Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is an infection transmitted by the bite of a tick * . At first its symptoms are mild, but without treatment the disease can become serious and cause organ damage and death.

What Is Rocky Mountain Spotted Fever?

Rocky Mountain spotted fever (RMSF) is the most serious of the rickettsial (rih-KET-see-ul) infections, diseases caused by bacteria from the Rickettsiaceae family. These bacteria typically spread to people through blood-sucking parasites * such as ticks and fleas. In Rocky Mountain spotted fever, the bacterium Rickettsia rickettsii lives and reproduces in the Ixodidae (ik-SAH-dih-day) family of hard-bodied ticks, such as the American dog tick and the Rocky Mountain wood tick, before it infects people. Once it does infect a person, it enters cells lining the blood vessels and can cause serious disease.

Several of the disease's first symptoms can be confused with those of other infections. As the condition grows worse, it often causes a widespread rash, which led people to call RMSF “black measles” when it was described in the late 19th century. If the infection is not treated, it can damage several organ systems and sometimes lead to death.

How Common Is It?

Despite its name, the infection is not limited to the Rocky Mountains. It is found throughout the United States, and most cases actually occur in the southeastern part of the country. The disease also has been found in southern Canada, Mexico, some countries in Central America, and parts of South America. According to the Centers for Disease Control and Prevention, between 250 and 1,200 cases are reported in the United States each year, with most in children under the age of 15. About 5 percent of Rocky Mountain spotted fever cases are fatal, usually because a person does not receive treatment quickly.

Is It Contagious?

A closeup view of the right side of a child's face with the characteristic rash caused by Rocky Mountain spotted fever. Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by the bacterium Rickettsia rickettsia.

A closeup view of the right side of a child's face with the characteristic rash caused by Rocky Mountain spotted fever. Rocky Mountain spotted fever (RMSF) is a tick-borne disease caused by the bacterium Rickettsia rickettsia. This organism is a cause of potentially fatal human illness in North and South America, and is transmitted to humans by the bite of infected tick species. In the United States, these include the American dog tick (Dermacentor variabilis), Rocky Mountain wood tick (Dermacentor andersoni), and brown dog tick (Rhipicephalus sanguineus). CDC.
How to Remove a Tick

Petroleum jelly, lit matches, nail polish, or other products do not help in tick removal and should not be used.

What Are the Infection's Signs and Symptoms?

Symptoms of infection include severe headache, fever, confusion, chills, nausea (NAW-zha), vomiting, loss of appetite, and muscle pain. Many infections have these symptoms, so they may not be immediately identified as RMSF. As the disease worsens, it may cause joint pain, abdominal * pain, extreme thirst, hallucinations *

How Do Doctors Diagnose Rocky Mountain Spotted Fever?

Doctors usually identify the infection based on symptoms seen during an examination, reports of the disease in the area, and knowledge of a recent tick bite. Fever, rash, and history of a tick bite are considered the classic features of RMSF. The doctor also may take a blood sample to look for antibodies * to the bacteria.

What Is the Treatment?

People with RMSF often need to be in the hospital, where they can receive supportive care. The disease is treated with antibiotics, which are given as soon as a doctor suspects that a patient might have RMSF. Waiting until laboratory tests confirm the diagnosis could put the patient at greater risk because the infection can progress so quickly. Patients continue taking the medicine for at least three days after the fever goes away.

What Medical Complications Can Occur?

Treatment typically takes 5 to 10 days, but it can last much longer. Without treatment or with delayed treatment, severe cases of illness can lead to death. In addition, the disease can cause problems with the central nervous system * , the kidneys, the digestive system * , and the respiratory tract * . This worsening condition can lead to partial paralysis * , hearing loss, meningitis * , heart failure, brain damage, kidney failure, and shock * .

How Can Rocky Mountain Spotted Fever Be Prevented?


Even if people have heard about Rocky Mountain spotted fever, they may not know the name Howard Taylor Ricketts (1871–1910). Dr. Ricketts discovered the bacterium that causes the disease and figured out that it spreads to people through tick bites. In recognition of that work, Rickettsia rickettsii, the RMSF bacterium, received its double Ricketts name. Dr. Ricketts also did research on typhus (TIE-fis), another rickettsial infection. He died of typhus in 1910.

* can protect exposed skin. After being outside in tick-infested areas, people should remove clothing and check their body, including the hair, thoroughly for the parasites. Doctors recommend that any ticks that are found be removed with tweezers as soon as they are discovered. Generally, infected ticks have to be attached to the body for at least 24 hours before they pass on the RMSF bacterium.

See also Rickettsial Infections • Tick-Borne Illnesses: Overview • Zoonoses: Overview


Books and Articles

Lee, Rhodi. “Rocky Mountain Spotted Fever: Cause, Symptoms, and Prevention.” Tech Times. June 20, 2015. (accessed August 12, 2015).

“New Study Unravels Mystery of Why Deadly Tick Disease Appears to Be Surging, Yet Fatalities Have Not.” Medical Xpress. October 26, 2015. (accessed June 18, 2016).


Centers for Disease Control and Prevention. (accessed November 16, 2015).

Healthbeat. “Rocky Mountain Spotted Fever.” Illinois Department of Public Health. (accessed August 12, 2015).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-232-4636. Website: (accessed August 12, 2015).

National Institute of Allergy and Infectious Diseases. Office of Communications and Government Relations, 5601 Fishers Ln., MSC 9806, Bethesda, MD 20892. Toll-free: 866-284-4107. Website: (accessed August 12, 2015).

National Organization for Rare Disorders. 55 Kenosia Ave., Danbury, CT 06810. Telephone: 203-744-0100. Website: (accessed August 12, 2015).

* tick is a small blood-sucking creature that may transmit disease-causing germs from animals to humans through its bite.

* parasites (PAIR-uh-sites) are organisms such as protozoa (one-celled animals), worms, or insects that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. Parasites live at the expense of the host and may cause illness.

* abdominal (ab-DAH-mih-nul) refers to the area of the body below the ribs and above the hips that contains the stomach, intestines, and other organs.

* hallucinations (ha-LOO-sin-AYshuns) occur when a person sees or hears things that are not really there. Hallucinations can result from nervous system abnormalities, mental disorders, or the use of certain drugs.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

* central nervous system (SEN-trul NER-vus SIS-tem) is the part of the nervous system that includes the brain and spinal cord.

* digestive system is the system that processes food. It includes the mouth, esophagus, stomach, intestines, colon, rectum, and other organs involved in digestion, including the liver and pancreas.

* respiratory tract also called the respiratory system, includes the nose, mouth, throat, and lungs. It is the pathway through which air and gases are transported down into the lungs and back out of the body.

* paralysis (pah-RAHL-uh-sis) is the loss or impairment of the ability to move some part of the body.

* meningitis (meh-nin-JY-tis) is an inflammation of the meninges, the membranes that surround the brain and the spinal cord. Meningitis is most often caused by infection with a virus or a bacterium.

* shock is a serious condition in which blood pressure is very low and not enough blood flows to the body's organs and tissues. Untreated, shock may result in death.

* DEET (abbreviation for N, Ndiethyl-meta-toluamide) is the active ingredient in many insect repellants.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)