How can RMSF be prevented?

Limiting exposure to ticks reduces the likelihood of infection with RMSF. In persons exposed to tick-infested habitats, prompt careful inspection and removal of crawling or attached ticks is an important method of preventing disease. It may take several hours of attachment before the organisms are transmitted from the tick to the host.

It is unreasonable to assume that a person can completely eliminate activities that may result in tick exposure. Therefore, prevention measures should emphasize personal protection when exposed to natural areas where ticks are present:

• Wear light-colored clothing which allows you to see ticks that are crawling on your clothing.

• Tuck your pants' legs into your socks so that ticks cannot crawl up the inside of your pants' legs.

• Apply repellents to discourage tick attachment. Repellents containing permethrin can be sprayed on boots and clothing, and will last for several days. Repellents containing DEET (N, N-diethyl-m-toluamide) can be applied to the skin, but will last only a few hours before reapplication is necessary. Use DEET with caution on children. Application of large amounts of DEET on children has been associated with adverse reactions. Always follow label directions carefully whenever using any repellent or insecticide.

• Conduct a body check upon return from potentially tick-infested areas by searching your entire body for ticks. Use a hand-held or full-length mirror to view all parts of your body. Remove any tick you find on your body.  Save the tick for identification by health officials.

• Parents should check their children for ticks, especially in the hair, when returning from potentially tick-infested areas. Ticks may also be carried into the household on clothing and pets and only attach later, so both should be examined carefully to exclude ticks.

 Removing ticks properly      

• Use tweezers to grasp tick by mouthparts

• Pull gently straight-out

• Avoid squeezing or crushing the tick

• Wash the bite site w/ soap and water

• Do not use hot matches, cigarettes, fingernail polish, petroleum jelly, etc. to remove or suffocate the tick

• Save the tick for identification:

• Click here to see the Flyer for Tick Removal [PDF 172K]

• Physicians:  If you would like to send in a tick for identification, please contact the VBZD program or call (602) 364-4562. 

Mortality/morbidity

The mortality rate from RMSF in the United States has historically been around 4%, with death usually occurring eight days after onset of symptoms. Long-term scarring, blindness, and deafness have been documented. Patients treated five or more days after onset of symptoms experienced three times the mortality rate of patients treated earlier.

Long-term morbidity is most usually seen in patients in whom treatment has been delayed.  Patients who died received antibiotics an average of 2 days later than patients who lived. Mortality in patients older than 60 years is roughly twice that of younger patients. A 2002-2005 outbreak in Arizona was traced to the common brown dog tick (Rhipicephalus sanguineus), a tick not previously known to be a vector of disease in the U.S.

Mortality rates as high as 30% were reported for RMSF in the preantibiotic era compared with 4% currently. A significant portion of this persistent mortality likely is due to delay in diagnosis and treatment.

In the United States, where do most cases occur?

RMSF is a seasonal disease and occurs throughout the United States during the months of April through September. Over half of the cases occur in the south-Atlantic region of the United States (Delaware, Maryland, Washington D.C., Virginia, West Virginia, North Carolina, South Carolina, Georgia, and Florida). The highest incidence rates have been found in North Carolina, Oklahoma, and more recently in Eastern Arizona. Although this disease was first discovered and recognized in the Rocky Mountain area, relatively few cases are reported from that area today.

Frequency in the United States

In the US: In 2004, 1514 cases were reported—more than 4 times the 365 cases reported in 1998. The reasons for this increase are not known, but wide swings in the incidence of RMSF have occurred since 1920. Seasonal outbreaks of RMSF parallel the activity of the tick; 90% of cases are reported from April 1 to September 30, with peaks in May and June. Cases are geographically distributed; North Carolina and Oklahoma account for one third of total cases reported. South Carolina, Tennessee, and Georgia accounted for the third, fourth, and fifth highest number of cases. Less than 5% of the total number of cases are found in the Rocky Mountain states.  Asymptomatic infection may be common; 12% of children living in high-risk zones in one recent study had positive serology test results, indicating past exposure to RMSF.

How is RMSF diagnosed?

A diagnosis of RMSF is based on a combination of clinical signs and symptoms and specialized confirmatory laboratory tests. Other common laboratory findings suggestive of RMSF include thrombocytopenia, hyponatremia, and elevated liver enzyme levels.  

How is RMSF treated?

RMSF can be a severe and potentially life-threatening disease.  Diagnosis and treatment decision should be made by a physician. RMSF is best treated by using a tetracycline antibiotic, usually doxycycline. This medication should be given in doses of 100 mg every 12 hours for adults or 4 mg/kg body weight per day in two divided doses for children under 45 kg (100 lbs). Patients are treated for at least 3 days after the fever subsides and until there is unequivocal evidence of clinical improvement. Standard duration of treatment is 5 to 10 days. Because laboratory confirmation is generally not available during acute illness, treatment is initiated based on clinical and epidemiological information.

Can a person get RMSF more than once?

Infection with R. rickettsii is thought to provide long lasting immunity against re-infection. However, prior illness with RMSF should not deter persons from practicing good tick-preventive measures or visiting a physician if signs and symptoms consistent with RMSF occur, especially following a tick bite, as other diseases may also be transmitted by ticks. 

How can ticks be controlled?

The most effective strategy to control ticks is an integrated approach which includes:

1. Use appropriate spot-on treatments, tick collars, sprays, or dips to control ticks on pets.  Follow the label and your veterinarian's instructions.

2. Apply appropriate pesticides to control ticks in your yard.  You can use a pest control service or do it yourself.  Be sure to follow label instructions for the pesticide product.  Repeated applications may be indicated.

3. Remove tick habitats on your property, including leaf litter, brush, and yard clutter (boards, mattresses, old furniture, etc.).

Community-based integrated tick management strategies may prove to be an effective public health response to reduce the incidence of tick-borne infections. However, limiting exposure to ticks is presently the most effective method of prevention of tick-transmitted diseases.