Eastern equine encephalitis is a concern in Massachusetts, and has implemented lockdown in high-risk counties. Let’s get into the nitty-gritty details of eastern equine encephalitis, how it infects humans, and ways to prevent and treat it.
What is eastern equine encephalitis?
Eastern equine encephalitis is a disease caused by a virus transmitted through the bite of an infected mosquito. It is a rare but fatal disease with a mortality rate of 30%. Also, 50% survivors may suffer some sort of neurological damage.
Let’s break down the complex name for understanding:
- Eastern signifies the eastern coast of the US where the infected mosquitoes bread.
- Equine implies the mammal family of Equidae, which includes horses, donkeys, zebras, and assess.
- Encephalitis is the inflammation of the brain.
History of eastern equine encephalitis
The EEE virus was isolated in 1933 from infected horse brains. In 1938, the first human cases came to light and led to the death of 30 kids from virus-induced brain injury in the northeastern United States. These cases coincided with the outbreak in horses in the same area. It was later found that the virus spread through the infected horses to humans, and therefore, the disease is known as eastern equine encephalitis.
How does eastern equine encephalitis spread?
The eastern equine encephalitis transmission occurs through the bite of an infected mosquito.
Birds, reptiles, amphibians and mammals such as horses and donkeys are the primary hosts of the virus. The virus is transmitted from animals to humans through mosquitoes. Three mosquito species that feed on the blood of these animals and are involved in the virus life cycle are Culiseta, Aedes, and Culex.
The viral transmission in humans ends the lifecycle of the virus because the low levels of circulating virus in the blood can’t infect the biting mosquitoes. Also, the disease isn’t transmissible from one human to another.
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Where is eastern equine encephalitis found, and how common is it?
EEE virus infection affects people living in the eastern part of North America, along the Gulf and Atlantic coasts, and in some midwestern states around the Great Lakes. The people from the states west of Mississippi and parts of South America have also been seen positive for the infection. EEE is rare and typically infects 6-8 Americans (0.03 cases per million population) every year.
The recent major viral breakout occurred in 2019, where 38 human cases and 12 deaths were reported in the northwest US. In the 1959 breakout, the virus affected 32 people and succumbed to 4 people in New Jersey.
Massachusetts lockdown
Currently (26th Aug 2024), ten Massachusetts counties are on high alert. The Massachusetts Department of Public Health announced (16th August 2024) the first case of EEE in an 80-year-old male in Oxford, Worcester County.
Oxford health officials have recommended a voluntary lockdown from dusk to dawn – the peak hours for mosquitoes. Plymouth, a town south of Boston, is on high alert. All the public parks and fields in Plymouth would remain closed during the peak hours from 23rd August after an EEE case was found in a horse.
Moreover, the state Department of Public Health plans to conduct aerial and truck-mounted spraying to eliminate mosquitoes in Plymouth and Worcester County.
The New York health department has announced that EEE had been isolated in horses in Orange, Saint Lawrence, Madison, Ulster, Cayuga, Wayne, and Washington counties. There is no risk of human transmission of the virus directly from horses.
Who is at risk for pesticide spray?
The EPA-registered pesticide Anvil 10+10 will be sprayed across the high-risk areas. Therefore, it is advised to stay indoors during spraying to avoid inhaling the pesticide and use masks if you’re outdoor and sensitive to chemicals or have respiratory problems such as asthma or COPD.
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What does EEE look like (Eastern equine encephalitis symptoms)?
The incubation period of EEE is 2-10 days after the bite from an infected mosquito. Most (96%) patients shows no symptoms, others experience non-specfic flu-like symptoms. Encephalitis develops in less than 5% of the patients.
The flu-like symptoms include fever (103-106°F), chills, headache, muscle and joint pain, abdominal pain, vomiting, and diarrhea. Also, the abdominal pain can be severe enough to bring you to the ER.
Swelling and inflammation of the brain, known as encephalitis, is the most dangerous complication of the disease. The disease progresses rapidly and involves the brain within 5 days, and in severe cases may lead to a coma. The symptoms include headache, confusion, focal neurological deficits, tremors, fits, paralysis, and coma. Almost 30% of the patients lose their lives, and many survivors suffer prolong neurological damage.
Symptoms of EEE in a child?
Children with EEE infection may develop swelling of the face or eyes. Viral illness in children may cause fever and resemble dengue. Dengue-like symptoms include cough, rash, and inflammation of the eyes and tonsils.
Most patients recover within 1-2 weeks after the infection. However, some develop neurological symptoms after a short recovery.
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Is there any eastern equine encephalitis vaccine?
There is no vaccine for the triple E virus available. So, you need to rely on other preventive measures to avoid getting the infection, as the virus causes death in 30% of the infected patients.
What tests can be done to diagnose eastern equine encephalitis?
Patients infected with the EEE virus are diagnosed by antibody titer (IgG). There is a fourfold increase in antibodies in blood or a significant rise in specific IgM antibodies in cerebrospinal fluid (CSF) (brain fluid).
Virus and its breakdown (antigenic) products circulate in the blood during the early flu-like symptoms. However, the blood test often shows negative results for the virus before the onset of encephalitis. However, CSF or brain tissues can test positive for viral particles at autopsy.
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What is the Eastern equine encephalitis treatment?
EEE requires symptomatic and supportive therapy. The treatment includes
- Few days off from work and rest
- Lots of fluids to prevent dehydration
- Over-the-counter pain medication to lower the fever and flu-like symptoms.
When to report to the ER?
If you develop neurological symptoms such as confusion, drowsiness, pressure in the brain, or persistant headache, immediately report to the ER; it can be a symptom of encephalitis and have serious consequences.
How to protect yourself from Eastern equine encephalitis?
The following measures can prevent and control the spread of disease:
- Avoid outdoor activities during peak mosquito hours
- Avoid mosquito habitats such as marshes and freshwater bodies where they reproduce and are found in abundance
- Using repellants and protective clothing such as mesh outerwear, long trousers, and long-sleeved shirts can prevent you from mosquito bites
- Wear gloves, and proper precautions should also be taken to prevent exposure to body fluids when contacting potentially infected animals.
Conclusion
In a nutshell, eastern equine encephalitis (EEE) is a disease caused by a virus transmitted through the bite of an infected mosquito. It is a rare but fatal disease with a mortality rate of 30%. Also, 50% survivors may suffer some sort of neurological damage.
In the United States, 6-8 cases are reported every year, between the summer months (May- October, largely in Florida, Georgia, Maryland, Wisconsin, and New Jersey.
You can protect yourself from mosquito bites by avoiding outdoor activities during the peak mosquito hours and using repellants and protective clothing.