Effects of climate change on transmission of vector-borne diseases Howard S. Ginsberg, Ph.D. USGS Patuxent Wildlife Research Center University of Rhode Island
Dec 17, 2015
Effects of climate change on transmission of vector-borne diseases
Howard S. Ginsberg, Ph.D.
USGS Patuxent Wildlife Research Center
University of Rhode Island
precipitation
hurricanes
sea level
Predicted effects on precipitation differ in different parts ofNorth America. Some areas are predicted to see more precipitation,some less, and some are predicted to show greater variability with more intense periods of rainfal and of drought.
Some models predict similar frequency of hurricanes in the future, but with greater average strength.
Sea level is rising and is predicted to continue to rise.
Arthropod vectors
• Lice - epidemic typhus• Kissing bugs – Chagas disease• Fleas – plague• Sand flies – Leishmaniasis• Black flies – River blindness• Mosquitoes – malaria, dengue, yellow fever, Japanese
encephalitis, West Nile encephalitis, filariasis
• Tsetse flies – African sleeping sickness• Chiggers – scrub typhus• Ticks – Lyme disease, Tick-borne encephalitis, Rocky
Mountain Spotted Fever
Malaria
Predicted change in distribution of malaria based on predicted changes in temperature and precipitation.
Martens et al. (1999. Global Environmental Change 9:S89-S107) predict that malaria will spread from the tropics into more northern and more southern latitudes.
Predicted change in distribution of malaria based on models usingmean, maxima and minima of temperature, precipitation, and saturation vapor pressure.
Rogers & Randolph (2000. Science 289:1763-1766) predict <1% change in total # cases.
Malaria
West Nile Virus
enzootic vectors: Culex pipiens, Cx. restuans
reservoirs: robins, house sparrows, crows
bridge vectors: Culex pipiens, Cx. salinarius, Aedes albopictus
pathogen: WNV (flavivirus)
Arbovirus transmission dynamicsEffects of temperature
Effect of temperature on mosquito survival:
Reeves et al. 1994. J. Med. Entomol. 31:323.
Mosquito longevity declines as ambient temperature increases
Dohm et al. 2002. J. Med. Entomol. 39:221.
Effect of temperature on extrinsic incubation periodof WNV in Culex pipiens
Viral replication in mosquito is faster as ambienttemperature increases
Effects of precipitation and environmental moisture on arboviral transmission
- Humidity and adult mosquito longevity
- Precipitation, groundwater levels and mosquito abundance(larval habitat) and larval survival (e.g., EEE)
- Wetspots and concentration of mosquitoes and hosts(e.g., SLE, WNV?)
- Precipitation and human activity
Factors influencing distribution of Lyme disease
• Tick distribution and abundance• Tick phenology• Tick genetics• Distribution of hosts
Life cycle of Ixodes scapularis
adults larvae nymphs adultsPOPULATION 1
POPULATION 2 nymphs adults larvae
SPRING SUMMER FALL WINTER SPRING SUMMER FALL
hosts hosts
YEAR 1 YEAR 2
Tick phenology
Northeastern U.S.
Southeastern U.S.
Hosts of larval Ixodes scapularis[effects of climate change on distributions of hosts?]
Effects of global climate change on transmission of vector-borne diseases
- Some diseases will spread to areas where they are currently absent
- Some diseases will disappear from areas where they currently exist
- Intensity of transmission of some pathogens will changelocally, and yearly patterns will vary with changes in weather patterns
- Human activities will strongly influence disease transmissionin response to climate change