Beaufort Co. horse tests positive for mosquito-borne virus that can be deadly to humans
A mosquito-borne virus that can be deadly to humans was confirmed in Beaufort County after a horse died this month.
A horse found dead Nov. 8 on St. Helena Island tested positive last week for Eastern Equine Encephalitis — or Triple E — a disease caused by a virus carried by mosquitoes that can be contracted by humans, Beaufort County Animal Services director Tallulah Trice said. The case is the fourth found in an animal in South Carolina this year and the first in Beaufort County, according to the State Veterinarian Office.
The state office confirmed Monday that a 5-year-old gelding that died in Beaufort County had tested positive.
Beaufort County Mosquito Control sprayed the area from an airplane the morning the horse was found dead, director Gregg Hunt said. The agency also set mosquito traps on the property, Hunt said, but they netted a low number of the insects, and none carried the virus.
“If there’s any indication (of a mosquito-borne virus), we move very quickly in response,” Hunt said.
The disease is rare in humans, with fewer than 160 cases in the United States during the past 35 years and about five to 10 cases reported in humans each year, according to state and federal agencies. No human cases were reported in South Carolina from 2009 to 2018, CDC data shows.
Vaccinating to protect other horses
County animal control officials received a call about an ill horse on St. Helena Island on Nov. 7. The horse was treated and given fluids and able to stand back up, Trice said.
But another call came the next day: the horse was found dead. The infected animal was near Little Horse Island, where a population of seven wild ponies lives.
Trice said she is working with veterinarian Dessie Carter and the ponies’ caretaker to develop a plan to vaccinate the ponies and other horses nearby against the disease.
Venaye McGlashan, the St. Helena resident who looks after the ponies, is a retired big animal veterinarian and former director of the State Veterinary Office. She said the animals are fairly isolated on their island and have been safe from other cases of disease.
Because of how close the infected horse was found, McGlashan said she and others would likely try to vaccinate the ponies soon.
The process, which may involve using a mobile corral, risks traumatizing animals unaccustomed to human interaction, McGlashan said. She said protecting the remaining ponies from the deadly disease would likely be worth the effort.
Horse owners are typically advised to vaccinate their animals twice a year but should consult their veterinarian, said Mike Martin, associate state veterinarian who deals with epidemiology.
“It’s a case we hate to see, because it’s almost totally preventable by vaccination,” she said.
Mosquitoes are carriers
Mosquitoes contract the virus from certain birds and can pass it to other animals and people. Horses, some game birds and, more rarely, humans can develop serious disease from the virus.
Anyone in the area where the virus is circulating is at risk of being infected by a mosquito, according to the CDC. Those who live in woodland areas or work or play outside where they might be bitten by a mosquito are most at risk, the agency says.
Symptoms in humans can include brain swelling, fever, headaches, confusion, vomiting and seizures. Anyone experiencing severe headaches, high fever, muscle weakness or confusion should see a doctor immediately, according to state health officials.
There is no human vaccine for the disease, and about a third of the cases in humans are fatal, with many of those surviving suffering long-term mild- to severe brain damage.
This story was originally published November 18, 2019 at 4:41 PM with the headline "Beaufort Co. horse tests positive for mosquito-borne virus that can be deadly to humans."
