Protect Yourself & Your Equines Against This Preventable Deadly Disease

— Written By Samantha Foster

Ah, summer is finally here! With summer comes pool parties, BBQs, and mosquitos: which potentially means mosquito- transmitted diseases.

Eastern Equine Encephalitis (or EEE for short) is a disease considered endemic to the southeastern United States. Although NC typically doesn’t have as many EEE cases as some southern states,  it does occur and residents should act proactively to prevent it. Last year there were confirmed cases in counties in the Southern Piedmont region. So far this year, SC has had two confirmed cases in Horry County, which neighbors Brunswick County along the coast. Our State Veterinarian, Doug Meckes, urges equine owners to make sure that their animals are vaccinated.

How does it spread?

Wild birds (primarily songbirds) are the principal vertebrate hosts of this virus and serve as reservoirs. Culiseta melanura mosquitoes, which feed almost exclusively on birds, help to perpetuate the disease in wild populations. Other species of mosquitos, such as Aedes, Coquillettidia, and Culex species are responsible for spreading the virus to mammals. Most people have to be bitten by a mosquito to have the virus transmitted to them, but producers who raise pheasants and ratites are advised to use caution when handling infected birds.

What are the symptoms?

EEE is a neurologic disease that attacks the brain and spinal cord. Symptoms in horses include stumbling, circling, muscle twitching, weakness, and depression. These symptoms are similar to those seen with other neurologic diseases and problems. Contact a vet immediately.

Symptoms in humans start out as headaches, chills, vomiting, and high fever and progress to disorientation, seizures, or even coma. Most infected people will show no symptoms.

What is my risk?

Cases of EEE in humans are rare, and infection in horses generally uncommon. Populations most at risk are individuals (both human and horse) who live or spend time near swamps or in other mosquito- heavy areas, children, and people over 50. However, this disease has a high fatality rate and survivors will more than likely have permanent neurological damage.

What steps should  I take for prevention? 

Working with a veterinarian is an important part of horse ownership, and in the case of EEE, it may save your horses life. Vaccinating for EEE starts with two doses of vaccine given a few weeks apart, with a booster given every 4-6 months or prior to the onset of mosquito season. Make sure to talk to your veterinarian to come up with a vaccine schedule best suited for your needs. Even though EEE is generally uncommon in NC, it is best to be prepared for an outbreak, as vaccines need time to establish immunity. Waiting until the disease shows up nearby may be too late. 

General mosquito prevention will also help lower risks. Regularly dump out containers and objects that collect water such as lawn decorations, machinery, toys, et c. Try to wear long sleeves and pants when outdoors when mosquitos are active. Bti pellets and briquettes can be administered to standing water to kill larvae. These contain a bacteria that has spores toxic to swimming fly larvae, but it is safe for humans and other animals as well as plants. You may also use citronella candles in areas with low air movement. DEET- containing personal repellant is effective and comes in sprays and lotions. Pyrethroid containing products can be used to treat yards. However, they can be hazardous to beneficial insects like bees and to humans and pets and shouldn’t be used around plants intended for consumption.

To read more, visit this page on the CDC’s website and this article from