Rocky Mountain Spotted Fever May Be Spreading

In Recent Years, 16 Arizona Cases Linked to Tick-Infested Dogs

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Aug. 10, 2005 -- Rocky Mountain spotted fever may be spreading beyond its usual stomping ground, researchers say.

Doctors should keep that in mind, a journal editorial in The New England Journal of Medicine notes.

Far too physicians consider a diagnosis of Rocky Mountain spotted fever or take the time to inquire about tick bites or exposures -- critical information that can lead to diagnosis and to a lifesaving antibiotic treatment, write the editorialists.

Rocky Mountain spotted fever is a potentially life-threatening disease. It's transmitted by ticks.

Unexpected Rocky Mountain Cases

Sixteen people in Arizona definitely or probably had the disease from 2002 through 2004. That's more cases than expected since Rocky Mountain spotted fever is "rare" in Arizona, write Linda Demma, PhD, and colleagues. According to the CDC, more than half of the cases occur in the South Atlantic region of the U.S.

Demma's team investigated those cases. Their findings:

  • 13 patients were younger than 12 years old.
  • 2 of the 16 patients died of the disease.
  • 15 patients were hospitalized.
  • All confirmed cases were linked to tick-infested dogs.
  • 4 patients reported being bitten by a tick before their illness.

The patients' initial symptoms included high fever, rashes, cough or sore throat, and headache. Later symptoms include nausea, vomiting, pain, diarrhea, and abdominal pain. Rocky Mountain spotted fever is often nonspecific and may resemble many other infectious and noninfectious diseases, writes the CDC.

Looking back over past medical records, the researchers noted three more patients in the same communities who may have had Rocky Mountain spotted fever in 2001.

Tick-Infested Homes, Dogs, Furniture

Infested ticks were found in patients' homes (even in cracks on stucco walls), dogs, and discarded upholstered furniture left outside, where the dogs lounged and kids played.

Lots of dogs lived in the area, and many "roamed freely" among the homes, write the researchers. "Ticks in all life stages were distributed abundantly in and around many of the patients' homes."

Unexpected Source

The Arizona patients got the illness via the common brown dog tick, writes Demma. Usually, Rocky Mountain spotted fever is carried by another kind of tick.

The Arizona cases may show that Rocky Mountain spotted fever can now travel in a different kind of tick -- while staying as troublesome as ever.

Continued

Redrawing the Map

"No longer can we consider Rocky Mountain spotted fever a disease of only rural and southern venues," write J. Stephen Dumler, MD, and colleagues.

They didn't work on Demma's study. Instead, they wrote an editorial about it for The New England Journal of Medicine.

Rocky Mountain spotted fever tends to wax and wane over the years, and it's in the middle of its third emergence since 1920, writes Dumler, an associate professor of pathology at Johns Hopkins University's medical school.

Prevention

The CDC makes these recommendations for personal protection against tick bites when a person is in an area that increases their expose to ticks:

  • Wear light-colored clothing, allows you to see ticks that are crawling on your clothing.
  • Tuck your pant legs into your socks so that ticks cannot crawl inside your pant legs.
  • Apply repellents to discourage tick attachment. Repellents containing permethrin can be sprayed on boots and clothing and will last for several days. Repellents containing DEET can be applied to the skin but will last only a few hours before reapplication is necessary. Use DEET with caution on children. Application of large amounts of DEET on children has been associated with adverse reactions.
  • Conduct a body check upon return from potentially tick-infested areas by searching your entire body for ticks. Use a handheld or full-length mirror to view all parts of your body. Remove any tick you find on your body.
  • Parents should check their children for ticks, especially in the hair, when returning from potentially tick-infested areas. Ticks may also be carried into the household on clothing and pets and only attach later, so both should be examined carefully to exclude ticks.

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Sources

SOURCES: Demma, L. The New England Journal of Medicine, Aug. 11, 2005; vol 353: pp 587-594. Dumler, J. The New England Journal of Medicine, Aug. 11, 2005; vol 353: pp 551-553. CDC.
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