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Posted on Sat, Jul 7, 2012 : 9 a.m.

West Nile Virus season is approaching: Learn the signs, symptoms, and how to prevent it

By Washtenaw County Public Health

West Nile virus is a disease spread by mosquitos. The condition ranges from mild to severe.

The West Nile virus is a type of virus known as a flavivirus. Researchers believe West Nile virus is spread when a mosquito bites an infected bird and then bites a person.

Mosquitos carry the highest amounts of virus in the early fall, which is why the rate of the disease increases in late August to early September. The risk of disease decreases as the weather becomes colder and mosquitos die off.

Although many people are bitten by mosquitos that carry West Nile virus, most do not know they've been exposed. Few people develop severe disease or even notice any symptoms at all.

Risk factors for developing a more severe form of West Nile virus include:

  • Conditions that weaken the immune system, such as HIV, organ transplants, and recent chemotherapy
  • Older or very young age
  • Pregnancy

Symptoms
Mild disease, generally called West Nile fever, may cause some or all of the following symptoms:

  • Abdominal pain
  • Diarrhea
  • Fever
  • Headache
  • Lack of appetite
  • Muscle aches
  • Nausea
  • Rash
  • Sore throat
  • Swollen lymph nodes
  • Vomiting

These symptoms usually last for 3-6 days.

More severe forms of disease, which can be life threatening, may be called West Nile encephalitis or West Nile meningitis, depending on what part of the body is affected. The following symptoms can occur, and need prompt attention:

  • Confusion or change in ability to think clearly
  • Loss of consciousness or coma
  • Muscle weakness
  • Stiff neck
  • Weakness of one arm or leg

Signs and tests

Signs of West Nile virus infection are similar to those of other viral infections. There may be no specific findings on a physical examination. However, up to half of patients with West Nile virus infection may have a rash.

 

Treatment

Because this illness is not caused by bacteria, antibiotics do not help treat West Nile virus infection. Standard hospital care may help decrease the risk of complications in severe illness.

Expectations (prognosis)

In general, the outcome of a mild West Nile virus infection is excellent.

For patients with severe cases of West Nile virus infection, the outlook is more uncertain. West Nile encephalitis or meningitis may lead to brain damage and death. Approximately 10 percent of patients with brain inflammation do not survive.

Complications

Complications from mild West Nile virus infection are very rare.

Complications from severe West Nile virus infection include:

  • Brain damage
  • Permanent muscle weakness (sometimes similar to polio)
  • Death

Prevention

The best way to prevent West Nile virus infection is to avoid mosquito bites.

  • Use mosquito-repellant products containing DEET
  • Wear long sleeves and pants
  • Drain pools of standing water, such as trash bins and plant saucers (mosquitos breed in stagnant water)

For more information, please visit the Washtenaw County Public Health WNV webpage.

Comments

Candis Hale

Mon, Jul 9, 2012 : 11:58 p.m.

I have masquito bites that do not look good at all and ive been feeling sick should I worry?

Ash

Sat, Jul 7, 2012 : 9:54 p.m.

Wearing long sleeves and long pants are just not practical in the 100 degree weather we've been having. What about the insect repellant clothing that the military uses? I think it may be safer than DEET, but not sure.

bedrog

Sat, Jul 7, 2012 : 4:32 p.m.

very informative...and scary.