Shiga toxin-producing Escherichia coli infection

Causative agent

Escherichia coli (E. coli) is a bacterium that is commonly found in the gut of humans and warm-blooded animals. Most strains of E. coli are harmless. Some strains, however, such as Shiga toxin-producing E. coli (STEC), can produce powerful toxins and cause severe foodborne disease. The most recognised serogroup of STEC is E.coli O157:H7. Other strains e.g. E. coli O104:H4 may also cause serious disease and outbreaks.

Clinical features

Symptoms of STEC infection include abdominal cramps and diarrhoea that may in some cases progress to bloody diarrhoea. Fever and vomiting may also occur. In serious cases, the infection may lead to a life-threatening complication named haemolytic uraemic syndrome (HUS) which is a type of kidney failure. People of any age can become infected. Very young children and the elderly are more likely to develop severe illness, but even healthy older children and adults can become seriously ill.

Mode of transmission

STEC is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products, contaminated fruits and vegetables, unpasteurised dairy products, contaminated water, and direct contact with animals or their environment. Direct person-to-person transmission through the faecal-oral route can also occur. Exposure to recreational water sources like swimming in contaminated water is also a route of infection.

Incubation period

Can range from about 2 – 10 days, usually 3 – 4 days.

Management

Clinical management for STEC infection is usually supportive. Fluid and electrolyte replacement is important when there is severe diarrhoea. Patients with kidney failure may require specific supportive treatment and transfusion.

Prevention

Preventive measures for STEC infection are similar to those recommended for other foodborne diseases. Public are urged to observe good personal and food hygiene:

• Adopt the 5 Keys to Food Safety in handling food, i.e. Choose (Choose safe raw materials); Clean (Keep hands and utensils clean); Separate (Separate raw and cooked food); Cook (Cook thoroughly); and Safe Temperature (Keep food at safe temperature) to prevent foodborne diseases.
• Wash hands properly with liquid soap and water before handling food, after handling raw meat or poultry and before eating, and after going to toilet or changing diapers.
• Cook food and boil water thoroughly before consumption. When cooking or reheating, the core temperature of the food should reach at least 75℃.
• Avoid consumption of unpasteurised milk or undercooked food.
• Consult your doctor immediately if you have symptoms of STEC infection, particularly bloody diarrhoea.