Rickettsial zoonoses

1. RICKETTSIAL
ZOONOSES
(RickettsiaI diseases)

14. Diagnostic procedures
• These include :
• (a) isolation of rickettsiae.
• (b) established serological tests such as indirect
fluorescent antibody (IFA) test, the complement
fixation test, and the Weil Felix reaction.
• The newer techniques include ELISA and the
fluorescent antibody staining of frozen tissue
sections from rickettsial lesions.
TREATMENT
• Tetracycline is the drug of choice for specific treatment of
all rickettsial diseases.
• Long-acting antibiotics (doxycycline, minocycline) now
make single dose treatment possible

25. CONTROL MEASURES
• (a) TREATMENT : Tetracycline is the drug of choice.
With proper therapy the mortality is nil.
• (b) VECTOR CONTROL: Clearing the vegetation
where rats and mice live; application of insecticides
such as lindane or chlordane to ground and
vegetation.
• (c) PERSONAL PROPHYLAXIS : Impregnating clothes
and blankets with miticial chemicals (benzyl
benzoate) and application of mite repellents
(diethyltoluamide) to exposed skin surfaces
• No vaccine exists at present.

31. TRANSMISSION CYCLE
• Rat---Rat flea---Rat---Rat flea---Rat
Man
INCUBATION PERIOD
• 1 to 2 weeks, commonly 12 days
CONTROL MEASURES
(a) TREATMENT: Tetracycline is the only drug of choice.
Since rickettsial growth is enhanced in the presence of
sulfonamides, these drugs should not be given.
(b) CONTROL OF FLEAS : Residual insecticides (e.g.,BHC,
malathion) are effective against rat fleas. Rodent control
measures should be implemented in the affected areas.
No murine typhus vaccine is currently available.

35. Mode of transmission
• Man is only an accidental host. He acquires infection by
the bite of an infected tick. Contamination of skin with
crushed tissues or faeces of an infected tick may also
cause infection.
• The cycle of transmission is as follows :
Incubation period
Usually 3 to 7 days.

36. Control measures
(a) TREATMENT : Broad spectrum antibiotics have proved to
be effective.
(b) PERSONAL PROPHYLAXIS :tick-infested areas should be
avoided.
• Daily inspection of the body for ticks is particularly
important for those who are exposed to the risk of
infection.
• Disinfection of dogs will minimize the tick population.
• Health education of the people in the mode of
transmission by ticks, and the means of personal
protection is equally important.