Localization and Persistence of Toxoplasma in Tissues of Experimentally Infected White Rats.

Ruchman, Isaac V.; Fowler, John C.

doi:10.3181/00379727-76-18635

Cited by 33 publications

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“…The RH strain persisted in Ž . the brain longer than in any other tissue Ruchman and Fowler, 1951 . These differences ( )may be related in part to the strain of rats, the infecting dose, the subline of the RH Ž .…”

Section: ( ) 424 Persistence Of Chronic Infection With Immunity Prmentioning

confidence: 72%

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Toxoplasmosis of rats: a review, with considerations of their value as an animal model and their possible role in epidemiology

Dubey

Frenkel

1998

Veterinary Parasitology

130

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We critically review and summarize information on the prevalence of Toxoplasma gondii infections in rats, mainly Rattus norÕegicus, and their possible role as a source of infection for larger carnivores and omnivores. We also review information on immunology and natural resistance, contributing to the model value of rats in the analysis of human infection. Rats can be Ž . Ž . successfully infected with oocysts sporozoites , tissue cysts bradyzoites , and tachyzoites. Even adult rats, that are resistant to clinical toxoplasmosis, can be infected orally with a few oocysts or tissue cysts. Infections with tachyzoites of the RH strain are highly variable. Congenital transmission of T. gondii occurs at a high rate when rats are infected during pregnancy. Congenitally infected rats can harbor viable T. gondii in the absence of detectable antibodies to T. gondii and rats with low antibody titers may harbor few or no organisms. The isolation of viable T. gondii by bioassay is the only reliable means to determine persistence of chronic T. gondii infection in feral rats. No evidence was found for maintenance of T. gondii in rats by vertical transmission in the absence of cats. q 1998 Elsevier Science B.V. Ž . PII S 0 3 0 4 -4 0 1 7 9 7 0 0 2 2 7 -6 ( ) J.P. Dubey, J.K. Frenkelr Veterinary Parasitology 77 1998 1-32 2

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Section: ( ) 424 Persistence Of Chronic Infection With Immunity Prmentioning

confidence: 72%

“…The persistence of the RH and other strains, beyond 1 month after inoculation in rats Ž varies greatly in different reports Ruchman and Fowler, 1951;Eyles and Jones, 1955; . Jacobs and Melton, 1957;Remington et al, 1958Remington et al, , 1961a .…”

Section: ( ) 424 Persistence Of Chronic Infection With Immunity Prmentioning

confidence: 99%

Toxoplasmosis of rats: a review, with considerations of their value as an animal model and their possible role in epidemiology

Dubey

Frenkel

1998

Veterinary Parasitology

130

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“…Because of the generalized distribution of parasites early in the infection, the possibility was considered that despite their tolerance, chickens might nevertheless harbor Toxoplasma in latent form for long periods, as do pigeons (Jacobs, Melton and Jones, 1952) rats (Ruchman and Fowler, 1951) and other hosts. A number of tests was made of the persistence of Toxoplasma in the tissues of infected chickens.…”

Section: Distribution Of Parasites In Tissuesmentioning

confidence: 99%

Experimental Toxoplasmosis in Chickens

Jones¹,

Melton²,

Lunde³

et al. 1959

The Journal of Parasitology

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“…Dubey (1998) does not mention any hypothesis to explain these results, either. The parasitological titers of brain suspensions of rats inoculated with a cyst-forming line of the RH strain of Toxoplasma did not show any decline even 24 months after inoculation (Ruchman and Fowler 1951). With regard to the mean percentage of rats infected, there appears to be a plateau in infection with the higher inocula (Table 1).…”

Section: Discussionmentioning

confidence: 92%

Residual infection of 15 Toxoplasma strains in the brain of rats fed cysts

Freyre¹,

Falcón²,

Correa³

et al. 2001

Parasitol Res

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Thirty-seven groups of 4±32 Wistar rats were fed 2±10 3 cysts of 15 Toxoplasma strains. After 2 months, the rats were euthanized and their brains screened for Toxoplasma cysts and bioassayed in mice if negative. The brains of 323 of 411 rats (78.6%) were found to be infected 2 months after inoculation with Toxoplasma cysts. Two hundred cysts were necessary to infect nearly 90% of the rats. With lower doses, only 60% of the rats had residual brain infection. Brain cysts were formed only in 146 of 411 rats (35.5%). The numbers of cysts formed were in the order of tens to hundreds, only occasionally one or two thousands. The mean percentage of rats with brain cysts, and the number of cysts formed in rat brains by dierent inocula, increased with higher doses of cysts and then declined. This pattern is dicult to explain and similar results regarding the number of cysts formed have been published. In relation to the mean percentage of rats infected, there appears to be a plateau in infection with the higher inocula. Neither the number of rats with cysts in their brains nor the numbers of cysts formed were dependent on the Toxoplasma strain used, with the exception of one strain. Instead, individual variations were marked, and are presumably related to variations in the individual genetic resistance to Toxoplasma infection in the rat. The information gathered is considered a preliminary step for a rat model of immunity against acquired toxoplasmosis.

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Localization and Persistence of Toxoplasma in Tissues of Experimentally Infected White Rats.

Cited by 33 publications

References 0 publications

Toxoplasmosis of rats: a review, with considerations of their value as an animal model and their possible role in epidemiology

Toxoplasmosis of rats: a review, with considerations of their value as an animal model and their possible role in epidemiology

Experimental Toxoplasmosis in Chickens

Residual infection of 15 Toxoplasma strains in the brain of rats fed cysts

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