Published Date: 2011-08-29 12:59:11
Subject: PRO/AH/EDR> Diarrheal shellfish poisoning - Canada (02): mussels
Archive Number: 20110829.2648
DIARRHEAL SHELLFISH POISONING - CANADA (02): MUSSELS
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Mon 29 Aug 2011
Source: The Vancouver Sun [edited]
A shellfish toxin has surfaced in British Columbia (BC) for the 1st
time, poisoning 60 people earlier in August 2011 and raising concerns
in the province's aquaculture industry. Investigators traced the
outbreak to mussels that had been harvested off Cortes Island between
19 Jul 2011 and 2 Aug 2011.
The mussels were shipped to retailers and restaurants in British
Columbia, Alberta, Saskatchewan, Manitoba, and Ontario under 5
different brand names. Investigators determined the mussels had been
contaminated with a biotoxin that causes diarrheal shellfish poisoning
"It was the 1st-ever documented DSP outbreak in western Canada," said
Dr Eleni Galanis, a physician with the BC Centre for Disease Control,
who noted Canada's only other outbreak hit Nova Scotia in the early
1990s. Galanis said DSP is not fatal, but is often accompanied by
diarrhea, nausea, vomiting, abdominal cramps, and chills.
She said the outbreak surprised officials, but that it was quickly
contained through a recall by the Canadian Food Inspection Agency
[CFIA]. "We have a lot of lessons to learn from this unusual
occurrence," said Galanis, who added work is continuing to determine
why it showed up, and what to do if it happens again.
"I don't think we can prevent it from occurring in ocean waters," she
said, but added that CFIA tests for the poison to prevent contaminated
products from making it to consumers.
According to the CFIA website, DSP is one of 3 "biotoxins of concern"
in Canadian waters, the other 2 being responsible for amnesic
shellfish poisoning and paralytic shellfish poisoning.
The presence of the toxin in shellfish is impossible for consumers to
detect. It cannot be seen, smelled, or tasted. It is also not
destroyed by heat, meaning that cooking shellfish does nothing to
reduce chances of becoming ill with DSP. There is no antidote, but
recovery usually begins within 3 days of consuming the biotoxin.
Roberta Stevenson, executive director of the BC Shellfish Growers
Association, said DSP is a common toxin in other parts of the world,
but not here. "We're studying where did it come from (and) is it here
forever?" said Stevenson. "We don't know the answers to those
According to a 2004 paper on marine biotoxins prepared by the UN Food
and Agricultural Organization, Japan, Europe, Chile, Thailand, Canada
(Nova Scotia), and potentially Tasmania and New Zealand have all seen
cases of DSP. But the report notes incidents are increasing and
"frequently reported from new areas."
They are not minor nuisances. In 1984, cases of DSP shut down Sweden's
mussel industry for nearly a year.
[byline: Matthew Robinson]
[Diarrheal shellfish poisoning has few symptoms. Symptoms usually
begin within 30 minutes to 12 hours after eating the contaminated
shellfish. Diarrhea is the most common symptom, but other symptoms
that have been reported to public health officials are nausea,
vomiting, abdominal cramps, and headache.
DSP is often mistaken for Norwalk-like virus disease. It is treated
with rehydration and affected individuals usually recover in 1-2 days.
DSP is most commonly found in the shellfish in Europe and Japan but
can appear anywhere. - Mod.LL
British Columbia and Cortes Island can be located via the
HealthMap/ProMED-mail interactive map at
http://healthmap.org/r/1ba_. - Sr.Tech.Ed.MJ]