Federal health authorities in the USA reported yesterday, 9th July, that the number of confirmed cases of people infected since April by the same strain of Salmonella Saintpaul, a rare form of the foodborne bacterium, now exceeds 1,000 and that they have extended their list of likely sources to include fresh jalapeño peppers, fresh serrano peppers, and fresh cilantro, in addition to the already suspected raw red tomatoes, in an outbreak that has now spread to 41 states, the District of Columbia, and Canada.

The US Centers for Disease Control and Prevention (CDC), said that as well as collaborating with public health bodies in many states, they were also working closely with the Indian Health Service, and the US Food and Drug Administration (FDA) to try and get to the bottom of what is being reported as the biggest multi-state outbreak of illness due to a single strain of Salmonella.

The investigation first concentrated on certain types of raw red tomatoes because this was found to be what linked the people who fell ill in May, when the outbreaks appeared to be confined to New Mexico and Texas.

But since then, a larger, nationwide investigation comparing people who fell ill in June with people who did not get ill, found that those who fell ill were more likely to have recently consumed raw red tomatoes, fresh jalapeño peppers and fresh cilantro. However, the CDC said it was still not possible to say which of these caused the illness because they were not always eaten together.

As of 9 pm EDT, on 8th July, the official number of cases of people falling ill since April from a single strain of Salmonella Saintpaul bacteria identified by its unique genetic fingerprint, is now 1,017, said the CDC. More recently, many of the cases have clustered around groups of people who ate at restaurants, with up to 5 people affected in each cluster.

However, there have also been three larger clusters, which following intensive investigation revealed that in one, the illnesses were associated with a single dish containing fresh tomatoes and fresh jalapeños. In the other two, the cases were linked to a dish containing jalapeños but none of the other suspected foods.

When they put together all the investigation data, health official found that it was likely that fresh jalapeño peppers caused some of the illnesses, but they did not cause all of them, so raw tomatoes, fresh serrano peppers, and fresh cilantro are still in the frame, and investigators from many different authorities are working to try and trace the ingredients back to their point of origin.

The CDC describes the investigation as “complex and difficult”. They have 20 experts working in the field with public health officials, and one particular problem is that people find it difficult to remember what they ate, never mind what the specific ingredients were in each dish. Plus, while lab testing helps to prove if an ingredient is infected or not, in this case many of them are perishable and samples from the same batch are no longer available. The other difficulty is that when food items are eaten together, the statistics shows them all to be linked to the illnesses, making it difficult to untangle the likely suspects from the less likely ones.

Most people who fall ill from Salmonella get ill about 12 to 72 hours after eating an infected food item, and have diarrhea, fever, and abdominal cramps for about 4 to 7 days. Infection is usually confirmed by lab tests on a stool sample.

Most people recover without treatment, but severe infections can occur, and babies, the very young, the very old, the infirm, and people who have weak immune systems are most vulnerable. When severe infection sets in, it can spread from the intestines to the bloodstream where it travels to other parts of the body and can eventually be fatal, though so far, no deaths have been reported as being directly caused by the infection. Treatment is usually by antibiotics.

Consumers are advised that contaminated product is still on the market because the source of the outbreaks is still unknown, so they should be extra careful about what they eat. Those at greatest risk of infection, babies and infants, the elderly, and those with weakened immune systems (for instance if they are having chemo), should avoid raw jalapeño and raw serrano peppers, said the CDC, and they should only eat the raw red tomatoes that are on the FDA safe list.

The FDA said that cherry tomatoes, grape tomatoes, tomatoes sold with the vine still attached, and tomatoes grown at home are safe to eat, as are red plum, red Roma, and round red tomatoes from sources listed at: http://www.fda.gov/oc/opacom/hottopics/tomatoes.html, and recommends that shops, food outlets and restaurants only offer tomatoes that the agency has described as safe.

The CDC said consumers should also be aware that “raw jalapeño peppers are often used in the fresh preparation of salsa, pico de gallo, and other dishes”, and that “raw tomatoes are often used in the preparation of fresh salsa, guacamole, and pico de gallo, are part of fillings for tortillas, and are used in many other dishes”.

Consumers are also advised to:

  • Refrigerate within 2 hours or throw away cut, peeled, or cooked produce items, including tomatoes and peppers.
  • Avoid buying bruised or damaged tomatoes, peppers, and other foods, and throw them away if they look bad or spoiled.

  • Thoroughly wash all tomatoes, peppers, and other raw foods under running water.
  • Keep ingredients that are going to be eaten raw separate from raw meats, raw seafood, and other raw produce.
  • Wash cutting boards, dishes, utensils, and counter tops with hot water and soap when switching between different food types (eg cutting cheese or salami to cutting fruit).

Source: CDC .

Written by: Catharine Paddock, PhD