As climate change expands the habitats of vectors, infectious diseases carried by mosquitoes, ticks, and fleas may spread into LA County. The spread of vector-borne diseases is unpredictable, as vector-borne disease incidence depends on many variables, including changing land use, human behavior, demographics, and other factors. However, what is known is that climatic conditions such as temperature, rainfall, and humidity all affect the population size and geographic distribution of vectors, and that changes to these conditions will correspondingly change the range of vector-borne diseases.
One important vector in the context of climate change in LA County is the mosquito. West Nile virus (WNV) cases are increasing in LA County.11 It has been shown that higher temperatures correlate with the increased incidence of West Nile virus in humans.12 In addition, the invasive Aedes mosquitoes (Aedes aegypti and Aedes albopictus) responsible for the transmission of dengue, Zika, and chikungunya, have now been found in Southern California. Although there have been no known locally acquired human infections with any of these three diseases in California to date, the possibility of local transmission is a concern as infected travelers arrive from areas where these diseases are endemic.13