Florida EEE cases up sharply with mosquitoes on rise - DVM
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Florida EEE cases up sharply with mosquitoes on rise
75-plus horses affected in northern counties; risk of WNV also heightened


While salt-marsh mosquitoes are a huge annoyance for humans, they aren't responsible for spreading EEE or West Nile virus. They can, however, spread heartworm in dogs and cats, prompting veterinary clinics to place even greater emphasis on preventive medication.

"There probably are 60 different mosquito species in Florida," Burgess explains. "The salt-marsh variety live about 30 days, feed at night and can fly up to 20 miles on the wind. Fresh-water mosquitoes live about two weeks and feed in the daytime. The ones that carry encephalitis lay their eggs in standing water. The particular one responsible for EEE, culiseta melanura, breeds mostly in swampy areas in central and northern Florida."

That mosquito typically doesn't bite mammals but does amplify the virus, after which a "bridge vector" mosquito such as Cq perturbans, passes the virus on to horses and humans, according to James Clauson, environmental administrator for the state's Bureau of Entomology and Pest Control, Department of Agriculture and Consumer Services, in Tallahassee.

"EEE season normally peaks in late summer to early fall, and West Nile is more prevalent in the later part of the season," through late September and early October, Clauson tells DVM Newsmagazine.

Only one case of West Nile virus in a horse was reported in the state by mid-August, in Madison County near the Georgia border. The mosquito Culex pipiens carries West Nile.

"Human cases of WNV are most frequent between July and September, although we have not had any human cases yet this year. WNV activity currently is low to average in our animal sentinels," says Danielle Stanek, DVM, medical epidemiologist in the Bureau of Environmental Public Health Medicine, Florida Department of Health. "With that said, it only takes the bite of one infected mosquito for transmission to a person, and there are certainly mosquitoes carrying WNV out there, so good control and bite prevention are essential."

"The state experienced a drought the past two years, and only now are we seeing normal rain patterns. The eggs that have laid dormant for the past couple of years may be hatching off with the recent rains, and that may explain some of our unusually high numbers of mosquitoes," Clauson says.


Source: DVM360 MAGAZINE,
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