| Etiologic Agent |
| Protozoa found in the rodent, Ctenodactylus gundi in Tunisia | Nicolle and Manceaux (1908) |
| Protozoa found in a rabbit in Brazil | Splendore (1908) |
| Name T. gondii proposed (taxon = bow, plasma = form, in Greek) | Nicolle and Manceaux (1909) |
| First viable T. gondii isolate obtained from an animal | Sabin and Olitsky (1937) |
| First isolate of T. gondii from human | Wolf et al. (1939) |
| Human and animal T. gondii proven identical | Sabin (1941) |
| Pathogenesis of toxoplasmosis, including hydrocephalus | Frenkel and Friedlander (1951); Frenkel (1953, 1956) |
| Parasite Morphology and Life Cycle |
| Tachyzoite (trophozoite, feeding form, proliferative form, endodyozoite) |
| Term tachyzoite proposed (tachy = fast, zoite = life) | Frenkel (1973) |
| Endodyogeny described | Goldman et al. (1958) |
| Ultrastructure described | Gustafson et al. (1954); Sheffield and Melton (1968) |
| Tissue cyst, bradyzoite, cystozoite |
| Cyst recognized | Levaditi et al. (1928) |
| Cyst described cytologically | Frenkel and Friedlander (1951); Frenkel (1956) |
| Ultrastructure described | Wanko et al. (1962); Ferguson and Hutchison (1987) |
| Term bradyzoite proposed (bradys = slow, zoon = animal) | Frenkel (1973) |
| Term tissue cyst proposed | Dubey and Beattie (1988) |
| Bradyzoite resistance to digestive enzymes recognized | Jacobs et al. (1960a) |
| Development of tissue cysts and bradyzoites described | Dubey and Frenkel (1976) |
| Complete biology of bradyzoites and tissue cysts reviewed | Dubey et al. (1998) |
| Feline enteroepithelial stages |
| Coccidian phases described | Frenkel et al. (1970); Hutchison et al. (1970); Sheffield and Melton (1970); Dubey and Frenkel (1972) |
| Oocyst morphology described | Dubey et al. (1970b) |
| Five asexual T. gondii types (A–E) described | Dubey and Frenkel (1972) |
| Ultrastructure of coccidian stages described | Sheffield (1970); Piekarski et al. (1971); Ferguson et al. (1974, 1975, 1979a, 1979b); Christie et al. (1978); Speer, Clark, and Dubey (1998); Speer and Dubey (2005) |
| Lipid metabolism determines host specificity of T. gondii oocyst excretion in cats | 310 |
| Transmission |
| Congenital |
| Transmission demonstrated in human | Wolf et al. (1939) |
| Repeated transmission found in house mouse | Beverley (1959) |
| Congenital transmission found in a large wild animal species, white-tailed deer | Dubey et al. (2008) |
| Carnivorism, transmission by meat of intermediate hosts |
| Suggested carnivorous transmission | Weinman and Chandler (1954) |
| Transmission by meat found in humans | Desmonts et al. (1965) |
| Fecal-oral |
| Transmission by a resistant fecal form of T. gondii demonstrated | Hutchison (1965) |
| Coccidian phase recognized | Hutchison et al. (1970, 1971); Frenkel et al. (1970); Dubey et al. (1970a, 1970b); Sheffield and Melton (1970); Overdulve (1970) |
| Definitive and intermediate hosts defined, including excretion of oocysts only by felids | Frenkel et al. (1970); Miller et al. (1972); Jewell et al. (1972) |
| First oocyst-inhaled/ingested human toxoplasmosis outbreak described | Teutsch et al. (1979) |
| Genetics and Different Genetic T. gondii Strains |
| Recombinants and genetic crosses produced | Pfefferkorn and Pfefferkorn (1980) |
| Isoenzyme differences used to distinguish T. gondii strains | Dardé et al. (1987); Tibayrene et al. (1991) |
| Restriction fragment length polymorphism used to group T. gondii strains into 3 Types (I–III) | Sibley et al. (1992); Howe and Sibley (1995) |
| National, continental, intercontinental, and pandemic T. gondii strains distinguished | Lehmann et al. (2006) |
| T. gondii genome annotated | Khan et al. (2005) |
| Immunity and Protection |
| T. gondii neutralizing antibody recognized | Sabin and Ruchman (1942) |
| Antibodies found to kill extracellular but not intracellular T. gondii | Sabin and Feldman (1948) |
| Protection transferred by immune lymphoid cells but not by antibodies | Frenkel (1967) |
| Interferon gamma found to be main cytokine for protection | Suzuki et al. (1988) |
| Role of CD4+ and CD8+ cells in protection defined | Gazzinelli et al. (1991) |
| Toxoplasmosis in Humans |
| Congenital |
| First proven case of congenital toxoplasmosis described | Wolf et al. (1939) |
| Typical tetrad clinical signs described (hydrocephalus or microcephalus, chorioretinitis, intracerebral calcification) | Sabin (1942) |
| Acquired |
| First case in a child | Sabin (1941) |
| Fatal toxoplasmosis in adults found | Pinkerton and Weinman (1940) |
| Lymphadenopathy recognized as the most frequent symptom | Siim (1956); Beverley and Beattie (1958) |
| Susceptibility to toxoplasmosis in AIDS patient recognized | Luft et al. (1983) |
| Chronic infection |
| Cysts found in autopsy slides, indicating chronic asymptomatic infection | Plout (1946); Kean and Grocott (1947) |
| Toxoplasmosis in Other Animals |
| Toxoplasmosis found in a domestic animal, dog | Mello (1910) |
| Immunosuppressive Canine Distemper Virus influenced clinical toxoplasmosis outcome in dogs | Campbell et al. (1955) |
| Epidemic toxoplasmosis abortions in sheep recognized | Hartley and Marshall (1957) |
| Toxoplasmosis in animals reviewed critically | Dubey and Beattie (1988) |
| Toxoplasmosis found a common infection in a marine mammal species, sea otter | Cole et al. (2000) |
| Diagnosis |
| Novel Sabin–Feldman dye test described | Sabin and Feldman (1948) |
| Toxoplasma skin test as a survey tool | Frenkel (1948) |
| Tests developed to detect IgM antibodies in cord blood | Remington et al. (1968); Desmonts et al. (1981) |
| Simple direct agglutination test developed (DAT, MAT) | Desmonts and Remington (1980); Dubey and Desmonts (1987) |
| First validation of a serologic test using isolation of the parasite as standard | Dubey et al. (1995a); Dubey (1997) |
| PCR test developed to detect T. gondii DNA using B1 gene | Burg et al. (1989) |
| Treatment |
| Sulfonamides found effective against T. gondii | Sabin and Warren (1942) |
| Pyrimethamine found synergistic with sulfonamides against dividing tachyzoites | Eyles and Coleman (1953) |
| Folic acid and yeast improve activity of sulfadiazine and pyrimethamine | Fre... |
