First report and record of nematode Eustrongylides africanus larvae in a vertebrate host mudfish Clarias species from Bida floodplain of Nigeria

The nematode specimens from Clarias species were confirmed to be the larval forms of nematode Eustrongytides africanus that occurs in a wide diversity of fish-eating aquatic animals. And its effective third- and fourth-stage larval development was also described. The physical presence of this parasite in Clarias species is manifested by swellings or undulations on skin surfaces as grub-like. On close inspection, they were grossly observed as tiny white or pink (third-stage) or bright red (fourth-stage) blood-sucking larvae, at different depths of the body cavity, with relatively long bodies. The third-stage larvae are shorter than the fourth-stage larvae both larval stages retained the second-stage cuticles. There was no significant difference (P>0.05) in body length between male and female third-stage larvae. Female fourth-stage larvae were significantly (P<0.05) longer than males fourth-stage larvae. The most useful characteristics for describing the third-and fourth-stage larvae are body length and head shape, which were easily observed. But the characteristics of the cephalic and labial papillae, although more difficult to observe, were the most definitive. This is the first report and record of the confirmation of the larval forms of Eustrongylides africanus and the description of its third- and fourth-stage larval development from a vertebrate host Clarias species from Bida floodplain of Nigeria (or West Africa) with natural infection.