Rocky Mountain Spotted Fever, caused by rickettsia ricketsii bacteria, is an infection transmitted by hard ticks (Ixodidae). Rocky Mountain Spotted Fever is spread by the bite of an infected tick. Man, dogs, cats, farm animals, and wildlife species are affected. In the eastern United States, children are infected most frequently, while in the western United States, disease incidence is highest among adult males. In the eastern United States this bacteria is carried by the dog tick (dermacentor variabilis) and in the Rocky Mountain States by the wood tick (dermacentor andersoni). Also, although rare, the lone star tick (amblyomma americanum) is a carrier in the West. Rickettsia bacteria are transmitted to humans through tick bites. Hence, the disease appears most often during the months where ticks are active (spring and summer months). This infection is so called because it was first recognized in the Rocky Mountain region of the US. It is most common in Virginia, Georgia and the Carolinas, however it also occurs on the East Coast northward to Massachusetts and also westward into Tennessee, Kentucky, Arkansas and Oklahoma. Some areas of the United States are more affected than others, though at least one case has been reported in nearly every state.

The symptoms of the Rocky Mountain Spotted Fever may follow within one to fourteen days after the victim has been bitten. There is a high fever, often 39?C to 40?C, with chills, muscle aches and a severe headache concentrated in the forehead area. Also, eyes may become red, muscles may feel weak and there may be body swelling. A rash also forms anytime around the third to fifth day. It looks like small red blemishes beginning on the wrists, ankles, palms and soles and gradually spreading up the arms and legs toward the trunk, but often sparing the face. These red spots may change in appearance as the infection progresses, to look more like bruises under the skin. The symptoms and signs of this disease are secondary to the invasion by the rickettsial organisms of the cells lining the blood vessels, causing thrombosis of the blood vessels. The bacteria multiply within the endothelial cells lining the small blood vessels and spread throughout the body through the blood stream. Negative nitrogen balance appears to be extreme. Early in infection this may be related to nitrogen mucus in the urine, but after several days it is related to insufficient protein intake. Serum albumin concentration may be lowered due to protein losses, hepatic dysfunction, and endothelial damage with protein discharge. Extreme hyponatremia is common and is related to extra-cellular change of fluid, urine loss, and exchange of sodium for potassium at the cellular level.

The Rocky Mountain Spotted Fever usually causes a moderate to severe illness that may damage the lungs, liver and kidneys. Rocky Mountain spotted fever affects about 800 people in the United States each year. Before anti-biotic treatment was available, 20 to 30 percent of the cases were fatal. However, with the discovery of an antibiotic, the suffering and danger has decreased; it causes death in about 15 percent of its victims over age 70, and in only about two percent of infected victims under age 30. If an antibiotic is started rapidly, the mortality rate is ten percent.

Some patients may require supportive therapies, such as intravenous fluids, steroids, and nasogastric feedings. Improvement should be rapid (36 to 48m hours). Doctors confirm the diagnosis by taking at least two different blood samples, several weeks apart, and looking for antibodies against the infection. However this process usually takes many days for these tests to show positive results so the treatment usually begins before the results are available. Treatment with antibiotics such as tetracycline or chloramphenicol is usually successful. If the disease is treated early on, it is rare for any lasting changes to a person’s health.

Rickettsia rickettsii, the etiologic agent in RMSF, consists of small coccobacillary microorganisms. Usually they occur singly but may also appear in strands. EM reveals a two-layered cell wall and a cytoplasmic membrane. The chemical composition of rickettsiae is similar to that of gram negative bacteria. RMSF rickettsiae do not kill their arthropod hosts but are passed through unending generations of tick’s transovarially. Many small wild animals as well as dogs possess antibodies to RMSF, indicating that they may be involved in the life cycle.

Rocky Mountain Spotted Fever is caused by rickettsia rickettsii bacteria that infect humans through a tick bite, and the longer it stays attached to the skin, the greater chance of infection; usually, several hours are necessary. The infection can also be transmitted through broken skin that comes in contact with body fluids from a crushed tick. Rocky Mountain Spotted Fever however, is not contagious from person to person. Luckily, one attack probably provides permanent immunity.

Works Cited
www.ccm.lsunic.edu/bugbites/volume3/Bb-v3n5.htm
www.healthlinkusa.com/
www.mc.vanderbilt.edu/peds/pidi/infect/rmsf.htm
www.kidshealth.org/parent/common/rocky.html.
www.cdc.gov/ncidod/diseases/rmsf/rmtnsfrr.htm
www.surry.com/rockyz.html

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