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United States Department of Agriculture

Agricultural Research Service

Title: Sensitivity of Direct and Indirect Methods for the Detection of Trichinellosis in Pigs and Horses

Authors
item Gamble, Howard
item Gajadhar, A - AGRICULTURE OF CANADA
item Solomon, Morse

Submitted to: Trichinellosis International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 22, 1997
Publication Date: N/A

Interpretive Summary: Trichinellosis, caused by the human pathogen Trichinella spiralis, is a significant cause of public health concern worldwide. Most developed countries, with the exception of the United States, inspect pork and horses at slaughter for the presence of this parasite. Currently used methods for inspection are based on several variations of the pooled sample digestion method. The requirements for testing pigs include the use of a 1 gram tissue sample, while the testing of horses requires a five gram sample. Since these methods obviously have different sensitivities, the present study was undertaken to determine the actual sensitivity. Using groups of pigs and horses, the pooled sample digestion method using a one gram sample had a sensitivity of 3-5 larvae per gram of tissue, while using a five gram sample this sensitivity was reduced to 1 larvae per gram. Since parasite infection levels of greater than 1 larvae per gram are sufficient to cause human disease, the first method is not suitable for detecting all animals of public health significance. The use of serology testing was highly sensitive, but positive animals were not detected until 3 to 7 weeks following infection. Both direct (digestion) and indirect (serology) methods both have limitations, but are each useful in an integrated program for control of trichinellosis.

Technical Abstract: Artificial digestion methods using 1- and 5-gram samples were compared for the detection of Trichinella spiralis in various tissues from pigs and horses. In all cases, 1-gram samples detected infections of > 3-5 larvae per gram (LPG) of tissue. Digestion testing using 5-gram samples was effective in detecting infections of > 1 LPG. Indirect diagnosis enzyme immunoassay (EIA) was effective in detecting low level infections, but seroconversion did not occur until as long as 7 (horses) or 8 (pigs) weeks following inoculation.

Last Modified: 10/21/2014
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