Rickettsial Infection Follow-up

Patients with rickettsial infection may require hospitalization only if they are clinically unstable or have developed complications.

Rickettsial infections with severe complications may require transfer to tertiary care facilities.

Personal avoidance of ticks (wearing proper clothing and use of repellants) remains an integral part of protection against rickettsial infections. In case of bites, prompt removal of ticks might prove extremely beneficial in prevention of infection. Attempting to control the tick reservoir is not usually feasible. Use of antibiotics following tick exposure is not currently indicated to prevent rickettsial infection.

• Rocky Mountain spotted fever (RMSF): Various vaccines have been developed; however, they have not yet been proven efficacious or safe to recommend for routine use in patients. An improved killed chicken embryo vaccine has shown that it may provide partial protection against RMSF and ameliorate the illness when it occurs.^[31]
• Rickettsialpox: Avoidance of contact with and control of house mouse infestations is important to prevent acquisition of infection.
• Boutonneuse fever: Natural immunity occurs following infection. Effective vaccines are not yet available.
• Typhus group (epidemic and endemic typhus): Delousing of individuals and use of insecticides to treat clothing are effective preventive measures against the spread of louse-borne typhus. Killed vaccines that are no longer available in the United States were shown to reduce mortality rates but were not effective in prevention of disease.
• Brill-Zinsser disease (ie, relapsing louse-borne typhus): This is analogous to primary louse-borne epidemic typhus.
• Murine (endemic or flea-borne) typhus: Prevention is primarily by controlling the flea and rat populations. Insecticides should be used before rodenticides to prevent rat fleas from seeking alternate hosts if rats are no longer available. As with louse-borne typhus, a vaccine is no longer available in the United States.
• Tsutsugamushi disease (ie, scrub typhus): Prevention can be achieved by vector control or chemoprophylaxis. The agent of choice for chemoprophylaxis is doxycycline, given as a weekly dose started before exposure to infection and continued for 6 weeks postexposure.
• Q fever: A whole-cell vaccine for Q fever has been developed in Australia for clinical use in the occupational setting.^[5] Control of disease in domestic animal population has been difficult because animals that have no detectable antibodies to C burnetii still shed the organism at parturition. Q fever outbreaks in research laboratories using animals (especially sheep) can be prevented by instituting proper control measures designed to protect the environment from fomite and aerosol transmission.

• RMSF: Complications are uncommon, especially if patients receive proper treatment. Acute complications may include a superimposed bronchopneumonia and congestive heart failure (caused by fluid overload). Long-term health problems following acute RMSF infection include partial paralysis of the lower extremities; gangrene requiring amputation of fingers, toes, arms, or legs; hearing loss; loss of bowel or bladder control; movement disorders; and language disorders. These rare complications are usually seen in severely affected individuals.^[19]
• Rickettsialpox: This is usually a self-limited disease with no complications.
• Boutonneuse fever: Similarly to RMSF, the disease occasionally may follow a malignant and rapidly fatal course with multiorgan failure, encephalopathy, and coagulopathy.^[9]
• Louse-borne (epidemic) typhus: Complications are uncommon but include gangrene, parotitis, otitis, myopericarditis, pneumonia, and pleurisy.
• Brill-Zinsser disease (ie, relapsing louse-borne typhus): Complications are similar to the primary illness; however, relapses usually are less severe.
• Murine (endemic or flea-borne) typhus: Complications are similar to those observed in louse-borne typhus and are uncommon.
• Tsutsugamushi disease (scrub typhus): Complications are generally uncommon. Deafness, atypical pneumonia, disease similar to adult respiratory distress syndrome, myocarditis, and disseminated intravascular coagulopathy have been reported.
• Q fever: Complications include chronic Q fever, endocarditis, myocarditis, meningoencephalitis, glomerulonephritis, and syndrome of inappropriate antidiuretic hormone (SIADH).

RMSF

• The overall mortality rate without specific therapy is approximately 25%; however, the mortality rates are higher for men, elderly persons, and black men with G-6-PD deficiency.
• In the United States, the overall mortality rate currently is 5-7%.
• Fatalities are mainly caused by delay in diagnosis and treatment.
• Solid immunity usually follows recovery from RMSF.

Rickettsialpox

• Rickettsialpox is usually self-limited.
• Deaths have not been reported.

Boutonneuse fever

• Boutonneuse fever generally runs a benign course.
• Very rarely, it may follow a rapidly fatal course in otherwise healthy children.

Louse-borne (epidemic) typhus

• The mortality rate in untreated cases correlates with the patient's age.
• Mortality may be uncommon in children younger than 12 years, but rates rise to as high as 60-70% in individuals older than 50 years.
• Most patients who recover develop immunity.

Brill-Zinsser disease (ie, relapsing louse-borne typhus)

This is analogous to primary louse-borne epidemic typhus, except that patients who recover do not develop immunity.

Murine (endemic or flea-borne) typhus

This is usually a mild illness without significant sequelae.

Tsutsugamushi disease (ie, scrub typhus)

• Fatalities are rare with use of antibiotics.
• The heterogeneity of scrub typhus strains accounts for the frequent reinfections.
• Sporadic short courses of doxycycline or chloramphenicol may be required to prevent relapses.

Q fever

• Patients with uncomplicated Q fever recover within 1-3 months without sequelae.
• The mortality rate is less than 1%.
• On the other hand, complicated cases have a higher rate of permanent disabilities and fatalities.

• Education of patient population regarding effective avoidance of ticks is highly important.
• Physician education is also important to promote early diagnosis and proper treatment.
• For excellent patient education resources, visit eMedicine's Bites and Stings Center. Also, see eMedicine's patient education article Ticks.