January 22, 2008

Health Districts Release West Nile Study Results

Today the Central and Southwest District Health Departments are releasing preliminary results of a study of those affected by the West Nile virus outbreak of 2006.

In 2006 the disease accounted for over 1000 confirmed cases statewide. Six-hundred and sixteen of the total was attributed to people living in the two health districts in southwest Idaho.

The health districts teamed up with researchers from the University of Pittsburgh, the University of Florida and the University of Oklahoma in an effort to learn more about how the human immune system responds to the disease, and what sort of long-term symptoms some of those affected may experience.

The study began in the summer of 2007 when Central and Southwest District Health Departments recruited 230 people with 2006 West Nile virus infections to participate in the research.

Here are some of the preliminary findings:

• Average age of study participant – 52.
• 60% of study participants were women.
• 33% of participants who had been working at the time of infection reported missing two or more weeks of work.
• 27% of the entire group required some form of hospitalization.
• The majority of participants reported symptoms lasting more than two weeks.
• 72% reported feeling fatigued.
• 63% reported decreased levels of activity as a result of infection.
• 62% reported weakness.
• Women appeared to be more severely affected than men, and were more likely to experience long-term symptoms like headaches and decreased activity.
• Those over the age of 60 appear to have experienced longer lasting symptoms.

Research from the Centers for Disease Control and Prevention (CDC) estimates that 80% of the people infected with West Nile virus won’t know they are infected because they won’t experience any symptoms. However, the majority of the remaining 20% of those infected, which the study authors believe include the 230 study participants, will experience multiple and long-term symptoms of the disease. On-going symptoms interfere with work tasks and overall quality of life.

There is currently no cure for West Nile virus and treatment is generally reserved to those with the most severe symptoms.

The most effective methods of preventing infection involve efforts to avoid getting bitten by mosquitoes:

• Insect-proof your home by repairing or replacing screens;
• Reduce standing water on your property that provides mosquito breeding habitat, such as bird baths and decorative ponds;
• Cover up exposed skin when outdoors;
• Apply insect repellent approved by the EPA to exposed skin and clothing. Follow instructions on the product label, especially for children;
• Avoid mosquitoes when they are most active at dawn and dusk; and

For more information on West Nile virus please visit:

• State of Idaho West Nile website
• Central District Health Department - What is West Nile?
• Southwest District Health Department