Common Dog Tick Spreads Rocky Mountain Spotted Fever

Unexplained cases of Rocky Mountain Spotted Fever may be explained by the discovery that a very common dog tick carries the disease, as do two other less common ticks. Health officials made the discovery after investigating a spotted fever outbreak in Arizona that resulted in two deaths.

'We may have been missing this in the past,' said Linda Demma, who led the study for the federal Centers for Disease Control and Prevention.
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Rocky Mountain spotted fever was first recognized a century ago in Idaho but has spread through much of the United States. More than half of cases are reported from the south-Atlantic states — Delaware, Maryland, Washington D.C., Virginia, West Virginia, North Carolina, South Carolina, Georgia, and Florida. Oklahoma and North Carolina have reported the most.

The disease is caused by bacteria that infect ticks, which then bite and infect animals and people.

Symptoms occur 5 to 10 days later and can include fever, nausea, vomiting, muscle pain, lack of appetite and severe headache — signs often mistakenly attributed to common viral ailments. Late symptoms include a spotted rash, abdominal pain, joint pain and diarrhea.

Antibiotics, particularly doxycycline, are effective when given early. But fatality rates as high as 20 percent have been reported when cases are not recognized, and the disease is especially severe in children.