Persistence of Toxoplasma gondii tissue stages in poultry over a conventional fattening cycle

Toxoplasma gondii is a widely spread protozoon in humans, mammals and poultry. Regarding the latter, nothing is known yet about the duration of T. gondii persistence and distribution over a conventional fattening cycle of turkeys and chickens. Twenty-four turkeys and 12 broiler chickens were infected intravenously with 1×106 T. gondii tachyzoites (strain NED). Serum antibody levels were determined weekly by ELISA (turkeys) or immunofluorescent antibody test (chickens). Turkeys were slaughtered at 4, 8, 12 and 16 weeks post-infection (p.i.), and chickens 5 or 10 weeks p.i. (n = 6 per group). Sixteen different tissue samples per bird were analysed for T. gondii by PCR. All infected animals showed seroconversion. In turkeys, 15·9% of all samples were tested positive for T.-gondii-DNA. Among the edible tissues (drumstick, thigh, breast muscle, heart, liver and gizzard) 7·8% tested positive. Among poultry slaughtered after different periods of time after infection no significant differences (P>0·05) regarding the number of positive samples were observed. Only 4 out of 192 samples (2·1%) from infected chickens contained detectable T. gondii DNA.The PCR findings suggested that T. gondii may persist in poultry. Particularly in turkey it was shown that edible tissues stay infected for at least 16 weeks p.i. which indicates a potential risk for consumers of undercooked turkey meat whereas chickens appear less susceptible to T. gondii infection.