Mouse inoculation

Sample is inoculated intraperitoneally (ip) in Toxoplasma seronegative mice. In cases in which the organism is virulent for mice, T. gondii can be demonstrated in the peritoneal fluid after 5-10 days (examined either fresh or in Giemsa- or Wright-stained smears). If the isolate is relatively avirulent for mice, a period of 4-6 weeks is usually required for definitive demonstration of the parasite. Surviving mice are bled after six weeks from the tail vein for serologic testing. If antibodies are present, proof of infection must be obtained by demonstration of the parasite. This may be performed by examining Giemsa-stained smears of fresh brain for demonstration of cysts. If cysts are not seen, ip injection of brain tissue into fresh mice should be performed (Remington and Desmonts 1990). Animal inoculation is more sensitive than tissue culture; the sensitivity from clinical samples ranges from 60 to 80% (Derouin et al. 1988; Hohlfeld et al. 1994). The disadvantage of the animal culture is the length of time required, usually from 4 to 6 weeks.

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