Author
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Gasbarre, Louis |
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Submitted to: North American Veterinary Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 9/10/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Gastrointestinal nematodes cost the American cattle industry in excess of $2 billion per year. Because the different species of parasite vary greatly in their pathogenicity, control of these parasites requires easy and accurate means to identify the parasite species in both individuals and din the entire herd. The current method of choice involves collection of feces from the cattle, followed by culture of the parasite eggs to grow larval worms. These worms are then identified to determine the parasite species present. We found that this technique cannot be used to determine the numbers of each parasite species present unless the efficiency of the culture technique is defined for each species. We found that under a given set of conditions certain parasites will develop at higher rates than will other species. A second means to determine parasite especies involves differentiation of the parasite eggs in the feces. Simpl visual identification is inaccurate. Recent reports have used computer measurements to aid the differentiation. These techniques can differentiate the parasite eggs but they are very time consuming, and require expensive equipment. Recent attempts to differentiate eggs based on techniques of modern molecular biology offer promise, but still require extensive testing and adaptation to clinical laboratory conditions before they will be of everyday use. Veterinarians and animal health consultants can use this information to design better parasite control programs. Technical Abstract: The different species of gastrointestinal nematodes of cattle vary greatly in their pathogenicity, and as such control of these parasites requires precise and accurate means to identify the parasite species in both individuals and in the entire herd. The current method of choice involves culture of cattle feces and subsequent differentiation of the larvae developing in culture. Studies involving cultivation of known percentages of eggs from the different parasite species has shown that this technique cannot be used to determine the numbers of each parasite species present unless the efficiency of the culture technique is defined for each species. We found that under standard culture conditions the development of Ostertagia is enhanced, while the development of Haemonchus and Oesophagostomum is diminished. As such the cultures greatly overestimate the numbers of Ostertagia present. A second means to determine parsite species involves differentiation of the parasite eggs in the feces. Simple visual identification is inaccurate. Recent reports have used computer measurements to aid the differentiation. These techniques can differentiate the parasite eggs at levels between 60-90% accuracy, but they are very time consuming, and require expensive equipment. Recent attempts to differentiate eggs based on PCR technology, show great promise in quantification of the different species, but they require extensive testing and adaptation to clinical laboratory conditions before they will be of everyday use. This information is of direct use to veterinarians and animal health consultants in the formulation and evaluation of parasite control programs. |
