HEALTH & SCIENCE

West Nile infections spreading, but anxiety is mounting faster

Doctors grapple with often outsized concerns as this mosquito-borne virus is detected in more states.

By Victoria Stagg Elliott, AMNews staff . Aug. 26, 2002. Additional information

Robert Goldstein, MD, a preventive medicine resident at Tulane University in New Orleans stepped on his back porch at dusk one evening in June. In the five minutes that passed before he went back inside he was bitten by dozens of mosquitoes. A few days later he had severe muscle aches, chills, and a rash that covered his body.

Having moved to town from Pennsylvania only about a week earlier, this was not the welcome he expected. Ultimately, he was found to have one of this year's first human cases of West Nile fever. Dr. Goldstein has since recovered and has joined the public health team investigating the outbreak.

"It's kind of ironic," he said. "But it was a surprise because the odds of even having symptoms are against it."

His case illustrates several aspects of what makes the West Nile virus situation so tricky for physicians. There are two primary means of prevention: Eliminating standing water that allows mosquitoes to breed and wearing mosquito repellant -- a step that most concede is tough to do consistently.

Also, because the index of suspicion was low at the time he contracted the virus, it was challenging for Dr. Goldstein to get a diagnosis.

And this is another issue physicians face.

West Nile experts say that a diagnosis for moderate, mild or asymptomatic cases is not that crucial -- it's more important for surveillance than for patient care. Mostly because there is no available treatment except supportive therapy in the most dire cases. Dr. Goldstein, for example, confirmed that he had West Nile with a blood test after he had recovered. In the meantime, he had treated himself with over-the-counter pain relievers.

"I've had people ask if they need a blood test for it because they have mosquito bites," said Robert Hopkins, MD, associate professor of internal medicine and pediatrics at the University of Arkansas for Medical Sciences in Little Rock. "But the person I would worry about is someone who is 50 or older, especially if they have diabetes or another illness that affects their immune response. If they're out harvesting rice or doing other things that put them at high risk for exposure and they come in with fever, muscle aches and a stiff neck, in that situation, I would test."

Confirmed cases of West Nile fever or the more serious encephalitis are also rare, with just more than 100 reported for 2002, as of press time. Those numbers are escalating as the season progresses, although this may be due to intense monitoring in areas that have had human cases.

"It's not hard to test but do you want to test mass quantities of people, particularly the worried well, knowing you can't do anything?" said Sandra Kemmerly, MD, medical director of infection control at the Ochsner Clinic Foundation in New Orleans.

But the heightened alert across the country, particularly in states that have reported human cases, has meant that some physicians are getting calls after every mosquito bite. Some parents are saying they don't even want to send their kids to school.

"There's much angst," said Dr. Kemmerly. "We're getting calls all day long about mosquito bites that are really red and itchy, but a mosquito bite is a mosquito bite. There's no way you can look at it and tell. We could do the blood test, but the health department is completely inundated with people who want to be tested."

Watching, waiting, preventing

While physicians are dealing with high anxiety among their patients, for public health officials, the emergence of West Nile virus from New York City to more than 30 states in four years has been a fascinating example of how a virus can arrive from overseas and spread to nearly the whole country in a very short time. Experts expect it to be in every contiguous state within the year.

"We are a global village," said Mohammad N. Akhter, MD, MPH, executive director of the American Public Health Assn. "And once it's introduced in the country, there's no way to stop it, particularly when it's carried by mosquitoes or birds."

The situation is also a lesson in how a new virus moves through a population. The first felled were the most vulnerable, the frail elderly who already had complicated medical conditions.

This year the virus has started hitting younger people, and the suspicion is that over the next few years the country will see a death rate in the shape of a bell curve. Those most susceptible will be killed by the virus. Those less vulnerable will catch the virus but will remain asymptomatic or become only moderately ill. They will then develop lifetime immunity.

That's just one theory, however, and experts warn that viruses tend to be unpredictable.

"Germs are smarter than we are and trying to predict patterns of spread by a brand new agent is notoriously difficult," said Jeffrey R. Starke, MD, director of infection control for Texas Children's Hospital in Houston.

But after being surprised by the virus four years ago, public health officials, even those in states without any cases yet, say they are more ready than ever, particularly because of additional money allocated for bioterrorism preparedness. The money is beginning to build an infrastructure that is being used to deal with any public health crisis, including West Nile.

"The most likely bioterrorism event is none," said Dr. Starke, who was also involved in developing a bioterrorism surveillance plan for his area.

"Our whole goal was that whatever we did for bioterrorism would improve public health in general, and West Nile is one of the first tests of that," he said. "Every day I get an e-mail from our county health department updating me on what's going on. That wasn't previously the case for a variety of these diseases. We're already seeing some small but distinct dividends."

Public paying more attention

The public health system in the post-anthrax world has also gained more respect. People are more tuned in to public health messages and are more likely to listen. They are also more able to respond appropriately.

"Anthrax was just another public health problem like this one, and hopefully people -- both clinicians and the public -- learned about how things are done by public health and why," said Dr. Starke.

But while physicians are calming patients' fears about their mosquito bites and public health is working to keep the mosquito population under control, scientists are working to develop a vaccine. One is available for horses and several are in the works for humans, although many question how useful they might actually be.

Despite all the attention being paid to West Nile, its actual numbers continue to be low, and there are concerns that adverse reactions from a vaccine may outweigh the possible benefit.

"Any time you have a disease that has such a low attack rate, you have to ask yourself about the worth and the cost/benefit," said Dr. Starke. "Even if we can make a vaccine, there's still going to be a question of whether it's a good idea to vaccinate the population."

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Symptoms

• West Nile infection: mild fever, headache, body aches, rash, swollen lymph glands.
• West Nile encephalitis: rapid onset of severe headache, high fever, stiff neck, muscle weakness, confusion, stupor, disorientation, loss of consciousness, tremors, paralysis.

Infection and incubation

• Less than 1% of people infected will get severely ill. Fatality rates for those with severe illness are 3% to 15%.
• Symptoms occur 3 to 15 days after infection.

Steps toward diagnosis

• Take a history to assess risk.
• People in areas with virus activity are at risk; those older than 50 are at highest risk.
• If a patient is at risk and is symptomatic, a blood sample can be sent to a public health lab for confirmation.

Source: Centers for Disease Control and Prevention

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The virus first noted in New York is migrating throughout the country. As of Aug. 7, 112 people had confirmed infections this year. While the majority of illnesses are in Louisiana, cases have been reported as far west as Texas.

First appearance in 1999: Connecticut, Maryland, New Jersey, New York

First appearance in 2000: Delaware, Massachusetts, New Hampshire, North Carolina, Pennsylvania, Rhode Island, Virginia

First appearance in 2001: Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Michigan, Mississippi, Missouri, Ohio, Tennessee, Wisconsin

First appearance in 2002: District of Columbia, Kansas, Minnesota, Nebraska, North Dakota, Oklahoma, South Carolina, South Dakota, Texas, Vermont, West Virginia

States reporting human cases: Alabama, Connecticut, District of Columbia, Florida, Georgia, Illinois, Indiana, Louisiana, Maryland, Massachusetts, Mississippi, New Jersey, New York, Pennsylvania, Texas

Source: CDC West Nile virus surveillance and control page (http://www.cdc.gov/ncidod/dvbid/westnile/surv&control.htm)

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NIH fact sheet on West Nile virus (http://www.niaid.nih.gov/factsheets/westnile.htm)

CDC West Nile Virus Basics page (http://www.cdc.gov/ncidod/dvbid/westnile/)

Ideas Inc. West Nile virus links page (http://www.westnilefever.com/)

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Copyright 2002 American Medical Association. All rights reserved.