‘Tis the season for mosquitoes, so ‘tis the season for some nasty vector-borne diseases. Few are worse that Eastern Equine Encephalitis (EEE), a viral infection that causes typically fatal disease in horses, and less commonly other species, including people. Cases tend to start mid-summer and peak late summer to fall, depending on the mosquito dynamics in the particular area.

This series of maps from WormsAndGermsMap (below) shows the progression of this disease in horses along the east coast of the US so far this year. Note that some flags represent multiple cases that occurred in the same area, so just counting flags doesn’t tell you the whole story.

I haven’t seen any reports of EEE in Canada in 2016 – yet. It’s a rare disease here but we often see a handful of equine cases each year.

Prevention

For horses, there is an effective vaccine. Vaccination is recommended in horses that live in (or travel to) typically affected areas. In areas where occurrence of EEE is rare but still plausible, it’s a good insurance policy, considering the safety of the vaccine and serious nature of disease, but it’s not considered a “core” vaccine.

The other important part of prevention is mosquito avoidance. That’s easier said than done, to some degree, but there are a number of things that can be done to reduce mosquito exposure, thereby reducing the risk of EEE as well as other mosquito-borne diseases (e.g. West Nile).

For people, the key is mosquito avoidance. A human vaccine is not available.

We haven’t heard the last of EEE this season, and we probably haven’t even neared the peak, unfortunately. The map is updated as cases come in so check WormsAndGermsMap for updates at any time.

July 16

July 1

June 1

May 1