Table 14.

Characteristics of the reported cases of laboratory-acquired infection with Toxoplasma gondii a

CharacteristicNo. (%) of cases (n = 47)
Decade of occurrence (if known) or publication
 1940s4 (8.5)
 1950s18 (38.3)
 1960s9 (19.1)
 1970s7 (14.9)
 1980s6 (12.8)
 1990s3 (6.4)
Country or region of occurrence
 United States23 (48.9)
 Europe20 (42.6)b
 Unknown2 (4.3)
 Australia 1 (2.1)
 Asia1 (2.1)
Route of exposurec
 Parenteral14 (29.8)
 No accident recognizedd 12 (25.5)
 Ingestion (presumptive route)e 9 (19.1)
 Mucous membrane8 (17.0)
 Nonintact skin1 (2.1)
 Bite (see the text)1 (2.1)
 Aerosol transmission? (no evidence provided)1 (2.1)
 No available information (during autopsy)1 (2.1)
Clinical manifestations
 Asymptomatic cases9 (19.1)
 Symptomatic casesf 38 (80.9)
 Severe cases4 (8.5)g
 Fatal cases1 (2.1)
  • a The median incubation period was 8.5 days (range, 3 days to 2 months) for all infections related to exposure to tissue stages of the parasite (20 cases with available data), 8 days (range, 3 to 13 days) for the subset of infections due to parenteral exposures (n = 11), and 7 days (range, 3 days to 2 months) for the subset of infections due to mucosal exposures (n = 7).

  • b For five case-patients, Europe was the presumptive region of occurrence based on the little available information.

  • c If there was uncertainty about the nature of the exposure or no accident was recognized but evidence suggested that one route of transmission was most likely, the most likely route usually was presumed, for the purposes of this table, to have been the mode of transmission. However, the threshold for doing this was somewhat subjective. Similarly, the distinction between “no accident recognized” and “no available information” was not always clear in the case reports. See the text for caveats about the cases.

  • d See footnote c. At least three persons who did not recall an accident had performed the dye test and therefore might have gotten tachyzoites on their skin. The person whose case was fatal (156) had not reported an accident and is assumed, for purposes of this table, not to have recalled a specific accident.

  • e Eight persons are thought to have ingested oocysts, and one person “often pipetted toxoplasma exudate” and might have become infected per os (161).

  • f The presence of lymphadenopathy was classified as being symptomatic.

  • g Four persons had encephalitis, two of whom also had myocarditis; one person with both conditions died (156).