“In the United States, for equine encephalitides for which vaccines are available include eastern equine encephalomyelitis (EEE), western equine encephalomyelitis (WEE), Venezuelan equine encephalomyelitis (VEE) and West Nile Virus encephalomyelitis. The availability of licensed vaccine products combined with an inability to completely eliminate risk of exposure justifies immunization against EEE and WEE as core prophylaxis for all horses residing in or traveling to North America and any other geographic areas where EEE and/or WEE is endemic. Adult horses previously vaccinated against EEE/WEE: Annual revaccination must be completed prior to vector season in the spring. In animals of high risk or with limited immunity, more frequent vaccination or appropriately timed vaccination is recommended in order to induce protective immunity during periods of likely exposure.”
American Association of Equine Practioners
“Know there’s no cure for Eastern equine encephalitis, or EEE, but there is a vaccine for the mosquito-borne illness. It’s just not commercially available for humans.The United States military developed it in the 1980s as part of a vaccine program to protect military personnel from dangerous pathogens, says Sam Telford, an epidemiologist at Tufts University.”
Common Health
”
EEE affects areas throughout North and South America, with outbreaks occurring mainly in the eastern coastal areas of the United States and Canada, the Caribbean, and Argentina.
In the U.S., Culiseta melanura is the mosquito responsible for the spread of EEEV in the mosquito-bird-mosquito cycle. Known as the black-tailed mosquito, Cs. melanura can be found in swamps from the Great Lakes and Maine to southern Florida and southeastern Texas. It is distinguished by its unusually long, curved dark-scaled proboscis. This mosquito is also unique because it overwinters as larvae, as opposed to most mosquito species that overwinter as adults or eggs.
EEEV is mainly transmitted to humans by bridge vectors that contract the virus by feeding on infected birds. Bridge vectors may include Aedes, Coquillettidia, and Culex species.
Aedes mosquitoes have distinct black and white markings on their body and legs. They bite during the daytime only, with the highest levels of activity occur in the early morning and evening hours. Members of the Aedes genus are known vectors of EEE, Zika virus, dengue, yellow fever, West Nile virus, and chikungunya.
Coquillettidia mosquitoes have slender bodies and long legs. They are commonly found in humid, low-lying areas that have warm summer and lots of vegetation. In addition to acting as vectors for EEE, Coquillettidia mosquitoes are also known to transmit West Nile virus to humans.
Culex mosquitoes are brown with whitish markings on the abdomen. They typically bite at dusk and at night, and are known to vector several diseases including EEE, West Nile virus, Japanese encephalitis, St. Louis encephalitis, and avian malaria.
“We don’t know some of the basic details about these [mosquito-transmitted] diseases, unfortunately. The ideal is to anticipate outbreaks, which is very, very difficult. But we need to be prepared for an outbreak when it comes.”
Stephen Higgs (a pathobiologist and director of the Biosecurity Research Institute at Kansas State University in Manhattan)
Eastern equine encephalitis (EEE) belongs to a category of viruses known as arboviruses, or arthropod-borne viruses. Arboviruses are spread by the bites of blood-sucking insects, such as mosquitos and ticks. EEE is spread by the bite of certain kinds of mosquitoes.
The overall risk of becoming infected with EEE depends on:
Some people with EEE may develop a severe infection that causes brain tissue to become inflamed (encephalitis).The factors that increase one’s risk of getting a severe EEE infection include:
Symptoms of EEE generally occur four to 10 days after a person has been infected and include:
The symptoms of encephalitis depend on the part of the brain that is inflamed, the amount of inflammation and the person’s age and overall health.
Some of the most common symptoms of encephalitis include:
In one-third of cases, encephalitis can be fatal or lead to permanent brain damage.
Because the initial symptoms of EEE resemble those caused by many illnesses, it may be difficult to determine if a child’s symptoms are related to encephalitis. In general, you should take your child to see a doctor if your child has a bad headache, nausea and vomiting, fever or any worrisome changes in behavior (confusion, extreme sleepiness, acting very different, listlessness, lethargy, seizures).
The worst outbreak of eastern equine encephalitis since U.S. health officials began monitoring the mosquito-borne disease 15 years ago is prompting aerial bug spraying and dire warnings to avoid the biting insects well into fall. As of October 1, 31 cases — including nine deaths — have been reported by the U.S. Centers for Disease Control and Prevention.
Known as EEE or Triple-E for short, the incurable brain infection is still relatively rare — there have been only 103 reported infections in the United States in the past decade. Only five percent of people bitten by an infected mosquito will develop the disease. But about a third of EEE patients die, and many who survive experience permanent neurological problems.
Science News spoke with several researchers about how the virus spreads, and possible factors that might be contributing to the recent surge in cases.
“We don’t know some of the basic details about these [mosquito-transmitted] diseases, unfortunately,” says pathobiologist Stephen Higgs, director of the Biosecurity Research Institute at Kansas State University in Manhattan. “The ideal is to anticipate outbreaks, which is very, very difficult. But we need to be prepared for an outbreak when it comes.”