Just as detectives conduct thorough investigations during criminal cases, public health scientists and investigators in Alberta are employing similar tactics, interviewing individuals, amassing proof, and waiting on laboratory test results, all in a bid to unravel the origin of a widespread E. coli outbreak across several daycare institutions.
The crux of this scientific pursuit resembles that of a criminal investigation, posits Siyun Wang, a seasoned associate professor of food safety engineering at the University of British Columbia. The most explicit link, or the proverbial smoking gun, occurs when the exact DNA fingerprinting discovered at the scene of the outbreak is a precise match to the suspect.
However, achieving a definitive conclusion can be arduous, say Wang and other renowned experts alike. As of last Tuesday, the bacterial infection has been substantiated by lab-confirmation in no less than 264 instances ever since the outbreak was officially reported on September 4, in 11 Calgary daycares. Data reveals that 25 patients have been hospitalised, with 22 laying victim to hemolytic uremic syndrome – a complication that adversely affects the blood and kidneys – while six individuals are currently on dialysis at Alberta Children’s Hospital.
The chief medical officer of health in Alberta speculates that the contaminations are most likely due to a central kitchen catering to the daycare centres. Yet digging deep to uncover the source of E. coli outbreaks can be complex, and don’t always secure a firm cause, opines Timothy Sly, an epidemiologist and emeritus professor at Toronto Metropolitan University.
Continually, the root cause of such predicaments leads back to a singular origin: cattle. E. coli outbreaks borne of water contamination usually have their source tainted by runoff from cattle feedlots. Similarly, E. coli outbreaks related to romaine lettuce occur since the vegetable is cultured adjacent to where cattle feed. Even apple juice outbreaks have been traced back to cattle meandering through orchards. However, as per Sly, it’s often directly attributed to undercooked beef, as he suspects may be the case in Calgary.
Getting to the bottom of such mysteries is far from easy, admits Sly. Investigators must examine food handlers, the afflicted individuals, and indeed the food itself. Sly points out that swabs would have been taken from individuals preparing the food for the daycares and those who fell ill with the E. coli infection. Thereafter, laboratory professionals attempt to connect genome markers to identify the same strain, and subsequently, food specimens from the kitchen are tested for a match.
Unraveling the actual source of the E. coli requires isolating the strain of the outbreak from one type of food item that was served, explains Michael Gaenzle, professor and Canada Research Chair in the University of Alberta’s Department of Agricultural, Life, and Environmental Sciences.
The shift in focus towards contaminated food is supported by the notion that the size and scale of the Calgary outbreak make it unlikely that the main cause was cross-contamination or cockroaches found in the kitchen, according to Gaenzle. The additional observation that leafy greens such as lettuce and spinach are less likely plausible culprits since other consumers of these produce would have also been afflicted suggests that investigators will probably discover a link to undercooked beef being served.
The investigations themselves may span several weeks, with Gaenzle sharing that folks from Alberta Health Services have indicated that laboratories are inundated, and a clear-cut answer matching food samples to the infected individuals may potentially remain elusive, despite their best efforts.
Gaenzle argues the outbreak is indicative of a need for improved oversight of food service companies, particularly those supplying meals to daycare facilities, underpinning his claim by referring to a recent report that details health violations including improper sanitation, presence of live cockroaches and flawed food handling at the central kitchen. Gaenzle concludes that the takeaway lesson from this unfortunate incident might be a simple, unadorned truth: ‘humans make mistakes’.