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United States Department of Agriculture

Agricultural Research Service

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Research Project: Assessing Predominant Transmission Routes for Toxoplasma Gondii Using Nhanes 2007-2010

Location: Animal Parasitic Diseases

2012 Annual Report


1a.Objectives (from AD-416):
The objective of the research is to establish a baseline prevalence of oocyst-transmitted Toxoplasma in the U.S. population. These data will support science-based decisions on the most effective methods to reduce or eliminate Toxoplasma transmission to humans in the U.S. Additionally, development of current Trichinella prevalence data in humans will inform policy makers on the effectiveness of farm level controls of this zoonotic parasite for reduction of risk in the human population.


1b.Approach (from AD-416):
Sera will be acquired from a sample of the NHANES III participants aged 6 and over, and tested for Toxoplasma in duplicate by ELISA using an in-house developed test using an 11 kDa sporozoite protein related to embryogenesis (TgERP). Trichinella seroprevalence will be determined using a commercially available test kit which uses T. spiralis excretory/secretory proteins (E/S) as the antigen in an ELISA format. The collected prevalence data for Toxoplasma will be used to determine the predominant route of infection (oocyst versus tissue cysts in meat) from a representative sampling of the U.S. population and ascribe demographic features to those found to be infected. The collected prevalence data for Trichinella will be used to measure the impact of the elimination of Trichinella from the U.S. swine herd on human health and the prevalence of Trichinella infection in the U.S. population.


3.Progress Report:

The Animal and Parasitic Diseases Laboratory (APDL) continued a serological survey of Toxoplasma infection using 4,000 sera and demographic data collected during the National Health and Nutrition Examination Survey (NHANES) from 2007-2010. The survey used an enzyme-linked immunosorbent assay (ELISA) based on a Toxoplasma sporozoite-specific antigen which differentiates oocyst (cat) versus tissue cyst (meat borne) transmission. The survey will provide, for the first time, a measure of the proportion of Toxoplasma infections in humans which result from consumption of T. gondii oocysts (from cat feces) versus consumption of tissue cysts (contained within infected meat).


Last Modified: 12/28/2014
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