BERLIN – A dangerous but scarce, mosquito-borne virus has turned up in a mosquito pool from northwest Worcester County, only a week after the first probable case of West Nile Virus (WNV) in 2007 was identified in Worcester County.
A state lab found eastern equine encephalitis (EEE) in a mosquito pool from a swamp on the Worcester County side of the Pocomoke River, just west of Whaleyville. Luckily, these sinisterly named “dark swamp mosquitoes” rarely leave the swamp and feed mostly on birds.
EEE is no exotic virus, having been present in Worcester County for certain since 1933, unlike WNV, which arrived in the United States in 1999. According to Maryland Department of Agriculture mosquito control chief Cy Lesser, historical accounts going back to colonial times describe symptoms in horses similar to EEE.
“It’s rare and it’s not,” said Lesser. “We have periods when we’ll find multiple collections of mosquitoes harboring the virus, for a couple years in a row. Then it’ll disappear for a couple years.”
The virus is not restricted to horses, despite the name, occurring most frequently in local birds. While the local avians are adapted to EEE and rarely suffer more than a minor illness, humans, horses, emus and ostriches can develop serious illnesses and die from the disease.
Although the disease is rare, it carries a 50-percent fatality rate in those who develop illness, and the survivors do not emerge unscathed.
“Even if there’s not a fatality, the people who do survive have really severe neurological complications for the rest of their lives,” Lesser said. “It’s a very nasty virus.”
In contrast, less than 10 percent of WNV sufferers with neurological symptoms die.
Horses and flightless birds can be protected with a vaccine, but there is no EEE vaccine for humans.
Maryland’s last human case of EEE was reported nearly 20 years ago, in 1989, but there were two horse victims in Worcester County in 2003 near Pocomoke City.
Lesser said there are no plans for more mosquito-spraying in the area where the EEE infected mosquitoes were found because of its isolation. The historical presence of EEE means that the area is already intensely monitored, he said, and that will continue into the fall. “The risk of the virus diminished greatly as the weather starts to cool,” he said.
The possible West Nile Virus case identified in Worcester County last week, the first this year in Maryland if proved, has not been confirmed yet.
“We have not received the final testing results. They’re not complete yet,” said Kelly O’Keane, from the office of the Worcester County Health Officer.