Humans are considered dead-end hosts for which mosquito-borne illness?

Humans are considered dead-end hosts for several mosquito-borne illnesses, including St. Louis Encephalitis (SLE), Eastern Equine Encephalitis (EEE), and La Crosse Encephalitis (LAC). Being a dead-end host means that the virus cannot replicate effectively within the human host, leading to minimal or no transmission back to mosquitoes.

For instance, even though humans can become infected with these viruses, they typically do not reach high enough levels of the virus in their bloodstream to pass the infection on when bitten by mosquitoes. As a result, while humans can experience illness from these pathogens, they do not serve as a significant reservoir for the transmission cycle of these viruses. This is an important aspect of vector biology and control strategies, as recognizing the role of humans as dead-end hosts can guide public health efforts to control mosquito populations and reduce the risk of disease transmission.

In this context, it is correct to state that humans serve as dead-end hosts for all the mentioned encephalitides, supporting the assertion that option 'D' is the right answer.