Toxoplasmosis and laboratory workers: a case-control assessment of risk.

The health risks to staff employed in a toxoplasma reference unit were studied. Sixteen laboratory staff exposed to Toxoplasma gondii and age/sex-matched controls from the general population and a routine microbiology laboratory were assessed. Multiple assays were performed to establish the presence of toxoplasma infection, and laboratory workers were questioned regarding environmental and work-related exposure to the parasite. Details of all of environmental exposure to toxoplasma between the two groups of laboratory personnel, and seroprevalence rates were comparable in all three groups. Three laboratory accidents were recorded, a rate of one per 9300 hours exposure. One case of presumed work-related infection was identified, but significant illness was not observed. Given adequate training, strict adherence to conventional laboratory protocols and medical supervision, laboratory accidents are infrequent and work-associated toxoplasma infection is uncommon. The risks associated with occupational exposure to T. gondii have been over-estimated and we conclude that this organism does not represent a significant health hazard to laboratory technicians.