Seasonal trends in infectious diseases have been well studied. The peak transmission of the malaria parasites, for example, Plasmodium vivax and Plasmodium falciparum, tracks rainy seasons, which increase the abundance of the mosquito vectors, the parasite development in the mosquito vectors, and the vectors' biting activity. The survival of certain pathogens, such as the diarrheal disease cholera (Vibrio cholerae), is enhanced by warmer temperatures. Rapid fall cooling promotes the seasonal synchrony of larval and nymph ticks, promoting viral transmission of tick-borne encephalitis.
A wide range of events shape the behavior and social interactions of the human host. The spread of childhood communicable diseases mirrors school calendars and congregate activities. Holidays spur travel and novel social "mixing patterns," increasing the spatial distribution of disease transmission, even more efficiently vectored through packed planes and other modes of mass transportation. Seasonal shifts in immunity and host susceptibility, exacerbated by increased exposure through crowds during the colder months, will also increase patterns of infectious disease spread.
"Agent" and "host" are united by "environment," composing a trinity of factors that explain the distribution and transmission of disease within populations. This third element poses elevated concerns as we contemplate the effect of climate change on the incidence of infectious diseases.
Medscape Infectious Diseases © 2008 Medscape
Cite this: Climate Change and Infectious Diseases - Medscape - Jun 13, 2008.