Posts tagged "Rickettsia typhi"

Typhus: Endemic Murine Typhus

Endemic murine typhus is caused by Rickettsia typhi. R. typhi is maintained in mammalian host-flea cycles, with rats (Rattus rattus and R. norvegicus) and the Oriental rat flea (Xenopsylla cheopis). Fleas get R. typhi from rickettsemic rats and carry the organism throughout their life. Humans are infected when rickettsia-laden flea feces contaminate itchy bite lesions. Rats are infected if they are not immune to R. typhi. The flea bite can also transmit the organisms, but much less frequently. Transmission can occur via inhalation of aerosolized rickettsiae from flea feces. Rats are rickettsemic for about 2 weeks, though they appear healthy.

Epidemiology: endemic typhus occurs year-round, in warm (often coastal) areas throughout the tropics and subtropics, where it is highly prevalent. In USA Murine typhus occurs mainly in southern Texas and southern California. The classic rat-flea cycle is absent and an opossum-cat flea (C. felis) cycle is prominent in USA.

Symptoms & signs: The incubation period typhus is 8–16 days. Headache, arthralgia, myalgia, nausea, and malaise develop 1–3 days before onset of chills and fever. Nausea and vomiting is very common. The duration of untreated illness ranges from 9–18 days. Rash is present in some patients in axilla or the inner surface of the arm.

About one third of the patients have respiratory problems like a hacking, nonproductive cough, pulmonary edema, and pleural effusions. Abdominal pain, confusion, stupor, seizures, ataxia, coma, and jaundice can be seen less frequently.

Diagnosis: Diagnosis is mainly by clinical symptoms. Cultivation and PCR in acute and convalescent-phase sera can provide a specific diagnosis of endemic murine typhus.

Treatment: Doxycycline 100 mg twice orally for 7–15 days on the basis of clinical suspicion is the treatment of choice.

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Posted by - September 30, 2008 at 1:07 pm

Categories: Ricketssial Diseases   Tags: , ,