RALEIGH -

A four-year-old Halifax County horse has been euthanized after becoming North Carolina's first victim this year of the mosquito-borne disease Eastern Equine Encephalomyelitis.

State Veterinarian David Marshall said Monday this is the peak time of year for diseases caused by mosquito bites. Marshall says the number of cases fluctuates. Last year, there were six, but in 2009 there were 23. Marshall says that for every case that is confirmed, there may be four others that go unreported.

The disease can be prevented by an annual vaccination for horses, mules and donkeys. Although humans and horses can get the disease from mosquito bites, there's no evidence that horses can transmit the virus to people.