Epidemiology and isolation of viable Toxoplasma gondii strain from macropods

Wallabies and other marsupials are highly susceptible to Toxoplasma gondii. In this study, 26 macropod samples were collected (8 red kangaroos, 4 Parma wallabies, 8 red-necked wallabies, 5 albino red-necked wallabies and 1 Eastern grey kangaroo), including tissue (n = 9) and serum (n = 17) samples. According to the modified agglutination test (MAT) results (cutoff 1:25), 50% (95% Cl: 32.06-67.94%) of the macropods had T. gondii antibodies. Among them, species, survival state, and sampling date were risk factors for T. gondii susceptibility (P < 0.05). T. gondii DNA was detected in two (cases #14 and #15) of the nine cases obtained from macropod tissues. One viable T. gondii strain (TgRooCHn4) was isolated from an albino red-necked wallaby (Macropus rufogriseus, case #14) via bioassay in mice. TgRooCHn4 belongs to ToxoDB genotype #3, using the 10 multilocus PCR-RFLP markers. The ROP18 and ROP5 gene allele types of TgRooCHn4 were 2/2, which was predicted to be non-lethal to mice. The virulence of TgRooCHn4 tachyzoites was avirulent in mice. Most macropods sampled from Hernan province in 2021 and 2022 were positive with T. gondii infection. A flood occurred in July 2021 in Zhengzhou from Henan province may promote the transmission of T. gondii oocysts. To our knowledge, this is the first T. gondii strain isolated from albino red-necked wallaby. However, further investigation is required to enhance our understanding of the transmission and prevention of toxoplasmosis in sensitive zoo animals.