Scotland has updated guidance for the public health management of E. coli O157 and other Shiga toxin-producing (STEC) infections.

The Scottish Health Protection Network (SHPN) document replaces the 2013 guidance. It is designed to help in response to E. coli cases by health protection teams and environmental health departments.

Health Protection Scotland (HPS) has a surveillance system in collaboration with the Scottish E. coli O157/STEC Reference Laboratory (SERL). Reports of STEC O157 infection increased in the mid-1990s and rates remain high compared with other UK and European countries.

The number of STEC O157 infections in the country has remained steady in the last 10 years, with an average of 220 per year. Of the STEC cases in 2016, 15 percent travelled outside the UK in the 14 days prior to onset of symptoms.

There has been an increase in the number of non-O157 STEC infections, partially due to a change in referral pattern for diagnostic testing. Over the past five years, non-O157 infections have accounted for an average of 20 percent of STEC cases.

Phage type (PT) 21/28 and PT 8 are the most common, making up an average of 39 percent and 23 percent respectively of STEC O157 cases during the past five years.

For cases between 2012 and 2016, the ages ranged from under one to over 90 years. Children under 16 accounted for 33 percent of infections with the highest rate in the zero to four year old age group.

Numbers tend to be higher in summer months. Approximately 60 percent of cases in Scotland in 2012 to 2016 were reported between mid-May to the end of September.

In 2015 and 2016, 36 percent of STEC cases were admitted to hospital for at least one night during their illness and 9 percent of cases developed hemolytic uremic syndrome between 1999 and 2008.

From 2008 to 2017, 18 STEC outbreaks were reported in Scotland where the main mode of transmission was foodborne or multiple but including a foodborne component. Suspected foods were identified in 10 outbreaks; meat/meat products in five, salad leaves in two, vegetables in one, and other foods in two.

There is increasing evidence of the disease burden of E. coli O157 Shiga-toxin negative organisms. These isolates are frequently sorbitol-fermenting and more difficult to detect by current diagnostic lab methods.

STEC are capable of producing the toxins Shiga toxin 1 (stx1) and Shiga toxin 2 (stx2). Symptoms of STEC infection range from asymptomatic infection, mild non-bloody diarrhea, to bloody diarrhea, abdominal pain and occasionally fever. The incubation period for diarrheal illness caused by STEC O157 infection is usually three to four days, with a range of one to ten days.

Approximately, 10 to 15 percent of people infected with STEC go onto develop hemolytic uremic syndrome (HUS). Children under 15 years of age and adults over 65 years are more likely than other age groups to develop STEC-related HUS, particularly children under five years.

STEC was first associated with minced (ground) beef products such as beef burgers but pork, mutton and cooked meats have all caused outbreaks. Unpasteurized milk products, such as cheese, and pasteurized items where there has been a failure in the process or post-pasteurization contamination as well as lettuce and berries have been linked to outbreaks.

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