Survey of haemoprotozoa and Toxoplasma gondii in little penguins in Lutruwita/Tasmania, Australia

Parasitism poses potential health risks to penguin populations, yet the prevalence of protozoan parasites in wild free-living populations remains poorly understood. We conducted a survey of haemoprotozoa and <i>Toxoplasma gondii</i> in little penguins (<i>Eudyptula minor</i>) across 23 colonies in Lutruwita/Tasmania, Australia. Blood samples were screened for haemoprotozoa using light microscopy and nested PCR. Suspect intraerythrocytic inclusions were seen in the blood smears of 25 % of the penguins examined (62/247), but morphological and molecular evidence only confirmed <i>Babesia</i> sp. infection in 2.4 % of penguins (6/247). A single blood smear exhibited sufficient parasite life stages to allow morphological identification, and the morphology was consistent with <i>Babesia peircei</i>. Sequencing of the <i>18S rRNA</i> gene of 4 samples confirmed a close relationship to <i>Babesia</i> sp. previously reported in little penguins in Lutruwita/Tasmania. A subset of samples (<i>n</i> = 50) with intraerythrocytic inclusions tested negative for <i>Haemoproteus</i> sp., <i>Leucocytozoon</i> sp., and <i>Plasmodium</i> sp. Antibodies against <i>T. gondii</i> were detected in 3/122 penguins, though only one sample (0.8 %) was considered seropositive (titre ≤1:64). This study provides a contemporary baseline for protozoan parasite occurrence in wild little penguins at the southernmost part of their Australian range. As changing climates are facilitating range expansion of vector species, studying the health of populations at the edge of their range is critical.