typhus (ti'fus) [Gr. typhos, fever]
Any of several rickettsial infections transmitted to humans by lice, fleas, or mites. The causative microbe invades the lining of blood vessels and smooth muscle cells, causing widespread vasculitis. The most common causes of typhus are Rickettsia prowazekii
, R. typhi
, and Orientia tsutsugamushi
. R. prowazekii
causes the epidemic typhus found in crowded conditions with poor sanitation, e.g., refugee camps.
The disease may be mild, marked only by a flat rash that spreads out from the trunk and petechiae or by flulike symptoms. In more severe cases, patients have fever, skin necrosis, and gangrene on the tips of the fingers, toes, earlobes, and penis as a result of thrombus formation in blood vessels; focal inflammation and thrombosis in organs throughout the body, including the brain, produce organ-specific signs. Rickettsial infections are diagnosed by identifying the organism through immunofluorescent staining.
Typhus is treated with doxycycline for 7 days.
Bronchopneumonia occurs more frequently than lobar pneumonia. Hypostatic congestion of the lungs, nephritis, and parotid abscess also may occur.
The prognosis is variable. Mortality may be quite high in epidemic typhus and almost nonexistent in murine typhus. Broad-spectrum antibiotics are life-saving if given early enough.
endemic typhusMurine typhus.
An infectious disease caused by Rickettsia prowazekii and transmitted by the human body louse (Pediculus humanus corporis).
flea-borne typhusMurine typhus.
louse-borne typhusRickettsia prowazekii.
A louse-borne epidemic typhus present in certain portions of Mexico.
mite-borne typhusScrub typhus.
A disease caused by Rickettsia typhi and occurring in nature as a mild infection of rats and transmitted from rat to rat by the rat-louse or flea. Humans may acquire it by being bitten by infected rat fleas or ingesting food contaminated by rat urine or flea feces. Synonym: endemic typhus; flea-borne typhus
Queensland tick typhus Abbreviation: QTT
A febrile illness causing a spotted fever and transmitted to humans by the bite of Ixodes ticks infected with Rickettsia australis. The disease is found principally in eastern coastal Australia and is similar to Rocky Mountain Spotted Fever in the U.S.
The recurrence of epidemic typhus after the initial attack.
An acute febrile illness, occasionally complicated by pneumonia, meningoencephalitis, respiratory distress syndrome, or septic shock caused by Orientia tsutsugamushi. Generally limited to Asian and Pacific nations, the disease is transmitted to humans by the bites of infected mites and chiggers. It can be treated with tetracyclines or azithromycin. The mortality rate in untreated patients is about 1% to 4%. Synonym: mite-borne typhus; tsutsugamushi disease