Parasitology


Research Article

Toxoplasmosis in rats (Rattus norvegicus): congenital transmission to first and second generation offspring and isolation of Toxoplasma gondii from seronegative rats


J. P. DUBEY a1 , S. K. SHEN a1 , O. C. H. KWOK a1 and P. THULLIEZ a2
a1 United States Department of Agriculture, Agricultural Research Service, Livestock and Poultry Sciences Institute, Parasite Biology and Epidemiology Laboratory, Beltsville, MD 20705-2350, USA
a2 Laboratoire de la Toxoplasmose, Institut de Puériculture, 26 Boulevard Brune, F-75014, Paris, France

Abstract

To study congenital transmission of Toxoplasma gondii during acute and chronic infections, 4 pregnant Sprague-Dawley rats were each fed 10000 oocysts of the VEG strain. Toxoplasma gondii was recovered from 33, 55, 83 and 57% of rats (F1) when dams were inoculated at 6, 9, 12 or 15 days of gestation, respectively. Progeny of 15 congenitally infected female rats were examined for T. gondii. Toxoplasma gondii was recovered from tissues of 1 of 155 rats (F2) born to congenitally infected dams. A total of 4 (F2) females were mated; 0 of 40 (F3) rats born to them were infected. None of the acutely infected 4 dams that had given birth to congenitally infected litters produced congenitally infected offspring during the second pregnancy. Thus, unlike mice, evidence for repeated congenital transmission of T. gondii in the rat was found in <1% of cases. Of the 16 congenitally T. gondii infected pups with demonstrable tissue cysts, 5 were seronegative (<1[ratio]4) in the Sabin-Feldman dye test and 5 were seronegative (<1[ratio]20) in the modified agglutination test by the use of whole formalinized tachyzoites and mercaptoethanol.

(Received November 27 1996)
(Revised January 2 1997)
(Accepted January 6 1997)

Key Words: Toxoplasma gondii; rat; Rattus norvegicus; congenital transmission.

Correspondence:

United States Department of Agriculture, Agricultural Research Service, Livestock and Poultry Sciences Institute, Parasite Biology and Epidemiology Laboratory, Beltsville, MD 20705-2350, USA. Tel: +301 504 8128. Fax: +301 504 9222. E-mail: JDUBEY@GGPL.ARSUSDA.GOV.



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