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Last Big Cyclospora Outbreak Was Traced to Guatemalan Raspberries

Seventeen years ago, an outbreak of the protozoan parasite cyclospora was quickly blamed on California strawberries — but these would later turn out not to be the source. What was missed in the investigation was the steady increase in imports of raspberries from the poor Central American nation of Guatemala.

U.S. imports of raspberries from Guatemala were doubling every year and American consumers were literally gobbling them up when they arrived in the produce section every spring.

But spring of 1996 was the year when Cyclospora arrived with those raspberries in both the U.S. and Canada. Before it was over, the federal Centers for Disease Control and Prevention (CDC) in Atlanta and Health Canada in Ottawa would find 1,465 confirmed cases of infection with the parasite in the two countries.

But investigators first focused on California strawberries, causing a scare that Golden State growers have not forgotten. Health officials’ mistake was at least partially due to the fact that all the Guatemalan raspberries had been consumed before anyone got sick.

What they did not know at the time was that cyclospora was endemic in Guatemala.

A couple years later, fieldwork by CDC’s Center for Infectious Diseases found conditions in the Latin American country’s raspberry-growing area were more than ripe for the parasite.

The CDC team conducted a study at health care facilities and among raspberry farm workers.

“From April 6, 1997 to March 19, 1998, 126 (2.3 percent) of 5,552 surveillance specimens tested positive for Cyclospora: prevalence peaked in June (6.7 percent),” CDC reported. “Infection was most common among children 1.5 to 9 years old and among persons with gastroenteritis. Among 182 raspberry farm workers and family members monitored from April 6 to May 26, six had Cyclospora infection.”

The study found that 88 of the 120 Guatemalans infected had drunk untreated water. Risk factors identified by the team included water sources, type of sewage drainage, ownership of chickens and contact with soil, especially among children under two years of age.

But none of that was known when the outbreak began.  And when attention did turn to imported Guatemalan raspberries, North American health officials got pushback from the Guatemalan Berry Commission. The grower’s organization had built up its market in the U.S. and Canada and was not anxious to take the blame for the outbreak.

Early on, the U.S. Food and Drug Administration (FDA) lacked any physical proof that the Guatemalan berries were the source. It based its conclusions solely on its epidemiology. FDA would not collect physical proof of cyclospora on Guatemalan raspberries until 2000.

The Guatemalan Growers Association did come up with a new approach by 1997. It assigned risk values to raspberry farms and allowed only berries grown in low-risk areas to be exported north. But even after these measures were taken, the outbreak picked up again right where it left off, and by May, Guatemala voluntarily stopped exporting raspberries to the U.S.

U.S. and Canadian officials headed south to help Guatemala solve its cyclospora problem. The berry imports did not resume until 1999 under a new Model Plan of Excellence (MPE) program worked out by the Guatemalan government and growers.

In 1999, imported Guatemalan raspberries were cyclospora-free. But in 2000, FDA traced two outbreaks back to a single Guatemalan farm. Guatemalan raspberries have not been a problem since then.

In 1996, about 85 raspberry growers were exporting to the U.S. and Canada, but that number has shrunk to a handful due to the MPE program and other controls. Mexico and Chile today dominate the U.S raspberry import market Guatemala once thought it might own.

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