A few months a child died following an outbreak of E. coli O157 in Scotland. The child was among 20 confirmed cases of infection, detected in July, of which 11 received hospital treatment.
Epidemiological investigations identified a blue cheese as the most likely cause of the outbreak. The artisan Scottish cheese is made from unpasteurised cow’s milk. The outbreak is being investigated by the multi-agency Incident Management Team (IMT) chaired by Health Protection Scotland that includes EHOs from South Lanarkshire Council where the suspect food business operator is based.
So what is E.coli 0157 and how does it cause illness?
Escherichia coli (E. coli) is a type of bacteria common in human and animal intestines and forms part of the normal gut flora. It does not cause illness. Carriage is dynamic and prevalence in herds and flocks is very variable, some animals (supershedders) excrete millions per gram of faeces.
Disease–causing strains of E. coli O157 as in the above case produce Shiga toxin type 2. The classic symptoms linked to this strain, include severe stomach cramps, vomiting and diarrhoea that may be bloody. The symptoms usually last up to seven days if there are no complications, but some infections can be severe and may even be life threatening.
A life-threatening complication called haemolytic uremic syndrome (HUS) may develop in 5-10% of people infected with a toxin-producing form of E. coli. This is a severe kidney-related complication that may, in extreme cases, lead to renal failure and the need for renal replacement therapy.
People can become infected through several routes including the consumption of contaminated foods, direct contact with animals, contact with animal faeces and person-to-person spread both in families and institutions. In relation to food consumption, dairy products such as milk, cheese, butter, yoghurt were the source in 12% of cases.
E. coli O157 does not form spores, but is tough, and can survive on surfaces for days. No control measures that can reduce carriage levels in cattle and sheep are available. So E. coli O157 and preventing its ‘manure to mouth’ transmission is a very big challenge for EHPs – and will remain so for years to come.
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