Researchers say current guidance on excluding children with E. coli from childcare does not need to be changed despite the recording of more non-O157 cases.

According to the researchers, excluding children with Shiga toxin-producing E. coli (STEC) until the pathogen is microbiologically clear disrupts families, education, and earnings.

Scientists examined shedding duration by serotype and transmission risk to guide exclusion advice.

They investigated STEC patients younger than 6 years old, living in England, and attending childcare, with diarrhea onset or sample date from March 2018 to March 2022. Duration of shedding was the interval between the date of onset or the date of the first positive specimen and the earliest available negative specimen date. Childcare settings include nurseries, preschools, primary schools, and childminders/nannies.

In England, children infected with presumptive STEC O157 and non-O157 exhibiting virulence profiles associated with the potential to cause hemolytic uremic syndrome (HUS) are excluded until two consecutive negative clearance fecal specimens, taken at least 24 hours apart, are obtained.

A month for STEC clearance
There were 1,033 confirmed cases of STEC in children. Of the 367 patients who attended childcare, 243 were STEC O157 and 124 non-O157. O26:H11 and O145:H28 were the most common, according to the study published in the journal Epidemiology and Infection.  

The median age was 3, and 185 children were male. Of 274 patients with information on ethnicity, 218 were white, 25 were Asian or Asian British, nine were black or black British, and 22 were mixed or other.

Symptoms included diarrhea for 315 of 330 patients wher information was known and/or bloody diarrhea for 141 of 301 cases. 37 patients developed HUS, and two died.

The median shedding duration was 32 days, with no significant difference between O157 and non-O157. Of these, 148 were shedding for up to 30 days, 137 for between 31 and 60 days, 24 for 60 to 100 days, and six for more than 100 days. All cases that shed for over 100 days were symptomatic but did not develop HUS. Four were female, and three were aged 1 to 2. Younger children shed for longer, and the duration of shedding was reduced by 17 percent among cases with bloody diarrhea.

Scientists found that a quarter of children took more than six weeks to achieve clearance, with a maximum period of 142 days.

Exclusion periods and impact
More than 350 patients were excluded from childcare settings for a median duration of 29 days. The exclusion periods were generally shorter than required, based on symptom onset and microbiological clearance. The median duration of actual exclusion was 31 days, nearly 10 days shorter than the median necessary exclusion.

In 261 cases, the period of actual exclusion and duration of shedding were available. Thirty-four patients were excluded for at least two weeks longer than their duration of shedding. Scientists said this was due to a delay in taking a second sample following an initial negative.

The most common difficulties in implementing exclusion were parental dissatisfaction, financial losses, and working parents. Effective communication was the most frequently reported strategy for managing these challenges. More work is ongoing to understand the impact of exclusion on children and parents.

The study highlighted a median delay of 10 days from symptom onset to formal exclusion by public health staff. 

Of excluded patients with available information, 67 of 288 returned to childcare prior to clearance. The most common reasons for this were reassessment of risk, late exclusion, and the family unknowingly or deliberately sending children back.

More than half of 313 patients went to childcare while infectious. This was usually for a short time, but five attended for more than two weeks while the patient was infectious.

“Our findings suggest that current guidance regarding exclusion and supervised return of prolonged shedders in England remains valid despite recent changes to STEC epidemiology,” said researchers.