Rocky Mountain Spotted Fever

What Is Rocky Mountain Spotted Fever (RMSF)?

RMSF is a disease which causes a potentially fatal illness in North and South America, and is transmitted to humans by the bite of infected tick. It has been a reportable condition in the United States since the 1920s.

What are the symptoms?

The first symptoms of Rocky Mountain spotted fever (RMSF) typically begin 2-14 days after the bite of an infected tick. A tick bite is usually painless and about half of the people who develop RMSF do not remember being bitten. The disease frequently begins as a sudden onset of fever and headache and most people visit a health care provider during the first few days of symptoms. Because early symptoms may be non-specific, several visits may occur before the diagnosis of RMSF is made and correct treatment begins. The following is a list of symptoms commonly seen with this disease, however, it is important to note that few people with the disease will develop all symptoms, and the number and combination of symptoms varies greatly from person to person.

  • Fever
  • Rash (occurs 2-5 days after fever, may be absent in some cases)
  • Headache
  • Nausea
  • Vomiting
  • Abdominal pain (may mimic appendicitis or other causes of acute abdominal pain)
  • Muscle pain
  • Lack of appetite
  • Conjunctival injection (red eyes)
  • Rash

While most people with RMSF (90%) have some type of rash during the course of illness, some people do not develop the rash until late in the disease process, after treatment should have already begun. Approximately 10% of RMSF patients never develop a rash. It is important for physicians to consider RMSF if other signs and symptoms support a diagnosis, even if a rash is not present.

A typical case of RMSF involves a rash that first appears 2-5 days after the onset of fever as small, flat, pink, non-itchy spots (macules) on the wrists, forearms, and ankles and spreads to include the trunk and sometimes the palms and soles. Often the rash varies from this description.

How is Rocky Mountain Spotted Fever treated?

Early diagnosis is important in the treatment and prevention of long-term complications. If you have a fever or rash within 4 - 6 weeks after a tick bite, consult your physician for specific RMSF testing. Most people can be successfully treated with antibiotics if treatment is begun immediately following a suspicion of a possible infection of RMSF.

How do people catch this disease?

RMSF cannot be transmitted from person to person.

Transmission of the bacteria most often result from an infected the American dog tick ( Dermacentor variabilis ) , Rocky Mountain wood tick ( Dermacentor andersoni ) , or brown dog tick ( Rhipicephalus sanguineus) .

What can be done to stop the spread of this disease?

Ticks live in woods, brushy areas, and areas with tall grass and weeds. Children who play on uncleared land or in brush or weeds should be checked closely at least twice a day, especially in the hair where ticks are hard to see.

Adults should also examine themselves after being involved in similar outdoor activities. Ticks must be removed as soon as possible to prevent the transmission of possible disease pathogens. Bathe or shower and shampoo hair after outdoor activities to prevent the attachment of ticks.

If found, ticks should be pulled out with tweezers or with fingers covered by a piece of tissue or paper towel. Ticks should not be jerked or twisted, but pulled out with a steady motion. The use of heat, solvents, nail polish, Vaseline or other material to cause the tick to release is not advised. Antiseptic should be applied to the bite area and hands washed with soap and water. Remember to document the date the tick was discovered.

General precautions can help prevent tick bites. These include using an insect repellent that can be sprayed on clothes as well as a repellent that can be used on exposed skin. Follow label directions and use extra precautions for children. Other precautions include wearing protective, light-colored clothing tucked in around the ankles and waist, keeping weeds and tall grass cut, and avoiding tick-infested places such as grassy and marshy woodland areas when possible. Stay in the center of paths when hiking or walking through woods.

Pets should be checked for ticks at least once a week, and tick collars, shampoos and other tick repellents are recommended. Oral and topical medications are also available from veterinarians.

References and Additional Information



Health Infectious Diseases