Health officials in Canada are closely monitoring the public health situation in Massachusetts following reports of a person contracting Eastern Equine Encephalitis (EEEV) from a mosquito bite. A man in his 80s contracted the disease, becoming the first known human case of EEEV in the state since 2020.
Ten Massachusetts communities have closed parks and plazas after dark and urged some residents to cut back on outdoor activities.
“EEEV is endemic in Canada; however, the diagnosis of EEEV in humans is a rare event,” the Public Health Agency of Canada wrote in a statement to CTV News.
“There have been only four confirmed human cases of locally transmitted EEEV in Canada since 2016, the most recent occurring in 2022.”
Sporadic cases of EEEV in horses are observed each year and promptly reported to the Canadian Food Inspection Agency. As of August 17, 2024, no human cases have been reported and six confirmed cases of EEEV in horses (five in Ontario and one in Quebec) have been reported for the 2024 mosquito season. PHAC is taking a One Health approach, recognizing the interconnectedness of humans, animals, plants and their shared environment, and working with human and animal health partners to closely monitor the situation.
“At this time, while the overall risk of EEEV to humans is low in Canada, some local public health units in Canada have recommended taking precautions in areas where EEEV activity in horses has recently been reported.”
Infectious disease specialist Dr. Lisa Barrett said the mosquitoes that carry the virus are typically the type that come out at night. To avoid contact, people living in high-risk areas should reduce their outdoor activities at night.
“There are several things you can do to reduce your risk,” says Dr. Barrett, including staying out of the water, covering your skin with long sleeves and pants, and wearing plenty of insect repellent.
Dr. Barrett is not surprised that Massachusetts officials are taking the risks seriously.
“This virus does not spread from human to human and sometimes if an infected mosquito bites a human, the person that is bitten can become infected and the mortality rate is high,” said Dr. Barrett, who added that the mortality rate is between 30 and 50 percent and that symptoms usually appear in about 10 days. “They will have fever, headache, changes in their thinking and become very confused, and sometimes diarrhea and muscle aches.”
Dr. Barrett added that in rare cases, children and older people who contract the virus can suffer brain inflammation that can lead to permanent disability.
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