Encephalitis In The News

Encephalitis In The News

A recent news article came out about a 14 year old Michigan girl who was hospitalized after a mosquito bite, suspecting it could be Eastern Equine Encephalitis (EEE).  Recently there had been 6 horse cases in 3 Michigan counties with 3 of the horses dying.

I find it troubling that we are hearing about more instances where mosquitoes are carriers of diseases that started in animals and is transferred to humans.

What exactly is encephalitis?

Encephalitis is an inflammation of the brain.  Meningitis is similar; however meningitis is an inflammation of the tissue or membranes that cover the brain or spinal cord.  Both conditions can exist at the same time.

Encephalitis is rare but complications can be serious.

Encephalitis can be spread through mosquitoes and ticks.  Viruses that are transmitted through insect bites cannot be passed from person to person.

Viral encephalitis can develop after a viral illness:  measles, mumps, rubella, rabies, chickenpox, herpes simplex or influenza.  Because we are able to vaccinate for many of these infections the incidence of encephalitis from this type of virus has been greatly reduced.


5 US Mosquito Spread Viruses:

West Nile – Generally a bird infection that can be transmitted to humans through mosquito bites.

Eastern Equine Encephalitis (EEE) – There is an average of 6 human cases per year since we started keeping track in 1964.  This virus is usually found along the Gulf and East coasts.  Horses are infected first and then human cases follow.  EEE can cause death in both humans and horses.  Horses can be vaccinated and have immunity.

Western Equine Encephalitis (WEE) – A virus generally found in horses and mules.  Mortality rate in horses is 90%. Mosquitoes transmit the virus and it can be found in birds and can infect humans.  Horses can be vaccinated and be immune.


St. Louis Encephalitis


Symptoms of Encephalitis

Symptoms present from 4 to 10 days after the bite of a mosquito.  Symptoms can last for 2 to 3 weeks.  Initially, the symptoms often mimic the flu but symptoms worsen as time passes.

  • Fever
  • Fatigue, Extreme Drowsiness
  • Headache
  • Poor Appetite
  • Loss of Energy
  • Nausea and vomiting
  • Trouble with Speech or Hearing
  • Stiff Neck
  • Muscle weakness, Paralysis
  • Confusion
  • Hallucinations
  • Seizures
  • Double Vision
  • Trouble walking
  • Sudden Personality Changes, Irritability, Emotional Outbursts
  • Memory Problems

In Infants:  bulging in fontanels of skull, vomiting, body stiffness, not waking to feed, irritability


Risk Factors:

Anyone can be infected but anyone with a compromised immune system, the very young and the very old are particularly vulnerable to complications if infected.

More likely to be bitten in the summer months when mosquitoes and ticks are more prevalant.

Exposure to wooded or forested areas where mosquitoes and ticks live.

Traveling to countries that don’t vaccinated against many childhood diseases.



  • EEG to check electrical brain activity
  • MRI – to check for brain swelling
  • Blood tests to look for bacteria or viruses
  • Lumbar puncture to check spinal fluid



Treatment is dependent on your age and condition and the specific virus.  Complications can be serious