Rocky Mountain spotted fever (RMSF) is an acute febrile tick-borne illness caused by Rickettsia Rickettsii. In North America, it is both the most severe and the most common Rickettsial infection.

Rickettsial diseases are infections that you can get from some tick bites.

Rocky Mountain Spotted Fever (Rickettsia Rickettsii),is probably the best known Ricketsial disease in the United States.it is caused by Rickettsia Rickettsii. Despite its name (it was first recognized in the Rocky Mountain area), it is most common in the south eastern states and Appalachia. This Rickettsia is a parasite of ticks and is usually passed from one generation of ticks to another through their eggs, a mechanism called transovarian passage. Surveys show that in endemic (regularly occurring within an area or community) areas, perhaps 1 out of every 1000 ticks is infected.

About a week after the tick bites, a macular rash develops that is sometimes mistaken for measles, however it often appears on the palms and souls, where viral rashes do not occur. The rash is accompanied by fever and headache. Death, which occurs in about 3% of the approximately 2000 cases reported each year, is usually caused by kidney and heart failure. Serological tests do not become positive until late in the illness. Diagnosis before the typical rash appears is difficult; symptoms vary widely. Also on dark skinned individuals, the rash is difficult to see. If treatment is not prompt and correct, the mortality rate is as high as 20-30 percent.

Antibiotics such as Tetracycline and Chloramphenicol are very effective if administered early enough. There is no vaccine to prevent RMSF.

ETIOLOGY

Rickettsia Rickettsii, the most well-described and most lethal of the spotted group Rickettsiae, causes Rocky Mountain spotted fever (RMSF). It is a coccobacillary, obligate, intracellular organism that accidentally infects human hosts after a bite with an infected tick vector. Transmission is believed to occur very quickly after a bite from an infected tick, with a rapid entry of the bacteria into human endothelial cell

Patients typically present with symptoms four to ten days after exposure to the Rickettsia via tick bite. Patients may or may not recall the tick bite, as the tick does not need to have prolonged contact with the host to cause infection. A detailed travel history is important to identify any outdoor activities in endemic areas and areas with other endemic Rickettsia, as symptoms overlap between the various Rickettsial infections.

Symptoms classically include the triad of fever, headache, and a petechial or maculopapular rash( a skin condition that appears as a combination of flat ,discolored areas of skin “macules” and small, raised bumps,” papules” ) but may also include lymphadenopathy (Lymphadenopathy refers to the swelling of lymph nodes which can be secondary to bacterial, viral, or fungal infections, autoimmune disease, and malignancy), central nervous system changes such as confusion or nuchal rigidity (neck stiffness caused by bacterial meningitis and other serious medical condition), myalgias (muscle pain) and arthralgias (joint pain), hepatitis, vomiting, and cardiovascular instability.

The rash often begins as a maculopapular rash around the wrists and ankles that progresses to petechia. It is essential to have a high index of suspicion for rickettsial infection when patients present with these “influenza-like” symptoms during the summer months, regardless of known tick or insect exposure.

RMSF does not result in chronic or persistent infections. Some patients who recover from severe RMSF may be left with permanent damage, such as:

Amputation of arms, legs, fingers, or toes (from blood vessel damage)

Hearing loss

Mental Disability
To avoid tick bites and infection, experts advise:

Avoid tick-infested areas, especially during the warmer months.

Wear light-colored clothing so ticks can be easily seen. Wear a long sleeved shirt, hat, long pants, and tuck pant legs into socks.

Walk in the center of trails to avoid overhanging grass and brush.

Clothing and body parts should be checked every few hours for ticks when spending time outdoors in tick-infested areas. Ticks are most often found on the thigh, arms, underarms, and legs. Ticks can be very small (no bigger than a pinhead). Look carefully for new “freckles”.

The use of insect repellents containing DEET on skin or permethrin on clothing can be effective. Follow the directions on the container and wash off repellents when going indoors.

Remove attached ticks immediately.