A ban on Mexican papayas entering the United States will make it a little harder to find the tasty Vitamin C-laden fruit at your favorite grocer. 

More costly papayas from other growing areas will replace them on the shelf.

The U.S. Food and Drug Administration closed the American border to Mexican papaya on Thursday because too many — 15.6 percent  sampled between May 12 and August 18 — tested positive for Salmonella.

Those positive samples were from 28 different firms and included nearly all major papaya producing regions in Mexico, according to FDA. The agency’s import alert denying admission of Mexican papayas into the U.S. means that it’s up to importers to show that their produce is not contaminated with Salmonella.  

The action follows reports from multiple states that more than 100 people in the U.S. have been infected with Salmonella Agona.  The federal Centers for Disease Control and Prevention (CDC) in Atlanta identified Mexican papaya from a single importer as the likely transmission vehicle for the pathogen.

“Using the information provided by the cases, tracebacks were conducted in multiple states,” the agency the import alert announcing the ban. “FDA also collected samples of papaya to test for the outbreak strain.  Based on information from the outbreak investigation, the outbreak has been associated with papaya from at least one grower and its shipper in Mexico.”

Mexico’s government is supporting the ban even though a month ago there were rumblings from the country’s growers that the U.S. was targeting Mexico’s fruit out of protectionist motives by going after Agromod Products Inc., the world’s largest grower of Maradol papayas.  

“I am confident that this joint effort will reduce the risk of contamination of produce moving across our common border,” says Enrique Sanchez Cruz, director in chief of Mexico’s National Service for Agroalimentary Public Health, Safety, and Quality (SENASICA).

FDA’s stepped up collaboration with SENASICA and Mexico’s Federal Commission for Protection Against Sanitary Risks (COFEPRIS) will involve tracebacks, laboratory methodologies, and product testing.  

Michael R. Taylor, FDA deputy commissioner for food, said both governments are committed to preventing “contamination throughout the chain of production, processing, distribution and sale.”

The ban on Mexican papaya is the latest event in a tough year for the fruit.  Even before the Salmonella contamination, there was the drought in Brazil, hurricanes in Guatemala and Belize, and floods in Mexico.

Southern Mexico is believed to be where papayas got their start, before making their way around the world to other tropical regions. Mexican varieties, like the Maradol, have red flesh.  Hawaii’s papayas have orange flesh with the best known variety known as Solo.

The ringspot virus might well have eliminated all papayas grown on the Hawaiian islands had it not been for an artful bit of genetic engineering by Dr. Maureen Fitch of USDA’s Agricultural Research Service (ARS). She created the ringspot virus-resistant SunUp variety that kept Hawaiian papaya growers in business.

Most of the 170 papaya tree farms on the Big Island and Oahu in Hawaii are both small and producing the virus-resistant fruit.  Since May 2010, several acres including thousands of trees have been chopped down in the middle of the night.

No one has accepted blame for the destruction. Hawaiians know genetic engineering saved their papayas, and it remains the most popular fruit on the islands. What Hawaiians don’t eat is shipped to the mainland.

Also to possibility ensure Americans will not suffer too much from a papaya shortage, USDA’s Animal and Plant Health Inspection Service approved the sale of papayas from Malaysia shortly before the ban on Mexican papaya was announced.

Malaysian papaya got the green light to enter the U.S. on Aug. 11. One string was attached — Malaysian papaya must irradiated before they arrive.   Irradiation is a key step that kills pathogens like Salmonella.

Papayas imported to the U.S. from all sources in 2010 totaled 153,990 metric tons and almost 75 percent or 115,200 metric tons were from Mexico.

Agromod recalled all its papayas sold in the U.S prior to July 23, 2011. It is based in Tapachula, Mexico, a major papaya growing area. Its products enter the U.S. through McAllen, TX.

Mexico produces 11 percent of the world’s papayas. Mexican growers who can show evidence that their papayas are not contaminated can work their way on to a “green” list of shippers who will be able to get their product back into the USA.