Prevalence of parasites, species composition and abundance of rodents and shrews in Ilemela District, Mwanza Region, Tanzania

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Date

2024-05

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Publisher

Sokoine University of Agriculture

Abstract

Rodents and shrews are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat. The diversity of rodents and shrews varies with vegetation type, habitat and season. There are tremendous impacts attributed to rodents and shrews which include but not limited to damaging field crops, causing post-harvest losses, contaminating stored food and water supplies. Nevertheless, they are reservoir of different parasites of public health importance and play an important role in the transmission and spreading of zoonotic diseases in Tanzania and worldwide. Generally, this study aimed to determine rodents and shrews species composition and prevalence of parasites, in Ilemela District, Mwanza region, Tanzania. Rodents and shrews were live-trapped using Sherman and modified wire cages from Peridomestic, indoors and agricultural fields and their morphological data were recorded for identification to the genus and species level. Morphological data such as sex, weight, head- body, tail, ear, and hind foot lengths were recorded. They were then anaesthetized with diethyl ether, blood samples were collected aseptically from heart, thin and thick smears were made for haemoparasites identification and their ectoparasites were also collected for identification purposes. The Gastro-Intestinal Tract (GIT) was carefully removed and their contents were evaluated for GIT parasites. A total of 149 small mammals were captured and identified that includes 144 rodents belonging to four species namely Mastomys natalensis 66.4% (99/149), Mus .musculus 21.5% (32/149), Rattus rattus 7.4% (11/149) and Aethomys spp 1.3% (2/149) and the rest 3.4% (4/149) were shrews belonging to Crocidura spp. The overall prevalence of ectoparasites was 56.4% (84/149) and the following ectoparasites were identified, Laelaps echininus 39.6% (59/149), Polyplax spp. 4.0% (6/149), Xenopsylla cheopis 2.7% (4/149) and Heamaphysalis leachi 0.7% (1/149). The highest prevalence of ectoparasites was recorded in M. natalensis at (67.7%). In context to sex, males harbored more ectoparasites 59.0% than females. Additionally, the study also found a prevalence of haemoparasite was 35.5% (53/149) and the identified parasites namely, Anaplasma spp 18.8% (28/149), Trypanosoma lewisi 0.7% (1/149), Plasmodium spp. 1.3% (2/149). There were also two bacteria genus, bipolar coccobacilli2.7% (4/149) and Bacillus spp 3.4% (5/149) identified. Anaplasma spp was found in all of the infested rodent species and its highest prevalence was recorded in M. musculus 34.4% (11/32) followed by M. natalensis 27.3% (27/99). However, T. lewisi was only found in Rattus rattus whereas none of the haemoparasite was identified in Crocidura spp. The relative abundance of the captured rodent’s species were Mastomys natalensis 99 (68.75%), Mus musculus 32 (22.22%), Rattus rattus 11(7.63%) and Aethomys spp 2 (1.38%). Mastomys natalensis was widely distributed in all the habitats and its highest abundance was recorded in agricultural farms (83%, n=82/99). Mus.musculus (96.9%) and all R. rattus (100%) exclusively captured from in-doors, while Aethomys spp 2 (1.3%) were only captured from the Peridomestic habitats. The study found a significant association of the villages) with the captures (p < 0.01). In six of the villages selected for current study, M. natalensis was the most prevalent and abundant species captured. The overall prevalence of GIT parasites was 53.7% (80/149) and the following parasites were recovered, (nematodes 80.5% (91/113), cestodes 14.2% (16/113), trematodes 0.9 (1/113) and protozoan oocysts 4.4% (5/113). The recovered nematode parasites include; Trichuris spp 52.2% (59/113), Angiostrongylus spp 4.4% (5/113), Nippostrongylus spp 6.2% (7/113), Strongyloides spp 13.3% (15/113), Capillaria spp 3.5% (4/113), Physaloptera spp 0.9% (1/113) and Syphacia obvelata 0.9% (1/113). The identified Cestode was Hymenolepis diminuta 14.2% (16/113) while in Trematode, only Echinostoma spp 0.9% (1/113) was identified. Apart from worms also protozoan Oocyst 4.4% (5/113) were identified. Majority of the captured rodents were infected with nematodes 65% (91/113) and the highest prevalence of GIT parasites was recorded in M. natalensis 64.6% (64/99). Trichuris spp was found to be the most prevalent parasite in rodents. Among the identified parasites, Hymenolepis diminuta, Angiostrongylus spp, Capillaria spp and Syphacia obvelata are of public health importance. This study has revealed the presence of parasites of public health and livestock importance in rodents and shrews and we recommend for the control of rodents and shrews as well as screening of human’s population to check for presence of the identified zoonotic parasites reported in rodents and shrews.

Description

MSc Dissertation

Keywords

Rodents, Shrews, Ectoparasites, Gastrointestinal parasites, Species composition, Ilemela, Tanzania

Citation