Submitted to: Clinical Microbiological Reviews
Publication Type: Review Article
Publication Acceptance Date: August 20, 2000
Publication Date: N/A
In the United States, production of cattle, swine and broiler chickens is valued at more that 63 billion dollars. The current review discusses recent developments in biology, epidemiology and control of important internal parasites of production animals. Nematode parasites of cattle are important disease organisms because of the economic value of this livestock species. Disease caused by gastrointestinal nematodes of cattle varies with climati and management conditions. Among several species that parasitize livestock, the medium brown stomach worm Ostertagia ostertagia, where it occurs, is the most important GI nematode. Recent advances in epidemiology have shown the importance of climatic conditions in transmission of disease. Diagnosis of GI nematodes by the traditional methods of fecal egg count have been shown to be poor estimates of worm burden and therefore can lead to underestimation of parasite worm burden. Modern control of GI nematodes is best directed towards control of pasture contamination by a variety of methods. GI parasites of swine continue to be a significant factor in production. The round worm of swine, Ascaris suum has an egg which is very persistent in the environment and may provide a source of potential contamination in sewage and manure sludge. The swine whip worm Trichuris suis, is an important pathogen and recent data indicates the infection with T. suis may potentiate microbial infections thus increasing pathology. Coccidia of genus Eimeria are important parasites of broiler chickens. Many of current drugs used for control are ineffective because of widespread resistance. Alternative therapies are being developed. These include natural products which may change the oxidative state of the intestine, live attenuated vaccines, and recombinant vaccines.