Ostertagia Ostertagi

Clinical Condition, Recognition of Disease States, and Approaches to Control through Anthelmintics and Management

Abstract

Ostertagia ostertagi is the most important parasites of cattle and occurs in all major cattle raising sections of the United States. Recognition, diagnosis, management and treatment for ostertagiasis are often misunderstood because of the complex epidemiology of the parasite in northern and southern regions of the country. It has become evident that the different disease phases of 0. ostertagi, i.e., type I, pre-type II, and type 11, as described from other parts of the world, do occur in this country. In
northern temperate regions inhibition-prone larvae are acquired in autumn, persist through winter, with type II disease being a threat from late winter into spring. Larval inhibition occurs during spring in southern temperate regions such as Louisiana, the larvae remain in the inhibited state through summer and type II disease outbreaks may occur from late summer through autumn. Based on research in other parts of the world in which integrated forms of parasite control have been developed and implemented, there is an increasing interest in such control programs in this country. Appropriatelytimed anthelmintic treatment, tied in with some alteration of pasture management which provides safe pasture or pasture of reduced infection potential for younger, susceptible cattle is based on parasite epidemiological data. Such data is available for some sections of the country. Some aspects of research into parasite epidemiology and integrated control conducted in Louisiana are discussed.