The Cyclospora outbreak that began in June sickened 631 people in 25 states before ending in late September, according to the Centers for Disease Control and Prevention which issued its final report on the outbreak today. Health investigators determined that there were multiple sources for illnesses reported. In Iowa and Nebraska, the food source was identified as commercial bagged salad mix and in Texas many illnesses were caused by cilantro.
Cyclospora, a rare parasite usually associated with travel to tropical areas, causes an infection called cyclosporiasis. Symptoms include a watery diarrhea that lasts an average of 57 days if untreated. Other symptoms include fatigue, loss of appetite, weight loss, bloating, increased gas, nausea, vomiting, muscle aches and low-grade fever.
Onset of illness dates ranged from June 1, 2013, to August 29, 2013. Case patients, about 58 percent of whom were female, ranged in age from less than 1 year to 94 years old. The median age was 52 years. Eight percent of those sickened were hospitalized. No deaths were reported. By state the case count for each state was as follows: Arkansas (16), California (1), Connecticut (2), Florida (33), Georgia (5), Illinois (14), Iowa (140), Kansas (4), Louisiana (3), Massachusetts (3), Michigan (1), Minnesota (3), Missouri (5), Nebraska (87), New Hampshire (1), New Jersey (4), New York City (10), Ohio (3), Pennsylvania (1), South Dakota (1), Tennessee (1), Texas (270), Virginia (4), Wisconsin (18), and Wyoming (1).
The outbreak was first announced July 8 by health departments in Iowa and Nebraska. Soon after the initial announcement, health investigators in those states indicated that they suspected fresh produce as the source of the outbreak. Nine days after the initial announcement, Texas health officials reported a 37 cases of Cyclospora, but said it was too early to tell if the cases were related to those in Iowa an Nebraska.
On July 19, Food Poisoning Bulletin was reporting a multi-state outbreak. The CDC’s first acknowledgement of the outbreak came three days later. For several weeks the agency’s updates lagged behind actual outbreak numbers.
DNA “fingerprinting” tools for Cyclospora don’t exist. So, unlike food poisoning outbreaks caused by bacteria such as E.coli and Salmonella, there isn’t a lab test for Cyclospora that can determine the genetic fingerprint of isolates and match them. Without that technology, investigators rely on information gathered from interviews with patients and from traceback investigations of possible food sources.
There were other unusual ripples in the CDC’s reporting. Restaurants and suppliers involved were not initially named in Iowa and Nebraska, then, on August 2, they were named. In Texas, they weren’t named and still haven’t been.
In addition, when Iowa and Nebraska identified the source of illnesses in those states as commercial bagged salad mix produced by Taylor Farms of Mexico and served at Olive Graden and Red Lobster restaurants, the CDC and U.S. Food and Drug Administration (FDA) reports did not initially make it clear that they stood by those results and that the outbreak was likely multiple outbreaks with multiple food sources. Without an explanation of why restaurant salad was not the source for illnesses in all states, some public health and food industry professionals speculated publicly that Iowa and Nebraska were in error. It took three weeks for the bagged salad named as the source in Iowa and Nebraska to be ruled out as a source in Texas.
By late August, the CDC was advancing the idea that the outbreak was actually multiple overlapping outbreaks as was the case with a Cyclospora outbreak in 1997. The investigation stagnated and then was interrupted by the government shutdown which began October 1.
In their final reports, the CDC and the FDA concluded that many of the 278 cases of cyclosporiasis in Texas were caused by contaminated cilantro imported from Mexico, that the 239 cases in Iowa and Nebraska were caused by contaminated bagged salad imported form Mexico and that the cause of 126 illnesses in 22 states was unknown.
