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Virus killing Ontario lambs has troubling echoes of Zika
Veterinarians are alarmed at a recent outbreak of the little-known Cache Valley virus, which can cause birth defects in sheep. Among the many mysteries: what are the possible health risks to humans?
By: Jennifer Yang Global health reporter, Published on Mon Mar 21 2016
By now, the plot is familiar: A mysterious virus appears. The disease, spread by mosquitoes, is linked to an alarming surge in birth defects. There is no vaccine or treatment.
The world has been watching this nightmare unfold in countries such as Brazil, where the Zika virus is suspected of causing birth defects and other neurological disorders. Now, in Ontario, another viral outbreak is being linked to a surge in newborn deformities, albeit in a different population: sheep.
The little-known Cache Valley virus has long circulated in Canada but veterinarians are alarmed by what they say is the largest outbreak in recent memory.
And there are reasons to worry about Cache Valley beyond its disturbing impact on baby lambs. While its risk to humans is currently low, there are signs that the virus could be causing more problems than we realize ? and, if it ever explodes the way Zika has, the world will be just as unprepared.
?Cache Valley is not very well understood at all. It was kind of ignored for a long time,? said medical entomologist Philip
Armstrong, who studies the virus and conducts mosquito surveillance for the Connecticut Agricultural Experiment Station.
?As a veterinary pathogen of sheep, it?s certainly important ? as to human disease, I think the jury?s still out.?
For veterinarian Paula Menzies, the first sign of trouble in Ontario came around Christmas.
?It was like this huge explosion of cases,? said Menzies, a professor at Guelph University. ?Veterinarians were sending (us) these deformed fetuses and I got an email from a couple of (sheep) producers saying, ?This is happening on my farm. What the heck is this???
The answer, as a Texas laboratory later confirmed, was Cache Valley virus. First discovered in Utah in 1956, Cache Valley is spread by several mosquito species and is believed to circulate in deer. It mostly affects other ruminants, such as sheep and goats.
While outbreaks have been documented in sheep flocks since the early 1980s, the recent Ontario outbreak has caught everyone by surprise.
?It?s certainly the largest that anybody that I?ve worked with is aware of,? said Menzies, who is trying to determine the scope of the outbreak but knows of at least seven affected flocks. ?The question is why??
Among Cache Valley?s many mysteries is also the extent to which it affects humans ? a question that remains unresolved 60 years after the virus was discovered.
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Veterinarians are alarmed at a recent outbreak of the little-known Cache Valley virus, which can cause birth defects in sheep. Among the many mysteries: what are the possible health risks to humans?
By: Jennifer Yang Global health reporter, Published on Mon Mar 21 2016
By now, the plot is familiar: A mysterious virus appears. The disease, spread by mosquitoes, is linked to an alarming surge in birth defects. There is no vaccine or treatment.
The world has been watching this nightmare unfold in countries such as Brazil, where the Zika virus is suspected of causing birth defects and other neurological disorders. Now, in Ontario, another viral outbreak is being linked to a surge in newborn deformities, albeit in a different population: sheep.
The little-known Cache Valley virus has long circulated in Canada but veterinarians are alarmed by what they say is the largest outbreak in recent memory.
And there are reasons to worry about Cache Valley beyond its disturbing impact on baby lambs. While its risk to humans is currently low, there are signs that the virus could be causing more problems than we realize ? and, if it ever explodes the way Zika has, the world will be just as unprepared.
?Cache Valley is not very well understood at all. It was kind of ignored for a long time,? said medical entomologist Philip
Armstrong, who studies the virus and conducts mosquito surveillance for the Connecticut Agricultural Experiment Station.
?As a veterinary pathogen of sheep, it?s certainly important ? as to human disease, I think the jury?s still out.?
For veterinarian Paula Menzies, the first sign of trouble in Ontario came around Christmas.
?It was like this huge explosion of cases,? said Menzies, a professor at Guelph University. ?Veterinarians were sending (us) these deformed fetuses and I got an email from a couple of (sheep) producers saying, ?This is happening on my farm. What the heck is this???
The answer, as a Texas laboratory later confirmed, was Cache Valley virus. First discovered in Utah in 1956, Cache Valley is spread by several mosquito species and is believed to circulate in deer. It mostly affects other ruminants, such as sheep and goats.
While outbreaks have been documented in sheep flocks since the early 1980s, the recent Ontario outbreak has caught everyone by surprise.
?It?s certainly the largest that anybody that I?ve worked with is aware of,? said Menzies, who is trying to determine the scope of the outbreak but knows of at least seven affected flocks. ?The question is why??
Among Cache Valley?s many mysteries is also the extent to which it affects humans ? a question that remains unresolved 60 years after the virus was discovered.
...
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