Infectious oocysts of Toxoplasma gondii are not readily killed by chemicals or by exposure to the environment. Sterilization is required to ensure eradication.
Sources of infectious oocysts:
(1) animals experimentally infected with toxoplasmosis
(2) feces from humans or animals infected with toxoplasmosis
(3) autopsy on humans or animals infected with toxoplasmosis
(4) handling of laboratory cultures, especially liquid suspensions
Route of exposure:
(1) needlestick injury
(2) splash into the eye or other mucosal surface
(3) ingestion via unwashed or underwashed hands
(4) ingestion via contaminated food and beverages
(5) animal bite
(6) broken skin (scratch, open wound, etc)
(7) undetermined
Risk factors:
(1) high levels of infectious oocysts
(2) inexperience on the part of the laboratory worker
(3) sloppy laboratory technique
(4) accident
(5) failure to wear adequate personal protective equipment
(6) poor handwashing
(7) failure to sterilize laboratory surfaces, instruments and glassware
(8) failure to report exposures or to take prophylactic antibiotics
Prophylactic therapy may be unnecessary and it may not prevent seroconversion but it does offer some protection from serious complications.
Laboratory workers at particular risk if they become infected:
(1) pregnant women
(2) immunosuppressed or immunodeficient workers
Recognition of infection:
(1) seroconversion (which may be detected by annual serologic testing)
(2) fatigue, malaise or flu-like symptoms
(3) cervical lymphadenopathy
(4) encephalitis
(5) myocarditis
(6) ocular and facial edema (following ocular exposure)
The differential diagnosis of laboratory-acquired infection includes infection outside of the laboratory.
