New Tools to Combat West Nile As Number of Infections Increases by Gina Shaw At first, we didnít take it all that seriously. Some mosquito-borne virus that killed a lot of birds? We had international terrorists, anthrax and smallpox to worry aboutówe didnít have time for the West Nile virus. But in the past few months, West Nile has taken on a mounting sense of urgency as the case rate climbs and the death toll mountsóeven more sharply at the end of the summer. The Centers for Disease Control and Prevention (CDC) had reported only 32 deaths from the disease all year as of Sept. 3, but then 104 people died in September alone. In the Washington area, some 20 cases of the virus had been identified as of early October, and the disease has killed at least three people: a 54-year-old diabetic woman in Sterling, Va., a 65-year-old man in Prince Georgeís County, and an 87-year-old woman in Montgomery County. (Another death in Anne Arundel County may also be attributable to West Nile.) The West Nile virus is transmitted to humans through bites by mosquitoes that have already bitten infected birds. Symptoms take between three and 15 days to develop and are mild in most people. Some will develop the more severe type of the diseaseóencephalit isówith symptoms that can include high fever, severe headache, neck stiffness, muscle weakness or paralysis, nausea, vomiting, sore joints or confusion. Recently, a new and alarming aspect of the virus has been reported in some casesóan apparent ability to cause a sudden, polio-like paralysis. Although itís the elderly and people with compromised immune systems who are most at risk of death from the virusóand only 1 percent of people bitten by an infected mosquito ever show any symptomsóanyone can contract West Nile, and at least 5 percent of diagnosed cases of the disease end in death. ìOur concern for the human toll of this disease is enormous,î CDC Director Dr. Julie L. Gerberding told a Senate panel in September. Cases should drop off over the next few weeks in all but the warmest climates in the United States as winter approaches. Temperatures drop and mosquitoes disappearóbut Gerberding believes that the virus is ìhere to stayî and will probably return with a vengeance when mosquito season does. With the overall death rate from West Nile nationwide at 173 and rising, and the number of cases reported to the CDC edging past 3,000, tools for tracking and preventing the virus have become an urgent priority. So whatís being done about it, other than telling people to use lots of bug spray, wear long sleeves, and stay away from standing water? For starters, scientists have identified a promising candidate for a vaccineómade from an amalgam of West Nile and yellow fever, a closely related cousinóand itís passed animal tests with flying colors. Acambis Inc., the Massachusetts-based lab developing the vaccine with funding from the National Institutes of Health (NIH), expects to start human trials by early next year. If it works, that doesnít mean we will necessarily all be advised to get ìWest Nileî vaccines along with flu vaccines. Public health experts might employ it in ìoutbreak periodsî and ìoutbreak areas,î specifically to protect particularly vulnerable populations. But even if the vaccine research and approval is fast-tracked by the Food and Drug Administration, it will probably be three years before itís available to the general population. So what to do in the meantime? For one thing, itís possible that already-existing yellow fever vaccines might also protect against West Nile, since the diseases are so closely related. During the winter, the NIH will be testing people vaccinated for yellow fever (itís required for travel to some parts of Africa and South America) to see if theyíve acquired a cross-immunity to West Nile. Another option is to improve virus tracking and target programs to spray for the mosquitoes that West Nile hitches a ride with. In this venture, epidemiologists and public health experts have found a surprising new partner: NASAóvia the International Research Partnership for Infectious Diseases based at Goddard Space Flight Center in Greenbelt, Md. NASA researchers are using a system called the advanced very high resolution radiometer instrumentóplaced aboard polar-orbiting satellites that observe the earth through the National Oceanic and Atmospheric Administrationóto track environmental conditions in which mosquitoes and infected birds thrive. After collecting data on variations in temperature, vegetation and available moisture during the summer, scientists will use the winter ìdown timeî to compile the information. Combining the view from space with the CDCís on-the-ground epidemiological case data, researchers will build tracking maps that can show agencies where to target early prevention efforts, such as mass spraying programs and public awareness campaigns. The system has already proven its mettle in Africa, helping to track malaria, another deadly mosquito-borne disease. Also in the works is a screening test for the West Nile virus in the blood. As evidence has mounted that the virus can be transmitted via blood transfusions (as well as organ transplants and possibly by nursing mothers), similarly to the HIV virus, the Food and Drug Administration (FDA) is now working with blood banks and medical labs to develop a test to be used with donated blood. Although FDA representatives have said they expect to have a test ready by mosquito season next year, it promises to be a challenging endeavor because the amounts of West Nile virus found in the blood are miniscule compared to other blood-borne diseases, such as HIV. In the meantime, blood banksóespecially those in areas where the virus is most activeóhave been urged to exclude donors with early symptoms of any illness that might be West Nile, such as fever and headache. Gina Shaw is the medical writer for The Washington Diplomat. Preventing West Nile Transmission For now, the basics on West Nile prevention remain the same and are particularly important for older people and those with weakened immune systems: ï Wear insect repellent containing DEET when you are outdoors in even moderately temperate weather. ï Wear long-sleeved clothing when outside in buggy areas. ï Do not linger outside in the early morning and early evening (peak mosquito hours). ï Eliminate standing water near your home, such as in flowerpots, pet dishes and rain gutters. Up-to-date information on prevention, case tracking, and local and regional mosquito control efforts is available from the Centers for Disease Control and Prevention online at http://www.cdc.gov/ncidod/dvbid/westnile/index.htm. ó Gina Shaw