The investigation of O157 outbreak due to contaminated bagged spinach finally came to a breakthrough. FDA has quietly canceled the warning of E. Coli infection in the bagged spinach last week. Health investigators have found a strain of E. Coli in the cattle manure from a California ranch matched with the pathogen from the tainted spinach. The bacteria has the same genetic characteristics as the one contaminated the spinach. In fact, this discovery is “unprecedented”, so claimed in the NYT. Usually in food borne outbreaks, you always have suspects, but are never able to pinpoint where the bacteria come from.

Most important, there is no new case any more. Life, it seems, returns to normal.

There are many interesting issues in this outbreak. The O157 strain of E. Coli is common in cattle intestines. The outbreak of O157 is often due to contaminated beef. It is very unusual to link O157 to vegetables such as spinach.

A few weeks ago NPR interviewed an epidemiologist from the Oregon Health Department about the investigation. The interviewee explained that it was indeed a difficult task to investigate the source. After informed by clinicians that there were several O157 infected cases, they started from a conventional food questionnaire to investigate which food was responsible for this outbreak. But they couldn’t pin down any specific food. Then they used a very comprehensive food list and asked more detail about their food history. The culprit, also surprised to them, turned to be spinach.

They reported their findings to CDC and were informed that similar outbreak had occurred in Wisconsin in which spinach was the culprit too. Every body got nervous about this. Was it a national O157 outbreak? They did more work and informed the FDA. After reviewing the evidence, FDA issued the warning against bagged spinach. The panic began.

Ironically, although the FDA warning stirred the public, FDA has no legal authority to mandate the food packing companies or retailers to take any action. Nevertheless, related industries voluntarily removed spinach from the market.

Now we had the bacteria corned in the unlucky ranch, though the ranch is still far away from the spinach field. To the public, the outbreak is almost over. Nothing needs to be worried about anymore. But to the food industry, the pain is still there. The organic food processing companies suffered a great loss in profit, let alone the reputation. The farmers lost profit too. They also have to improve their harvesting methods and irrigation. Furthermore, there are some class lawsuits waiting for the food companies. They will be unhappy for a while.