West Nile Virus: First Horse in Delaware in 10 Years Tests Positive

| by Denise A Justin
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A horse in Kent County has tested positive for West Nile Virus, the Delaware Department of Agriculture announced on Friday. This is Delaware’s first confirmed equine case of West Nile Virus since 2003, said State Veterinarian Heather Hirst.

“Prevention is key, and effective vaccines are available to help protect horses against these types of diseases,” said Hirst, who heads the Delaware Department of Agriculture’s Poultry and Animal Health Section.

In addition to this case of West Nile Virus, another mosquito-borne disease, Eastern Equine Encephalitis (EEE), was recently detected in a sentinel chicken flock in Sussex County, Delaware. The viruses normally exist in a cycle between mosquitoes and birds, but occasionally EEE can be transmitted from mosquitoes to mammals.

Both horses and humans can contract WNV and EEE if bitten by a mosquito carrying the virus. However, viruses are not transmitted between horses or from horses to people.

The horse in Kent County is now recovering and doing well, reports the official Delaware state news site.


The Center for Disease Control reports that, as of August 27, 2013, 45 states and the District of Columbia have reported West Nile virus infections in people, birds or mosquitoes.

A total of 421 cases of West Nile virus disease in people, including 13 deaths, have been reported to CDC. Of these, 197 (47 percect) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 224 (53 percent) were classified as non-neuroinvasive disease.


Last year, Louisiana reports of West Nile virus infections surged to their highest levels since the disease first made its appearance. On Friday the Louisiana Department of Health and Hospitals reported eight new human West Nile cases, bringing the total so far this year to 21, and mosquito activity doesn’t usually peak until September.

Commissioner Mike Strain, D.V.M., with the Louisiana Department of Agriculture and Forestry, urges people to prepare for another bad year and he expressed concern not just for people but for horses as well. Last year the state reported 76 confirmed cases of WNV in horses and 59 cases of EEE.

Strain recommends that horses be vaccinated when they are 3 months old, with a booster shot at 4 months. Traditionally it was recommended the vaccine then be given annually, but he urges horse owners consider twice-a-year vaccinations. “Horses are at a very high risk if not vaccinated,” said Strain, pointing out that roughly a third of all infected animals died.

The main risk to humans is the West Nile virus, but as rule it is not serious. Roughly 90 percent of people who get infected never even know they have it. About 10 percent of infected humans will develop West Nile fever with symptoms similar to a bad case of influenza. Only a very small number of infected individuals will show the serious symptoms associated with neuroinvasive disease, which can lead to brain damage and even death, states the Daily World.

For humans, the number one defense is non-exposure: staying indoors during early morning and evening hours when mosquitoes are most active, wearing mosquito repellent and long-sleeve shirts when outside and making sure windows and door screens are in good shape. Also empty any vessels that hold standing water to destroy mosquito breeding grounds.

Check the West Nile Virus Activity by State [Map]

Sources: Delaware 1059,, CDC, Daily World