GAINESVILLE, FLA. — It's a big year for mosquitoes in Florida, and one result is a much higher incidence of Eastern equine encephalitis (EEE).
"We want to get the word out that EEE is a serious problem here this year, so anyone bringing horses down from the North should
make sure the animals are vaccinated," Maureen Long, DVM, MS, PhD, Dipl. ACVIM, assistant professor of equine and large-animal
medicine at the University of Florida's College of Veterinary Medicine, tells DVM Newsmagazine.
About 75 horses, mostly in north and north-central Florida counties, which have the state's highest equine populations, were
infected with EEE by the middle of August, Long says, adding that "we're only at the beginning of the peak season for EEE.
We haven't seen numbers like that at this point in the season for a long time."
While most horses are vaccinated against EEE, younger horses that haven't had time to build up sufficient immunity from vaccines
are most at risk, she explains.
Emu farms, which raise the large birds for meat and for pets, also present a risk. "They're very pathogenic for EEE," Long
says. The birds shed the virus, putting producers at risk while butchering, and veterinarians while examining the pet birds.
There can be spillover risk to dogs and other animals, too. "Any mosquito-borne virus can be seen in many animals; mosquitoes
may seek a blood meal from anything that walks. When you start seeing it (virus) in species in which you don't normally see
it, that's a strong indication of a serious problem. So the warning is out there that it's time to adjust behaviors as necessary
to deal with it," Long says.
In addition to the nearly 75 equine cases of EEE, three emus, one alpaca and one dog have been infected, but so far no human
cases have been reported.
Populations of mosquitoes that breed in salt marshes near Florida's ocean and Gulf shores, where most people live, are surging
in concentrations not seen in more than a decade, entomologists say, and they're tough to control because of built-up resistance
to several pesticides and the fact that water levels in the marshes are low.
Because salt-marsh mosquitoes don't lay their eggs in free-standing water, many counties, including Brevard County on the
eastern coast around Cape Canaveral, have built mosquito impoundments, or earthen dikes, around marshes and mangrove swamps
to flood out the pests, but this year water levels in them are much lower because of insufficient rain, allowing the mosquitoes
to lay their eggs in moist soil above the water mark.
The same is true on the state's Gulf coast.
"This is indeed one of our worst years for salt-marsh mosquitoes," James Burgess, entomologist with the Lee County Mosquito
Control District near Fort Myers, tells DVM Newsmagazine. "I don't believe we've seen them in these numbers in the last four or five years, following some good years when there was
enough rain to flood them out."