Prevalence and intensity of Ascaris infection and heavy metal accumulation in Battygobius soporator (Frilfin gobby) of the Lagos lagoon

Abstract

An assessment of the prevalence and intensity of Ascaris infection as well as the heavy metal accumulation in the tissues and Asacaris parasites of the Frillfin Gobby, Bathygobius soporator was carried out over three months in the Lagos Lagoon. A total of one hundred fishes collected with gill nets and traps were examined for gastrointestinal helminthes and heavy metals. Ascaris sp. was observed in the fish gut with a prevalence of 47% (i.e. 47 fishes). Fishes with body weight range of 16-18 g had the highest prevalence (64.3%) and mean intensity of 10 parasites per fish; infestation rate was slightly lower in males (45.1 %) compared to the females (49.0 %). The overall worm burden was independent of fish sex, age and size (p>0.5). Analysis of heavy metals (Pb, Fe, Cd, Zn) in water, fish and fish parasites were also conducted using Atomic Absorption Spectrophotometry. Infected fishes and parasites had lower concentration of heavy metals compared to uninfected fishes. B. soporator, irrespective of infection status accumulated mostly Zn while the parasites accumulated mostly Fe. There were no traces of Pb in infected fishes but some parasites had detectable levels of Pb. The findings from this study showed that B. soporator which is a commonly harvested fish in the Lagos Lagoon for subsistence consumption may pose risk of zoonotic Ascaris infection if not properly cooked. The absence of Pb in infected fishes and its presence in some parasites implies that there is need to further investigate the mechanism of accumulation of this metal so as to provide possible explanation which may be of public health importance.

Keywords: helminth parasite, pollution, fish consumption, bioaccumulation.