Toxoplasma gondii infection in white spoonbills (Platalea leucorodia) from Henan Province, China.

Toxoplasmosis is a foodborne parasitic disease. Toxoplasma gondii oocysts in the environment are a threat to humans and animals. White spoonbills could serve as a sentinel animal for T. gondii contamination in the environment because of their food intake from soil or water. This study is aimed to evaluate the prevalence of T. gondii in white spoonbills and isolate viable T. gondii from white spoonbills. In 28.6% (2/7) of white spoonbills, T. gondii antibodies were found in heart juice by the modified agglutination test (cut-off: 1:4). T. gondii DNA was detected in tissues of 42.9% (3/7) white spoonbills. One viable T. gondii strain, named TgSpoonbillCHn1, was isolated from the myocardium of a white spoonbill by bioassay in mice. DNA extracted from TgSpoonbillCHn1 tachyzoites was characterized by PCR-restriction fragment length polymorphism with ten markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) and the virulence genes ROP5 and ROP18. The results revealed that it was ToxoDB#2 (Type III). The ROP18/ROP5 genotype combination predicts that this strain is avirulent for mice, which is supported by the infection experiments in mice. This is the first report of the isolation of viable T. gondii strain from white spoonbil. The prevalence of T. gondii in white spoonbills may be indicative of environmental contamination of oocysts. This report provides direct evidence of white spoonbill as an intermediate host of T. gondii.