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Your Environment. Your Health.

Vector-borne Diseases

Climate Change and Human Health

Health department workers of KMC (kolkata municipal corporation) waiting outside a residential house, for spraying disinfection liquid to stop the spread of mosquito born diseases
(Editorial credit: suprabhat / Shutterstock.com)

Climate change, notably through temperature extremes and precipitation patterns, is affecting the geographic distribution, seasonality, and incidence of vectors and the diseases they transmit, known as vector-borne diseases1. Vectors like mosquitoes, ticks, and fleas, can carry infective pathogens, such as viruses, bacteria, protozoa, and parasitic worms. The most common way vectors can transfer pathogens to other animal hosts, including humans, is by biting or bloodsucking.

Climate Change Impacts on Vectors and Human Health

Vectors and vector-borne diseases are found throughout the world. Globally, hundreds of millions of cases and over 700,000 deaths occur from vector-borne diseases annually2, 3. The most well-known diseases include dengue, malaria, chikungunya, yellow fever, and Zika from mosquitoes; Lyme disease from ticks; plague from fleas; and schistosomiasis from aquatic snails. Symptoms from these diseases can vary and include headache, pain, fatigue, dengue hemorrhagic fever (DHF), encephalitis, and nausea. The impact on health effects from vector-borne diseases, including their extent and frequency, will vary as the climate changes.

Side-by-side maps of the Northeast and Upper Midwest in 1996 and 2018, showing a dot for every reported case of Lyme disease.
Climate Change Indicators: Lyme Disease. Lyme disease cases reported in 1996 and 2018. (Graphics courtesy of EPA.gov)

Vectors are sensitive to their environments, including climate and land use characteristics and socioeconomic factors4. Short-term and long-term changes to climate are affecting vectors. Short-term seasonal changes in temperature affect the life stages of vectors and pathogen replication within hosts5, 6. Increased precipitation can amplify the number of vector breeding sites, while more frequent or lengthening drought cycles in some areas can cause a decrease in vectors that require water for their life cycle and habitat7. Long-term changes to climate are expanding the geographic range and distribution of vectors, allowing species to inhabit and thrive in new areas8.

Opportunities for Public Health Improvement

Vector control is an essential approach to preventing and responding to vector-borne disease outbreaks. Stabilizing ecosystems through greenhouse gas reduction and forest and wetland preservation to limit climate variability and contain vector habitats are some strategies. In addition, improving surveillance systems and implementing early warning systems can reduce exposure to vectors and reduce the susceptibility of vector-borne diseases in exposed populations.

Research Needs

Research is critical to further understand the effects of climate change and vector-borne diseases. Because of the intricacies of climate and non-climate factors that affect vectors, additional research is needed to better understand the mechanisms of how these factors interact and influence pathogen transmission. Modeling these interactions is an important strategy and accounts for multiple considerations, such as vector-host interaction, vector and host habitats, host immunity, pathogen evolution, and land use. These tools and the increase in research on vector-borne diseases will lead to better translation to public health actions to reduce exposure and prevent disease.

Socioeconomic drivers, along with altered human behaviors and increased adaptive capacity, can influence exposures and transmission of vector-borne diseases. Further research in this area can help communities reduce the chance of future vector-borne disease threats.

  1. Vector-borne diseases. Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Every year there are more than 700,000 deaths from diseases such as malaria, dengue, schistosomiasis, human African trypanosomiasis, leishmaniasis, Chagas disease, yellow fever, Japanese encephalitis and onchocerciasis. (2020). World Health Organization. [Full Text Vector-borne diseases. Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Every year there are more than 700,000 deaths from diseases such as malaria, dengue, schistosomiasis, human African trypanosomiasis, leishmaniasis, Chagas disease, yellow fever, Japanese encephalitis and onchocerciasis. (2020). World Health Organization.]
  2. Diseases Carried by Vectors. Climate is one of the factors that influence the distribution of diseases borne by vectors (such as fleas, ticks, and mosquitoes, which spread pathogens that cause illness). (2020). Centers for Disease Control and Prevention. [Full Text Diseases Carried by Vectors. Climate is one of the factors that influence the distribution of diseases borne by vectors (such as fleas, ticks, and mosquitoes, which spread pathogens that cause illness). (2020). Centers for Disease Control and Prevention.]
  3. Campbell-Lendrum, D., Manga, L., Bagayoko, M., & Sommerfeld, J. (2015). Climate change and vector-borne diseases: what are the implications for public health research and policy? Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 370(1665), 20130552. [Abstract Campbell-Lendrum, D., Manga, L., Bagayoko, M., & Sommerfeld, J. (2015). Climate change and vector-borne diseases: what are the implications for public health research and policy? Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 370(1665), 20130552.]
  4. Cissé, G., R. McLeman, H. Adams, P. Aldunce, K. Bowen, D. Campbell-Lendrum, S. Clayton, K.L. Ebi, J. Hess, C. Huang, Q. Liu, G. McGregor, J. Semenza, and M.C. Tirado, 2022: Health, Wellbeing, and the Changing Structure of Communities. In: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. In Press. [Full Text Cissé, G., R. McLeman, H. Adams, P. Aldunce, K. Bowen, D. Campbell-Lendrum, S. Clayton, K.L. Ebi, J. Hess, C. Huang, Q. Liu, G. McGregor, J. Semenza, and M.C. Tirado, 2022: Health, Wellbeing, and the Changing Structure of Communities. In: Climate Change 2022: Impacts, Adaptation, and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press. In Press.]
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