According to researchers, the rate of severe complications after E. coli infection has remained mainly stable over several years but went up in Ireland.

Hemolytic uremic syndrome (HUS) is a rare but severe complication associated with E. coli infections that causes kidney failure.

Previous figures showed no notable changes in England, Wales, or Northern Ireland. In Ireland, however, the incidence was estimated to have increased three-fold. The reasons for this are unknown but coincide with a rise in Shiga toxin-producing E. coli (STEC) infections.

HUS remains a significant public health concern four decades since its emergence, with no reduction in incidence seen over time. However, the number of deaths has fallen, said scientists.

The study, published in Epidemiology and Infection, provided estimates of pediatric HUS incidence in England, Wales, Northern Ireland, and the Republic of Ireland.

Patient and E. coli details

Between October 2011 and 2014, 288 HUS patients were included in the study, of which 256 were diagnosed as typical HUS. Incidence was highest in Ireland. 

Most typical HUS cases were 1 to 4 years old and female. In Ireland, incidence was highest in infants younger than 1 year.

Clinical symptoms included diarrhea and bloody diarrhea, abdominal pain, and fever. The median time from onset of diarrheal symptoms to hospital admission or HUS diagnosis was six days.

64 cases were admitted to the pediatric intensive care unit (PICU).

Clinicians reported 177 cases had made a seemingly full recovery when a questionnaire was completed. Kidney damage, hypertension, and neurological impairment were the most common complications at discharge. While only one death was recorded, other issues were relatively frequent, with 69 percent of cases fully recovering.

wher STEC was isolated, 141 strains were E. coli O157, and 11 were E. coli O26.

For E. coli O157, 137 isolates were phage-typed; the most frequent type was PT21/28. wher toxin type was available, the main one was Stx2 only, with just eight strains that were Stx1+2.

Surveillance system sensitivity

The British Paediatric Surveillance Unit (BPSU) deals with rare childhood illnesses in the UK and Ireland. Two previous studies on pediatric HUS in the UK and Ireland have been conducted from 1985 to 1988 and from 1997 to 2001.

In 2011 to 2014, England had 228 cases, Wales had 10, and Northern Ireland had nine. From 1997 to 2001, England had 287 cases, Wales had 17, and Northern Ireland had 16. Cases rose in the Republic of Ireland from 30 to 41.

A gap in confirmation of culture-positive STEC via fecal samples restricts UKHSA’s ability to detect outbreaks, limits opportunities to implement health protection measures, and reduces the ability to determine the true burden of STEC and HUS by different serogroups, said scientists.

A comparison of the BPSU cases to national surveillance system data indicated an additional 166 HUS cases were captured through the study. Many were known as STEC patients but not confirmed as HUS cases. Some HUS cases were reported in surveillance systems but not through the BPSU study.

“Our study highlighted the limitations of the current surveillance system for STEC for monitoring the clinical burden of STEC and capturing HUS cases. Due to the high morbidity of HUS in children, the continued monitoring and control of STEC remains a high public health priority,” said researchers.

They added more studies are needed to assess whether certain antibiotics may reduce the severity and length of symptoms for STEC patients.