Eastern Equine Encephalitis Confirmed In Sentinel Chickens

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Eastern Equine Encephalitis

Two sentinel chickens in the Grand Bay area have tested positive for Eastern Equine Encephalitis (EEE).

For nearly 20 years, the Mobile County Health Department's Vector Control Department has been monitoring encephalitis in sentinel poultry flocks strategically placed throughout the county to detect the presence of viruses carried by mosquitoes. Additionally, mosquitoes are trapped throughout Mobile County and tested for EEE, West Nile Virus (WNV), and St. Louis Encephalitis.

According to Health Department Vector Control personnel, this is the first incidence this year of dead birds testing positive for EEE, and aggressive surveillance and control activities are ongoing in the area. To date, there have been no dead birds or mosquitoes in Mobile County that have tested positive for West Nile Virus (WNV).

Eichold says that with outdoor activities, it is extremely important that residents take every effort to reduce their exposure to mosquitoes and that they should keep mosquito repellent with them at all times when working or taking part in recreational activities outdoors.

"Humans with encephalitis often have symptoms of high fever, severe headaches, confusion, and seizures that are severe enough to require medical attention," he says.


EEE and other mosquito-borne viruses such as WNV are transmitted from bird to mosquito to bird. Mosquitoes can spread these viruses by feeding on the blood of infected birds and then biting another host animal or mammal such as a horse or human. Although humans and horses can become ill from the infection, the diseases cannot be spread from people or horses. The likelihood of transmission to humans and horses can be decreased by personal mosquito avoidance and the use of an EEE and WNV vaccine in horses. There is no vaccine available for humans, health officials said.

Eichold advises all horse owners to have their animals vaccinated against WNV and EEE, and to call their veterinarian immediately if signs of encephalitis are observed. Clinical signs vary, but they include depression, staggering, uncoordination, stupor, hyper-excitability, paralysis, and coma.

EEE can be more dangerous to people and other mammals than other mosquito-borne viruses. However the same mosquito-prevention measures reduce exposures to all such viruses. Bites to children should be watched for secondary infections that need to be treated by a physician. Mosquito bites can be treated with topical agents such as calamine and menthol lotions. Cortisone creams and oral antihistamines are available as over-the-counter medications that can reduce itching.

The most effective and economical method to reduce adult mosquitoes is to reduce their emergence from as many breeding sites as possible with larviciding treatments. Inspectors regularly check areas with standing water for mosquito breeding and treat as necessary using both portable and truck mounted equipment. The inspectors also respond to service requests from residents to inspect backyard areas as well as to treat identified breeding areas and to provide education. Due to large volumes of calls received daily, service requests are responded to on a first-call, first-served basis and may take a few days to be addressed.

Each day, the Vector Control Department evaluates surveillance data, inspection reports, and service requests in order to target 10-12 routes out of a total of 50 routes for nightly (Monday-Friday) mosquito control and spraying. When necessary, weekday morning, weekend, and holiday spraying is provided. Spray trucks used for these operations dispense low volumes of aerosol insecticides and are equipped with a system that sprays the correct amount of insecticide for the speed of the vehicle. This allows for the proper application of insecticide at variable speeds.

People taking part in outdoor activities such as picnics, concerts in the park, or playing at the playground should take extra precautions to avoid being bitten by mosquitoes. Mosquito activity peaks at dusk and again at dawn; People should restrict outdoor activity during these hours in heavily infested areas. The Vector Control Department suggests taking the following precautions:

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