I get asked about the noroviruses more than just about any other of our Microbial Overlords. Pretty much daily, in fact. They are a nightmare to control for a number of reasons I go into here and I’ve just written a piece for one of the trade mags on the same subject. I’ll post a link when it’s published.
With any outbreak it can be incredibly difficult – often nigh-on impossible – to pin down precisely where it came from. If an organism is exclusively foodborne or has a particular mode of transmission you might have a slightly better chance of finding that smoking gun – but this is rarely the case for the noroviruses. Low infectious dose, indiscriminate, tough to kill.
When you examine the natural history of an outbreak often you’re often left balancing probabilities and not just because infection prevention and control isn’t the natural home of evidence-based practice. If everything is squeaky-clean in terms of processes, procedures, adherence and compliance all you can say is that everything reasonably possible was in place to minimise risk. But if – for example – the kitchens are minging and they’re wiping their arses on the salad you know where to start to look for trouble.
I read with interest some reports from the CDC about a recent cruise ship outbreak and the industry’s response. Logical Fallacy Bingo time again: unsurprisingly the CDC could not pin down the precise cause of the outbreak so the cruise industry blames the passengers.
But absence of evidence is not evidence of absence. Just because the CDC didn’t prove a causal link doesn’t mean the cruise line was blameless. Their trade association reckons that you’re less likely to get norovirus on a ship: the industry is scrupulous in its reporting and there were only 1,238 cases in 21m passengers last year. But that’s just Utter, Utter Bollocks (µ²B). These data apply to ships that visit a US port during their voyage and where more than 2% of the passengers present with acute gastroenteritis. So you can automatically almost halve the numbers of punters immediately as their data refer to global PAX, not just those on cruises under CDC scrutiny.
Moreover, if the report on the Norwegian Star is representative it’s a pretty piss-poor indictment of the industry. If you look at the detail of the report you will see many crew members worked while suffering from acute gastrointestinal illnesses and then went to the ship’s infirmary after working. Plus the cruise line failed to properly document and log many of the cases and report them to the CDC as they are required to. The number of sick passengers went over 2% (the point at which they legally need to get the CDC involved) but they didn’t. As if that all wasn’t bad enough, cabin mates of sick staff weren’t interviewed – another legal requirement ignored.
So, cruise line operators, before you blame your customers for getting sick on your watch get your house in order. Once norovirus gets into a business – especially a food business or one with an isolated cohort of people (like a cruise ship, school, nursing home or hospital) it is extremely difficult to shift. I know. Been there, done it, got the t-shirt.
But just because you don’t get taken to court doesn’t mean you’re blameless and it’s your customers’ fault. Especially when your basic hygiene procedures are found to be so seriously lacking.
Want to know more about the noroviruses? Groovy free poster for your office available here.