What is primarily affected by mosquito-borne viruses like West Nile virus and Western equine encephalitis?

Mosquito-borne viruses such as West Nile virus and Western equine encephalitis primarily affect humans because these viruses are adept at utilizing mosquitoes as vectors to transmit the pathogens to humans. In the cycle of transmission, mosquitoes acquire the virus while feeding on infected hosts, often birds, which serve as the primary reservoir for these viruses. When these mosquitoes bite humans, the viruses can then be transmitted, potentially leading to illness.

The impact on human health is significant, as these infections can result in neurological diseases and other serious health complications. While birds are the primary hosts and play a critical role in the ecology of the viruses, it is humans and other mammals that are often the focus of public health concerns due to the direct health implications of virus transmission. Understanding this dynamic is crucial for effective mosquito control and public health strategies aimed at reducing the incidence of these viral diseases.