Identification and Molecular Characterization of Spirurid Nematode Associated With Giraffe Skin Disease in Ruaha National Park, Tanzania.

Abstract

Giraffe skin disease (GSD) is an emerging skin condition mainly affecting adult and subadult populations of free-ranging giraffe, including Masai giraffe (Giraffa tippelskirchi) in the southern and northern protected areas (PAs) in Tanzania. Even though GSD has been described in Tanzania, the specific involvement of the spirurid nematode as the underlying cause of the lesions has been suggested but not definitively established. This cross-sectional study aimed to characterize spirurid nematodes associated with GSD lesions by analyzing 10 skin biopsies collected between October and November 2022. Histopathological examination revealed spirurid larvae in 6 out of 10 skin biopsies, with variable numbers found within the dermis, alongside the presence of clear vacuoles, eosinophils, neutrophils, lymphocytes, and fibrous connective tissue. Three biopsies tested positive for the 28S rDNA using a conventional polymerase chain reaction and provided a sequence of Thelazia spp. submitted in GenBank (accession no. 0R466406). The phylogenetic tree showed close similarity to T. callipaeda (99.11%, accession no. MF953480, and 99.38% accession no. MK214873, respectively). This study has shown the presence of the Spirurida, Thelaziidae worm in skin lesions of Masai giraffes affected by GSD. Specifically, this research documents the occurrence of T. callipaeda in the skin lesions providing valuable insight into parasitic involvement. Despite these findings, the mechanisms by which the nematode is transmitted to the giraffe's skin remain unknown. Further study is required to understand the impact of Thelazia callipaeda on both GSD and non-GSD giraffes to better understand the potential cause of GSD.