Officials from the Vermont Department of Health and the U.S. Centers for Disease Control, or CDC, want to conduct a study in Vermont that hasn’t been carried out in the U.S. for more than four decades.
On Town Meeting Day, they hope to test hundreds of Vermonters in three towns for the incidence rate of eastern equine encephalitis, or EEE.
Department Commissioner Harry Chen and four other state officials met with more than 50 concerned residents in Whiting’s town hall on Thursday to talk about how the state and town might handle the incurable and potentially fatal mosquito-borne illness. Discussion wandered from the nature and history of the disease to the state’s proposed research project to concerns about aerial spraying of insecticides and state practices.
Thursday’s meeting follows the EEE-caused deaths of a Sudbury and a Brandon man this fall and the aerial spraying of insecticides over large swaths of land in six Addison and Rutland county towns.
In 2010, state officials discovered the virus for the first time in Vermont by sampling the blood of deer and moose brought in by hunters. The ruminants were carrying EEE antibodies but appeared to have successfully fought off the virus. Erica Berl, an infections disease epidemiologist for the Health Department, said mammals either fight off the virus or die.
EEE appeared again in September 2011, when the virus killed more than a dozen emus in Brandon. Then, this past summer, the state discovered EEE in humans and mosquitos for the first time.
Alan Graham of the Vermont Agency of Agriculture has sampled more than 1 million mosquitos over a 15-year period and did not come across the virus until 2012. He said that although he began using a more effective EEE test this year, the sheer volume of mosquitos found with EEE this summer and fall — the densest concentration of which was in Whiting — suggests to him that the disease spiked in Vermont this year, which mirrors a similar uptick in Massachusetts. The only species of mosquitos found to be carrying the disease in Vermont were Culista melanura.
The problem for officials looking to address the problem is that there is very little information and data on the virus and its effects on humans. It is not prominent in the winter, when mosquitos aren’t active. But it will lay low for years, said Graham, and then, all of a sudden, it will explode.
“It just disappears,” he said.
Chen told the room that very little research has been done on the virus.
“As much as everyone in this room wants certainty, there is none,” said Chen.
A state-proposed study could bring some unknowns into focus — for both Vermont and the nation.
The study
Department of Health officials hypothesize that a number of Vermonters who live in the Addison and Rutland county areas with high EEE concentrations have contracted the disease without knowing it.
“What we don’t know is how many people become infected that don’t have severe symptoms or recover and don’t have symptoms at all,” said Chen.
To answer that question the department is proposing a human research project, where volunteers 12 and older from Brandon, Whiting and Sudbury would donate a blood sample on Town Meeting Day.
“It would be completely voluntary, but we’d love to get 100-200 individuals,” said Patsy Kelso, a state epidemiologist who was present at the meeting. “We could really learn how many people have antibodies to EEE and were never infected, so that could really add a lot to our understanding of this and what the risk is of being infected and getting sick if you are infected.”
The U.S. Centers for Disease Control (CDC) supports the proposal, and the federal body has agreed to carry out the testing for the state if it’s approved.
Dr. John-Paul Mutebi, a CDC entymologist who specializes in vector-borne illnesses, said that the last time such a study was conducted was in New Jersey in 1969.
“It would give us a pretty good idea of, one, the transmission potential of the virus, and, number two, how effective it really is,” he said. “This information would help us find a better way to protect people. Not only to use in public outreach, but also in planning control and prevention programs.”
Right now, a team of physicians from Fletcher Allen Health Care and the state Health Department are drawing up a study proposal for the Vermont Agency of Human Services’ Institutional Review Board, or IRB. The state IRB will evaluate the ethics and soundness of the proposed study. If the state IRB approves it, Kelso said the proposal would then go through an expedited IRB approval process via the Fletcher Allen and CDC boards.
The reason officials want to draw blood on Town Meeting Day is because a lot of people will be in one place at one time, and Kelso hopes 200 volunteers will participate in each town.
The tests won’t be conducted for diagnostic purposes, said Kelso, and no participants will find out the results.
“This is a research project,” said Kelso. “It’s a selfless act, giving blood and participating.”
Chen qualified that the aim of the study is purely for gathering information.
“There’s a heck of a lot we don’t know and one of the ways we can learn more is by doing studies,” said Chen.
Concerns
Those present at the meeting did not voice concern about the study, but many did take issue with other practices.
One concern that frequently came up was the state’s aerial application of insecticides in September, which was the first time the Agency of Agriculture targeted mosquitos from the sky.
One of the main reasons the state used this method, officials said, is because mosquito havens in remote Addison and Rutland county wetlands are not accessible from roads.
“We only sprayed because we saw repeated piles of mosquitos with EEE,” said Graham. “So the question is do we spray or not? Do we let you know there’s a high risk and not do anything? If we only spray part of it, we don’t really hit the problem.”
The state sprayed a synthetic insecticide called Anvil, which was used instead of its organic cousins in the pyrethrin pesticide family. The synthesized version was used to mitigate negative effects on bee populations. State officials said Anvil is designed to dissipate within hours, and field tests after the spraying showed bee populations weren’t affected, said Graham.
Anvil is classified as an “adulticide” and the state used it to target adult mosquitos. The reason the state didn’t go after the larvae of the Culista melanura, said Graham, is because they burrow deep into the ground where larvacides can’t penetrate.
Paul Quesnel, a local farmer, took issue with the USDA’s practice of buying up cropland and returning it to wetland. He said that land once used for crop cultivation has been turned into hotbeds for mosquito breeding.
“They’re using tax dollars to take this land out of production to create wetlands and now we’re being forced to pick up the price of spraying,” he said. “And who wants to spray insecticides widespread?”
Agency of Agriculture officials told him that the issue was beyond the scope of the meeting and that in some wetlands increased fish activity keeps mosquito populations down.
“We’re seeing fish in (Leicester) that we have not seen for 10 years,” said Graham. “There will not be mosquitos in areas that retain water like that with fish.”
