A new analysis applied to Northern Europe’s deadly 2011 E. coli O101:H4 outbreak calls the official assumption that the pathogen, spread by “its natural origin,” is “questionable.” Further, the Serbian-German researchers say that neither accidental nor deliberate spreading of the pathogen can be ruled out as the cause.
Based on their findings, the researchers are calling on the European Union to conduct further epidemiological, microbiological and forensic investigations into the incident. In other words, they want to re-open the case. Their analysis is found in the European Journal of Public Health.
The 2011 outbreak killed 53 people in an event that pushed local medical facilities, mostly in Germany, to their limits and tested the European Union’s Early Warning and Outbreak Response System. It began on May 1, 2011, and peaked around May 21-22, 2011. The Robert Koch Institute in Berlin declared the outbreak over on July 26, 2011.
Until now, the EU’S official explanation for the sudden and severe outbreak was the introduction of fenugreek sprouts from seeds imported from Egypt contaminated with the fairly new O104:H4 E. coli strain through normal commercial transactions.
However, that explanation has always been a little murky because the rare E. coli strain was not found in places that might have resulted in a more definite conclusion.
“Assessing the likelihood of criminal or terroristic act behind a UEE ( unusual epidemiological event) is of great public health importance, as it may be helpful in improved response and the resolution of epidemics,” the Serbian-German researchers write.
The research teams used “epidemiological assessment tools” to differentiate between natural, accidental and deliberate epidemics. Two are “scoring models” and the third is based on “typical clues to a deliberate epidemic without a numerical ponderation.” The models and scoring used are found in detail in the team’s report.
They point out that these techniques are not new, having been used to investigate the 1984 Salmonellosis outbreak in The Dalles, OR; the 1996 shigellosis outbreak in Dallas, TX; the 2001 anthrax cases in the U.S., the 1979 anthrax cases in Sverdlovsk, Soviet Union; the 1999 West Nile Virus outbreak in New York City, and the 1999 tularemia cases in Kosovo.
The team is the first to apply the facts of the 2011 outbreak to these investigative models, and they’ve concluded that the possibilities that the pathogen was introduced accidentally or intentionally into the food chain are theories that cannot be discarded.
“From the onset of the outbreak, there was confusion about the source and mode of transmission. On 10 June 2011, German authorities announced contaminated sprouts of one particular charge of fenugreek seeds imported from Egypt in 2009 as the most probable culprit source of this outbreak,” the new report states. “The conclusions of the EHEC Task Force were accepted by the European Food Safety Agency (EFSA) who supported the investigations. However, although it might have been expected, no data or evidence on similar outbreaks in Egypt caused by the new German EHEC O104:H4 strain and on the origin of the suspected seeds were available.
“Raw vegetables have shown up in the past years as an important transmission factor of enteric pathogens, which may infect or persist dormant in a ‘viable but non-culturable’ state in/on plants and their seeds. Until the (German) outbreak, sprouts were known as a possible but rare vehicle in some outbreaks caused by enteric pathogens,” the report continues.
“The high environmental persistence of E. coli O157:H7 on raw nut shells imported from the USA was a likely cause of a multi-provincial E. coli O157:H7 outbreak in Canada in April 2011. The EFSA therefore some years ago warned that raw sprouts may be contaminated under poor hygienic conditions and become a health risk. However, neither the fenugreek seeds nor remains of the suspected sprout lots distributed in Germany were positive for EHEC O104:H4. The (outbreak) demonstrates the high impact of awareness of practitioners and clinicians to detect and notify early even ‘small clusters’ of a disease as an alerting clue of a developing outbreak requiring immediate microbiological and epidemiological investigations of the possible causes.
“In conclusion, after using three published models for the analysis of UEE, a generally accepted assumption the (outbreak) in 2011 was a natural one may not be accepted without reserve. This is the first time ever that an E. coli O104:H4 pathotype of a high virulence suddenly emerged, which may indicate an unnatural phenomenon. In the interest of the safety and biosecurity of food chains, further epidemiological, microbiological and forensic analyses are needed for a definite answer on a question concerning (the outbreak) : ‘What was it, actually?.'”
Funding for the study was provided by the Serbian Ministry of Education.© Food Safety News