Mosquitoes — they are still out there

Although summer is officially over, Islanders are reminded that mosquitoes and the diseases they may carry are still with us. The state Department of Health and Environmental Control reported earlier this week that mosquitoes continue to be a problem this time of year.

 “We should continue to be aware of West Nile virus and other diseases that mosquitoes carry,” said DHEC Commissioner C. Earl Hunter. “Mosquitoes are active until after a killing frost.” 

“West Nile virus and Eastern Equine Encephalitis are different viruses that can be transmitted from animals to humans through the bite from an infected mosquito,” said Lena Bretous, M.D., epidemiologist for vector-borne diseases with DHEC’s Bureau of Disease Control. “What West Nile virus and Eastern Equine Encephalitis have in common is that a mosquito that feeds on a bird infected with one of these viruses can then bite and transmit the virus to a person.”

Bretous said most people infected with West Nile virus do not get sick, while those that do get sick may have two types of illness.

“About 20 percent of those infected with West Nile virus get a mild case of West Nile fever, which lasts about two weeks,” Bretous said. “People recover very well from West Nile fever. 

“About 1 out of 150 people infected with the West Nile virus develop West Nile encephalitis. Encephalitis is a more severe illness involving infection in the brain. People over 50 are more at risk to develop West Nile encephalitis,” Bretous said.

Another type of encephalitis, Eastern Equine Encephalitis, can result in symptoms including a rapid onset of fever and headache or flu-like symptoms. There is no cure for this potentially dangerous disease. While rare in humans, EEE can be very serious since up to 35 percent of people who contract EEE die from the disease. Treatment includes efforts and medications to relieve the symptoms.

Hunter urged South Carolinians to continue to protect themselves from mosquito bites by wearing long sleeves and long pants when outdoors and using a repellent containing DEET, picaridin or oil of lemon eucalyptus. Follow the label directions when using any repellent.

 “Be sure to look around your home and property and empty any standing water from containers. Be especially diligent in keeping your gutters clear of leaves throughout the fall,” Hunter said. Screens on porches and windows should be used to keep mosquitoes from getting into your home on mild autumn days.”

Bretous said West Nile virus is well established throughout South Carolina and some areas have experienced an increase in confirmed cases of the disease.

“West Nile virus has been confirmed by DHEC in three people in the state this year. One case resulted in the death of a Darlington County resident in August. The other two human cases this year were from Columbia in Richland County. Both people are recovering,” Bretous said.
Testing by DHEC laboratories this year has confirmed West Nile virus in 30 birds and in 15 mosquito pools. A mosquito pool is a group of mosquitoes of the same species that are collected from the same location and date. Geographically, Charleston and Aiken counties have had the most confirmations. Thirteen birds and 12 mosquito pools have been confirmed in Charleston. Aiken has had nine birds and one mosquito pool.

There have been 14 cases of EEE this year in equines, one in birds and two mosquito pools. 

While there is no vaccine against either virus for humans, there are separate vaccines to protect against both WNV and EEE available for horses and other equines. If you vaccinated your equine against WNV and EEE in the spring, it is time for the necessary boosters to extend the protection. For information on WNV or EEE in animals, owners and veterinarians may contact Clemson University’s Livestock Poultry Health Laboratory at (803) 788-2260.

“Our state has warm weather for most of the year, which is wonderful for outside activities,” Hunter said. “On the other hand, that makes South Carolina a great place for mosquitoes to breed long after we think they’re no longer a threat.”

South Carolina’s current surveillance results on West Nile virus and links to EEE information are available on DHEC’s Web site at http://www.scdhec.gov/news/westnile/. You may also contact DHEC’s local county public health departments during regular office hours.