Tropical Diseases - Rocky mountain spotted fever

The name of an increasingly common tick-borne disease, Rocky Mountain spotted fever , is misleading, because humans are most likely to become infected in regions far from the Rocky Mountains. The disease, also known as tick fever , has become most prevalent in rural and suburban areas of the southern and eastern United States. It is caused by a rickettsial organism transmitted by a tick bite. Wild rodents are a reservoir of the infected ticks that carry the disease.


Rocky Mountain spotted fever may be relatively mild or dangerously severe. The symptoms of headache, chills, and fever may begin suddenly and persist for a period of two or three weeks. Fever temperatures may reach 104° F and may be accompanied by nausea and occasional vomiting. Headaches have been described in some cases as excruciating, with the pain most intense along the forehead. Muscles of the legs, back, and abdomen may ache and feel tender. The most serious cases seem to develop within a few days after a tick bite; milder cases usually are slower to develop. A rash usually develops a few days after the onset of other symptoms and is most likely to be concentrated on the forearm, ankles, feet, wrists, and hands. If untreated, Rocky Mountain spotted fever symptoms may abate h two weeks, but the infection can be fatal, particularly in persons over the age of 40.


Treatment includes administration of antibiotics and, in some cases, steroid hormones. Careful nursing care and adequate intake of protein foods and liquids also are needed.

Preventive measures are similar to those recommended to guard against tularemia. Wear adequate protective clothing that forms a barrier against tick invasion of the skin surfaces, check the scalp and other hairy body areas regularly for ticks, and remove and destroy any ticks found. In addition, ground areas known to be inhabited by wood ticks should be sprayed with an effective insecticide safe for humans; insect repellents also should be applied to clothing and exposed skin surfaces when venturing into wooded or brushy areas. Ticks may become attached to dogs and other animals and care should be used in removing them from the pets, because the disease organism can enter the body through minor cuts and scratches on the skin. A vaccine is available for protection of persons who are likely to use possibly infested tick areas for work or recreation. Immunity usually is established by two inoculations, about a month apart, and booster shots as needed.

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