Arbovirus: A class of viruses transmitted to humans by arthropods such as mosquitoes and ticks.
Some mosquito species rarely bite humans; they feed on infected birds called “hosts”. Newly infected mosquitoes then feed on non-infected birds causing an amplification of that virus in the local bird population. These mosquitoes are referred to as “primary vectors”.
The infected birds then become a blood-meal source for other mosquito species who themselves become infected. These other infected mosquito species can then bite humans. The species capable of infecting humans are known as “bridge vectors”.
Humans and other mammals affected in this cycle are known as “dead end or incidental hosts”. This means they do not develop high levels of the virus in their bloodstream needed to pass the virus to other biting mosquitoes.