Epidemiology of dairy cattle gastro-intestinal nematodes in the São Carlos region, SP, Brazil

Abstract

The epidemiological observation on gastro-intestinal nematode parasites in crossbred dairy cattle (Holstein x Zebu) were carried out from January 1981 to January 1984 in the São Carlos region, State of São Paulo, Brazil. At necropsy the following species of adult and immature nematodes were collected: Cooperia punctata and C. pectinata; Haemonchus contortus and H. similis; Trichostrongylus axei; Oesophagostomum radiatum; Dictyocaulus viviparus and Trichuris discolor. The number of adult Haemonchus started rising in the spring, followed by a sharp fall in early Summer. The highest incidence was observed in late Summer, coinciding with the end of the rainy season. The arrested development of the nematode Haemonchus was observed in May, July and August. Bioclimatographs shows the existence of unfavorable condition for development of larvae at free-living stage in June, July, August and early September.