Parasite in Polluted Welsh River Attacks Swimmer

Here’s a piece of trivia for you: the most common intestinal parasite in the United States is Giardia duodenalis. A robust little microorganism, Giardia duodenalis prefers to shack up in the small intestine of humans and animals. Once infected, the host will have to endure a nasty nauseous and diarrheal condition – for most humans, a brief one, although many smaller mammals aren’t so lucky. Indeed, most Americans blame one of these mammals, the beaver, for giving us the parasite in the first place. Since Giardia duodenalis is capable of sticking it out without a host for months in cold water, it’s believed that beavers – so common in North America – can contaminate streams, lakes and pools. This is why giardiasis, the condition produced by Giardia duodenalis, is better known as ‘beaver fever’ in the States.  

How, then, did David Deveney contract a serious case of ‘beaver fever’ from the Welsh stretch of the River Severn, from which beavers have been absent for almost eight centuries? 

Safety Not Guaranteed 

In the winter of 2020, David Deveney, an HGV technician from Gloucestershire, was leading would-be lifeboat volunteers through exiting and entering drills at the mouth of the River Wye – a routine occurrence for Deveney, who volunteers for the Severn Area Rescue Association himself in his free time. As usual, the lesson took around two hours, all in all. Everything had gone off without a hitch. But later, as he settled down to sleep, Deveney was suddenly wracked by intense nausea.  

The search-and-rescue volunteer was laid up in bed for three days, hoping against hope that this was some routine illness, before presenting himself to his GP. Their professional opinion shattered this comforting delusion – and forced David to confront the shocking state of British waterways. Since Deveny had not eaten at any restaurants or knowingly consumed un-treated water in the 48 hours before the onset of his condition, David Deveney’s GP considered giardiasis, or ‘beaver fever’, to be the most likely diagnosis, although, of course, they could not be completely certain.  

Indelicate Matter 

The illness ran its grisly course over three-and-a-half weeks, leaving Deveney out of pocket and in excruciating pain. “I’ve been through physical hell with the after-effects of the contaminated water,” the volunteer rescuer told BBC Wales. It’s a grim tale, and it prompts a question as to how exactly Giardia duodenalis found its way into David’s system. 

In general, epidemiological research into the behaviour of the parasite reveals two principal vectors of transmission – and beavers pottering around in streams are not one of them. The chief pathological pathway for Giardia duodenalis is untreated drinking water, but the next likeliest option is the ingestion of matter contaminated by human sewage. Worryingly, Public Health Wales reportedly told David Deveney that there was an “80% chance” that his personal Giardia duodenalis took the latter route to his small intestine.  

The news was a wake-up call for Deveney, but it wasn’t a shock. “We’re always on the lookout,” he responded. “You see brown, you see toilet paper in some parts of it, condoms, sometimes sanitary products.” (If you’d like an in-depth exploration about the causes and solutions to the proliferation of personal care products in British rivers, click through to reveal an academic article on the topic.)  

Today, David Deveney is back at work, having thankfully recovered. Tomorrow, however, who knows who might fall sick?