The epidemiology of nematode and fluke infections in cattle in the Red River Delta in Vietnam

Over a period of 13 months, faecal samples were collected monthly from appr oximately 45 cattle over 3 months of age. Additionally, 74 calves of 1-2 mo nths were sampled to determine the presence of Toxocara vitulorum eggs. Ind ividual egg counts and infective strongyle larvae from pooled faecal sample s were examined. Post-mortem worm counts were carried out on six groups of tracer calves (n = 12) that had been kept for 4 weeks on pasture in and aro und the village studied. The following helminths were identified: T. vitulo rum, Cooperia punctata, C. pectinata, C. oncophora, Oesophagostomum radiatu m, Trichostrongylus axei, T. colubriformis, Haemonchus spp., Fasciola spy, and Paramphistomum spp. In 8% of the samples collected from young calves, i ndividual egg counts for T. vitulorum were found indicative for pathogenic worm burdens. Strongyle egg counts and worm counts indicated that transmiss ion is low without a distinct seasonality. In animals of 3-9 months old, a strongyle egg count peak can be demonstrated which at a higher age steadily and significantly decreased. In faecal cultures Cooperia spp, were most pr ominent in all age groups throughout the year with the exception of the per iod September-November when Haemonchus spp. and Oesophagostomum spp, were m ost prevalent. Fasciola spp. eggs were found in 22% of the collected faecal samples and the egg counts were low indicating that the intensity of Fasci ola spp. infection is mild. Based on the present data, regular anthelmintic treatments seem not to be justified, except fur a single treatment at the age of 2 weeks against toxocariosis. (C) 2000 Elsevier Science B.V. All rig hts reserved.