Mosquito-Borne Virus Takes Two Lives

On Sept. 4 concerned Vermonters gathered together in the Brandon Town Hall for a public informational meeting held by state officials regarding the recent outbreak of Eastern Equine Encephalitis (EEE) in the Brandon area. The deputy secretary of agriculture, the chief of the pesticide division, three representatives from the Vermont Department of Health and other government officials called the meeting to make a presentation about EEE and the state’s decision to spray a pesticide in hopes of reducing the adult mosquito population as well as to answer questions from the public.

Concern surrounding EEE emerged in late August when two men, one in his late 80’s the other mid-40’s, fell ill with confirmed cases of the virus. At the time of the meeting, one of the men had passed away and the other remained in a coma; he died a few days later. Wanting to take immediate action to mitigate further infection from the virus, state officials agreed the best solution was to spray swampy areas, which posed the greatest risk in Brandon, Whiting, Leicester and parts of Shoreham.

Eastern Equine Encephalitis is a rare, but potentially fatal, mosquito-borne viral infection. Those infected with the disease can develop two main types of symptoms: flulike symptoms that evolve gradually and a more severe set of illnesses which affect the central nervous system and cause convulsions, headaches, irritability, drowsiness and comas. One of the men who died had been in a coma for days before his death. EEE does not have a treatment and is difficult to detect due to the similarity its symptoms have with other, more common diseases. Oftentimes, therefore, by the time an infected person is hospitalized, it is too late to treat. According to Vermont Health Commissioner Harry Chen, the EEE virus is fatal in one third of all cases.

According to Vermont State Representative Will Stevens of Shoreham, the number of cases contracted annually is typically low.

“What’s odd about this [virus], is that nationwide annually, there are about six reported cases,” Stevens said. “And we’ve had two in Vermont [so far this year] and both were fatal.”

Not surprisingly, this rare occurrence has sparked fear in Vermonters. This year’s outbreak was the first time EEE has been contracted by a human in the state; in 2011, emus were tested and confirmed to be infected with the disease. Chen declared this human infection an imminent health emergency.

“We want to take every reasonable action to prevent people from becoming infected,” said Chen in a public health announcement.

One of these actions was to spray a mosquito pesticide, Anvil 10+10 (Sumithrin), from a fixed-wing plane over areas where state officials had trapped mosquitoes that tested positive for EEE and in the vicinity of where the two victims had lived. The spraying, which was intended to target the adult population of mosquitoes before they were due to lay eggs, would occur at dusk when mosquitoes were most active.

As a result, the spraying was time sensitive. Vermont currently has 45 species of mosquitoes present, most of which are nuisance mosquitoes that lay their eggs in ephemeral pools of still water.

“The problem here is that [mosquitoes carrying EEE] are not like the nuisance species,” Stevens said. “Mosquitoes that carry EEE are different. Peak emergence is in middle to late August and then they lay their eggs, which then hatch into larva and mature over winter. Their habitat is acidic, hardwood swamps. So you can’t treat them the same way as the nuisance species and that is one of the reasons that justified that they needed to aerially treat.”

To spray from the air, the Vermont Agency of Agriculture used the mosquito control fund to pay for a Dynamic Aviation plane to fly up from Texas. These planes possess sophisticated computer systems, which account for wind direction and speed and can spray within exact coordinates. This was important, as many organic farms are located on the periphery of where EEE was located. The conditions for the spray, therefore, needed to be very specific; it couldn’t be too windy or overcast.

“Given the conditions, they needed to act right away to get one application [of pesticide] done,” said Stevens.

The spraying took place on Sept. 6, two nights after the informational meeting in Brandon, but not without some hesitation from the public.

“The general reaction of the public was resignation,” Stevens said. “I think there was general support for [the officials’] decision.  There were expressions of concern about the product, but in general I think people were resigned to the fact that something had to be done, and spraying was that thing at that time.”

As fall and the promise of cold weather approaches, the threat of contracting EEE becomes less imminent. A hard frost will kill off any remaining mosquitoes. Nevertheless, a statement released by the Vermont Department of Health reminds individuals to reduce the likelihood of infection by limiting time spent outdoors at dawn and dusk, wearing long sleeved pants and shirts and using effective insect repellents.

“So long as mosquitoes are out there, [EEE] is always a risk,” reflected Stevens.  “We’re entering a new time — we have pests and diseases now that we didn’t have 31 years ago. I think that this is all part of a new normal that we’re going to have to figure out our relationship with.”

Although EEE was never a direct threat to the town of Middlebury or the College, officials maintain that individuals all around the state should remain cautious. The symptoms of EEE are largely undistinguishable from those of other diseases, but still can have serious, potentially fatal side affects.