Typhus: Epidemic (Louse-Borne) Typhus

Epidemic or louse borne typhus is transmitted by Rickettsia prowazekii. The infection is transmitted from man to man by infected louse (Pediculus corporis, P. capitis). Lice acquire R. prowazekii when they ingest blood from a rickettsemic patient. Pediculus corporis lives in clothing under poor hygienic conditions and usually in impoverished cold areas. The rickettsiae multiply in the midgut of the louse and are shed in the louse’s feces. The infected louse leaves a febrile patient and deposits infected feces on its new host during its blood meal and the new host autoinoculates the organisms by scratching.

Epidemic or louse borne typhus can cause devastating outbreaks during war and disasters. In humans the organism can persist for many years with out any symptoms and the disease can manifest itself as Brill-Zinsser disease and can be transmitted by louse to other humans.

Signs & Symptoms:  Incubation period is about 1 week. Onset of illness is abrupt, with severe headache and fever. Fever rises rapidly to 38.8°–40.0°C (102°–104°F). Cough is prominent (70% of patients get). Myalgia (muscle pain) if present is severe. There is characteristic “crouching” posture. Rash can be seen on the upper trunk, on the fifth day, and then becomes generalized and involve the entire body except the face, palms, and soles. But more than half of the patients do not develop rash. Photophobia, dry, brown, and furred tongue, skin necrosis and gangrene of the digits, confusion and coma are other symptoms.

Fatality is 7–40% in untreated cases.

Diagnosis: Epidemic or louse borne typhus is sometimes misdiagnosed as typhoid fever in tropical countries. It can be diagnosed by the serologic or immunohistochemical diagnosis of a single case or by detection of R. prowazekii in a louse found on a patient.

Treatment: Doxycycline (200 mg/d, given in two divided doses) is the treatment of choice. If there is vomiting or patient is unconscious doxycycline can be given intravenously. Treatment is continued for 2-3 days after symptoms subside, though single 200 mg doxycycline is sufficient.

During pregnancy chloramphenicol early in pregnancy or, if necessary, doxycycline late in pregnancy is the treatment of choice.

Prevention: The best way to prevent is to maintain good personal hygiene. Clothes should be washed and changed regularly. Insecticides can be used every 6 weeks to control the louse population.

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