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United States Department of Agriculture

Agricultural Research Service

Research Project: Managing the Emerging Risk of Trichinellosis in Organic and Free Range Pork

Location: Animal Parasitic Diseases Laboratory

Title: Development of a single larva microsatellite analysis to investigate the population structure of Trichinella spiralis

item La Rosa, Giuseppe
item Marucci, Gianluca
item Rosenthal, Benjamin
item Pozio, Edoardo

Submitted to: Infection, Genetics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2012
Publication Date: 3/1/2012
Citation: La Rosa, G., Marucci, G., Rosenthal, B.M., Pozio, E. 2012. Development of a single larva microsatellite analysis to investigate the population structure of Trichinella spiralis. Infection, Genetics and Evolution. 12(2):369-376.

Interpretive Summary: Trichinella spiralis is a parasite transmitted by consumption of infected meat. Historically, this parasite imposed great public health burden on American consumers of pork, but effective measures have virtually precluded the risk of acquiring infection in this way. The threat remains appreciable in certain parts of the world, however, mandated testing in the European Union impose significant costs on American exports. This study developed and tested variable genetic markers on 48 larvae from each of 22 animals infected with T. spiralis in order to determine how many times each animal had become infected (and, therefore, whether or not the larvae comprising infections were full siblings). In all but one case, infections were found to be comprised of sibling larvae, meaning that the animal had been infected exactly once. Our study also confirmed previous work attesting to the highly inbred nature of parasites in Europe and the Americas, as compared with more diverse infections in Asia. This work will be of interest to parasite biologists, epidemiologists, and public health officials seeking to limit zoonotic risk by better understanding transmission patterns.

Technical Abstract: Trichinella spiralis is the most important etiological agent of human trichinellosis. It has a cosmopolitan distribution and is transmitted to humans mainly through the consumption of pork. In nature, transmission occurs among animals through the ingestion of an infected carcass by one or more hosts. Microsatellite markers have provided insight into how the parasite has dispersed geographically over its evolutionary history. The objectives of the present study were to develop microsatellite markers capable of differentiating single larvae for investigating the inter and intra-specific population structure of T. spiralis and to determine their usefulness as genetic markers to study transmission mechanisms of this zoonotic parasite. A panel of 48 larvae derived from 22 distinct isolates originating from the Americas, Asia and Europe, were investigated. A total of 27 alleles were detected in these samples using seven new markers. The sequences of the amplified fragments containing the microsatellites support the homology of the amplified products and validate their use for genetic population studies. We documented the first known occurrence of a genetically variable larval admixture, indicating that more than two adults gave rise to the ensuing population of this host’s muscle larvae. Globally, T. spiralis was observed to harbor less genetic variation than other nematodes, a result consistent with previous assays of nuclear and mitochondrial variation.

Last Modified: 10/16/2017
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