Climate change effects population health (Anthony et al., Lancet 2006;367:859-69)

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• ???
• 2006-04-26

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Climate change effects population health (Anthony
et al., Lancet 2006367859-69)

• 1. Thermal stress deaths, illness injury/
• death from floods, storms, cyclones,
• bushfires
• Effect of these events on food yields.
• 2. Microbial proliferation
• Food poisoningSalmonella species, etc
• unstable drinking water.

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Climate change effects population health (Anthony
et al., Lancet 2006367859-69)

• 3. Changes in vector-pathogen-host relation
• and in infectious disease geography/
• seasonalityeg, malaria, dengue,
• tickborne viral disease, schistosomiasis.
• 4. Impaired crop, livestock and fisheries
• yields, leading to impaired nutrition, health
• , survival.

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Climate change effects population health (Anthony
et al., Lancet 2006367859-69)

• 5. Loss of livelihoods, displacement, leading
• to poverty and adverse health mental
• health, infectious diseases, malnutrition,
• physical risks.

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• ?????????????,?????
• ???????????????????
• ??? A
• 1??????
• 2????????
• 3???????? H E
  

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???????(A)???

• 1.???(infectivity)The ability of an
• agent to cause infection in a susceptible
• host ( The minimal number of infectious
• particles required to establish infection).
• 2.??? (pathogenicity) the ability of a
• microbial agent to induce disease.

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???????(A)???

• 3.?????(virulence) The severity of
• the disease after infection occurs (CFR).
• 4.???(immunogenicity) The ability of an
• organism to produce an immune response
• capable of providing protection against re-
• infection with the same or similar agent.

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???????????(E)

• ?????????????
• ???????? A
• ??????????
• ????B????C???
• ??????? H E

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????(H)?????

• infection ?????(A)?????????
• ?????,?????infection?
• ??
• ????.Salmonella infection risk??
• ???.Pulmonary tuberculosis risk
• ???

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????????????

• ?? Intergovernmental Panel on Climate
• Change 2001 ????
• Global average temperatures are projected
• to increase between 1.4 and 5.8?C by the
• end of this century.

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????????????

• Climate-related thermal stress
• Floods
• Infectious diseases
• ?????????

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?????????

• In the Asia-Pacific region, El Nino and La
• Nina events seems to have affected the
• occurrence of dengue fever outbreaks(Hales
• et al. Lancet 19963481664-5Hales et al.
• Eviron Health Perspect 199910799-102.
• Hopp M et al. Clim Resear 20032585-94)

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• All strains of the dengue virus are carried
• principally by the Aedes aegypti mosquito
• It is strongly affected by ecological and
• human drivers, particularly the density of
• water-bearing containers, but is also
• influenced by climate, including variability
• in temperature, moisture, solar radiation.

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Temperature and dengue fever

• Currently, dengue viruses are being
• transmitted in the tropics between 30?north
• and 20?south latitude (Trent, 1983) since
• frosts or sustained cold weather kills adult
• mosquitoes and over wintering eggs and
• larvae (Chandle, 1945).

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Temperature and dengue fever

• Warming trends can shift vector and
• disease distribution to higher latitude
• or altitudes, as was observed in Mexico
• when dengue reached in altitude of
• 1700 M during an unseasonally warm
• summer in 1988 (Herrera-Besto, 1992).

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Temperature and dengue fever

• In Mexico in 1986, the most important
• predictor of dengue prevalence was found
• to be the median temperature during the
• rainy season, with an adjusted fourfold
• increase observed between 17? and 30?C
• (Koopman, 1991).

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Temperature and dengue fever 1.Rueda,
19902.Scott,19933. McDonald, 1956.

• Temperature also affects the transmission
• dynamics of dengue. Warmer temperatures
• reduce larval size of A. aegypti, ultimately
• affecting adult size (1). Smaller adults must
• feed more frequently to develop an egg
• batch (2), boosting the incidence of double
• feeding within each enotropic cycle (3).

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Temperature and dengue fever

• Regarding viral development, the extrinsic
• incubation period shortens with higher
• temperatures, increasing the proportion of
• mosquitoes that become infectious at a
• given time (Pocks, 1995).

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Temperature and dengue fever

• For example, the EIP for dengue type-2
• virus requires 12 days at 30? C and only 7
• days at 32? to 35? C (Watts, 1987).
• Shorting the incubation period by 5 days
• translates to a potential three-fold higher
• transmission rate of disease.

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Temperature and dengue fever

• In short, slightly higher temperatures within
• the range of mosquito viability lead to more
• infectious mosquitoes that bite more
• frequently.

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Infectious Diseases SOI
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El Nino/Southern Oscillation

• ??????????El Lino, ??
• ?Christ child??????????
• ????????????,???
• ????????????????
• ????

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El Nino/Southern Oscillation

• ????????,???????
• ??,?????????,???
• ??????,???????,?
• ???????????,????
• ????????,???????
• ?????????

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El Nino/Southern Oscillation

• ???????????????
• ???????,???????
• ???????????????
• ???,???????????
• ?,????????????
• ???????????,???
• ??????????

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El Nino/Southern Oscillation

• ???????,??????????
• ???????????????,??
• ??????????????,???
• ?????????(Southern Oscillation
• ) ,????????????????
• ????????,????ENSO?

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El Nino/Southern Oscillation

• ??????????????????
• ??????,??????,?????
• ?,?????,???????????
• ???????????????,??
• ???????????????????
• ??????????,????????

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La Nina?El Nino

• La Nina(???)????????,??
• ????????????,??????
• ????,???????????90?150
• ???????,???????????
• ????????,?????????0.5
• ?C?????,?????0.5?????

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La Nina?El Nino

• ??,??????????
• ?????,???????
• ????????????

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????????? Intergovernmental Panel on Climate
Change, 2001

• The number of people at risk from flooding
• by coastal storm surges is projected to
• increase from current 75 million to 200
• million in a scenario of mid-range climate
• changes, in which a rise in the sea level of
• 40 cm is envisaged by the year 2080s.

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Martens WJ. Environ HealthPerspect
1998106(suppl 1)241-51.

• The comfortable or safest temperature
• range is closely related to mean
• temperature, with an upper bound from
• As low as 16.5?C for the Netherlands and
• 19?C for London, to as high as 29?C in
• Taiwan.

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Gubler DJ, et al. Envion Health Perspect
2001109223-33.

• Infectious agents (protozoa, bacteria, virus)
• and their associated vector organisms (such
• as mosquitoes, ticks) are devoid of
• thermostatic mechanisms, and reproduction
• and survival rates are thus strongly affected
• by fluctuations of temperature.

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• ?????????????????,
• ???????????????1.??
• ?????????????????,
• ??????????2.???????
• ????????-???????????
• ?????3.????????????

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????????

• ???????????????????
• ??????,??????????,?
• ????????????(vector
• abundance)?????????(???
• )???????????(???,
• anthropophily)????????????

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?????(vector abundance)

• ??????????(Aedes aegypti),
• ???????????,???????
• ????,?????????,??16?
• C?,?????????,???????
• ?????,????????????
• ?????,????????????!

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?????(vector abundance)

• ???????,???????????
• ??????????????????
• ?????????????,?????
• ?????????????,?????
• ?,????????????????
• ???????,??????????

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• ??????????,????????
• ???????????????????
• ??????????,????????
• ????????????????

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??????

• ??????,?????????,
• ???????????,?????
• ?????????(host preference
• )????????????????
• ????,????????????
• ?,?????(anthropophily)?

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????(feeding interval)

• ????????????????
• ???????????????
• ??(Capture-recapture)???
• ????????????????
• ?????

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St Louis encephalitis (SLE)

• Human outbreaks of SLE are highly
• correlated with several- day periods when
• temperature exceeds 30?C (Monath et al,
• 1987) as was the case during the 1984
• California epidemic that followed a period of
• extremely high temperatures.

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St Louis encephalitis (SLE)

• Precipitation patterns are also important for
• transmission of SLE (Monath TP, 1990).
• Computer analysis of monthly climate data
• has demonstrated that excessive rainfall in
• January and February, in combination with
• draught in July, most often precedes SLE
• outbreaks (Bowen et al, 1980).

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Temperature and cholera(Patz et al.,JAMA
1996275217-23)

• Climate-related increases in sea surface
• temperature and sea level can lead to higher
• incidence of water-borne infections and
• toxin-related illnesses, such as cholera and
• shellfish poisoning.

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Temperature and cholera

• Cholera reappeared in Peru with El Nino
• event of 1991-92 and seems to fluctuate
• seasonally in Bangladesh with sea surface
• temperature in the Bay of Bengal (Lobitz et
• al, 2000). A positive effect of ENSO is
• observed on the 2-month-ahead predictions
• of cholera incidence in the fall.

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Temperature and diarrheaCheckley, Lancet
2000355442

• During the 1997-98 El Nino episode, mean
• ambient temperature in Lima increased up
• to 5?C above normal, and the number of
• daily admissions for diarrhea increased to
• 200 of the previous rate, 6225 excess
• admissions were attributed to El Nino and
• cost US 277,000 dollars.

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Temperature and diarrheaCheckley, Lancet
2000355442.

• During the period before the El Nino episode
• , admissions for diarrhea increased by 8
• by 1?C increase in mean ambient
• temperature.

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Temperature and Malaria

• Malaria transmission has been associated
• with anomalies of maximum temperature
• in the highlands of Kenya. In the highland
• of Debre Zeit sector of central Ethiopia an
• association was found between increase
• of malaria incidence and concomitant
• warming trends (Tulu AN , 1996).

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Climate and emerging infection(Wenzel RP. NEJM
1994)

• Pulmonary hantavirus epidemic in the South
• West United States was felt to be due to an
• upsurge in rodent populations related to
• climate and ecological conditions.

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Climate and hantavirus infection(Levin et al. Am
Science 1994)

• Six years of draught followed by extremely
• heavy spring rains in 1993, resulted in a 10-
• fold increase in the population of deer mice,
• which are the known reservoir of
• hantaviruses.

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Climate and meningococcal meningitis(Moore PS.
Clin Infect Dis 1992)

• In Sub-Saharan Africa, meningococcal
• meningitis follows a distinct seasonal pattern
• Epidemics consistently erupt during the hot
• dry season and subside soon after the
• onset of the rainy season.

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Temperature and food-borneinfectious diseases.

• Higher than average temperature contribute
• to an estimated 30 of reported cases of
• salmonellosis across much of continental
• Europe (Kovats et al, 2004).

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Temperature and food-borneinfectious diseases

• In the UK, the monthly incidence of food
• poisoning is most strongly associated with
• temperatures occurring in the previous two
• to five weeks.
• (Bentham et al., Int J Biometeorol 200145
• 22-26.)

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Schistosomiasis and climate

• Schistosomiasis has increased in
• prevalence in arid warm regions primarily
• from expansion of irrigation systems where
• snails serves as the intermediate host.
• Warmer temperature influences infectivity
• and development of the parasite within the
• snail (Shiff et al, 1975).

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Schistosomiasis and climate

• During winter, cercarial infection in water
• snails becomes dormant and potential
• transmission sharply diminished. Therefore,
• if temperatures increase, snails could
• spread schistosomiasis over a longer during
• the year (WHO, 1990).

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Onchocerciasis?????

• A blackfly-borne disease primary found in
• West Africa and. Climate plays an important
• role in the occurrence since the vector
• requires fast-flowing water for successful
• reproduction, and the adult vector can be
• spread by wind (WHO, 1985).

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Onchocerciasis?????

• Studies found that if temperature and
• precipitation change across portions of
• West Africa, blackfly populations may
• increase by as much as 25 at their current
• breeding sites (Mills DM, 1995).

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Tick-borne diseases

• In the Southern United States, Rocky
• Mountain spotted fever may decline due to
• ticks intolerance of high temperatures and
• diminished humidity (Haile DG, EPA,1989).

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Cholera and toxic algae

• Over the past century, average sea surface
• temperature has increased approximately
• 0.7?C (Houghton et al., 1992), and marine
• growth of algae has been observed to
• respond to localized temperatures
• increases in nutrient-replete waters.

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Cholera and toxic algae

• Warm water favors the growth of
• Dinoflagellates and cyanobacteria that
• include more toxic organisms (Vallela I,
• 1984). Zooplankton, which feed on algae,
• can serve as reservoirs for Vibrio cholerae
• and other enteric pathogens .

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Rainfalls and infection1.Nicholls,
19932.Glantz, 1991.

• Extreme heavy rainfalls were correlated with
• outbreak of Murray Valley encephalitis and
• Rose River virus in Australia, eastern equine
• encephalitis in the United States (1), West
• Nile fever in southern Africa (2), and cyclic
• malaria epidemics in Argentina Parkistan.

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El Nino and mosquito-borne diseases (Kovats RS.
WHO Bull 2000781127-35.)

• 1. Rainfall is known to affect diseases
• spread by mosquitoes that breed in surface
• water 2. Increases in temperature decrease
• the intrinsic incubation period of the malaria
• parasite and vectors become infectious
• more quickly.

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El Nino and mosquito-borne diseases (Kovats RS.
WHO Bull 2000781127-35.)

• 3. Increases in temperature also
• accelerate vector life cycles or allow
• the vector to colonize areas that were
• previously too cold.
• 4. Temperature may also affect the behavior
• of human population with regard to exposure

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El Nino and malaria(Najera JA et al., WHO, 1998)

• 1. In Venezuela, malaria increased an
• average 37 in the post-Nino year.
• 2. In Colombia, malaria cases increased
• by 17.3 during the El Nino and by
• 35 in the post-Nino year.

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Murray Valley encephalitis and Ross River viral
disease in Australia

• MVE also known as Australian encephalitis,
• an arboviral disease. Epidemic polyarthritis
• is caused by infection with Ross River virus.
• The virus is thought to persist in mosquito
• eggs for a considerable time.

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Murray Valley encephalitis and Ross River viral
disease in Australia

• When environmental condition become
• favorable, such as with heavy rains or
• flooding, the eggs hatch into infected
• mosquitoes and a localized outbreak of the
• disease may occur.

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Rift Valley fever (RVF) and Temperature (Davies
FG et al., Bull WHO 198563941-3).

• RVF is an arboviral disease that primarily
• affect cattle. Outbreak of RVF in humans
• have occurred in East Africa following
• heavy rainfalls. In Kenya, outbreak in the
• usually dry grasslands are always
• associate with periods of heavy rain.

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Rift Valley fever, temperature,and rainfalls

• The a997-98 El Nino event has been linked
• to very heavy rainfall in Northeastern Kenya
• and Southern Somalia, from Oct. 1997 to
• Jan. 1998. The rain was 60 to 100 folds
• heavier than normal. In Dec. 1997, a large
• Outbreak of RVF was noted in these areas.

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Rift Valley fever, temperature,and rainfalls

• Linthincum et al found an association
• between RVF activity (1950-98), monthly
• SOI, and sea surface temperatures
• anomalies in the Pacific and Indian Oceans
• (Linthincum KJ, et al., Science 1999285
• 397-400.)

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Arthropods and Infections

• Arthropods such as mosquitoes and tics
• are extremely sensitive to climate. Two
• components of climate change can
• significantly influence the pattern of
• infectious diseases.

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Arthropods and Infections

• Warming affects their range, while extreme
• weather (e.g., excessive rains) affects the
• timing and intensity of outbreaks.

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Arthropods and Infections

• Warming alters the boundary conditions for
• transmissional potential, while atmosphere,
• land surface and ocean warming also alter
• the intensity, frequency and temporal /
• spatial distribution of extreme weather
• events that are associated with outbreaks.

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??????(WHO)??

• ????????????????,??
• ????????1.Malaria 2.Dengue
• and dengue hemorrhagic fever/ dengue
• shock syndrome 3.Arboviral encephalitides
• 4. Cholera (found to be harbored by
• zooplankton) 5.toxic algae (red tides).

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Status of Major Vector-borne Diseases and
Predicted Sensitivity to Climate Change (WHO,
1990)?1989?????48????

• Malaria Lymphatic
  Onchocerciasis
• Population filariases
• at risk x106 2,100 900
  90
• Prevalence 270 90.2
  17.8
• /106
• ?? Tropics, Tropics,
  Africa, Latin
• Subtropics Subtropics
  America
• Possible C Highly likely Likely
  Likely
• Possible change of distribution as a result of
  climatic C.

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Status of Major Vector-borne Diseases and
Predicted Sensitivity to Climate Change (WHO,
1990)?1989?????48????

• ???? ?????
  Leishmaniasis
• Population
• at risk x106 600 50
  350
• Prevalence 200 / 106 ??25000 12 M
  infected
• 
  0.4x 106/year new
• ?? Tropics, Tropical Asia,
  southern Euro.
• Subtropics Africa
  Africa, S. America
• Possible C Very likely Likely
  Unknown
• Possible change of distribution as a result of
  climatic C.

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Status of Major Vector-borne Diseases
andPredicted Sensitivity to Climate Change(WHO,
1990)

• ??? ??? ???? ????
• Population
  ????
• at risk . .
  . .
• Prevalence . . .
  .
• ?? Tropics ?? ??
  Tropical to
• Subtropics ???? ???
  temperate zone
• Possible C Very likely Likely Likely
  Likely
• Possible change of distribution as a result of
  climatic C.

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????????????

• In Scotland, campylobacter infections are
• characterized by short peaks in the spring
• (Colwell RR, Partz JA, 1998).
• In Bangladesh, cholera outbreaks occur
• during the monsoon season (Colwell RR.
• Science 19962742025-31.)
• ?????????????????SARS

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Climate sensitivity of infectious disease(Madico
G, et al. Clin Infect Dis 199724977-81.)

• In Peru, cyclospora infections peak in the
• summer and subside in the winter.
• Epidemics of meningococcal meningitis
• tend to erupt during hot and dry season
• and subside soon after the beginning of
• rainy season in Sub-Saharan Africa.
• (Moore PS. Clin Infect Dis 199214515-25.)

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Temperature effects on selected vector-borne
pathogens Vector

• 1. Survival can decrease or increase
• depending on species
• 2. Some vectors have higher survival at
• higher latitudes and altitudes with
• higher temperatures

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Temperature effects on selected vector-borne
pathogens Vector

• 3. Changes in the susceptibility of vectors to
• some pathogens, e.g., higher
• temperatures reduce size of some vectors
• but reduces activities of others

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Temperature effects on selected vector-borne
pathogens Vector

• 4. Changes in the rate of vector
• population growth
• 5. Changes in feeding rate and host
• contact
• 6. Changes in seasonality of
• populations.

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Temperature effects on selected vector-borne
disease pathogen

• 1. Decreased extrinsic incubation period
• of pathogen in vector at higher
• temperatures
• 2. Changes in transmission season
• 3. Changes in distribution
• 4. Decreased viral replication.

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Effects of changes in precipitation on pathogens

• 1. Increased rain may increase larval
• habitat and vector population size by
• creating new habitat
• 2. Excess rain or snowpack can eliminate
• habitat by flooding, decreasing vector
• population

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Effects of changes in precipitation on pathogens

• 3. Low rainfall can create habitat by
• causing rivers to dry into pools (dry
• season malaria)
• 4. Decreased rain can increase container-
• breeding mosquitoes by forcing
• increased water storage

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Effects of changes in precipitation on pathogens

• 5. Epic rainfall events can synchronize
• vector host-seeking and virus
• transmission
• 6. Increased humidity increases vector
• survival decreased humidity decreases
• vector survival.

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Effects of changes in precipitation on pathogens

• Increased rain can increase vegetation,
• food availability, and population size.
• Increased rain can cause flooding
• decreases population size but increase
• human contact.

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??

• The impacts of long-term climate change
• may interact with the impacts of
• increased variability and weather
• extremes affecting the incidence,
• prevalence, seasonality and distribution
• of infectious diseases.