Study suggests drinking water may be source of winter norovirus outbreaks
Source of Article: http://canadianpress.google.com/article/ALeqM5geABCRcDUrTuqi2KxRm71laVqmxQ
The research, which looked for patterns that might explain norovirus outbreaks in
The findings suggest that under certain environmental conditions, noroviruses from human sewage may proliferate in bodies of water that are used both as municipal water sources and sewage treatment outlets, eventually finding their way back into human gastrointestinal tracts through drinking water.
"It's not the time of year when people are swimming or using the
beaches or anything like that," said lead author Amy Greer, a
post-doctoral fellow working on the ecology and evolution of infectious
diseases at the Research Institute of the Hospital for Sick Children in
"So the question is, if we have a reservoir in the lake of environmental virus, essentially how is it that people are coming in contact with it? . . . Our findings may suggest that that (drinking water) might be something that we should look at."
The research was presented Sunday at a joint scientific conference of the
American Society for Microbiology and the Infectious Diseases Society of
The findings are preliminary, Greer cautioned in an interview from
She and two colleagues from the Ontario Public Health Laboratory and
They studied 253 norovirus outbreaks that were investigated by the Ontario Central Public Health Laboratory between Nov. 10, 2005 and March 6, 2008, looking to see whether precipitation levels, air temperature, and other environment conditions seemed to coincide with the outbreaks.
The only factors that seemed to be linked to outbreaks were water temperatures
The researchers did not take and test water samples for norovirus levels, so they do not have direct evidence
with which to back up their theory. They hope, however, that scientists in
The researchers also only looked at outbreaks in
Greer noted, though, that there is some laboratory evidence of this virus
Noroviruses trigger explosive and debilitating bouts of vomiting and diarrhea. The viruses are transmitted by what's known as the fecal-oral route. People pick up viruses on their hands - for instance in a bathroom recently used by an infected person - and then transfer the germ to their mouths by handling food or putting fingers into the mouth.
While these outbreaks can occur at any time of the year, they most commonly happen in winter month - which is why norovirus infection was formerly called "winter vomiting disease."
It has been thought that human dynamics are behind the seasonal pattern of these outbreaks.
"It's essentially for many of the same reasons that influenza tends
to be seasonal," said Dr. Aron Hall, a norovirus expert with the U.S. Centers for Disease
"People are typically indoors more and therefore have more contact with one another. They're in closer contact with one another. ... And so the more humans you pack together in a smaller area over a longer period of time the more likely you are to have infection."
According to the CDC, most norovirus outbreaks are trigger by contamination of food by an infected food handler.
The CDC website says that of 232 outbreaks of norovirus
illness reported in the
"The waterborne outbreaks of norovirus that we typically see are either due to drinking water sources in which chlorination or other disinfection systems have broken down, or in recreational situations in which either the same - disinfection or chlorination breaks down in the case of a swimming pool or something along those lines - (happened)," said Hall.
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