Experts creating model to track virus prior to outbreak

Monday, August 5, 2002

ALBANY, N.Y. -- More than half a dozen states worried about West Nile virus are using climate-based computer models to predict the course of the mosquito-borne disease before a fatal outbreak occurs.

Public health officials usually rely on reports of dead birds as an early warning sign that West Nile is spreading in their region. Scientists say this new method would warn local officials in advance if their counties are at high risk for the virus.

"We look at this as another tool we can potentially use to help us as we try to protect people from catching West Nile," said Bryon Backenson, assistant director of the New York State Health Department's arthropod-borne disease program.

Last year, the state collaborated with NASA and Oxford University to create climate maps based on satellite data to track the virus. Delaware, Florida, Louisiana, Maryland, South Carolina and Virginia have since joined.

In the $504,000 NASA-funded project, state health departments tally the number of dead birds and mosquitoes that test positive for West Nile while NASA satellites pick up weather information like temperature and humidity.

The information is sent to Oxford, which uses a computer program to create "risk maps" showing areas infected with the virus, temperature and vegetable distribution and migratory routes of birds.

State health officials, in turn, will use the maps to warn counties when they are at high risk for West Nile so they can develop a plan to fight mosquitoes and the virus.

"Risk maps will help authorities take charge and control as well as anticipate the disease," said Oxford ecologist David Rogers, who helped create the maps.

Mosquitoes spread the virus from infected birds to humans, who can then develop deadly encephalitis, or swelling of the brain. Most people develop only flu-like symptoms and some don't get sick at all. Humans cannot pass the virus.

The virus is named after the West Nile district in Uganda, where it was first discovered in 1937. Since then, cases have been reported in Europe, the Middle East, West and Central Asia, and the Pacific Islands, as well as Africa and North America.

It was virtually unknown in the United States until New York City was stricken in a frightening summer outbreak in 1999, when seven people died and 62 were infected.

The city sprayed insect repellent, did intensive mosquito trapping and monitoring, and told residents to drain standing water from bird baths and wading pools.

Since the disease turned up three years ago, the virus has hit 34 states and the District of Columbia.

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