Rickettsial Diseases - MURINE TYPHUS

(Flea-borne Typhus Fever, Endemic Typhus Fever, Urban Typhus)

AGENT:

Rickettsia typhi

RESERVOIR AND INCIDENCE

Natural pathogen of rats and mice. Other mammals including cats, and their ectoparasites have been found infected. Outbreaks continue to occur in U.S., especially Texas. Natural lab infections have not been reported but lab acquired infections in people handling experimentally infected mice have been documented.

TRANSMISSION:

Transmitted by flea or lice (Xenopsylla cheopis, Nosopsyllus fasciatus) to rodents or man. Humans are infected by contamination of flea bites, broken skin or conjunctiva by flea feces. Domestic animals may transport the flea vector to humans. Inhalation of contaminated dust may be a route of infection.

DISEASE IN ANIMALS:

The agent localizes in the brain and various organs but with no known lesions.

DISEASE IN MAN:

There is a gradual onset of fever with severe headache, rigors, generalized pains and dry cough (sometimes developing to bronchopneumonia) of about 2 weeks. A macular rash appears by about 5 days, first appearing on the trunk and lasting about six days. CNS manifestations are possible. Damage is caused to vascular endothelia by invasion of rickettsia, possibly leading to thrombosis and hemorrhage. In untreated case, the case fatality rate is 1-2%.

DIAGNOSIS:

CF or IFA.

TREATMENT:

Tetracycline or Chloramphenicol.

PREVENTION/CONTROL:

Control wild rodents. In endemic areas control fleas while exterminating rats.