Tropical Diseases: Prevention

by Food and Drug Administration (FDA)

(Page 4 of 4)

Recently, 32 Persian Gulf War veterans were identified as leishmaniasis victims, 12 with viscerotropic leishmaniasis, a chronic syndrome associated with the infection, Magill says. They had fever and vague flu-like symptoms, but few signs of overt disease, he says. "Some had lymph-node enlargement that tended to come and go. A couple had slightly enlarged spleens."

A free clinical evaluation program has been set up to identify and treat all veterans infected with leishmaniasis. (See "Want More Information?")

The only current way to confirm a leishmaniasis diagnosis is by finding parasites in a clinical specimen. FDA is evaluating a skin test developed by the Defense Department for mass screening of troops.

Preventive measures are staying indoors from dusk to dawn and using bed nets with 18 or more holes per inch — sandflies are a third the size of mosquitoes. Treatment of choice is with injectable drugs containing pentavalent antimony, a potentially toxic metal. "Drugs in this class remain unapproved by FDA, and no manufacturer has applied for approval," says Andrea Meyerhoff, M.D., an infectious disease specialist with the agency.

Levy took one such drug, sodium stibogluconate, available on a patient by patient basis from CDC. Through home care, Levy had an intravenous dose each day for 20 days.

Although she had a reaction that she describes as "the worst scenario of flu symptoms," Levy urges those who get leishmaniasis, "Don't think, 'Oh, I'll knock it off.' Go on that medication if it's what your doctor ordered. It isn't worth taking a chance."

In 1994, FDA designated aminosidine, an antibiotic that does not contain antimony, as an orphan drug for visceral leishmaniasis, and a sponsor is working to develop it.

Goldman and colleagues are studying new ways to make a leishmaniasis vaccine. "We're trying to skew the immune response," he says, "so it gives a protective reaction to the infection."

Richard Kenney, M.D., a colleague, says, "Past efforts clearly show the need for a better understanding of the immune response to the parasite." Toward this end, Kenney and Shyam Sundar, of the Institute of Medical Sciences, Banaras Hindu University, India, collaborate on studies of the immune response at various stages of infection and treatment.

The Global Fight Continues

WHO Director-General Hiroshi Nakajima, M.D., Ph.D., in his message in the WHO 1996 report, writes that many diseases, including Chagas' disease and river blindness, "sooner rather than later ... will join smallpox as diseases of the past." But he also writes that the world is "on the brink of a global crisis in infectious diseases," requiring "a global response ... that goes beyond selfish interests and national boundaries."

Responses by WHO include development of a network of laboratories to strengthen collaboration in detecting and controlling outbreaks. WHO teams can be on site within 24 hours with supplies and equipment to set up epidemic control measures.

The Clinton administration last June established a Presidential Decision Directive on Emerging Infectious Diseases, including tropical disease, to improve U.S. and international disease surveillance and prevention and response measures.

Meanwhile, international travelers can find health advice in CDC's annually updated handbook, Health Information for International Travel.

As for Levy, her globetrotting has cooled. "My jungle trips are over," she says. Her latest trip, last August, was to Iceland.

Prevention Tips

Personal protection measures are the first line of defense against tropical diseases. The national Centers for Disease Control and Prevention advises that international travelers take these steps to avoid bites from bugs carrying infective organisms:

At least six weeks before departure, get current health information from CDC on regions you plan to visit. (See "Want More Information?") Other sources may be your health department, doctor, or travel agency.

Avoiding rural areas when possible may keep you away from some disease-causing vectors.

When outdoors, wear a hat, long-sleeved shirt tight at the wrists and tucked in at the waist, long pants tight at the ankles and tucked into socks, and shoes covering the whole foot.

On clothing, use a repellent containing permethrin. (Apply it before wearing the clothing, and let the clothing thoroughly dry before wearing, the Environmental Protection Agency advises.)

On skin, use a repellent containing DEET, no higher than 30 percent concentration. Follow instructions carefully. There have been associated rare cases of toxicity, including deaths.

When accommodations are inadequately screened or air-conditioned, use a bed net sprayed with permethrin repellent and tucked under the mattress. If in an area where Leishmania-infected sandflies are likely present, use a bed net with 18 or more holes per inch.

Spray screens with permethrin.

Use aerosol insecticides to clear rooms of insects. Follow instructions carefully.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.