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United States Department of Agriculture

Agricultural Research Service

Trichinella
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Systematics Success Stories

DNA- based methods used to identify species and genotypes of the food-borne parasite Trichinella based on single larvae.

Problem: Trichinellosis is a globally distributed zoonotic disease caused by the ingestion of raw or undercooked meats harboring parasites of the genus Trichinella. Disease eradication is problematic and challenges are compounded by the absence of host specificity for Trichinella larvae which are capable of infecting nearly all carnivores and omnivores.

Trichinellosis is both an emerging and re-emerging disease worldwide whereby the incidence derived from sylvatic sources is on the rise in both developing and developed countries. Infections from domestic pork continue to rise in Asia, East and Central Europe and South America, where the prevalence in swine herds can reach as high as 50%.

Within most parasite genera, distinct morphological and/or biological characters exist among the species that permit differentiation and accurate classification. The absence of distinguishing morphological characters, however, and the overlapping nature of the biological characters within the genus Trichinella, make these traits unsuitable as diagnostic characters.

Solution: An effort to evaluate the systematics of this genus using molecular markers has resulted in the development of a single DNA based method to differentiate all well-defined species and genotypes of Trichinella. Molecular systematics relying on single larval parasites provides unequivocal phylogenetic resolution among Trichinella spp.

Impact:

  • This work will greatly facilitate the identification of parasites within this genus providing the foundation for epidemiological studies as well as species diagnosis from host biopsies.

  • The test has been adopted as the gold standard by the International Trichinella Reference Center in Rome, Italy for all sample testing and isolate classification involving parasites of this genus.
(Contact- Dr. Dan Zarlenga, Bovine Functional Genomics Laboratory).


Last Modified: 9/14/2006
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