What type of hosts typically sustain the transmission cycles of EEE?

The correct answer identifies horses as key hosts that sustain the transmission cycles of Eastern Equine Encephalitis (EEE). Horses are considered amplifying hosts for EEE because they can become infected with the virus and develop high levels of the virus in their bloodstream, which then can be transmitted to mosquitoes that feed on them. This process perpetuates the cycle of the virus among mosquito populations, facilitating further transmission to other hosts, including humans.

While humans can become infected, they are typically incidental hosts, meaning they do not sustain the cycle of transmission because they do not produce sufficient viral loads to infect mosquitoes. Wild birds also play a critical role in the ecology of various arboviruses, but for EEE, horses specifically are known to be the primary amplifying hosts, enhancing the chance of the virus being passed on to mosquitoes. Small mammals can also be involved in some aspects of the transmission cycle for different arboviruses, but they do not play the same significant role as horses in the context of EEE. The focus on horse populations underscores the importance of monitoring and controlling EEE in equine species to reduce the risks of outbreaks affecting humans and other susceptible hosts.