The season’s first Eastern equine encephalitis-bearing mosquitoes have been detected in Bridgewater, Massachusetts, according to public health officials.
The news comes a day after officials elevated the health risk posed by West Nile virus, another mosquito-borne disease, in Boston and in Brookline, after more samples of infected bugs were found in those communities.
The batch of Bridgewater mosquitoes with EEE was collected July 19, officials said.
No people have been infected with either virus this year, but last season was an especially active summer for encephalitis.
One Massachusetts resident was infected with EEE in 2010, as well as a Rhode Island resident who, officials believe, was probably exposed to the virus in Massachusetts.
Because of the threat of further infections during 2010, disease trackers called for large-scale aerial spraying to lower the mosquito populations in Bristol and Plymouth counties.
Eastern equine encephalitis (EEE) is a seasonal and geographically variable disease. The variablity of the disease relates to the types of mosquitoes that transmit the virus to horses, where they tend to be found, and the time of year they are active.
This year infected horses have been identified in Marion County and Holmes County, in Florida.
People who have horses in areas where EEE tends to occur or who will be taking their horse to such an area should ensure that the horses are properly vaccinated against the disease. Ideally, the booster is given a month or so before the risk of infection really begins. That varies a little between regions but tends to be late July or early August.
The other key aspect of EEE avoidance is mosquito avoidance. While completely preventing mosquito exposure is pretty much impossible, practical measures should be taken to reduce bites.