No country wants to learn an E. coli serotype not previously associated much with human illness is making people sick — again. Especially when it wasn’t ever known to be a resident strain in the country until three years ago.
The new reality in the United Kingdom is the O55:H7 serotype, which scientists say is “a recent precursor to the virulent enterohemorrhagic E. coli O157: H7.” It’s E. coli O157:H7 and six other Shiga-toxin producing Escherichia coli serotypes known as O26, O45, O103, O111, O121, and O145 that cause foodborne outbreaks.
USDA’s Food Safety and Inspection Service (FSIS) declared those six strains as adulterants in meat. Previously, only E. coli O157:H7 was on the adulterants list and targeted for verification testing.
FSIS does not currently ban E. coli O55, which is making people sick again in the United Kingdom.
Public Health England (PHE), which has a short, but a somewhat rocky history of with O55, acknowledged late last week that it was again investigating “a confirmed case of E coli O55” and reported that case was “potentially linked” to other current E coli cases involving children.
PHE’s first round with the rare E. coli O55 strain was an outbreak in the Dorset area that began in July 2014 and caused 31 illnesses before it ended in November 2015.
No source was found, and PHE was under fire for less-than-transparent communications with the victims and their families. Parents of two of the child victims were especially critical, saying they were “disappointed and frustrated” by PHE’s controlled the information. The UK’s Food Standards Agency was also involved in the O55 outbreak investigation, which came to naught by the time it wrapped up its investigation in March 2016.
The case of a 19-year old woman who first experienced symptoms of diarrhea and abdominal pain on Sept. 16, 2017, confirms O55 is back. Her kidneys failed from hemolytic uremic syndrome (HUS). She was last reported in critical condition at St Bartholomew’s Hospital in London.
Since the first O55 outbreak, the UK’s Animal Plant and Health Agency has developed a microscopic test for identifying the rare strain in both people and animals. The investigation of the first outbreak found that O55 also affected cats. The only experience PHE had with O55 before 2014 was when someone was infected with it during travel and returned to the UK.
The outbreak strain for the first documented British outbreak of O55 had a Shiga toxin (Stx) subtype 2a associated with elevated risk of HUS, according to a report in the current issue of Eurosurveillance.
“The strain had not previously been isolated from humans or animals in England,” according to the report. “The only epidemiological link was living in or having close links to two areas in Dorset.”
The outbreak in Dorset County, England, resulted in 13 HUS cases among the 31 total confirmed cases.
The report authors, who were involved in the 2014-2015 investigation, say whole genome sequencing (WGS) shows those who became ill were infected with similar strains.
“There was little evidence to support the hypotheses of contaminated food items or drinking water or a specific recreational/environmental exposure,” the authors wrote. “Given this, and the geographical clustering around two areas of Dorset, the third hypothesis of a local endemic zoonotic infection acquired in humans from infected pets and directly from the environment seems the most likely cause of this outbreak.”
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