Morphological and molecular studies of the nematode parasite Heterakis gallinarum (Heterakidae) infecting the cattle egret Bubulcus ibis (Ardeidae)

Abstract

Parasites infecting migratory birds all over the world are still under investigation. The identification of parasitic taxa infecting ardeids was done concerning their morphological and morphometric features. A total of 20 Bubulcus ibis (Ardeidae) specimens were collected and investigated for nematode parasites. Only one nematode species, belonging to the Heterakidae family, has been identified, with a prevalence rate of 40% (8/20) among infected egrets. The Heterakis species isolated from the lumen of the ceca of the egret host is morphologically and morphometric compatible with Heterakis gallinarum. Additionally, utilizing the partial small subunit ribosomal RNA (18S rRNA) and mitochondrial cytochrome c oxidase subunit I (COI) genes, maximum parsimony based on the Tamura-Nei model was used to infer the phylogeny of the recovered Heterakis species. The query sequences revealed 99.61% and 97.11% identities for the 18S (MK844591.1) and COI (MF066715.1) genes of the previously mentioned H. gallinarum. In addition to clarifying several morphological features of H. gallinarum, this study also provided new DNA data for this species. The combination of morphological and molecular data could be helpful to other veterinaries in finding a way to treat and control this infection in the cattle egret.