West Nile Virus

Most people who get West Nile virus don’t have any symptoms. About 1 in 5 will have a fever and other flu-like symptoms. Feeling worn out could take months to go away completely. A few people get a more serious infection that causes brain swelling, or meningitis. There’s a very small chance you could die.

People in 48 of the 50 U.S. states, Africa, Europe, the Middle East, and West and Central Asia have had West Nile.


Mosquitoes can pass on viruses that cause inflammation around your brain and spinal cord. (The brain swelling with a serious West Nile infection is a kind of encephalitis.)

What type you could get depends on where you are:

  • LaCrosse — the 13 states east of the Mississippi River
  • St. Louis — throughout the U.S., especially Florida and Gulf of Mexico states
  • Eastern Equine — Atlantic, Gulf Coast, and Great Lakes states; the Caribbean; Central and South America
  • Western Equine — states west of the Mississippi River, areas of Canada and Mexico
  • Japanese — Asia and the Western Pacific

Your doctor can give you medicine to ease your fever and sore throat. You’ll need emergency care right away for severe symptoms, such as confusion, seizures, and muscle weakness, to prevent brain damage and other complications.
You can get shots to prevent Japanese encephalitis before you travel to the area.

Zika Virus

First found in Africa in the 1940s, this virus has spread to South and Central America, Mexico, the Caribbean, Southeast Asia, and the Pacific Islands.

Most people don’t know they have Zika. The symptoms are mild and usually run their course in less than a week. You may have a fever, joint or muscle painpinkeye, or a rash.

The virus has been linked to more serious problems: cases of Guillain-Barre syndrome and a birth defect called microcephaly.

Guillain-Barre is a nervous system disorder that can cause weakness and paralysis. Most people recover over time.

Microcephaly causes a baby’s head to be small and not fully develop. Babies with this condition may have developmental and intellectual delays and other problems.

There’s no vaccine to prevent the virus. The CDC recommends pregnantwomen avoid traveling to areas with ongoing Zika infections.