What is EHEC?
Enterohaemorrhagic E. coli, or EHEC, is a type of Escherichia coli (E. coli). E. coli is a bacteria that is common in the guts of humans and other warm blooded animals. While most forms of E. coli are harmless, there are a few strains that can cause very serious foodborne illness. EHEC is one of the types that can cause serious illness. EHEC were first identified as a public health risk in the early 1980s and one of the factors responsible for the illness caused by EHEC is the ability of these organisms to produce a toxin that is very similar to the toxin produced by Shigella (the causative agent of the illness dysentery). Note that other terms for this same group of bacteria include Shiga Toxin-producing E. Coli (STEC) or verocytotoxic E. coli (VTEC). These all generally refer to the same group of microorganisms.
Symptoms of the diseases caused by EHEC include abdominal cramps and diarrhoea that may in some cases be bloody diarrhoea (hemorrhagic colitis). Fever and vomiting may also occur. The incubation period can range from three to eight days. Most patients recover within 10 days. However in a small proportion of patients, particularly young children and the elderly, infection with EHEC can lead to a far more serious illness. The infection may lead to a life-threatening disease called hemolytic uremic syndrome (HUS). HUS is characterized by acute kidney failure. It is estimated that up to 10% of patients with EHEC infection may develop HUS. HUS has a fatality rate that ranged from 3% to 5%. Overall, HUS is the most common cause of acute renal failure in young children. It can cause neurological complications (such as seizure, stroke and coma) in 25% of HUS patients. In those that survive HUS about 50% of them can experience chronic long-term renal problems. (Source: World Health Organization)
Not only is the illness caused by this type of organism very serious, the number of organisms needed to make an individual ill is very small. The U.S. Food and Drug Administration has stated that ingesting as few as 10 bacteria to make an individual ill (Source: FDA Bad Bug Book) so preventing contamination of food with this organism is critical to controlling the illness.
How does EHEC spread?
EHEC live in the guts of ruminant animals, including cattle, goats, sheep, deer, and elk. The major source for human illnesses is food that has been contaminated with feces from cattle. Although, other kinds of animals including pigs and birds sometimes pick up EHEC from the environment and may spread it. Infections start when people swallow EHEC—in other words, when people get tiny (usually invisible) amounts of human or animal feces in their mouths. Unfortunately, this happens more often than we would like to think about. (Source: U.S. CDC
A wide variety of foods have been linked to outbreaks of EHEC. These include undercooked ground beef, unpasteurized apple cider, and a variety of dairy products. Also implicated more and more commonly are raw fruits and vegetables such as lettuce, peppers, spinach, sprouts, and tomatoes.
Although this is a foodborne illness, it is possible to spread this illness person-to-person, particularly if good hand hygiene practices are not followed. An asymptomatic carrier state has been reported, where individuals show no signs of disease but are capable of infecting others. The duration of excretion of EHEC is about one week or less in adults, but can be longer in children. EHEC can also be found on surfaces and in water that is contaminated with feces.
What do I need to know to help prevent the spread of EHEC?
The CDC and WHO have 5 recommendations for preventing the spread of EHEC, summarized here:
1. First on both lists is to clean and disinfect your hands. It is absolutely critical to wash hands after going to the bathroom, after handling raw produce or meat, and before handling or eating any food. Hand disinfection provides a better kill of bacteria than hand washing and is thus preferred over hand washing at any time. Hand washing remains mandatory for removing visible soil from hands. Due to the aggresive nature of this bacteria, if you are in contact with anyone displaying the symptoms of this illness, it is essential to clean your hands after contact with an ill individual.
2. Prevent cross contamination by separating raw and cooked food and by washing produce thoroughly and washing and disinfecting food contact surfaces and equipment used for food processing and preparation.
3. Cook food thoroughly. Heating to 70oC (160oF) will inactivate EHEC. When cooking food it is important to use a food thermometer as color is not always a good indicator of cooking temperatures.
4. Avoid unsafe water. Always make sure that the water you are using for cooking and cleaning is safe and potable.
5. Store food at a safe temperature. Keep cold foods cold (below 4o
C) and hot foods hot (above 65o
(Sources: WHO, CDC)