High susceptibility of partridges ( Perdix perdix ) to toxoplasmosis compared with other gallinaceous birds

Partridges ( Perdix perdix ), chukars ( Alectoris chukar ), wild guineafowl ( Numida meleagris ), wild turkeys ( Meleagris gallopavo ) and chickens ( Gallus domesticus ) were inoculated per os with 103 or 105 Toxoplasma gondii oocysts (K7 strain). Two of five partridges fed 103 oocysts and six of eight partridges fed 105 oocysts died between day 6 and 16 post-inoculation (p.i.); no clinical symptoms were observed in surviving birds. Antibodies to T. gondii were detected in the birds by the indirect fluorescence antibody test (IFAT) first on day 7 p.i. On days 14, 21 and 28 p.i. (end of the experiment), antibodies were found in all partridges, chukars, guineafowl and turkeys. In chickens, IFAT antibodies were first detected on day 14 p.i., and all chickens were serologically positive on days 21 and 28 p.i. Bioassay in mice revealed T. gondii in the brain, liver, spleen, heart and leg muscles of all partridges and chukars. Enteritis was the most striking lesion in partridges that died. Results indicated that partridges are highly susceptible to toxoplasmosis, while chukars, wild guineafowl and turkeys seem to be less susceptible. Chickens are highly resistant to T. gondii infections.