Four months after a deadly E. coli outbreak linked to romaine lettuce forced Santa Clarita stores and supermarkets nationwide to recall salad and other lettuce products, the Center for Disease Control and Prevention officially declared an end to the health emergency.

On June 28, the CDC announced that the outbreak, the deadliest in U.S. history, has ended and that preliminary sample results from Yuma, AZ have concluded that canal water around lettuce farms in the area tested positive for the O157:H7 strain of E. coli.

Escherichia coli (abbreviated as E. coli) is bacteria found in the environment, foods and intestines of people and animals. Although most strains of E. coli are harmless, others can make you sick, according to the CDC.

E. coli O157 is typically transmitted from animals to humans through animal excrement that has contaminated food or water. The symptoms of infection include cramping, vomiting, diarrhea, and, rarely, kidney failure and death, according to the agency.

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The U.S. Food and Drug Administration is currently examining all possibilities, including what contamination may have occurred at any point along the growing, harvesting, packaging and distribution chain before reaching consumers, according to the agency.

Since mid-March, there have been five deaths and 210 illnesses in 36 states caused by the infections linked to prepackaged lettuce. While no illnesses tied to the outbreak were reported in Santa Clarita, markets in the Santa Clarita Valley followed stores across the nation in recalling and throwing out any romaine lettuce that may have been contaminated.

The last shipments of romaine lettuce from the Yuma region were harvested on April 16, meaning the harvest season is over. Contaminated lettuce should no longer be available, according to the FDA.

Analysis of other samples such as water, soil and manure are still under review, but at this time the samples from the nearby canal water are the only matches to the outbreak, according to the administration.

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