Thursday, May 17, 2012

Name that Disease #22

Can you name this disease?

Image is from Wikimedia Commons under a Creative Commons license



This person has Rocky Mountain spotted fever. It's a tickborne disease that's carried by three different species of tick (American dog tick - Dermacentor variabilis, brown dog tick - Rhipicephalus sanguineus, and Rocky Mountain wood tick - Dermacentor andersoni). It is caused by a bacterium (Rickettsia rickettsii) that is transmitted through the tick's bite. Despite what the name implies, the disease is not restricted to the Rocky Mountains and does not always cause a spotty rash. The disease is found throughout the continental United States and the most cases are actually seen in states well to the East of the Rockies. Approximately two thousand five hundred human cases were reported in 2008. RMSF can also occur in dogs.

Though one of the characteristic symptoms is a rash like that seen above, approximately ten percent of people that become infected don't develop a rash. The first symptom to appear is usually fever, appearing anywhere from two to fourteen days after infection. The rash will then appear about two to five days after the onset of the fever. Other symptoms may include a lack of appetite, nausea, vomiting, headache, abdominal pain, muscle pain, and red eyes. The disease can be fatal if not treated, and treatment should be sought as soon as possible. Particularly sever infections can lead to secondary problems, including damage to blood vessels and the potential for bleeding into the brain. Unfortunately for those who don't develop the characteristic rash, these cases can go misdiagnosed. Also, diagnosis can be a bit difficult depending on the presentation of symptoms and the fact that lab tests are a bit hit or miss and frequently won't be able to detect the disease until rather late, at which time it may be too late for effective treatment. Treatment should be started as soon as RMSF is suspected, even if lab confirmation will not be available for several days to a couple of weeks.

The medication that is the first choice for treating this disease is doxycycline, an antibiotic that is a quite effective treatment. In any case, the best way to prevent RMSF is to not be bitten by a tick in the first place.

One of my favorite woods can be applied to this disease: zoonose. A zoonose is a disease that can be transmitted from any animal to a person.

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