A vector is an organism that can transmit infectious agents from one infected person or animal to another. Vectorborne diseases are responsible for an enormous amount of morbidity and mortality across the globe, although the heaviest burden falls on countries in tropical and subtropical areas. Weather (both temperature and rainfall) has an enormous effect on the prevalence of disease and on its range and geographical distribution. Scientists are concerned that climate change will extend the range of vector-borne diseases and increase the severity of seasonal epidemics.
A partial list of diseases that can be spread by vectors is shown below.
- Chagas disease - Transmitted through triatomine bugs, contaminated food, infected blood transfusion
- Chikungunya - Viral disease transmitted to humans by infected mosquitoes
- Dengue - Mosquito-borne infection that may cause lethal complications
- Dracunculiasis - Parastitic infection caused by drinking-water containing water fleas that have ingested Dracunculus larvae
- Human African trypanosomiasis - Glossina-borne parasitic infection, fatal without prompt diagnosis and treatment
- Leishmaniasis - Infection is caused if bitten by female sandflies
- Lymphatic filariasis - Infection occurs when filarial parasites are transmitted to humans through mosquitoes
- Lyme disease - Disease caused by infected ticks
- Malaria - Caused by a parasite plasmodium, transmitted via infected mosquitoes
- Onchocerciasis - Parasitic disease caused by the filarial worm onchocerca volvulus
- Schistosomiasis - Parasitic disease caused by trematode flatworms
- West Nile virus - Transmitted through the bite of infected mosquitoes; the mosquitoes acquire the virus when they bite infected birds
- Yellow fever - Viral disease transmitted via aedes mosquitoes
According to WHO, "Vector-borne diseases account for 17% of the estimated global burden of all infectious diseases. The most deadly vector-borne disease, malaria, caused an estimated 627 000 deaths in 2012. However, the world's fastest growing vector-borne disease is dengue, with a 30-fold increase in disease incidence over the last 50 years."