斑蚊（学名伊蚊，见下图）传播的。现在已进入登革热流行的季节，如发现学生突起高热，伴有较剧烈的头痛、眼眶痛、肌肉、关节和骨骼痛，面、颈、胸部潮红、结膜充血，出现四肢躯干或头面部的皮疹，验血发现白细胞和血小板减少，这时应怀疑是否患上登革热，需及时就医，早发现、早治疗，以免延误病情或者通过蚊子传染给其他人。 传播登革热的蚊子生长在水缸、水盆、罐及其他小型积水容器中。每隔3~5天洗缸换水，翻盆倒罐，清除小积水，可以控制蚊子，预防登革热。因此，预防登革热，最主要的措施是清除家居积水，防蚊灭蚊，同时做好个人防护，防止蚊虫叮咬。 一、清除家居积水 保持室内清洁，家庭内不留积水是减少蚊虫的最基础措施。传播登革热的蚊子生长在家居环境的小型积水容器中，清除积水，即可控制蚊子生长与繁殖，预防登革热。 （1）清除或倒置室外各种闲置的可积水容器，如放在户外、阳台、天台的不用的花盆、缸罐、轮胎、可积水的垃圾等。 （2）种养的水生植物（如富贵竹、万年青、佛手等）应每隔3-5天换水洗瓶、清洗根须。登革热流行期间最好不要种养水生植物，如要种养则改为用泥、沙种养，或者在水生植物中投放灭蚊幼虫缓释包。 （3）保持花盆托盘不积水，如有积水应随时清干。 （4）及时清除各种无用积水，如沟渠、天台等地面积水、填塞竹节、树洞，对于长期无法清除的积水，可以投放杀灭幼虫的缓释剂。 二、防蚊灭蚊 登革热通过蚊子叮咬传播，不会直接人传人。只要不被蚊子叮咬，就不会得登革热。 （1）家庭应安装蚊帐、纱门、纱窗等实物屏障；适时使用蚊香、电子驱蚊器、电蚊拍、防蚊灯等装备，还可以用杀虫喷雾剂对房间实施灭蚊处理。孩子睡觉时，可以给他的
防控登革热工作方案
防控登革热工作方案 SANY GROUP system office room 【SANYUA16H-
防控登革热实施方案 登革热是由登革热病毒引起、经蚊子传播的急性传染病，具有传播迅猛、发病率高等特点，已成为全球许多国家和地区严重的公共卫生问题。根据惠州市政府关于加强登革热防控工作的通知，制定本方案。 一、指导思想 坚持以科学发展观为指导，坚持以人为本，以《中华人民共和国传染病防治法》等法律法规为依据，坚持“预防为主”的方针，积极开展环境卫生整治，落实各项防控措施，切实加强登革热防控工作，最大限度降低登革热疫情的发生，保障施工现场人员身体健康，促进经济发展，构建和谐社会。 二、防控内容 开展健康教育宣传活动，宣传登革热防控的重要性，普及防控知识，提高建筑工人的卫生知识和防病意识，引导工人改陋习、讲文明、讲卫生，普及蚊虫孳生、繁衍生活习性等方面知识，清理蚊蚴孳生地，搞好环境卫生和组织统一灭蚊是有效预防和控制登革热的主要措施之一。 坚持以环境整治、清除室内外蚊蚴孳生环境为主要内容，落实结合化学药物灭蚊的综合性防控措施。 开展疫情监测，及时发现并有效控制疫情的发生和流行。三、防控成员小组名单
组长：王超 副组长：郑华勇 小组成员：时其军吴俊坚陈浩委李振河 具体分工如下： 施工现场：时其军吴俊坚 办公区：陈浩委 生活区：李振河 四、防控措施 （一）加强环境治理。办公场所、施工区、宿舍区、食堂等全面清除积水、杂草，定期对工地开展全面的环境清理；对工地现场及生活区的塑料薄膜、一次性杯、饭盒、水坑等容器积水进行清理，贮水池每星期清理更换一次。 （二）与惠州市惠阳区除四害消杀服务站签订消杀合同，每月4次定期对现场及生活区进行防四害消杀处理并做好登记台帐（三）对所有管理人员及工人宣传登革热疾病的病征，如出现发烧及时报告项目安全部。 （四）现场配备应急药品及体温计等，对疑似登革热病例要及时报告并送定点医院进行严格的隔离治疗。医院线路如下：惠台路-和畅东六路-仲恺大道-中信惠州医院。 天健阳光花园项目部 2014年9月30日
防控登革热灭蚊专项方案
目录 一、简介 (2) 二、工作目标 (2) 三、应急小组 (2) 四、灭蚊药械 (3) 五、灭蚊方法 (3) 六、孳生地的处理 (4) 七、施药过程中的注意事项 (5) 八、环境卫生管理方法 (7) 一、简介 登革热是由登革病毒引起的蚊媒传染病，主要通过埃及伊蚊和白纹伊蚊（俗称花斑蚊）叮咬传播，在东南亚、西太平洋和美洲加勒比海地区广泛流行。目前，广东省地区多个城市出现登革热疫情，中山市也发现多例登革热病例，根据《广东省登革热流行媒介应急控制技术方法》，结合当前的防控登革热灭蚊实际情况，为加强病媒生物防制工作，预防登革热疫情的发生及传播，制定本方案。 二、工作目标
在工地现场，大力开展环境综合整治，清除蚊虫孳生地，开展消杀灭蚊工作，大力清除蚊媒传播，预防登革热发生和传播，采取快速灭杀成蚊和清除伊蚊孳生地为重点的综合防制措施。 三、应急小组 针对登革热防控工作，成立应急小组，组长：黄顺根；副组长：黄华招；卫生清理负责人（赵壮光）、灭蚊行动负责人（方 子祥）、资料宣传负责人（陈坚真）；组员：黄海林、黄耀旭、林金鸿、周明雄、王泽发、魏发兴。应急小组负责登革热防控工作的组织管理、指挥和协调，负责疫情现场控制、监督检查、疫情报告、信息沟通等相关工作。 应急联系电话： 1、应急联动电话：110、119； 2、急救：120； 3、防蚊灭蚊人员组织架构
菊酯、氟氯氰菊酯、高效氟氯氰菊酯； 器械可选用背负式喷雾器、烟雾机、手推式喷雾机。 五、灭蚊方法 1、施药方法：将可用药物按产品说明书稀释一定倍数，喷洒于重点部位的蚊虫孳生栖息场所。 2、处理周期：每天处理1次，连续3次，以后每三天1次，直至应急程序结束，根据蚊虫监测结果考虑是否再进行处理。 3、重点滞留喷洒：蚊虫孳生栖息场所 4、 六、孳生地的处理 埃及伊蚊和白纹伊蚊是登革热主要传播蚊媒，埃及伊蚊主要孳生于水缸、水池和各种积水容器内，白纹伊蚊主要孳生于盆、罐、竹节、树洞、废轮胎、花瓶、壁瓶、建筑工地等清水型小积水。
病媒生物防制宣传资料
苍蝇的危害及防制 １、苍蝇可传播哪些疾病？ 苍蝇能携带60多种细菌，传播的疾病包括细菌性疾病：伤寒、副伤寒、菌痢、霍乱、肉中毒、沙门氏菌痢等；病毒性疾病：脊髓灰质炎、肝炎、沙眼、天花等；创伤性疾病：炭疽、破伤风、坏疽、化脓性球菌感染等，还可以传播原虫性疾病和寄生虫病；另外，成蝇还可以叮刺吸血传播锥虫、马来丝虫等疾病；蝇幼虫寄生引起蝇蛆症。 2、苍蝇是怎么传播疾病的？ 苍蝇可取食各种食物，包括人的食物，人、畜的分泌物和排泄物，垃圾等。苍蝇取食时先将唾液吐在食物上，将食物分解后再食入。苍蝇饱食后即可排粪，由于它排粪频繁，失水较多，又促使它频繁取食，因而它在人们的食物上边吃、边吐、边拉，给食物造成严重污染，人吃了苍蝇污染的食物就可能被染上多种疾病。 3、苍蝇有哪些生活习性？ 苍蝇是在白天活动频繁的昆虫，具有明显的趋光性。夜间则静止栖息。苍蝇的活动受温度影响很大。它在9～10℃时仅能爬行， 12℃时可以飞翔，15℃以上才能摄食、交配、产卵，30～35℃时尤其活跃。 4、灭蝇的主要方法有哪些？ 消灭苍蝇最根本的方法是有效控制苍蝇孳生的孳生场所和孳生物。 ①环境治理 包括及时清运垃圾粪便，消除卫生死角，提高环境卫生质量等，从而使蝇类不能孳生繁殖。 ②器械防治 可采用纱窗纱门、风幕、风道、水帘和水道等防蝇设施阻挡苍蝇进入；也可使用捕蝇瓶、捕蝇笼和灭蝇灯、粘蝇条等捕捉消灭苍蝇。 ③药物灭蝇 常用的杀虫剂有菊脂类、拟菊脂类、有机磷类等，可采用喷洒、涂抹粉刷、自制毒饵、毒蝇绳等方式使苍蝇接触杀虫剂面中毒死亡。家庭中也可配备杀虫气雾剂进行喷雾灭蝇。
蚊虫的危害及防制 1、蚊虫主要传播哪些疾病？ 蚊虫通过叮刺、吸血可传播80多种疾病，已知有蚊虫380余种。其中能传播疾病的主要有按蚊属、库蚊属和伊蚊属三个属的蚊类。主要传播疟疾、丝虫病、流行性乙型脑炎和登革热等。2、蚊虫为什么吸血？ 只有雌蚊才吸血，雄性不会吸血。雌蚊必须吸血其卵巢才能发育，繁衍后代。有的偏嗜人血，有的蚊则吸家畜的血，但没有严格的选择性，故蚊可传播人兽共患病。 3、蚊虫的栖息地有哪些？喜欢叮咬哪种人群？ 一般讲蚊虫喜欢在隐蔽、阴暗和通风不良的地方栖息，如屋内床下、柜后、门后，墙缝以及畜舍、地下室等，室外多在草丛、山洞、地窖、桥洞、石缝等处。雌蚊首先叮咬体温较高、爱出汗的人。 4、灭蚊方法有哪些？ 最根本的方法是控制蚊虫孳生场所，彻底清除蚊虫赖以生存的积水等。 其次是采取化学药物实施空间喷洒、熏杀、室内滞溜喷洒、浸泡蚊帐等杀灭成蚊。 5、夏天怎样才能不招引蚊子？ ①穿浅色的衣服，如黄色或白色，勤洗澡、多吃大蒜 ②在衣领、袖口等处喷洒花露水、口服维生素B ③涂抹驱蚊露，驱蚊霜等，可以达到8小时的驱虫效果。
五害介绍
第一部分病媒生物“五害”介绍 一、鼠 1、常见鼠的形态及生活习性 主要鼠种有:褐家鼠、黄胸鼠与小家鼠三种,属家栖鼠类,依靠人类提供的食物为生。其危害就是消耗粮食、啃咬衣物、家具、电线等造成各种事故灾害。还能传播鼠疫、流行性出血热等30多种疾病。 A、褐家鼠又称沟鼠身体粗壮,体型较大,体重150克—550克。 该种类繁殖能力强,一年四季均可繁殖,以春、秋两季为繁殖高峰。习惯于夜间活动,通常以黄昏与黎明前为活动高峰。 B、黄胸鼠体型细长,重100—250克,腹毛灰黄色,胸部黄色更深并呈棕黄色。尾长超过体长。 其繁殖能力略低于褐家鼠,一年四季均可繁殖,以夜间活动为主,以黄昏与黎明前为活动更为频繁。 C、小家鼠小型鼠种,体重12—20克。尾长于或等于头身长。 繁殖能力强,所在就是内阴暗角落、杂物箱、柜内筑巢产仔,昼夜活动,夜间活动较白天频繁。 2、一般防治措施 门窗与门框、窗框要包边(约30厘米)合缝;下水道管口应加碗盖与栅栏(栏间距不大于1、3厘米);地下室、地面房屋通风口必须装防鼠网;食品加工厂、仓库一楼的窗户也必须安装纱窗,既防鼠又防蝇;采用捕鼠器(鼠夹、鼠笼、粘鼠胶板)控制;环境治理(搞好环境卫生,改造下水道,清除房屋周围的杂物,定期检查绿化带并堵塞鼠洞)。 3、使用药物:敌鼠纳盐、大隆稻谷 二、蚊 1、蚊虫的形态特征 常见种类有:中华按蚊、至倦库蚊、三带喙库蚊、白纹伊蚊、埃及伊蚊。传播疾病有疟疾、丝虫病、乙型脑炎与登革热。 A、至倦库蚊成虫体型中等淡褐色,翅无黑白斑,足无白环,腹节背面各节基部有向后延伸呈半月形的白色横带。停息时身体于停落面平行。
B、白纹伊蚊又称花斑蚊,体型较小,呈黑色或深褐色。翅无黑白斑,体有多处银白色斑,胸背部有一条银白色纵纹,后足各节均具白环。停息时身体于停落面平行。 C、三带喙库蚊成虫体型较小,深褐色,喙中段有一白环,翅无斑。 D、中华按蚊体型中等,灰褐色,翅有黑白斑。停息时身体与喙呈一直线,同停落面呈角。 2、蚊虫的生活史 分为卵、幼虫、蛹与成虫四个阶段。 3、蚊虫的孳生习性 产卵场所也就是幼虫生长、发育的场所即为孳生地。分几种类型: A、容器型主要孳生白纹伊蚊与埃及伊蚊 B、污水型主要孳生至倦库蚊 C、稻田型主要孳生三带喙库蚊、中华按蚊 D、缓流型主要孳生微小按蚊 4、蚊虫的季节消长 一年四季蚊虫均可发育与繁殖。至倦库蚊发生在4-6月与9-11月两个高峰期。而白纹伊蚊则在5-10为高峰期。 5、一般防治措施 填平洼地清除积水;疏导引流;对废气容器等积水及时清理;清除人居、生产与活动周围杂物草等;住宅区及宾馆等须安装防蚊设施。 6、使用药物:家卫清(球型芽孢为控制孳生地药物)、凯素灵 三、蝇 1、常见蝇的形态 常见蝇主要有:家蝇、市蝇、大头金蝇、铜绿蝇、丝光绿蝇、麻蝇等。可传播痢疾、伤寒、小儿麻痹症,传染肝炎、蛔虫病等。 A、家蝇中小体型,体长5-8毫米,全身灰色,胸背部有4条黑色纵纹,腹部背面基部棕黑色,端部为桔黄色。 B、市蝇体长4-7毫米,较家蝇小,体色为浅灰色,胸背面有两条黑色纵纹,腹部深棕色。 C、大头金蝇体型较大而肥胖,体长7-11毫米,全身蓝绿色金属光泽,头部复眼巨大呈鲜红色。
预防登革热专项方案(案例)
预防登革热专项方案 根据传染病防治法和突发公共卫生事件应急条例等有关法律法规，结合本项目管理工作的实际情况，特制定本项目部登革热防控工作方案。 一、出现登革热的原因和传播 1、登革热是由伊蚊（俗称花蚊或花斑蚊）传播，人与人之间是不会传播的。伊蚊吸食了登革热病人的血后，会把登革热病毒传染给下一个被叮咬的健康人。人感染了登革热病毒后大约一周左右开始发病，会出现发热、头痛、全身肌肉关节酸痛等症状；发病第3-6天全身出现发疹，有的病人会出现皮肤粘膜出血症状，少数病人会突然病情加重出现登革热休克综合症，病情凶险，如不及时抢救，可于4-6小时死亡。目前还没有治疗和预防登革热的特效药物，但是只要消灭传播登革热的伊蚊，就可以防止登革热的流行。 2、要消灭伊蚊就要了解伊蚊的生活习性。伊蚊无论白天和晚上都会叮咬人，要切实做好防蚊叮咬的措施很困难，最有效消灭伊蚊的方法是消除伊蚊的孳生地。伊蚊繁殖的孳生地主要是小型盆罐、旧轮胎、塑料袋等积水也是伊蚊的孳生地，必须采取每星期翻盆倒罐消除积水，养鱼或放农药、清理弃臵容器等综合措施。伊蚊孳生地附近的居民危害最大，伊蚊飞行活动的半径为100米，所以需要大家互相督
促齐齐动手，你我齐参与共同开展消灭伊蚊的活动，防止登革热发生与流行。 二、工作目标 按照科学防控措施，坚持预防为主的原则，切实加大灭蚊、环境整治、疫情监测等综合防控工作力度，彻底扑灭登革热疫情，切实保障职工的身体健康和生命安全，保障本工程项目的顺利进行。 三、工作内容及防控措施 现本项目正处于基础施工阶段，且由于地质条件原因导致基坑内积水较多，为有限防止项目部出现“登革热”疫情，现专门成立一个由四人组成的小组来预防登革热的发生，针对工地上四周环境、生活区宿舍、厨房、厕所、施工场地等伊蚊能孳生的地方，每天派专职人员清理积水，进行灭蚊喷药防治，具体人员、做法安排如下：项目部安全领导小组其人员组成 1、安全领导小组人员的分工职责 1）组长职责：负责整体安全防护工作，安排各班组长做好安全防范措施，对伊蚊孳生的地方进行监督处理。 2）副组长职责：对各施工班组跟踪调查，如有在场人员发烧现
预防登革热讲稿
老师们同学们早上好： 从广州市疾控中心获悉，现在已发现广州本土感染登革热病例一百五十多例，荔湾区占了64%。国庆节前，广州市已经发动全市进行大面积的灭蚊大行动，但仍未能完全遏制住疫情。9月27日全市本地感染登革热病例为108例，国庆节后新增了44例。新增的例病主要集中在芳村，高发区在荔湾和南海交界一带。而我们**村正处于这一地带。海南村有较大范围的农田和专业的花卉市场，坑洼潮湿之地容易积水，蚊虫滋生地较多，环境脏乱，因此成为蚊子滋生的“重灾区”。据统计我们生活的这一区域的蚊子密度比广州市平均指数高出数倍之多。 经过学校和社区的宣传相信同学们已经知道登革热主要由蚊子中的伊蚊传播。广州地区一般是由白纹伊蚊传播。早上、中午、傍晚是伊蚊活动高峰期，也是它喜欢吸人血的时候。当成蚊吸了登革热病人或隐性感染者的血液后，登革热病毒就在蚊子体内大量复制繁殖。在气温32℃环境下，伊蚊自吸血后10天起再咬人时，就可把病毒传染给健康人，使人感染并发生登革热。 因此近段时间我们一定要行动起来做好登革热的预防工作，那么要注意哪些事项呢？白纹伊蚊只喜欢在较为洁净的积水中孳生。不光户外灭蚊预防登革热，家庭也是灭蚊的主要地方。虽然中秋过后，雨水渐少，气温也会有所下降，但我们不能掉以轻心，仍要积极翻盆倒罐，清积水。搞好环境卫生，防范蚊虫叮咬，涂抹防蚊液，穿长裤白鞋避免皮肤过度外露。不去人流密集的地方，注意个人卫生，注意增强营养，提高抵抗力。请同学们向家人宣传，提高家人的防范意识，以维护全家的身体健康。 给大家提个醒一旦出现发烧、皮疹、骨头酸痛、疲惫等症状应及时就医。对登革热病人要隔离在有防蚊设施的病房内，隔离时间不应少于5天。如有发烧应退热两天后才回校。
登革热防控工作方案
xxx登革热防控工作方案 登革热是由登革热病毒引起，伊蚊传播的一种急性传染病。2013年以来我省深圳、广州、珠海、中山等多个地市先后出现了本地感染的登革热疫情。布雷图指数调查高于安全区，一旦有输入性病例引入而未能被及时发现，则有可能引起登革热本地流行的风险，防控形势十分严峻。为做好我县登革热的防控工作，有效预防和控制登革热疫情的发生，特制定本防控工作方案。 一、工作目标 全县各级医疗卫生单位要坚持当地政府主导、防治技术支持与群众自发并重的防控机制，做好以清理积水容器和科学灭蚊为重点的环境整治、宣传与监测并举的长效防控体系，形成“人人懂防控”的防控局面，严防登革热疫情发生，切实保障人民群众身体健康和生命安全，保障经济平稳较快发展和社会稳定。 二、工作内容 （一）加强爱国卫生运动 全县各级医疗卫生单位要结合政府部门充分发动群众力量，对村（居）道路、建筑工地、菜市场、废品收购站、外来人员聚居地等难点部位；楼顶阳台、破空置房、锁门无人居住房、小夹巷、闲置用地和各类地下沟渠（下水道、房前屋后阴沟）等卫生死角开展全面的卫生整治行动。做到无卫生死角、无积水积留、无暴露垃圾、无蚊蝇孳生，创造良好的卫生环境。 （二）加强消杀蚊虫 1．建立消杀队伍。全县各级医疗卫生单位要成立灭蚊队伍，落实责任制度，明确责任人，实行“三统一”管理，即统一培训上岗、
统一规程消杀、统一编队管理。 2．落实灭蚊工作。全县各级医疗卫生单位要与政府部门结合严格消杀蚊虫，确保灭蚊有序、有力、有效开展。安排专人清理积水容器等蚊子孳生场所，对成蚊越冬栖息场所、孳生地如地下室、车库、窖井、柴堆、各类管道、垃圾站、各种水体、单位及小区绿化、居室内家具壁橱后面等重点部位，定期组织成蚊消杀，做到村不漏户、户不漏角。 3．完善”布雷图指数”监测制度。在人口密集的老城区、公园、学校、城中村、城乡结合部等重点环境和博贺镇建立监测网点，开展定期“布雷图指数”抽查，及时采集数据并分析，提供下一阶段工作建议。 （三）加强疫情监测和培训 1. 医疗机构门诊监测。要加强医疗机构发热门诊建设和管理，加大对具有发热、头痛、肌肉痛、皮疹和（或）面、颈、胸部潮红（即三红征）病人的筛查、诊断，发现疑似病例要及时向县疾控中心报告和采样送检，并对病例进行防蚊隔离治疗。对往来于东南亚、南美洲、非洲、云南、珠江三角州、台湾等登革热易发地区的人员进行监测，督促其出现发热等情况及时就诊或体检。发生疫情时，严格按照《广东省登革热防控工作指引（试行）》（粤卫[2007]31号）要求切实做好相关工作。 2.加强知识和技能培训。由疾控中心对消杀灭蚊队伍进行知识培训和技术指导，规范开展消杀灭蚊工作。医疗机构要加强对医务人员登革热防治知识与技能培训，提高登革热的诊断水平，减少误诊和漏诊。 （四）加强知识宣传活动
登革热防控专项方案.docx
目录 第一节工程概况.......................错误!未定义书签。第二节编制原因及登革热介绍...........错误!未定义书签。 一、编制原因...........................错误 !未定义书签。 二、登革热介绍.........................错误 !未定义书签。第三节工作目标及预防措施.............错误!未定义书签。 一、工作目标...........................错误 !未定义书签。 二、防控措施...........................错误 !未定义书签。
第一节工程概况 工程万科城市中心（地块一搬迁安置 工程地址香洲区上冲片区云峰路北 名称区） 1-10# 及 1-3# 配电房侧、诗僧路西侧 建设 珠海市万有引力房地产有限公司勘查单位四川省川建勘察设计院单位 设计 珠海泰基建筑设计工程有限公司监理单位广东华杰建设工程监理咨询 单位有限公司 质量 珠海市香洲区建筑工程质量安全总承包单 监督广东上城建设有限公司 监督站位 部门 本项目项目位于香洲区上冲片区云峰路北侧、诗僧路西侧，为珠海 TOD 小镇重点规划区域，总建筑面积约 30 万平方米，地块一用地面积为平方米,建筑物最大高度为。 第二节编制原因及登革热介绍 一、编制原因 由于近期内珠海特区出现登革热现象，较多的人员感染，事态比较严 重。为了加强本项目的安全生产工作，提高项目在施工生产过程中突发事 件的应变能力，尽快控制事态，尽量减少损失，尽早恢复正常施工秩序， 特制定此预防措施方案。 二、登革热介绍 1、登革热是由伊蚊（俗称花蚊或花斑蚊）传播，人与人之间是不会传 播的。伊蚊吸食了登革热病人的血后，会把登革热病毒传染给下一个被叮 咬的健康人。人感染了登革热病毒后大约一周左右开始发病，会出现发热、
病媒生物防制知识宣传材料
病媒生物防制宣传资料 老鼠的危害及防制 1 、老鼠对人类生产生活有哪些 工业、交通、通讯方面，由于老鼠咬坏电缆防线，造成精密仪器损坏、交通瘫痪、通讯中断、引发火灾。老鼠携带多种病原体，严重危害人类健康。有史以来死于鼠传染疾病的人数，远远超过历次战争死亡人数的总和。 2 、老鼠传播哪些疾病 老鼠能携带细菌、病毒、立克氏体、寄生虫等200余种病原体，其中能使人致病的有57种，对人类危害大的有：鼠疫、流行性出血热、钩端螺旋体病、恙虫病、森林脑炎、蜱回归热、地方性斑疹伤寒、野兔热等。 3 、家庭防鼠的有哪些方法 ①搞好防鼠设施，封堵一切老鼠可能进出的通道、孔洞。 ②控制好家中食物的存放，断绝老鼠的食源和水源，让老鼠无食物可吃。收藏好家中的各类食物存放，尤其是生活垃圾要及时清理。 4 、常用的灭鼠方法有哪些 采用以下方法进行灭鼠： ①物理灭鼠法：它包括使用鼠夹、鼠笼、粘鼠板、电鼠器等。 ②药物灭鼠法：使用抗凝血剂类慢性鼠药，如溴敌隆、大隆等。严禁使用急性鼠药。 5 、为什么慢性灭鼠药比急性灭鼠药好 慢性灭鼠药的优点是：用量小，鼠不拒食，至死方休，家畜中毒机会少，中了毒也可以用特效解毒药（维生素K1）来抢救。慢性灭鼠药符合老鼠少量、多次的取食习性。慢性
灭鼠药作用较慢，吃药3—5天多数老鼠死亡，死前没有剧烈的症状，故临死还在取食毒饵。因此，在鼠大量死亡时，几乎所有的老鼠都已吃足了鼠药的致死量，即使有的鼠不再吃或迁移，也难免一死。慢性灭鼠药对多种鼠类均有杀灭作用，大面积使用比较安全，灭鼠效果好，死鼠数量多，是目前灭鼠的主要武器。 6 、慢性灭鼠毒饵投放方法 在室内一般每一标准间（15㎡）投放2堆，每堆30g，放在门口两侧30—40㎝处墙脚下，距墙1㎝左右。仓库等大型房间每5—10m投放一堆。每晚6—7时投放，次日晨检查，吃多少补多少，全部吃完加倍补充，连续5—7天，或直至没有老鼠取食为止。 7 、购买投放灭鼠药注意事项 （1）必须选用经国家农药登记的灭鼠药物。 （2）要到有经营灭鼠资格的部门购买灭鼠药。 （3）要了解所有灭鼠药的成份、安全解毒方法。 （4）要按规定要求投放灭鼠药物，最关键是投药到位。（5）外环境投放灭鼠药应设置安全警示标示。 8 、死鼠如何处理 焚烧或深埋，不能乱扔。处理完死鼠后要用消毒液消毒可能被鼠污染的场所，并洗手消毒。