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Diseases & Topics

Rocky Mountain Spotted Fever and Other Tick-Borne Spotted Fevers

Rocky Mountain spotted fever (RMSF) is a potentially fatal human illness caused by the bacteria Rickettsia rickettsii, which is transmitted to humans by the bite of an infected tick. In the United States, ticks that carry RMSF include the American dog tick (Dermacentor variabilis), the brown dog tick, and the Rocky Mountain wood tick. In North Carolina, RMSF has been found in American dog ticks, which are common across the state. The lone star tick is also being investigated as a possible carrier of RMSF.

A second spotted fever-like illness has been found in North Carolina. This illness is caused by the bacteria Rickettsia parkeri, which can be transmitted by the Gulf Coast tick. This tick is often confused with the American dog tick since the two look very similar to the naked eye. Illness caused by Rickettsia parkeri is less severe than RMSF and rarely fatal.

Laboratory tests are not yet available to distinguish between the two rickettsias. Diseases caused by this group of bacteria are referred to as Spotted Fever Group, or Spotted Fever Rickettsiosis (SFR). SFR is the most common tick-borne illness reported in North Carolina.

Typical symptoms of RMSF/SFR include fever, headache, abdominal pain, vomiting, and muscle pain. A rash may also develop but is often absent in the first few days; some patients never develop a rash. A scab may also develop at the site of the tick bite. Antibiotics are most effective if started before the fifth day of symptoms. The initial diagnosis of SFR is made based on clinical signs, symptoms and medical history, and can later be confirmed by using specialized laboratory tests. Since RMSF/SFR can be difficult to diagnose in the early stages, patients with suspected SFR should be treated immediately in accordance with CDC published guidelines External link. Without prompt and appropriate treatment, the disease can be fatal.

RMSF and other tick-borne diseases can be prevented by avoiding tick bites. Use insect repellent, remove ticks promptly and eliminate tick habitat around your home through landscaping and integrated pest management practices.

In North Carolina

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