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.
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.
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.
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 *
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.
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.
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 * .
See also Rickettsial Infections • Tick-Borne Illnesses: Overview • Zoonoses: Overview
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Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-232-4636. Website: http://www.cdc.gov (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: http://www.niaid.nih.gov (accessed August 12, 2015).
National Organization for Rare Disorders. 55 Kenosia Ave., Danbury, CT 06810. Telephone: 203-744-0100. Website: https://rarediseases.org (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.