The mosquito-borne Eastern equine encephalitis, or EEE, has claimed the lives of two alpacas and has sickened a horse in Dunn County. According to state animal health officials, blood samples were sent to the University of Minnesota Veterinary Diagnostic Laboratory about a month ago, where initial positive results were then confirmed by the Pennsylvania Animal Diagnostic Laboratory System.
"Horse owners who have not already had their animals vaccinated this year for EEE and other mosquito-borne diseases should take this as a warning, and those who have vaccinated should check with their veterinarians to see whether a booster is indicated," said State Veterinarian Dr. Robert Ehlenfeldt. "There is no approved vaccine for alpacas. Alpaca owners should consult their veterinarians about preventive measures."
EEE may be transmitted by mosquito bite to horses, birds, and humans. It is unusual for alpacas and other mammals to be infected. The virus is not transmitted between animals or between animals and humans.
Ehlenfeldt says symptoms in horses include depression, loss of appetite, drooping eyelids and lower lip, aimless wandering and circling, blindness and sometimes paralysis. There is no cure for EEE, he says.
Wisconsin experienced a major outbreak of EEE in 2001. That's when 69 confirmed or presumptive positive cases were discovered, mostly in northwestern Wisconsin. Since then, sporadic cases have occurred.
The state's agriculture department says horses that have never been vaccinated will need two doses two to four weeks apart, and the vaccine will take at least two weeks to build up enough antibodies to protect them. A booster would normally be only one dose and would take about four days to be effective. Vaccines will not protect horses that have already been infected when they receive the injections. Vaccines are available that protect against other strains of equine encephalitis along with EEE, and a separate West Nile virus vaccine is also available.
EEE illnesses are caused by a virus that attacks the central nervous system. Although humans may also contract EEE, no human cases have appeared in Wisconsin.