Strategies for avoiding the diseases of summer


June 28, 1994|By Dr. Genevieve Matanoski | Dr. Genevieve Matanoski,Medical Tribune News Service

The arrival of summer, with its long, balmy days and corresponding outdoor activities, brings the potential for increased exposure to ticks and the infections they carry -- resulting most notably in Lyme disease and Rocky Mountain spotted fever.

Just how serious are these diseases, and what can women and their families do to keep from getting infected? What strategies are being explored to predict areas of highest risk and to better detect the disease-causing organisms?

I referred these questions to two colleagues at the Johns Hopkins School of Public Health: Harvey Fischman, an associate professor of epidemiology, and Gregory Gurri Glass, an assistant professor of immunology and infectious diseases.

Q: How does Lyme disease differ from Rocky Mountain spotted fever?

A: Lyme disease usually is transmitted by the small nymph of the black-legged tick (also known as the deer tick). This tick will attach itself to deer, rodents and other animals, as well as unwary people who happen to brush by.

Because the nymph is so small, its bites often go unnoticed. If left undetected and untreated, Lyme disease can have long-term debilitating effects, including chronic arthritis, vision problems and heart irregularities.

Rocky Mountain spotted fever is transmitted by a larger, mature tick. It can be fatal if not treated promptly, but early treatment generally ensures a complete recovery.

The occurrence of Lyme disease ranges from New England to Virginia, mostly along the coast; the upper Midwest, mostly in Wisconsin and Minnesota; and in California and Oregon along the West Coast. New York and Connecticut are the most prevalent areas for the disease.

Rocky Mountain spotted fever has a wider distribution -- basically nationwide -- but mostly is found in the eastern part of the United States, despite its name.

Q: What are the symptoms of these two diseases?

A: Lyme disease is difficult to diagnose, in part because the symptoms are so vague, and are common to many illnesses. Tiredness, a general feeling of malaise, aching joints, headache, fever, skin rashes and numbness in the arms, hands and face are reported. Because of this, Lyme disease often is misdiagnosed in its early stages.

One of the few distinctive symptoms of Lyme disease is the "bull's eye" rash, which can develop after a person is bitten by an infected tick. If you notice this early sign of the disease, contact your doctor immediately. Caught early, Lyme disease is treatable and curable.

Early signs of Rocky Mountain spotted fever also can be vague. Early symptoms are like those of upper respiratory infections or colds, but the rash that is part of the disease is unusual because it starts on the soles of the feet and the palms of the hands, spreading toward the torso. If the disease is treated promptly with antibiotics, recovery is complete, and the person becomes immune to this infection. If left untreated, however, the disease can be fatal.

Q: How can I protect myself, my family and my pets from tick bites?

A: Most ticks are not infected, but it is wise to avoid being bitten. Wear long pants tucked into socks or shoes if you plan to venture into areas where ticks are prevalent, such as meadows and woods.

Use of a commercially available tick repellent or insecticide also is a good idea. Finally, carefully examine yourself and your children regularly for ticks after all outdoor activities. Showering after these activities is a particularly good idea. Carefully remove any ticks found, using tweezers or a dab of oil to smother the tick.

If pets are exposed to tick-infested areas, they should be "dipped" in an insecticide, as well as examined for ticks.

Q: How will current research help combat the threat of disease?

A: Currently, researchers at the Johns Hopkins School of Hygiene and Public Health are mapping the occurrence of Lyme disease by geographic area to improve their ability to detect areas where ticks carry the disease-causing organism.

Using a method called Geographic Information Systems (GIS), cases of Lyme disease are plotted on a map, then environmental factors are overlaid, Bto predict conditions related to increased disease risk.

Other work has centered on amplifying the DNA of the organism carried by ticks that causes Lyme disease. This will lead to easier, swifter detection of the disease.

Dr. Genevieve Matanoski is a physician and epidemiologist at the Johns Hopkins School of Hygiene and Public Health. She is a founding director of the school's Institute for Women's Health Research and Policy.

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