Special Report: Population movement signals new threats - DVM
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Special Report: Population movement signals new threats

DVM InFocus

Western equine encephalitis hasn't been a problem in California for several years, largely because of vaccination coverage, Brault says, but the eastern variety has been an issue recently for the Northeast.

Officials in Massachusetts and New Hampshire already are preparing to go on the attack against the mosquitoes that cause both eastern equine encephalitis (EEE) and West Nile Virus after EEE affected eight persons in New Hampshire and 13 in Massachusetts over the last three years.

Both viruses affect horses and birds, but usually not pets.

New Hampshire earmarked $180,000, a third of it for mosquito surveillance and two-thirds to reimburse southeastern New Hampshire towns that adopt mosquito-control programs aimed at killing larvae.

Last year's severe drought in the Southeast eased somewhat over the winter and with recent spring rains. "Typically drought tends to shut down mosquito-borne illness like West Nile and EEE, but our drought situation turned around to some degree. Still, it's hard to predict what it (mosquito activity) will be like before about mid-June," says Jonathan F. Day, University of Florida professor of medical entomology at the Florida Medical Entomology Laboratory at Vero Beach.

"In urban areas, like Atlanta, even though the drought shuts things down, mosquitoes still are in storm drains. They just need a way to get out. If the drought persists, they don't do well, but if there's some wetting they can get out and that would favor tranmission of virus."

In Kentucky, meanwhile, University of Kentucky entomologists say they're seeing no indication of higher than normal numbers of the Eastern tent caterpillar, linked to mare reproductive loss syndrome (MRLS) in horses.

With the egg-hatch stage just completed, horse farms were advised to watch for the insect's white tents in cherry and crabapple trees and keep mares away from suspected caterpillar locations, or apply foliar sprays to the trees if the horses can't be moved from areas of potential exposure.

MRLS hit the state's Thoroughbred horse country especially hard in 2001.


Source: DVM InFocus,
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