Occurrence of Oxyurid-Type Nematode Eggs in Aldabra Giant Tortoises (Aldabrachelys gigantea) from Zoological Collections in Zanzibar, Tanzania.

A parasitological survey was conducted during May 2026 on captive Aldabra giant tortoises (Aldabrachelys gigantea) housed at three zoological facilities on Zanzibar Island, Tanzania: the Prison Island Giant Tortoise Sanctuary (Changuu Island), Zanzibar Park, and Zanzibar Nungwi Zoo. This study investigated the occurrence of gastrointestinal parasite stages in faecal samples from captive Aldabra giant tortoises and compared the proportion of positive samples among the three zoological facilities. A total of 84 fresh faecal samples were examined using Fülleborn's flotation and sedimentation techniques. Because individual tortoises could not always be reliably identified during sampling, repeated sampling of the same animal cannot be excluded. Therefore, the reported values represent sample-level proportions rather than individual-level prevalence. Oxyurid-type nematode eggs were detected only in samples collected from tortoises housed at Zanzibar Nungwi Zoo, whereas no gastrointestinal helminth eggs or larvae were detected using the applied coprological methods in samples from the Prison Island Giant Tortoise Sanctuary and Zanzibar Park. The overall proportion of positive faecal samples was 13.1% (11/84; 95% CI: 6.7-22.2%), while 42.3% (11/26; 95% CI: 23.4-63.1%) of samples from Zanzibar Nungwi Zoo were positive. Differences in the proportion of positive faecal samples were observed among the three zoological facilities. These findings provide baseline data on gastrointestinal parasites in captive Aldabra giant tortoises on Zanzibar Island and support future parasite surveillance, health monitoring, and management in zoological collections.