Pathological changes and description of Procamallanus (Spirocamallanus) spiralis Baylis from the freshwater fish, Parachanna obscura Gunther

Objective: To report the morphological details of the two species of Procamallanus with scanning electron microscopy. Methods: To gain insights into the phenology of Procamallanus spp., scanning electron microscopy descriptions of male and female parasites along with attendant histopathological consequences to the hosts species were undertaken. The two species were obtained from the intestines of the freshwater fish, Parachanna obscura. Parasites were fixed in 2.5% glutaldehyde and postfixed in osmium tetraoxide, sputter-coated and examined with the electron microscope. Results: Nominal parasitic species of Procamallanus could be distinguished with spiral thickenings in front of the buccal capsule. The male specimens of the parasite (n = 213) were recorded in a prevalence of 12.7% while the female specimens (n = 68) were recorded in a prevalence of 20.5%. An overall prevalence of 14.6% was obtained in the fish species. The two Procamallanus species differed from the described species of the genus Procamallanus (Spiracamallanus) with having the posterior end not ventrally bent, tail not short but elongate and straight bending slightly with no spikes, inner depression at the posterior region, excretory pore near the posterior end, wider cephalic region with an inner sieve-like compartment, longitudinal cephalic papillae, papillae of external circles distinctly larger and lateral cuticular extensions. These male and female species of Procamallanus exhibited novel morphometrics descriptions in the number of preanal and postanal papillae and different body and shape relationship. The histopathological changes seen in the host included hyperplasia of intestinal villi, mucosal hypercellularity of lamina propria and calcification of intestinal mucosa. Conclusions: This is the first scanning electron microscopy description of Procamallanus spp. in Nigeria describing the morphological details of the two species of Procamallanus