National researchers are testing whether the bacteria that led to unusual cholera infections on Vancouver Island last week are associated with cholera outbreaks seen in other parts of the world.
There are several types of bacteria that can lead to vibrio cholera infections and the testing being done at the Public Health Agency of Canada’s National Microbiology Laboratory should produce answers within the week, said Shannon Waters, a medical health officer with Island Health Authority.
“In the meantime, this is a unique situation that we wanted to let people know about,” Waters said Sunday on the heels of the closure of a traditional fishery believed connected to the infections.
The public health agency has a mandate to prevent and control infectious diseases and prepare for and respond to public health emergencies, among other things.
There have been eight main cholera pandemics in the past two centuries, according to the health agency. The disease is most common in tropical and subtropical areas and most cases are in the Indian subcontinent and Africa, according to the health agency.
More than 100,000 people die from cholera around the world each year, the U.S. Centers for Disease Control said.
Cholera killed at least 20,000 people in Canada in the 1800s, but the disease has largely been eradicated in this country.
The Ontario Ministry of Health says an average of one case per year is reported in that province, but all of those individuals were exposed to cholera in a country where the disease is endemic.
Cholera tends to be spread by consuming water contaminated with infectious feces, but epidemics caused by infectious raw fish and seafood have also been reported, according to the health agency. The disease incubates for a few hours to several days.
The cases in B.C. have been traced back to consumption of herring spawn, “a treasured traditional food source for First Nations throughout Vancouver Island,” Waters said.
The harvest in the area where the infections took place — a stretch of coastal waters from French Creek to Qualicum Bay, near Nanaimo — had just happened, Waters said.
On Friday, the Department of Fisheries and Oceans shut down three fishery management areas on the west coast of the island to hand-picking of herring eggs. That closure was the latest in an area with several existing sanitary closures for shellfish harvest, according to the fisheries ministry. Marine water sampling from the area earlier this month had shown elevated fecal coliform levels.
Asked whether the outbreak was caused by unsanitary waters in the area, Waters said that’s not known.
“We haven’t seen this before,” she said. “People have harvested herring eggs (in the area) and eaten them for generations and generations. This is new and we’re looking into, but it certainly makes us wonder a number of things. I think the marine environment, especially for First Nations, but for all of us, is a treasured resource of food, recreation and travel and it’s under a lot of pressure from sewage, boat traffic (and) rising temperatures and our health is connected to it.”
Island health is working with the First Nations Health Authority and the B.C. Centre for Disease Control to learn more, she said. Marine water, leftover food and clinical samples are all being tested, according to the fisheries ministry.
Waters stressed that the cholera concerns only pertain to the areas now closed to herring spawn fishing.
“Right now there’s no reason for people harvesting eggs from other areas to be concerned about eating them. We’ve had no reported cases of illnesses from other areas,” she said.
The cases are connected only to herring eggs laid in the marine environment, and not to roe harvested directly from the fish, as the First Nations Health Authority pointed out in a recent news release.
All three people confirmed infected are First Nations individuals. A spokesman at the First Nations health authority could not confirm from which First Nations the affected individuals were from. There are a trio of nations based near the areas subject to the closures.
— With files from The Canadian Press