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West Nile Virus is on its way back--this time,
probably sooner and stronger than before.
AmedNews.com / HEALTH & SCIENCE
Get ready for a new -- and nastier -- West Nile season
Last year's experience was unprecedented, with the detection of new routes of transmission and resulting chaos. Now experts are bracing for more.
By Victoria Stagg Elliott, AMNews staff. March 10, 2003.
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Epidemiologists expect that in the upcoming season the virus will reach into all 48 contiguous states. Its westward movement would build on 2002 momentum, in which confirmed human cases occurred in 39 states and the District of Columbia, killing hundreds and sickening thousands. What does that mean for health care professionals now?
With this article
West Nile: The latest count
Few states untouched
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"We're watching and waiting," said Sandra Kemmerly, MD, medical director of infection control at the Ochsner Clinic Foundation in New Orleans. "We know it's going to come, it's just a matter of when."
Specifically, physicians are bracing for patient anxieties and concerns. Health departments are readying public awareness campaigns and infection control mechanisms. Researchers are trying to learn why the virus kills a few but hardly fazes most. And everyone is hoping for a rapid test, and maybe even a vaccine.
It's all part of the reaction to West Nile's changing identity since its 1999 American debut. For instance, its first season did not begin until August. The dozens who became ill and handful who died were in New York state. Last year, the onslaught came earlier, in June, and was far more widespread. Now, four seasons into the experience, questions persist about the virus itself, as well as newly discovered routes of transmission that complicate the public health landscape.
In areas not yet hit, health officials say they have a hard time convincing people to prepare for an uncertain danger. But even in endemic areas, the most basic method of controlling transmission -- that of mosquito control -- is not always a done deal. Some municipalities have refused to fund programs either because of fears of new taxes or the widespread spraying it might involve.
The West Nile virus affected people in 39 states and the District of Columbia in 2002.
It's like other preventive measures, said Raoult Ratard, MD, MPH, state epidemiologist with the Louisiana Dept. of Health and Hospitals. "Some people are good and listen. The majority do not change their lives."
Overall, though, Dr. Ratard is optimistic. "We are better prepared than last year because we have better ways of reporting the information and we have fine-tuned testing. And if West Nile comes up, we'll have a better campaign."
The most difficult complications have to do with how fears about the virus' transmission -- an area of significant research interest for the Centers for Disease Control and Prevention -- are placed in context and properly balanced against the benefits involved. These are topics physicians likely will need to be prepared to discuss with patients, especially in areas that experience infections.
Transmission Issues
For starters, there were news reports last year about transmission via organs donated for transplantation. Although the reports caused significant concern, this scenario actually appears to be quite rare, and current testing protocols are not considered useful. As a result, organ procurement organizations are not likely to propose policy changes.
Similarly, last season's experience found evidence supporting the potential for transmission in breast milk. But because the likelihood of such transmission is slim and the health benefits of breastfeeding are well-supported, medical specialty groups have shied away from offering caution. At this point, they feel that recommending policy changes could do more harm than good.
Issues related to West Nile in the blood supply, however, will continue to get lots of action. Blood banks in endemic areas are taking precautions, stockpiling items that have long shelf lives and planning to alter screening protocols. For example, donors will now be asked to alert the blood banks if they develop flulike symptoms within two weeks of giving blood rather than the traditional 48 hours.
The West Nile virus first appeared in the United States in 1999.
The Food and Drug Administration also issued a call last year to develop a rapid test for presence of the virus. Experts say the need could be met before the end of the summer.
But although a lot has been achieved in a short time, there are certain factors that are going to make this season even more difficult than those in the past, particularly for those researching treatment or vaccines. With many areas of the country about to enter their second or third West Nile season, there may be many people walking around with antibodies to the virus who did not get sick before. If they become sick this year from something else, their test may result in a false-positive reading for the disease. Physicians say this is unlikely to affect the course of treatment, but it will certainly confuse tracking and research -- a phenomenon that could threaten the emerging understanding of the virus.
"It doesn't impact treatment right now, but it really complicates clinical trials that will attempt to develop treatments or vaccines," said Sharone Green, MD, associate professor of medicine in the Center for Infectious Disease and Vaccine Research at the University of Massachusetts Medical School in Worcester.
Meanwhile, some expect that the virus will take care of itself, eventually cycling out as it has in other locations, killing its weakest victims and leaving the rest of the population with a lifelong immunity. But it is too soon to know for sure.
"When you look at prior outbreaks in Israel and Romania, they had these very large outbreaks, and then they fizzled out," Dr. Green said. "In the United States, it seems like a different situation. In the coming year, one could anticipate that the places that have not had that much human illness may be at higher risk, but having said that, I don't think that Illinois -- which was hardest hit last year -- is out of the woods yet. There's a lot that isn't known about transmission and the epidemiology."
ADDITIONAL INFORMATION:
West Nile: The latest count
Laboratory confirmed human cases nationally: 3,893
Deaths associated with the virus: 254
Deaths in Illinois, the leading state for cases: 54
Deaths in Michigan, the second leading state for cases: 46
Deaths in Ohio, the third leading state for cases: 31
Source: Centers for Disease Control and Prevention; figures as of February
Few States Untouched
West Nile has been identified in 44 states and the District of Columbia since the first U.S. case in 1999. Five affected states have had no human infections: Idaho, Maine, New Hampshire, New Mexico and Washington. Only four states in the contiguous U.S. have not yet experienced any West Nile activity: Arizona, Oregon, Nevada and Utah.
1999: Connecticut, Maryland, New Jersey, New York
2000: Delaware, District of Columbia, Maryland, Massachusetts, New Hampshire, Pennsylvania, Rhode Island, Vermont, Virginia
2001: Alabama, Arkansas, Florida Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Michigan, Mississippi, Missouri, Ohio, Tennessee, Wisconsin
2002: California, Colorado, Idaho, Kansas, Minnesota, Montana, Nebraska, New Mexico North Dakota, Oklahoma, South Carolina, South Dakota, Texas, Washington, West Virginia, Wyoming
Source: Centers for Disease Control and Prevention
Weblink
West Nile Virus Basics, information about West Nile virus from the CDC (http://www.cdc.gov/ncidod/dvbid/westnile/)
West Nile resource page from the FDA (http://www.fda.gov/oc/opacom/hottopics/westnile.html)
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