Salmonella Outbreak Spreading, Clues Frustrating

By Anastacia Mott Austin

The recent salmonella outbreak, initially linked to tomatoes, has not abated; in fact, new cases are popping up daily. Nineteen new cases recently surfaced in Michigan.

This has frustrated experts who are trying to locate and contain possible sources of the infection.

The first reports tied the outbreak to consumption of fresh roma, plum, and regular round tomatoes. But even after several potential sources were located and tomatoes from those sources were no longer available to the public, people still continued to become ill with salmonella.

The next culprit identified was fresh peppers, the serrano and jalapeno varieties.

The problem was that some people had eaten only tomatoes, others had only eaten peppers, and some had consumed both, along with fresh cilantro, a possible third suspect. Identifying a single source for all of these products has been frustratingly slow.

"This has gone on longer and has been more complicated than anything I've worked on at FDA," said Dr. David Acheson, the FDA’s chief of food safety, to reporters.

Many of the cases are in the southwest United States, with few cases in the Northeast. This has been attributed to food distribution regions, as well as the possibility that a food consumed more in these areas may be responsible for the illnesses. Salsa, a popular food item in these areas, often contains tomatoes, peppers, and cilantro.

"I wish I could have a crystal ball and say it's one of those three things," said Dr. Acheson.

Typically in a food-borne bacteria outbreak, as with the 2006 e.coli contamination of spinach, the likely source of infections is fairly easily traced. The spinach culprit was identified within a couple of weeks, and all spinach products from that location were recalled from grocery shelves.

But this series of salmonella infections has continued for months and sickened more than 1,000 people nationwide, making it one of the worst outbreaks in recent history.

Experts thought they had seen the last of new cases of salmonella at the end of June, but Michigan’s new spate of cases this week has federal food safety professionals stymied.

They are looking for either food products that may have combined tomatoes and peppers (like salsa or pico de gallo), or farms which may have produced both.

Most individuals will experience nausea, fever, and diarrhea within 12 to 72 hours of ingesting a salmonella-contaminated product. The illness can be quite severe and last 4-7 days. Most people will recover on their own, but in people with weakened immune systems, or the very young or very old, the infection can become systemic and infect the blood. In those cases, prompt treatment with antibiotics may save the victims’ lives. Antibiotic use is not recommended for standard cases of salmonella, and treatment usually involves rest and fluids.

Usually salmonella is connected to animal products like meat, milk, or eggs, but produce can also become contaminated from irrigation water or soil, or by incorrect handling by workers.

The CDC estimates that there are more than a million U.S. cases of salmonella each year, with about 15,000 cases severe enough to warrant hospitalization, and about 400 deaths.

Usually the sources are fairly quickly identified and contaminated products are taken off store shelves.

The CDC recommends that consumers avoid all roma, plum, and round tomatoes, unless they were grown in locations known to be safe (for a complete list, visit http://www.fda.gov/oc/opacom/hottopics/tomatoes.html), as well as jalapeno and serrano peppers, and cilantro if they wish to be extra cautious.