What species have a natural transmission cycle associated with SLE and WN disease?

The correct response identifies wild birds as the species involved in the natural transmission cycles of St. Louis Encephalitis (SLE) and West Nile (WN) viruses. These viruses primarily propagate through a zoonotic cycle, where mosquitoes feed on infected wild birds, facilitating the transfer of the virus. Wild birds serve as key hosts for these viruses, allowing them to amplify and persist in the environment, which in turn enables mosquitoes to become vectors that can infect other birds and mammals, including humans.

In this dynamic, wild birds are particularly significant because many species are susceptible to infection by these viruses, and their populations can sustain viral transmission over time. Infected mosquitoes that feed on these birds then play a crucial role in contaminating additional hosts, maintaining the cycle of transmission. This interdependence between wild birds and mosquitoes is foundational to understanding the epidemiology of SLE and WN diseases.

While rodents, ungulates, and humans are affected by these viruses, they do not play a central role in the natural transmission cycle. Rodents and ungulates can serve as incidental hosts or dead-end hosts, meaning that while they can become infected, they are not involved in the primary transmission pathways. Humans are also not part of the natural transmission cycle