Equine encephalitis
Equine encephalitis is a serious mosquito-borne viral disease that primarily affects horses, zebras, and donkeys, but can also impact certain birds and humans. There are three primary types: eastern equine encephalitis (EEE), western equine encephalitis (WEE), and Venezuelan equine encephalitis (VEE), all transmitted through mosquito bites. Symptoms in animals include lethargy, fever, and neurological issues such as confusion and seizures. In humans, the disease can manifest in two forms: systemic and encephalitic, with the latter potentially leading to severe complications including brain swelling and coma.
While equine encephalitis is rare, it has a high mortality rate in infected animals, ranging from 75% to 90%, and about a 33% chance of death in humans. Survivors may experience long-term neurological problems. Currently, vaccines are available for horses to prevent the disease, but no vaccine exists for humans. Preventative measures focus on minimizing mosquito bites, such as wearing protective clothing and using insect repellent. Understanding these aspects can help individuals take necessary precautions and recognize the importance of vaccination for equine animals.
Equine encephalitis
Equine encephalitis is a mosquito-borne virus that affects the nervous system of horses, zebras, donkeys, and other equine animals. It can also affect some types of birds and humans. Although the disease is rare, it can decimate a group of animals in a short period if they are not vaccinated. In addition, equine encephalitis is among the most severe forms of encephalitis that can affect humans. The disease is also known as sleeping sickness or African sleeping sickness.
Background
There are at least three types of equine encephalitis: eastern equine encephalitis (EEE), western equine encephalitis (WEE), and Venezuelan equine encephalitis (VEE). All three are caused by mosquito bites. Twenty-three types of mosquitoes can carry these viruses. Equine encephalitis is transmitted when a mosquito bites an infected animal or human and then bites another animal or human. The disease cannot be spread from animal to human or vice versa. It takes four to ten days after a bite for symptoms to present.
Animals with equine encephalitis will show signs of depression and become lethargic. They may have a fever and will sometimes butt or press their heads against a stall wall or other object. Confusion, seizures, and paralysis may also occur.
Equine encephalitis is most likely to affect adults over fifty and children under fifteen years of age. People with the virus may have one of two forms of the disease: systemic or encephalitic. Both forms come on suddenly and include symptoms such as fever, chills, and achiness in joints and muscles. Patients with the systemic form do not experience any problems with their nervous system and generally recover in one to two weeks.
However, sometimes the disease progresses to include neurological symptoms caused by brain swelling. This is the encephalitic form of the disease. It can include all the symptoms of the systemic form in addition to headaches, irritability, sleepiness, eating issues, diarrhea, convulsions, and coma. It is also possible to have the disease but not develop any symptoms; this form of the disease is usually discovered when antibodies are found during testing for another purpose.
Equine encephalitis is diagnosed through blood tests and spinal taps that draw cerebrospinal fluid for analysis. There is no specific treatment for the disease beyond treating the symptoms. This may include hospitalization, during which the patient will be treated with intravenous fluids, breathing support, and medications to prevent other infections while the patient is weakened by the encephalitis.
Prognosis and Prevention
Horses and other animals affected with equine encephalitis have a 75 to 90 percent mortality rate. Humans have about a 33 percent chance of dying from equine encephalitis. Those who survive often suffer from neurological disorders that range from mild to severe.
While a vaccine exists to protect equine animals from this form of encephalitis, no such vaccine exists for humans. The best protection for people is to avoid being bitten by mosquitos. Prevention includes limiting outdoor activities during the periods of greatest mosquito activity (dawn and dusk), wearing long sleeves and pants, protecting ankles by tucking pants into socks, and using insect repellents with DEET. Other ways to minimize the risk of mosquito bites include removing standing water sources from areas surrounding the home and ensuring that windows and doors have well-fitting screens.
Bibliography
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"Eastern Equine Encephalitis." Centers for Disease Control and Prevention, www.cdc.gov/easternequineencephalitis/index.html. Accessed 21 Feb. 2017.
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Long, Maureen T. "Overview of Equine Arboviral Encephalitis." Merck Veterinary Manual, www.merckvetmanual.com/nervous-system/equine-arboviral-encephalomyelitis/overview-of-equine-arboviral-encephalomyelitis. Accessed 21 Feb. 2017.
Rey, J.R., and C.R. Connelly. "Eastern Equine Encephalitis." University of Florida, IFAS Extension, edis.ifas.ufl.edu/in179. Accessed 21 Feb. 2017.