Studies of the seasonal variations and prevalence of Helminth fauna on the black rat, Rattus rattus (Rodentia: Muridae) from different microhabitats in Nsukka, Nigeria

Abstract

A twelve-month epizooic survey was conducted to evaluate the helminth fauna of the Ngerian strain of the black rat, Rattus rattus from six microecological habitats in Nsukka area of Nigeria andto assess the zoonotic and public health implications of the findings. Altogether 1458 rats (565 % males and 43.5 % females) were trapped and examined for helminths. A total of 1098 rats (55.7 % males and 44.3% females) harboured helminth parasites thus providing and overall prevalence o 75.3% and a mean worn burden of 1.3. The between-sex difference was statistically signiicant (x² =2.64, P < 005) wth more males (53.2 %) than females (46.8 %) harbouring helmnhparasites. There was no marked variation in the infection pattern in the rat host from the different habitats, but the parasite prevalence and distrbution appeared to be season-dependent. Parasites (n = 1469) recovered were of 3 helminth groups (nematodes 72.4%, cestodes 27.5%, and trematodes 0.6%). Six nematode species identified were Nippostrongylus braziliensis (198%), Aspicularis tetrapera (17.5%), Syphacia muris 17.0 %), Angiostrongyus cantonensis 16.9%), Strongyloides ratti (16.0%) and Capiaria hepatca (12.8%). Also recovered from their rat hosts were the following six cestode species; Hymenolepis dimnua (22.7%), Taenia taeniaeformis (17.4%), T. muris (171%), T. hydatigera (166%), H. nana (164%) and Raillietina muris (9.8%). Trematodes(n=9) belonging to 3 species, Plagiochis muris, Platynosomoides muris and Corrigia muris were also recovered from five infected rats. A total of 103 rat hoss harboured single infections of nematodes, 818 (98.9%) had combined nematode/cestode infections, 5 (6.0%) haboured a combination of nematode/trematode whereas 4 (0.5%) showed concurrent cestode/trematode infections. The influence of seasonal fluctuations on the parasite-host relationship, le cycle patterns of the parasites and immunological potentials of the rat hosts are discussed.

Keywords: Epizootic, helminth, Rattus rattus, Nematode, Cestode, Trematode, Seasonal fluctuation