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Emory Study To Determine The Prevalence of West Nile Virus In Emergency Department Patients With Fever

ATLANTA ­ As part of a research study, Emory University investigators are expanding West Nile virus testing to include emergency room patients with fever. The effort seeks to determine the real prevalence of West Nile virus in a group where infection might otherwise go undetected because its symptoms are less severe or not specific for West Nile virus fever.

Researchers at Emory's School of Medicine and Rollins School of Public Health are collaborating with the Georgia Division of Public Health to conduct the study. While the state health department currently offers tests for West Nile virus infection in persons diagnosed with neurological diseases such as encephalitis or meningitis, the pilot study broadens the scope of testing to persons who present with fever to the emergency department of Grady Memorial Hospital.

Ruth Berkelman, MD, Rollins Professor and director of the Center for Public Health Preparedness and Research at the Rollins School of Public Health, is the co-principal investigator for the project, which includes a study being conducted in partnership with a similar study at Duke University Medical Center.

"The main purpose of this study is to increase our understanding of West Nile virus infection and the diseases it causes," Dr. Berkelman says. "Most often, doctors and other health care providers recognize the infection when patients have severe disease with neurologic signs. However, most patients with West Nile virus infection may develop minimal symptoms or non-specific symptoms such as fever, swollen glands, or muscle aches. As a result, the infection is not recognized at the time or is never detected."

Katherine Heilpern, MD, associate professor, Department of Emergency Medicine, and principal investigator for Emory’s participation, says that serious complications of meningitis or encephalitis are very rare, probably occurring in less than one percent of West Nile virus-infected patients.

"When we identify patients with the serious neurological complications of the disease, that is only the tip of the iceberg, although it probably is the most clinically significant tip," Dr. Heilpern says. "But we are missing a number of patients who have the West Nile virus infection, and this only because we have never looked at the minimally symptomatic patients before."

Drs. Berkelman and Heilpern noted that because surveillance efforts have been intensified, the public should be aware that more human cases of West Nile virus infection may be detected. West Nile virus infection is a notifiable condition and must be reported to the health department in Georgia.

"There is no reason to believe that the number of infections this year will be substantially different than last year. However, our more aggressive screenings will uncover more cases," Dr. Heilpern says.

Adult patients (18 and over) who present to Grady Memorial Hospital with fever and receive acute or emergency care are eligible for the study. Patients must sign a written consent in order for their blood sample (which will have already been taken as part of their care) to be tested for West Nile virus. The test is being performed in the summer months (July 1-October 1, 2003) when the mosquitoes that pass the virus to humans are most active.

The study is also collecting information on the patients’ symptoms, past medical history, and lifestyle interviews to help determine if certain behaviors may increase the risk of West Nile virus infection.

Beginning this year in Georgia blood donors will be screened for West Nile virus. To date in 2003, there have been no human cases of West Nile virus infection reported in Georgia, but cases have been confirmed in mosquitoes, birds and horses. South Carolina, Alabama, and Florida have reported human cases this year. Last year, there were 44 human cases and 7 deaths in Georgia, according to the Georgia Division of Public Health.

Other Emory physicians involved in the study include Carlos del Rio, MD, associate professor of medicine, Emory University School of Medicine and Chief of Medicine, Grady Memorial Hospital, and Henry Blumberg, MD, associate professor of medicine, Emory University School of Medicine and hospital epidemiologist, Grady Memorial Hospital.

Viruses that are carried by mosquitoes are called arboviruses. The most common way for humans to get an arbovirus, such as West Nile virus, is from the bite of an infected mosquito. The Georgia Division of Public Health suggests the following tips to take action against mosquitoes:

- Throw away or bring indoors anything that can collect water, such as old tires, cans, buckets, uncovered jars, and toys. Drill drainage holes in tires used as swings. Drain and scrub birdbaths, pet dishes, and kiddy pools at least once a week. Refill them with clean water.
-Empty water from saucers under potted plants and trash baskets.
- Clean gutters, flat roofs, and air conditioner drains frequently.
- When watering lawns or gardens, avoid leaving puddles behind. Drain or fill stagnant water pools, puddles and drainage ditches around the house.
- Eliminate water-holding tree stumps, and fill holes in trees.
- Keep fish such as goldfish in ponds and water gardens, to eat mosquito larvae.
- Keep window and door screens tight-fitting and in good repair.
- Store boats so they will not collect water, and turn over wheelbarrows.
- Maintain pools and hot tubs with proper chemicals and filtration. If you use covers over a pool, hot tub or boat, remove any water trapped on the covers after each rain.
- Repair leaky pipes and outside faucets so water does not collect.
- Keep grass and weeds mowed, especially on banks next to water, to reduce resting places for adult mosquitoes.
- Avoid spending time outdoors when mosquitoes are active. If you must be outdoors apply insect repellent. Do not use a DEET-based repellent on infants. DEET is only safe and effective for adults and older children when used according to package instructions.