Rocky Mountain spotted fever Rickketsial Diseases
What is Rocky Mountain spotted fever?
Rocky Mountain spotted fever (RMSF) is the most severe and the most frequently reported tick-borne illness in the United States. This disease, affecting humans and dogs, is caused by the bacterial organism Rickettsia rickettsii.
In the last 50 years, approximately 250-1,200 cases of Rocky Mountain spotted fever have been reported annually in the USA. It is likely that many more cases go unreported. States with the highest incidences of RMSF cases (35%) were North Carolina and Oklahoma. Since the year 2000, Ohio has seen between 2 and 26 cases per year.
How do people get Rocky Mountain spotted fever?
The bacterium that causes RMSF is transmitted by the bite of an infected tick. The most common tick in Ohio, the American dog tick, is the primary carrier for this disease.
Rocky Mountain wood ticks and the Brown dog tick have also been known to carry RMSF. RMSF can not be contracted directly from dogs or other people.
Who is most at risk for getting Rocky Mountain spotted fever?
People who spend time in the outdoors in tick-infested environments especially woodlands and brushy areas, are at an increased risk of exposure. Dogs or other pets that frequent these types of areas may also bring infected ticks home.
How long after a tick bite before symptoms appear?
Symptoms usually appear within 5 to 10 days.
What are the symptoms of Rocky Mountain spotted fever?
Early stages of disease are nonspecific (fever, nausea, body aches, loss of appetite, vomiting, and severe headache). Later signs may include a rash, abdominal pain, joint pain and diarrhea.
The rash usually starts on the arms and ankles and moves to the palms of the hands or soles of the feet. Three things that may suggest RMSF infection are fever, rash and history of a tick bite. RMSF can be a very severe illness and require hospitalization. The bacteria attack the cells lining blood vessels throughout the body and can involve the lungs, brain or kidneys.
How is Rocky Mountain spotted fever diagnosed?
A diagnosis of Rocky Mountain spotted fever is based on a combination of clinical signs and symptoms and specialized confirmatory laboratory tests. Other common laboratory findings suggestive of Rocky Mountain spotted fever include thrombocytopenia (decreased platelets), hyponatremia (low blood sodium), and elevated liver enzyme levels.