About 2700 McDonald’s outlets in the US are caught up in a food poisoning outbreak that has so far killed one person, hospitalised 10, and sickened 49.

The US Centre for Disease Control and Prevention said that quarter pounders were pulled from a fifth of McDonald’s US stores due to a toxic Escherichia coli (E. coli) infection.

One of the main causes of E. coli infection is under-cooked beef. While the quarter pounders patties are the prime suspect, the company said that freshly slivered onions were also a possible culprit.

American food chains have accidentally poisoned thousands of customers over the past 30 years with E. coli-contaminated food.

Between 1992 and 1993, four people died and more than 700 became ill in Washington, Idaho, California, and Nevada after eating undercooked Jack in the Box restaurant hamburgers contaminated with E. coli.

An investigation by federal regulators changed regulatory practices in the US. But large-scale E. coli fast-food scandals keep occurring every few years.

E. coli: friend and foe

Most strains of E. coli are part of the healthy bacterial flora in your gut. In fact, they’re found in the gut of most warm-blooded animals. They serve a useful purpose.

Some strains can cause illness in humans, including diarrohea, abdominal pain, fever, and sometimes vomiting.

When a foodborne outbreak occurs – such as the quarter pounder poisoning – the E. coli strain to blame produces a toxin known as shiga.

The most common shiga-producing strain is E. coli O157:H7.

In most cases, the illness caused by this strain isn’t pleasant, and can take a week or more to recover from.

However, it can be life-threatening in infants and people with a weakened immune system.

For these people, what starts out as an intestinal illness can progress to pneumonia; meningitis in newborn babies, and inflammation of the gallbladder.

Here’s the tricky part – with an E. coli infection, there is no cure or treatment beyond staying hydrated and rested.

Antibiotics are not advised because they can increase the risk of ‘haemolytic uraemic syndrome’ (HUS).

This is where the shiga toxin damages your red blood cells, causing anaemia and kidney failure.

HUS is a rare but serious illness.

Also, over-the-counter medications for diarrohea aren’t recommended. This is because they can slow down the digestive system, compromising the body’s ability to eliminate the toxins.

How do I get an E. coli infection?

According to Health Direct, E. coli infections arise from:

• Eating contaminated food such as under-cooked minced meat in hamburgers
• Eating or drinking unpasteurised dairy products, such as raw milk
• Eating or drinking fresh juices, and unwashed raw fruit and vegetables
• Swimming, showering or drinking contaminated water, especially in rural areas or swimming pools
• Personal contact with people who are sick, especially with their vomit or faeces
• Direct contact with animals who carry the bacteria.

Symptoms

According to Medical News Today, symptoms of an infection typically appear three to four days after exposure. But they can appear as early as 24 hours or as late as one week later.

These can include:

• Abdominal pain or severe abdominal cramping, often starting suddenly
• Watery diarrohea, beginning a few hours after the pain begins
• Bright red bloody stools around a day later, resulting from the toxin’s damage to the intestines
• Nausea and, in some cases, vomiting
• Fatigue which is usually caused by dehydration and the loss of fluids and electrolytes
• Some people have no noticeable symptoms, but they can spread the infection to others.

Prevention is best

Reduce your chance of E. coli infection by:

• Cooking meat well, especially ground meat
• Drinking pasteurised milk, apple juice, and cider, rather than unpasteurised
• Washing vegetables, especially leafy green ones
• Ensuring that cutlery and crockery are thoroughly washed with warm, soapy water
• Storing meat and non-meat foods separately, and using separate cutting boards
• Washing hands thoroughly with warm water and soap regularly, and especially after using the bathroom, after changing nappies, before and after preparing foods, and after touching animals.

Compared to the US and other countries, E. coli infection is relatively rare in Australia. In 2014, according to Meat and Livestock Australia, there were 0.4 cases of shiga toxin-producing E. coli infections per 100,000 people in Australia. This is much lower than other causes of diarrhoea.

Still, the health costs of these infections in Australia are estimated to be $2.6 million per year.