Table 2.
History of T. gondii and its emergence as a human pathogen
| Year | Event | Reference |
|---|---|---|
| 1900 | Description of toxoplasma-like parasites in Java sparrows | [246,247] |
| 1908 | First description of toxoplasma-like tissue cysts in humans (as sarcosporidiosis) | [248] |
| 1908 | Description of T. gondii merozoites in gondi (first named Leishmania gondii) | [2] |
| 1909 | Introduction of the genus Toxoplasma (type species: T. gondii) | [3] |
| 1923 | First recorded case of toxoplasmosis in an 11- month-old infant with congenital hydrocephalus and microphthalmia (recognised retrospectively) | [203,204,249] |
| 1928 | First description of the tissue cyst as a persistent stage in intermediate hosts | [205] |
| 1937 | First recorded case of fatal disseminated toxoplasmosis in an adult (22-year-old) human | [250] |
| 1937–39 | Recognition of T. gondii as a causative agent of encephalomyelitis in human neonates | [206–208] |
| 1939 | Description of classic triad of symptoms of congenital toxoplasmosis in humans (retinochoroiditis, hydrocephalus, encephalitis followed by cerebral calcification) | [208] |
| 1939 | Identity of isolates from humans and animals based on biological and immunological similarities | [6] |
| 1940–41 | Recognition of T. gondii as a causative agent of acute, acquired disease in adult humans | [250,251] |
| 1941–42 | Comprehensive description of toxoplasmic encephalitis in children with acquired toxoplasmosis | [252,253] |
| 1942 | Vertical transmission recognised in humans | [209] |
| 1948 | Methylene blue dye test introduced for detection of antibodies to T. gondii (gold standard for T. gondii-specific serology in humans) | [40] |
| 1951–52 | Recognition of T. gondii as a causative agent of lymphadenopathy in humans | [254,255] |
| 1952 | Description of T. gondii as a causative agent of retinochoroiditis in humans | [71] |
| 1952 | Description of classic tetrad of symptoms of congenital toxoplasmosis in humans (retinochoroiditis, cerebral calcification, hydrocephalus or microcephalus, and psychomotor disturbances) | [256] |
| 1953–54 | First recorded case of toxoplasmic encephalitis in a patient with Hodgkin’s disease | [257] |
| 1954–56 | Hypothesis that horizontal transmission to humans may occur via tissue cysts in undercooked meat (pork) | [258,259] |
| 1959 | Serological evidence of T. gondii infections in vegetarians | [260] |
| 1960 | Discovery that tissue cysts are resistant to proteolytic enzymes | [127,261] |
| 1960 | Description of major sequelae of congenital toxoplasmosis in humans | [262] |
| 1965 | Recognition of the coccidian nature of T. gondii based on the ultrastructure of extraintestinal merozoites | [263,264] |
| 1965 | Epidemiological evidence that horizontal transmission to humans occurs via undercooked meat | [265] |
| 1965 | Hypothesis that an infectious stage of T. gondii is passed into the environment via the faeces of cats | [9] |
| 1968 | Recognition of T. gondii as a complication in patients with malignancies | [266] |
| 1969 | Identification of the oocyst of T. gondii | [267–273] |
| 1970 | Description of the sexual phase of the life cycle in the small intestine of cats | [270,274– 277] |
| 1969–72 | Recognition of the epidemiological role of cats in the spread of T. gondii in different geographical areas | [171,172] |
| 1981–82 | First recorded cases of CNS toxoplasmosis in AIDS patients | [278] |
| 1984 | Recognition of T. gondii as an opportunistic pathogen in AIDS patients | [102] |
| 1995–99 | Largest recorded outbreak of acute toxoplasmosis in humans (100 individuals aged 6–83 years) associated with oocysts in municipal drinking water | [69,191,279] |