Comments
INITIAL SYMPTOMS:
Flu-like illness with fever, headache, and myalgias; A rash appears later in 50%-89% of patients. Children are more likely to have nausea, vomiting, and abdominal pain. [CCDM]
FINDINGS:
The macular rash starts 5-6 days after onset of the fever, appearing on the trunk, legs, and arms. It is present in more than 50% of cases. Splenomegaly, hepatomegaly, thrombocytopenia, and mildly elevated liver transaminases are common. Pneumonia and encephalitis are occasionally reported as complications. [ID, p. 1486-7] Other findings in a series of cases from Thailand, Texas, and Greece included abdominal pain (11% to 31%), vomiting (23% to 40%), jaundice (3% to 11%), and seizures (2% to 4%). The rash may not be visible in dark-skinned patients. Effects on the eye in endemic typhus include keratoconjunctivitis and uveitis. Hematemesis and cerebral hemorrhage are severe manifestations. [Guerrant, p. 1001, 331] Neurological symptoms include confusion, stupor, seizures, and ataxia. The rash is usually maculopapular and occasionally petechial. Some patients have leukopenia early and leukocytosis after the first week. Other complications are myocarditis, meningoencephalitis, renal failure, and respiratory failure. [PPID, p. 2222] Some patients, especially those with G6PD deficiency, may have hemolysis and anemia. [Cecil, p. 1959]
EPIDEMIOLOGY:
Transmitted by rat fleas, this disease can be prevented by applying insecticides to "rat runs, burrows and harborages." To lessen human exposure to fleas, kill fleas first, then rats. Animal reservoirs include rats, mice and possibly other small or medium sized mammals. "Occasionally, a case may follow inhalation of dried infective flea feces." [CCDM, p. 665] Fewer than 80 cases per year are reported in the USA peaking in late summer and autumn with a high proportion of cases in Texas and southern California. [ID, p. 1487]
For updated text and symptoms of infectious diseases, see iddx.com.
Diagnostic
Paired serology (antibodies usually positive in the 2nd or 3rd week); Weil-Felix agglutination test not recommended; IHC and PCR can detect typhus in skin biopsy samples of rash sites. [CCDM, p. 661-2]