- Hello Jeff - West Nile Virus season is officially OPEN
in North America. We have see cases in Mexico since Jan. 2003, but this
is the first case for North America.
- West Nilelike Virus has proven its resiliancy and is
endemic to North America, and I suspect Central, South America as well
as the Caribbean.
-
- Patty
-
- For background information on WNV in Canada, see the
Environmental Risk Analysis Program's
- "Historical Summary By State and Country":
http://www.cfe.cornell.edu/erap/WNV/Update/Update(A-E).cfm#can
-
- West Nile Spent Winter In Canada:
- Crow's Death Comes Early
-
- By Joseph Brean
- National Post - Canada
- 4-29-3
-
- The discovery of the first West Nile-infected crow in
Canada this year all but proves the virus survives the Canadian winter,
Health Canada acknowledged yesterday. ...
-
- The crow was found dead last week at a busy intersection
in Newmarket, north of Toronto. It was sent for testing, which was positive
but has not yet been confirmed.
-
- "It's a bigger risk if the virus can overwinter
and stay within the province," said Dr. Harvey Artsob, chief of the
health department's viral zoonotics and special pathogens division. "If
it couldn't, then it has to be reintroduced every year, say by migrating
birds or from down south."
-
- The crow's death comes almost a month earlier than the
first avian case of last year. In 2001, it was not until August that a
bird tested positive, marking West Nile's introduction to Canada. ...
- A positive result so early after the spring thaw does
not suggest this year's cases among humans will occur earlier; it still
depends on prolonged warm weather.
-
- But it is good evidence that the virus is "seeded"
in hibernating mosquito populations all across Ontario, Dr. Artsob said.
-
- The crow was among the first few to be tested, he said,
which suggests it is not an oddity, but that the virus is present in other
crows, waiting to be found. Reports are not available from other monitoring
programs in regions where West Nile has recently been introduced, such
as the northern United States, Manitoba and Quebec, because they have not
yet started testing for the year. Manitoba, for example, will start on
May 1.
-
- "It's just an opinion, but I think if they were
looking [for West Nile infected crows] in some of these areas, they would
be finding them," Dr. Artsob said.
-
- Dr. Michael Drebot, Health Canada's head of viral zoonosis,
said one way the West Nile virus can survive the winter is in culex pipiens
mosquitoes, which prey on birds but not humans, and which hibernate as
adults on the walls of dank places like sewers and drainage ditches.
-
- "As daylight hours increase and temperatures rise
during the spring these mosquitoes emerge from the sewers and look for
a blood meal," he said.
-
- This species does not prey on humans, but humans are
put at risk when other mosquito species prey on infected birds and then
on humans.
-
- "We still think it takes quite a while for the virus
to build up in nature, and get into other species of mosquitoes that feed
on humans," Dr. Artsob said. ...
-
- Clinical evidence gathered since last year's epidemic
suggests that healthy, middle-aged people will suffer some of the most
debilitating and long-lasting effects of the next outbreak. Patients who
have survived the initial onslaught of the disease have often developed
"acute flaccid paralysis," or a weakening of limbs as the virus
attacks a region of the brain stem.
-
- [WestNileVirus-L was alerted to this story by ProMED
mail posting number 20030428.1046.
- Edited from full story in the [Canada] National Post:
http://www.nationalpost.com/home/story.html?id=DE486F82-2A03-490C-9B0C-46A0CEF49300
-
-
-
- WESTNILEVIRUS-L is an email discussion group for communication
and discussion
- about West Nile Virus, particularly regarding policy,
risk reduction and public
- education issues. It is moderated by Dr. Lois Levitan
at Cornell University's Center
-
- Patricia A. Doyle, PhD
- Please visit my "Emerging Diseases" message
board at:
- http://www.clickitnews.com/emergingdiseases/index.shtml
- Zhan le Devlesa tai sastimasa
- Go with God and in Good Health
|
