How mosquitoes spread Eastern Equine Encephalitis

Interviewer – What role do mosquitoes play in the life cycle of the EEE virus?

Dr. Sydney Crawley – So, mosquitoes are actually the bridge vector of this virus. So what that means is that you have a reservoir host and then you have the end host. Mosquitoes are the bridge; they will bite the reservoir host – in this case that is a bird – they will pick up the virus, and when they go on to bite a human or a horse or another host, the virus is going to pass from the mosquito to the next host. Now in this case, for EEE, horses and humans are actually considered dead-end hosts. So that means if a mosquito were to bite an infected human or horse and then bite the next animal, they’re not going to transmit the virus from humans and horses to something else. So that is the definition of a bridge vector, and that is the role mosquitoes play in EEE transmission.

Interviewer – So, how does climate change impact the prevalence and distribution of EEE?

Dr. Sydney Crawley – Warmer weather could theoretically mean that we have longer mosquito seasons and more “mosquito-active” days per year. That being the case, that could potentially increase the number of chances of a human-vector interaction. So, if the season is longer, mosquitoes are able to bite for more days out of the year, and humans are also outside on those days of the year, we could see more cases annually than we currently see.

Interviewer – Can you share any interesting facts or myths about Eastern Equine Encephalitis that most people may not know?

Dr. Sydney Crawley – Most mosquito species do not actually transmit the Eastern Equine Encephalitis virus, and it’s not like the flu, so you can’t pass the pathogen back and forth between two different people. It is very rare, but it is extremely serious when you contract it. And, again, it can be fatal in one of three people. So it’s definitely not a pathogen that we want to ignore or take lightly if you are living in an area where there is an active outbreak, but it’s also not something we should be overly concerned about day-to-day for most people living in the United States.