State and local experts are urging area horse owners to seek vaccinations for their animals to prevent the spread of mosquito-borne diseases.

The level of urgency recently increased because a wet spring has left numerous areas with standing water, the perfect breeding ground for mosquitoes, which can carry West Nile Virus and Eastern Equine Encephalitis.

This week, Venaye Reece with Clemson University issued an equine alert that four cases of EEE were found in Berkeley County and one case in Georgetown County, the first cases this year, she said.

The disease can be deadly for horses and a serious risk for people, but vaccines reduce the chance of an outbreak, Reece said.

Humans rarely develop overt cases of EEE, according to a paper published by the Louisiana State University Agricultural Center.

Most people abort an EEE infection in its early stages, but children and the elderly are susceptible to severe cases. The disease causes serious illness in about one of 23 people with the chance of recovery less than 50 percent. Those who recover often develop mental problems.

"We strongly recommend vaccines to protect the horse and as public health protection," Reece said. "With Eastern, there is a 90 percent mortality rate [for horses], and with West Nile, the mortality rate is 35 percent."

Area weather conditions have been right for mosquito-borne diseases to flourish, officials said.

"We've had lots of moisture and we have lots of standing water where mosquitoes can do their thing," said Bruce Johnson, an extension specialist at Clemson Extension Service in Conway.

"It's like vaccinating your dogs and cats for rabies - you go ahead and do it. All it takes is one mosquito bite."

The risk of disease has prompted Ann Van Dyke of Beaver Dam Equestrian Center between Conway and Loris to vaccinate her 30 horses twice a year - at $25 a shot.

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Van Dyke first heard of the EEE and West Nile vaccinations in April 2002 and asked her veterinarian about it. At the time, Van Dyke said she was told the shots, which were developed in 2000, were too expensive and not proven to be effective.

But by September, all of the horses in Van Dyke's center were vaccinated.

"It's like any other vaccination, you just hope it's going to work. Without the shot, I think there could be real problems," she said.

Van Dyke said she is confident the vaccine will protect her horses but still worries that a vaccine has not been developed for humans and dogs.

State health officials confirmed the first S.C. case of West Nile Virus on August 13 in a dead blue jay in Lexington County.

Less than a month later, the state's first two horse cases were identified in Lexington and Anderson counties.