Mexico has blocked imports of Foster Farms chicken from three Central California processing facilities linked to an outbreak of salmonella.
The Mexican government told the U.S. Department of Agriculture on Tuesday that it was removing from its list of approved exporters two Foster Farms plants in Fresno and one in Livingston, where the poultry company is headquartered.
The blocked three plants were identified by the USDA as the likely origins of a salmonella outbreak that has sickened at least 338 people across the U.S. since March.
The USDA allowed the plants to remain open after Foster Farms established new protocols to reduce rates of contamination.
Federal inspectors and Foster Farms have maintained that poultry from the processing sites is safe to eat if handled properly and cooked to a minimum of 165 degrees Fahrenheit.
The strain of salmonella involved in the outbreak, known as Salmonella Heidelberg, is especially virulent and resistant to some antibiotics. That's one reason the outbreak's hospitalization rate is double that of the average salmonella outbreak.
The Mexican ban, which was first reported by the Oregonian of Portland, is believed to be the first time Mexico has blocked U.S. imports because of a health alert.
Mexico is the top destination for U.S. poultry exports, valued at $1 billion last year. That's nearly twice as much as the second-biggest importer, Canada.
The trade relationship hasn't always been perfect. America's southern neighbor imposed duties on U.S. chicken leg quarters last year on behalf of three Mexican poultry producers who accused their American counterparts of dumping products below cost. Mexico has yet to implement the ruling because of poultry shortages brought on by avian flu.
Foster Farms relies overwhelmingly on domestic sales for its annual revenue of $2.3 billion. Exports account for no more than 7% of its earnings, according to trade publication WATT PoultryUSA.
In an interview last week, Foster Farms President Ron Foster said company sales had declined 25% since the USDA announced its health alert on Oct. 7.