TYPHUS FEVER GROUP
TYPHUS FEVER GROUP:
(a) Epidemic typhus: The disease has been reported from all parts of the world. In India it occurs in Kashmir (India).
The causative agent is Rickettsiae prowazekii. Man is the only natural vertebrate host. No extrahuman reservoir has been suggested.
Pediculus humanus corporis (human body louse) is the vector. Lice is infected by feeding rickettsiemic patients. Rickettsiae multiply in the gut and appear in feces in 4 to 5 days. Lice dies within 4 weeks and it remains infective throughout. Lice defecates while feeding and infection is transmitted when contaminated louse feces are rubbed in by scratching through minute abrasion they cause. However, infection may be transmitted through inhalation of dried louse feces and also through conjunctiva.
About 5 to 21 days is incubation period. It starts with fever and chills followed by rash on 3rd days. The rash is maculopapular, starts on trunk and spreads over limbs, sparing face, palm and sole. In 2nd week patients become stuporous and delerious (typhus means cloudy state of mind). There is 15 to 70 per cent fatality.
(b) Brill Zinsser disease: It is mild, typhus like disease in New York among Jewish immigrants from S.E. Europe.
(c) Endemic typhus: It is milder than epidemic typhus. It is caused by Rickettsiae mooseri. There is always mild infection of rat transmitted by rat flea (Xenopsylla cheopis). Organism multiplies in the gut of flea and is shed in flea feces. Flea remains unaffected but infectious for others throughout.
Man acquires infection through the bite of infected flea or through consumption of food contaminated by rat urine, flea feces etc. Man to man infection does not occur. Human infection is a dead end. In China and Kashmir (India) lice is known to transmit murine typhus.
Tags: carcinomatosis, coronary occlusion, glomerulonephritis, malaria, nephrosis, Rheumatic Fever, serum sickness
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