The US Food and Drug Administration (FDA) is on high alert at the moment, due to the threat of a major salmonella outbreak which is said to have been caused by contaminated red tomatoes. As a result, many of the most popular fast-food chains in the States - McDonald's and Burger King among them - voluntarily withdrew plum, Roma, or Round Red tomatoes from their recipes, and shoppers all over the country have been warned to beware.

Salmonella is a foodborne bacteria that can be transmitted through contact with infected animal feces. It's very rarely fatal to healthy human beings, but it can cause death in vulnerable patients such as young children and elderly people, or in people with very weak immune systems - AIDS sufferers or cancer patients undergoing chemotherapy, for example. The Salmonella outbreak in the States is said to have been caused by an uncommon form of bacteria, which has so far caused 57 reported cases of salmonellosis (the disease triggered by the bacteria once it enters the human digestive tract) in New Mexico and Texas and another 30 reported cases in Arizona, Colorado, Idaho, Illinois, Indiana, Kansas, and Utah.

Scientists and public-health experts are not yet aware of how the tomatoes got contaminated, but one thing is for sure: once the bacteria enters the tomato fruit, it is hard to kill without cooking - which is why anyone in the States should treat raw tomatoes with extreme caution. Health officials have stated that cherry tomatoes, grape tomatoes and tomatoes sold with the vine still attached are still safe to eat.

As mentioned before, Salmonella causes salmonellosis, which causes flue-like symptoms such as fever, diarrhea (which may be bloody), nausea, vomiting, and abdominal pain lasting between 3 and 7 days. Most people recover without treatment, although some may get dehydrated due to the constant vomiting and diarrhea and may need to be admitted. In very rare cases, the bacteria can pass from the intestines into the bloodstream, where it causes a much more severe infection that needs rapid antibiotics treatment. Stay tuned for more news on this hot topic - coming soon.