Risk Factors for Parasite Infestation and Efficacy of Commonly Used Anthelmintics among Dorper Sheep in Kajiado County, Kenya
Morinket, Keshura Richard
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Cases of ineffective anthelmintics have been contributing to reduced productivity in livestock due to worm burdens in supposedly treated animals. Effective anthelmintics serve as the main control measure in the management of worm infestations in small ruminants. However, there have been rising cases of helminth infestations in de-wormed animals as reported by farmers. The unresponsive infestations become a serious health and productivity constraint. Effective management of infestations relies solely on the use of very effective anthelmintics. Nonetheless, widespread resistance towards available anthelmintics is threatening the potential utilization of this strategic plan. The present study sought to assess efficacy levels of the most frequently used anthelmintics (Ivermectin, Nilzan super and Valbazen) in sheep and goats in Kajiado and identify factors associated with the rising cases of these infestations. Questionnaire surveys were used to assess the community’s knowledge and attitudes on these infestations. Animals not treated within the last three months and with faecal egg counts of ≥ 150 egg per gram (epg) were identified and included in the study. The identified animals were allocated to 4 groups of 18 animals each using a complete randomized design. Group A was treated with Valbazen orally, Group B with Nilzan super orally, Group C with Supermec injection subcutaneously while Group D was used as the untreated control group. Faecal egg counts and larval cultures were done before treatment (day zero) and after treatment (day fourteen). Faecal cultures were used to identify the principal nematode genera present in the pre- and post-treatment phases. Efficacy levels of the used drugs established using the faecal egg count reduction test (FECRT) method. Results indicated that the mean faecal egg counts of the different groups including treated and the control was not significantly different during the pre-treatment phase. However, on day fourteen, the faecal egg counts of Group C were significantly different (P < 0.05) from the rest of the treated groups. The different anthelmintic drugs used displayed a significant reduction effect (P < 0.05) on the parasite levels after treatment. Results of the FECRT revealed 86%, 76% and 17% in worm reduction for Nilzan super, Valbazen and Supermec respectively. In the case of pre-treatment cultures, Haemonchus, Oesophagostomum, Cooperia, Trichostrongilus and Strongiloides were present indicating multiple parasitic infections. Post-treatment faecal cultures showed that Haemonchus, Oesophagostomum and Trichostrongilus had escaped the treatments with Haemonchus being the predominant genera present. Based on these findings, it can be concluded that multiple drug resistance has been confirmed in Kajiado County and this has negative effects on the productivity of these animals. However, the level of resistance observed was apparently very high in ivermectin. It is therefore, recommended that animal health extension services in the County should be deployed to create awareness on the emerging threat of anthelmintic resistance and how to manage it.
- MST-Zoological Sciences