rocky mountain spotted fever
Poster picture compiled form vector pictures courtesy:
Rocky Mountain Spotted Fever: A fever that rocks the developed world
By-Dr. M.v. Annalarasi
January 3, 2018

Rocky Mountain Spotted Fever or RMSF is one of the most common and lethal rickettsial diseases reported in the United States. The earliest records of the disease date back to the year 1873, documented by the US Public Health. The disease was first described in the year 1896, by Major W.W. Wood, after collecting descriptions of cases from eight Idaho Physicians.

The name Rocky Mountain Spotted Fever was derived from the laboratory by the same name, where most of the research was done on the disease. The research into the disease was first triggered by the death of a governor’s daughter and son-in-law in Montana. Howard Taylor Ricketts, after whom the Rickettsiaceae family and the Rickettsiales are named, was the first to establish the causative organism of this disease. He confirmed in the year 1906, that wood tick was the vector of the disease. The organism was also thus named after him. Ironically, the pathologist died due to typhus, when he had become interested in a strain of murine-carried typhus in a major outbreak in Mexico City, and the apparent similarity of the disease to spotted fever and had isolated the causative organism.

The synonyms of the disease include Black measles,’’ ‘‘tick typhus,’’ ‘‘Tobia fever’’ (Colombia), ‘‘S˜ao Paulo fever’’ or ‘‘febre maculosa’’ (Brazil), and ‘‘fiebre manchada’’ (Mexico). In Britain, it is termed as the tick typhus.


Rocky Mountain Spotted Fever Causative agent

Rickettsia rickettsia is the disease-causing agent of Rocky Mountain Spotted Fever. These are the gram-negative bacterium. R. rickettsia bacterium is transmitted to the humans by prolonged bite lasting for several hours of an adult tick. The bite and thus transmission also occur in small animals. The adult tick responsible is the wood tick (Dermacentor andersoni) in the western United States regions and the dog tick (Dermacentor variabilis) in the eastern parts of the country. In some instances, the organism R. rickettsia is also acquired through inhalation, especially in the laboratory settings where aerosolization of blood and specimens might occur). The transmission can also occur by coming in contact with the tick, over the abraded skin or via tissue juices. One of the reasons why people are advised not to crush ticks between their fingers while removing them from other people and animals. It is advised to dispose of these ticks by immersing them in alcohol or flushing it down the lavatory. In the major tick-infested areas, 1% to 5% of these ticks harbor the organism R. rickettsia.


At risk Population

The at-risk population is children aged between 5-9, Native Americans, and adults over the age of 70. People with immunosuppressive diseases are at increased risk of death.


Pattern of prevalence

Compared to the earlier days, when the disease was much more lethal and confined to the rocky mountain regions, the disease prevalence is now dependent on the distribution of the various tick vectors. The pattern of occurrence of the disease is more associated with outdoor activities like camping, trekking, backpacking and one of the reasons for the disease to occur more in the spring and summer months (Holidays!!). The disease is endemic throughout the North and South America.

In up to 40% of the cases, the patients do not report a dog bite but do give a history of travel or camping in a tick-infested area.


Rocky Mountain Spotted Fever Symptoms

The symptoms of the disease last for several days (10- 20). The initial set of symptoms, that occur before the eruptions or change over the skin include fever chills, severe headache, and photophobia. For the first three days, headache, fever, body pain, nausea, vomiting, and anorexia (eating disorder) can occur. It is during this stage that it becomes difficult to distinguish the disease from other self-resolving viral diseases.


Rocky Mountain Spotted Fever Rash

The characteristic rash occurs in only 14% of the patients on the first day.  By the third day, half of the patients develop skin findings. Blanching macules (pigmented non-raised skin lesions) develop on the wrists and ankles and then spread over to the legs and trunk.  The rash then spreads to palms and soles. The color of these rashes changes from bright red to dark red, then yellowish green to black. There also possibilities of the patients becoming hypotensive (reduced blood pressure) and developing noncardiogenic pulmonary oedema (fluid accumulation in tissue and air spaces of the lungs), confusion, lethargy, abnormal liver function, kidney failure, and encephalitis (inflammation /swelling of the brain tissue), finally ending up in a coma. In some cases, inflammation of the muscle tissue also occurs (myositis) and in some others’, the disease also affects the eyes, the problems ranging from inflammation of the conjunctiva to engorged retinal veins. Increased pressure in the brain causes the damage of the optic nerve too.

Be sure to tell your physician the correct history, be it a tick bite or a happily ended camping holiday!!

Most importantly, if you do find a tick on you and you remove the tick yourself and then develop any of the above symptoms ( fever or rash), visit your physician immediately.


The diagnosis of the Rocky Mountain Spotted Fever is difficult as mentioned previously. Therefore, if there was a right reporting by the patient regarding the history of exposure, it would be easier for the physician to arrive at a conclusion, without being distracted by the ‘n’ number of other diseases mimicking Rocky Mountain Spotted Fever.

So far, the only diagnostic test that has been proven to be useful in identifying the disease during the acute stage is the immunohistologic examination of cutaneous biopsy (skin) sample from the rash lesion.


Rocky Mountain Spotted Fever Treatment

The deaths due to the Rocky Mountain Spotted Fever has been decreasing since 1948, post the introduction of potent antibiotics with anti-rickettsial activity like chloramphenicol and tetracyclines. Before the administration of the curative drug, the tick if any present over the body, are carefully removed. Doxycycline (200 mg in two divided doses) is the recommended drug for both children and adults unless the patient is pregnant. The drug is given until three days after the fever subsides.  As described above, the disease comes with serious implications. Acknowledging the extent of severity, experience deems that Doxycycline should be given to any patient from a typical setting of prevalence presenting with the typical symptoms. Chloramphenicol is the choice of treatment for those patients who are either allergic to doxycycline or are pregnant. Other patients at various stages of severity of the disease are managed accordingly, in intensive care units.

Rocky Mountain Spotted Fever Prevention:

There are no vaccines to prevent the disease. Hence, the ability and the duty to protect yourself lies with you.

  1. Avoid getting bitten by ticks.
  2. Avoid visiting tick-infested areas.
  3. Tick check: If you own a pet or are an animal handler, check your body once or twice a day for the presence of ticks. Use a full-length mirror to aid you in your scrutiny. Check for the ticks especially Under the arms, In and around the ears, Inside the belly button, Back of the knees, In and around the hair, Between the legs, Around the waist.
  4. Shower: Shower within two hours of entering indoors after being outdoors. Any unattached ticks can thus be rid of.
  5. If you own a pet, make sure they do not get infected by ticks either.
  6. Reduce the ticks found in your yard by using appropriate chemical agents as well by removing litter and regular cutting of tall grasses. Your careful- lawn -maintenance is not just to impress thy neighbor but to keep your family and yourself free from ticks and their associated diseases.
  7. Wear protective clothing (long-sleeved shirt, pants securely tucked into laced boots, and a protective head covering such as a cap) while indulging in outdoor activities.
  8. Treat your clothes with products containing permethrin.
  9. Apply insect repellent (environmental protection agency registered) to exposed skin as well as to clothing.
  10. Remove the ticks with the help of fine-tipped tweezers grasping the tick as closely as possible to the skin and pulling upward with steady and even pressure.
  11. Clean the bite area with soap and water after removing the tick.



  1. Red Book Atlas of Pediatric Infectious Diseases by American Academy of Pediatrics, and MD, FAAP Carol J. Baker.
  2. Non-Neoplastic Hematopathology and Infections by Hernani Cualing, Parul Bhargava, and Ramon L. Sandin.
  3. Infectious Diseases: A Geographic Guide by Eskild Petersen, Lin Hwei Chen, and Patricia Schlagenhauf.
  4. Lippincott’s Guide to Infectious Diseases by Lippincott.

Also, read:


Rotavirus disease:

Leave a Reply

Your email address will not be published. Required fields are marked *