News of the West Nile virus’ rampant spread across the U.S. has dominated the media in recent weeks. During 2012, 48 states have reported West Nile virus infections in people, birds or mosquitoes and 1,118 cases of West Nile virus disease in people – including 41 deaths – have been reported to Centers for Disease Control and Prevention.
CDC officials have announced that the United States is on track for the worst outbreak of West Nile in the 13 years that the virus has been present in the country. In Arizona, 25 total cases have been reported.
The West Nile virus (WNV) belongs to a group of viruses known as flaviviruses, commonly found in Africa, West Asia, Europe, and the Middle East. Flaviviruses are spread by insects, most often mosquitoes. The virus can infect humans, birds, mosquitoes, horses, and other mammals. Since its first appearance in the Western Hemisphere in 1999, WNV has been classified as an emerging infectious disease in the U.S., as it has spread down the East Coast and to many Southern and Midwestern states. WNV occurs in late summer and early fall in temperate zones, but can occur year-round in southern climates.
According to the CDC, WNV infection in humans is rare. Approximately 20 percent of the people who become infected will develop symptoms of WNV. The onset is characterized by mild, flu-like symptoms that usually appear within 3 to 14 days of infection. Common symptoms of WNV include fever, headache, body aches, skin rash on trunk of body, and swollen lymph glands.
A more severe form of the WNV (West Nile encephalitis, West Nile meningitis, or West Nile meningoencephalitis), occurs when the virus crosses the blood-brain barrier. This condition develops in 1 out of every 150 cases. Symptoms may include headache, high fever, neck stiffness, extreme lethargy, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.
Because the symptoms of WNV may resemble other conditions or medical problems, always consult your doctor for a diagnosis.
WNV is transmitted to humans through the bite of an infected female mosquito. The mosquitoes acquire the virus through biting infected birds. According to the CDC, WNV is not directly transmitted between humans.
Specific treatment is determined by an individual’s doctor based on age, health history, extent of the disease, and tolerance for specific medications or therapies. People who develop the more severe form of the disease (West Nile encephalitis or meningitis), may require more aggressive treatment: hospitalization, intravenous fluids, respiratory support (ventilator), prevention of secondary infections (such as pneumonia, urinary tract infections, etc.), and nursing care.
No vaccine currently exists to prevent West Nile virus in humans. The CDC recommends taking the following steps to avoid mosquito bites and WNV:
Apply insect repellent containing DEET when you’re outdoors. According to the CDC, repellents containing a higher concentration of active ingredient (such as DEET) provide longer-lasting protection.
(Editor’s Note: Mauricio Valencia, M.D. practices with Northwest Allied Physicians and can be reached at 202-1585.)