Vector-borne and Zoonotic Diseases
The incidence of vector-borne and zoonotic diseases (VBZD) is difficult to predict and model. Climate is one of many variables known to affect the rates of these infectious diseases. Climate change may result in changing distribution of VBZD prevalent in the U.S. This could cause formerly-prevalent diseases such as malaria and dengue fever to re-emerge, or facilitate the introduction and spread of new disease agents, such as West Nile virus. At this time, scientists do not have the understanding of disease ecology in each instance needed to make predictions.
The potential for climate change to impact the range and incidence of VBZD in the U.S. rests with climatic influences on the ecology of insect vectors and animal hosts, and on the life cycles of the disease-causing germs they carry. For instance, as temperature increases, the malaria parasite reproduces at a higher rate, and mosquitoes take blood meals more frequently, up to a certain ceiling determined by individual species.
Some VBZD agents prevalent in the U.S., including Lyme disease and Hantavirus, show evidence of seasonality Current evidence suggests that the range of these diseases could change with a changing climate. Nevertheless, our current understanding of the complex transmission cycles of these diseases, along with incomplete understanding of the ecology of insect vectors and animal hosts, and the lack of long-term historical datasets linking weather with VBZD outcomes, makes projections very difficult for VBZD currently prevalent in the U.S.
Long-term research on weather and climate effects on VBZD, including variables not related to climate, such as population dynamics, preventive activities, land use changes, trade and travel, civil unrest, water availability, and other issues, are needed for more confident projections of climate change’s effects on VBZD. Effective prevention and control strategies are known for the majority of these diseases, and such research would greatly increase the effectiveness of early warning systems and other public health strategies for preventing epidemic disease.
Additional Information about Vector-borne and Zoonotic Disease
CDC National Center for Zoonotic, Vector-Borne, and Enteric Diseases
Additional Readings about Climate Change and Vector-borne and Zoonotic Diseases
Collinge SK, Johnson WC, Ray C, Matchett R, Grentsen J, Cully JF, Jr., Gage KL, Kosoy MY, Loye JE and Martin AP. Testing the generality of a trophic-cascade model for plague. Ecohealth. 2:1-11, 2005.
Eisen RJ, Glass GE, Eisen L, Cheek J, Enscore RE, Ettestad P, and Gage KL. A spatial model of shared risk for plague and Hantavirus pulmonary syndrome in the southwestern United States. Am J Trop Med Hyg. 77:999-1004, 2007.
Enscore, RE, Biggerstaff BJ, Brown TL, Fulgham RF, Reynolds PJ, Engelthaler DM, Levy CE, Parmenter RR, Montenieri JA, Cheek JE, Grinnell RK, Ettestad PJ, and Gage KL. Modeling relationships between climate and the frequency of human plague cases in the southwestern United States, 1960-1997. Am J Trop Med Hyg. 66:186-196, 2002.
Glass GE, Cheek JE, Patz JA, Shields TM, Doyle TJ, Thoroughman DA, Hunt DK, Enscore RE, Gage KL, Irland C, and Bryan R. Anticipating risk areas for Hantavirus pulmonary syndrome with remotely sensed data: re-examination of the 1993 outbreak. Emerging Infectious Diseases. 6:238-247, 2000.
Parmenter RR, Yadav EP, Parmenter CA, Ettestad P, and Gage KL. Incidence of plague associated with increased winter-spring precipitation in New Mexico, USA. Am J Trop Med Hyg. 61:814-821, 1999.