Pathology of eyes and brain of fish infected with diplostomids, southern Africa

Abstract

Only a few reports exist on diplostomid metacercariae found in southern African fish and even less information is available on the pathology associated with these infections. During surveys conducted in December 2008 and August 2010, different fish species were collected from the Okavango (Botswana) and Orange–Vaal (South Africa) River Systems. Histological sections were done from intact Tilapia sparrmanii A. Smith, 1840 and Coptodon rendalli (Boulenger, 1896) eyes and the brains of infected Brycinus lateralis (Boulenger, 1900) in order to determine the precise site of infection and the possible pathological effects. It was found that the encapsulated diplostomids from the eyes of the infected haplotilapiine species from the Okavango System caused localised retinal and/or choroid detachments. No pathological effects were observed in the histological sections of the brains of B. lateralis that were infected with diplostomids, except for the presence of red blood or rodlet cells. Tilapia sparrmanii collected from the Orange River were not infected with diplostomids.

Keywords: brain, Brycinus lateralis, diplostomid, eyes, haplotilapiine, Okavango, Orange–Vaal River System, pathology