Rocky Mountain Spotted Fever

Background

Rocky Mountain Spotted Fever or RMSF may resemble other infectious and noninfectious conditions. Only 3%-18% of patients present with rash, fever, and a history of tick exposure on their first visit, thus there should be a high level of suspicion of RMSF in infants and children even if one feature is lacking. The absence of tick exposure should not dissuade one from suspecting RMSF.

The most effective ways to reduce the risk for RMSF are:

1) Limit exposure to ticks, especially during April-September
2) Thoroughly inspect the head, body, and clothes for ticks after time spent in wooded or grassy areas, especially along the edges of trails, roads, or yards
3) Immediately remove attached ticks by grasping the tick with tweezers or forceps close to the skin and pulling gently with steady pressure.

SYNONYMS RMSF

GEOGRAPHY
Broadly distributed throughout the continental United States, as well as southern Canada, Central America, Mexico, and parts of South America
Between 1981 and 1996, this disease was reported from every U.S. state except Hawaii, Vermont, Maine, and Alaska.

PATHOGENESIS CHARACTERIZATION

Rickettsia rickettsii A species of bacteria that is spread to humans by ixodid (hard) ticks

PROGNOSIS AND TREATMENT CHARACTERIZATION

Prognostic Factors

Survival
Public Health Rep. 1941;56:1699-703.

Approximately 20% of the cases and 15% of reported deaths were in persons aged <10 years

Because of RMSF's rapid course, half the RMSF deaths in this age group occurred within 9 days of illness onset, leaving no more than several days to establish the diagnosis and initiate specific antibiotic therapy

Before the discovery of effective antirickettsial drugs, 13% of children with RMSF died

Despite the availability of treatment and advances in supportive medical care, the case-fatality ratio is 2%-3% for patients aged <10 years with RMSF

Treatment
Clin Infect Dis. 1995;20:1118-21
Pediatr Infect Dis J. 2000;19:871-4.

Respond quickly to tetracycline-class antibiotics (e.g., doxycycline) when therapy is started within the first few days of illness

Most broad-spectrum antibiotics, including penicillins, cephalosporins, and sulfa-containing antimicrobials, are ineffective treatments for RMSF

Am J Trop Med Hyg. 1995;52:405-13

Commonly Used Terms

Bacteria

Skin Rash

Last Updated 3/8/2001

SYNONYMS	RMSF
GEOGRAPHY	Broadly distributed throughout the continental United States, as well as southern Canada, Central America, Mexico, and parts of South America Between 1981 and 1996, this disease was reported from every U.S. state except Hawaii, Vermont, Maine, and Alaska.

PATHOGENESIS	CHARACTERIZATION
Rickettsia rickettsii	A species of bacteria that is spread to humans by ixodid (hard) ticks

PROGNOSIS AND TREATMENT	CHARACTERIZATION
Prognostic Factors
Survival	Public Health Rep. 1941;56:1699-703. Approximately 20% of the cases and 15% of reported deaths were in persons aged <10 years Because of RMSF's rapid course, half the RMSF deaths in this age group occurred within 9 days of illness onset, leaving no more than several days to establish the diagnosis and initiate specific antibiotic therapy Before the discovery of effective antirickettsial drugs, 13% of children with RMSF died Despite the availability of treatment and advances in supportive medical care, the case-fatality ratio is 2%-3% for patients aged <10 years with RMSF
Treatment	Clin Infect Dis. 1995;20:1118-21 Pediatr Infect Dis J. 2000;19:871-4. Respond quickly to tetracycline-class antibiotics (e.g., doxycycline) when therapy is started within the first few days of illness Most broad-spectrum antibiotics, including penicillins, cephalosporins, and sulfa-containing antimicrobials, are ineffective treatments for RMSF