Prevalence, population dynamics and pathological effects of intestinal helminths in Black Bengal goats

Abstract

Prevalence, population dynamics and pathological effects of intestinal helminths in Black Bengal goats were studied by examining 150 viscera collecting from different slaughter houses of Mymensingh district from the period of November 2005 to May 2006 in the Department of Parasitology and Pathology, Bangladesh Agricultural University, Mymensingh,  of which 94.67% goats were infected with one or more species of helminths. A total of 5 species of helminth parasites were identified such as Oesophagostomum columbianum (92%), Trchuris ovis (56.66%), Schistosoma indicum (38%), Moniezia expansa (10.66%) and Moniezia benedeni (2.66%). Single infection was observed in case of O. columbianum (16%) and S. indicum (2.66%). Single sex infection was established by S. indicum male (5.33%). Overall mean parasitic burden was 34.02±2.20. Mean parasitic burden was the highest in case of O. columbianum (29.91±2.00) followed by that of T. ovis (5.70±0.47), S. indicum (4.66±0.42), M. expansa (2.59±0.54) and M. benedeni (1.00±00). Prevalence of intestinal helminth was significantly (P < 0.05) higher in winter (100%) than that in summer (89.33%). Calculated odds ratio in between winter and summer was 18, which indicated that Black Bengal goats were 18 times more susceptible to helminth infection in winter. Parasitic burden was also higher in winter (41.53±3.15) than that in summer (25.52±2.57) season. Pathological lesions were observed in case of O. columbianum, T. ovis and S. indicum infection. In O. columbianum infection, hard, raised, slightly yellowish to greenish colored nodules measuring 0.25×0.50 cm were observed. Microscopically, it was characterized by catarrhal inflammation associated with destruction and desquamation of epithelial cells. Affected tissues were infiltrated chiefly with lymphocytes, macrophages, a few eosinophils and occasionally with plasma cells and neutrophils. Caseation and fibrous tissue proliferation were also noticed. But moderate infection with T. ovis was characterized by catarrhal inflammation along with the petechial haemorrhages on the intestinal mucosa where parasites were firmly attached. Histopathologically, it was characterized by destruction of lining epithelium of villi of caecum and colon along with the cellular infiltration predominantly with lymphocytes, few eosinophils and occasionally by macrophages. Lymph nodes of the lamina propria were enlarged. In case of S. indicum infection, haemorrhages were observed particularly on the rectal mucosa. Numerous eggs were found in the mucosal scraping from intestinal surface. Microscopically, lamina propria was thick and inflammed. Granulomatous response was observed which was characterized by the infiltration of epitheloid cells and proliferation of fibroblasts. The present study clearly suggests that Black Bengal goats are susceptible to intestinal helminths in both winter and summer seasons and most of the parasites recovered were associated with the production of variable degree of pathological lesions. That is why proper attempts should be made to control all these parasites. Key words: Prevalence, population dynamics, pathological effects, intestinal helminths, goat DOI = 10.3329/bjvm.v5i1.1313 Bangl. J. Vet. Med. (2007). 5 (1 & 2): 63-69