Submitted to: Review Article
Publication Type: Review Article
Publication Acceptance Date: May 3, 2007
Publication Date: July 4, 2007
Citation: Hill, D.E. 2007. Toxoplasma gondii in CAB international Animal Health Production, Compendium 2007. Review Article. p. 2887-2991.
Interpretive Summary: Infection with the protozoan parasite Toxoplasma gondii is one of the commonest parasitic infections of man and other warm-blooded animals (Dubey and Beattie, 1988). In most adults it does not cause serious illness, but it can cause blindness and mental retardation in congenitally infected children, blindness in persons infected after birth, and devastating disease in immunocompromized individuals. Consumption of raw or undercooked meat products and other food or drink contaminated with oocysts are major risk factors associated with T. gondii infection.
Toxoplasma gondii is a coccidian parasite with cats as the definitive host, and warm-blooded animals as intermediate hosts (Frenkel et al., 1970). It is one of the most important parasites of animals. There is only one species of Toxoplasma, T. gondii. Unlike many other microorganisms, and in spite of a wide host range and worldwide distribution, T. gondii has a low genetic diversity. Toxoplasma gondii strains have been classified into two to three genetic types (I, II, III), based on antigens, isoenzymes, and restriction fragment length polymorphism (RFLP) (Howe and Sibley, 1995; Guo and Johnson, 1996; Darde et al., 1988). Type I strains are highly virulent in outbred laboratory mice whereas Types II and III are less virulent in mice (Howe and Sibley, 1995; Howe et al., 1997; Mondragon et al., 1998; Owen and Trees, 1999) but there is no correlation between virulence in mice and clinical disease in other animals or humans.