<x-rich>I've pasted in below two articles about West Nile Virus that appeared
(no surprise!) in today's New York Times, following yesterday's
national press conference hosted by Centers for Disease Control:
<bold>Officials Working to Prevent Spread of West Nile Virus, </bold>by
Lawrence K. Altman and <bold><bigger>F</bigger>acing a Bug That Can
Fell a Horse</bold> by Sarah Kershaw.
Here is some background and "interpretive commentary" on some of the
points raised:
<bold>QUEENS EPIDEMIOLOGY SURVEY</bold> (para 4): Last fall 677 people
from northern Queens neighborhoods (of the area's 46,000 residents)
voluntarily gave blood for a study to see how widespread West Nile
Virus was in this "hotspot" -- the 3 sq-mile section where most human
WNV illness was reported. The people who gave blood had no signs or
symptoms of West Nile Virus.
Nevertheless, nineteen of the 677-person sample (=2.8%) tested positive
for antibodies to WNV. From this, epidemiologists estimate that 1.2 -
4.1 % of the population in that area (533 to 1,903 people older than 5
years) were infected.
The <bold>significance of this finding is that most people who are
infected do not get sick from West Nile Virus</bold>. Remember that
there were about 62 cases of West Nile Virus encephalitis in the entire
NY metropolitan area, and perhaps as many as 1900 people infected just
in this area of Queens. (This story was first reported in the New York
Times, March 21, 2000<bold>.)
BIRDS AS CARRIERS OF WEST NILE VIRUS: </bold>Altman's article gives a
lot of good background on the role of birds in disease transmission and
surveillance, but contains one error (see third paragraph from end).
It is already known that both American Crow and Fish Crow are
susceptible to (<italic><smaller>i.e.,</smaller></italic> get sick
from) West Nile Virus, as is their close relative, the Blue Jay. There
is concern about susceptibility among ravens, another close relation,
but to the best of my knowledge no reported cases. The studies Altman
refers to are to find out what other species may also be susceptible.
The USGS National Wildlife Health Center lists a total of 16 domestic
bird species known to be susceptible to West Nile Virus: American crow,
Rock dove (common NYC pigeon), Sandhill crane*, Blue jay, Bald eagle*,
Laughing gull*, Black-crowned night-heron*, Mallard*, American robin,
Fish crow, Red-tailed hawk, Broad-winged hawk, Cooper's hawk, Belted
kingfisher, American kestrel, Herring gull. Few individuals are known
to have been affected in most of these species, other than the crows.
The asterisk (*) indicates that susceptibility was known only in
captive individuals from these species. The number of species is down
from what had been reported because Ring-Billed Gull and Yellow-Billed
Cuckoo have been removed from the list.
<bold>RACING HORSES & CHICKENS</bold>: this (second) article is quite
dramatic (and fun to read, although may add to the frenzy of concerns
around WNV). It should be noted that the mosquito most associated with
WNV transmission is <italic>Culex pipiens</italic>, which far prefers
to bite birds than mammals. Thus chicken flocks may serve as a decoy,
reducing risk of bites to people and horses. (The chickens are not
susceptible to illness from WNV.) Research is being done now to figure
this out. The trapping of chickens at Belmont is in fact being done for
several reasons, although WNV may have been the final push. Chicken
populations had become too large and a nuisance around the tracks. The
trapped birds are being sampled for WNV and many are then being taken
to a bird sanctuary in upstate NY.
~~~~~~~~~~~~~~~
NY Times April 26, 2000
<bold><bigger>Officials Working to Prevent Spread of West Nile Virus
</bigger></bold>By LAWRENCE K. ALTMAN
<<Picture: B>ETHESDA, Md., April 25 -- A sound public health plan is in
place nationally to combat further spread of the mosquito-borne West
Nile virus, which caused an outbreak of encephalitis in New York City
last year, federal health officials said here today.
Despite the effort, there is no guarantee against new cases, the
officials said at a news conference.
------------------------------------------------------------------------
Increased knowledge and better tests, but no guarantees
.------------------------------------------------------------------------
"We may see some cases here and there this year," but no one knows when
and where the West Nile virus will strike, said Dr. Stephen Ostroff,
who is coordinating the West Nile effort for the Department of Health
and Human Services.
Last year, the virus caused 7 deaths and 62 cases of encephalitis in
the New York metropolitan region. The virus is believed to have
unknowingly infected as many as 1,900 Queens residents who did not
develop encephalitis, which is an inflammation of the brain and central
nervous system.
Federal officials have virtually ruled out the possibility that the
West Nile virus was deliberately introduced into this country as an act
of bioterrorism, Dr. Ostroff said.
When the West Nile virus was first detected in the New York City
outbreak last fall, "there were a variety of federal agencies that were
very concerned about bioterrorism, and some conducted investigations at
that time," said Dr. Ostroff, an epidemiologist at the Centers for
Disease Control and Prevention in Atlanta.
No agency concluded that "there was a serious likelihood that this is
how this occurred, and I don't believe that any agency is seriously
considering it at this point," Dr. Ostroff said.
Investigations were conducted even though bioterrorism was considered
unlikely, because most experts had put West Nile low on their lists of
possible biological warfare agents.
Nevertheless, some concern reflected the fact that a sample of the
virus had been sent to Iraq a decade ago for diagnostic purposes before
the extent of Iraq's biological warfare program was detected.
Dr. Ostroff said the West Nile virus from New York was not the same
West Nile virus that had been sent to Iraq.
Scientific studies performed over the winter showed that the West Nile
outbreak in New York City closely mirrored an outbreak in Romania in
1996 and that the strain of virus was very similar to one identified in
geese in Israel in 1998.
"This is not a strain that someone would have had 10 years ago in their
collection and that would have been sent elsewhere," Dr. Ostroff said.
The Centers for Disease Control and Prevention is the federal agency
responsible for tracking infectious diseases. The agency has given
grants totaling $2.7 million to 19 state and local health departments
to help develop surveillance to detect the West Nile virus in
mosquitoes, birds and humans. The aim is to shorten the time between
the onset of illness and the diagnosis of West Nile encephalitis.
The agency has developed standardized laboratory tests for West Nile
virus and has trained workers in the 19 state and local health
departments to perform the tests.
Because birds are the primary source of West Nile, the states receiving
the grants are mainly along the flyway of migratory birds along the
Atlantic Seaboard.
The states have varying capabilities, and federal officials will help
states that do not have facilities to test dead birds for West Nile,
said Dr. Robert G. McLean, who directs the National Wildlife Center at
the United States Geological Survey in Madison, Wis.
Federal and state health workers have tested about 1,200 birds found
dead last year for the West Nile virus. A crow found in Baltimore was
the only bird outside a 75-mile radius of New York City found to be
infected, Dr. McLean said, and scientists have not determined whether
the bird was infected in New York and flew to Baltimore or was infected
in Maryland.
None of about 300 birds found dead since Jan. 1 were infected, Dr.
McLean said.
In addition, blood from 1,300 live birds from 13 states is being
checked for West Nile. Tests have been completed in about half, and
none were infected, Dr. McLean said.
Scientists at the news conference said they know much more about the
West Nile virus than they did last fall, but that they still do not
know why crows are most vulnerable to it.
Experiments are about to begin to determine whether other species such
as fish crows, blue jays and ravens are just as suspectible to the
virus.
Health workers have long relied on flocks of chickens as an early
warning system for mosquito-borne infections. Now they are using
chickens to test for the West Nile virus in the blood because the fowl
do not become ill when infected with it.
Veterinarians are also checking horses because 25 developed West Nile
virus encephalitis on Long Island last year and many died or had to be
put to sleep. Two horses in New York City were infected b
~~~~~~~~~~~~~~
NY Times April 26, 2000
<bold><bigger>Facing a Bug That Can Fell a Horse
</bigger></bold>By SARAH KERSHAW
<<Picture: I>n the feverish world of horse racing and breeding,
mosquito season is about as welcome as a hurricane at the Preakness.
Especially this spring, given the prospect of a repeat of the West Nile
virus -- which killed seven people and nine horses in New York last
year, including a retired racehorse who was to breed thoroughbreds. The
possibility that the mosquito-borne illness could destroy a
multimillion-dollar celebrity like Fusaichi Pegasus, the Kentucky Derby
favorite who spent four days training at Aqueduct Race Track before
winning the Wood Memorial there on April 15, has racing officials more
hyper than in-bred thoroughbreds.
So, these days, there are some rather strange goings-on at Aqueduct and
Belmont Park, both near the epicenter of the outbreak in northern
Queens and both part of an industry that contributes more than $1
billion annually to New York State's economy.
Take the chickens at Belmont, the nation's largest track, on the
Queens-Nassau border. Once welcome to spend all their days scuttling
around the stables and barns there, they now have a $5 bounty on their
heads and are being rounded up.
Horsemen brought chickens to Belmont soon after the gates opened in
1905, to calm the high-strung thoroughbreds by lending a barnyard feel
to the stables.
But erstwhile friends, the fowl, now known to help spread West Nile,
are being trapped in padlocked coops and tested for the virus.
While kicking out the chickens, Belmont officials are bringing in fish.
After investigating the behavior of various species to find some that
eat mosquito larvae, racing officials last week dumped 4,000 goldfish
and catfish into the two lakes in the main track's infield, and into a
duck pond near the grandstand.
Then there was the pesticide deal with the Native American chief.
Racing officials spent $10,000 on a chemical called Ultracide produced
by the man's company, Native American Enviro-Tech.
They were told it would kill the bugs but not harm the horses. But the
state has blocked the use of Ultracide because it is not registered in
New York.
The obsession with mosquito control at the two tracks is no surprise,
given the routine frenzy surrounding the health and fitness of horses.
In addition to the nine horse deaths, on a cluster of farms near
Riverhead on Long Island, the virus infected 16 other horses, including
2 thoroughbreds that were racing at Belmont and another that raced at
Yonkers.
"The stars of this sport are the horses," said Francis J. La Belle Jr.,
a spokesman for the New York Racing Association, which owns and
operates New York's three largest tracks, at Belmont, Aqueduct and
Saratoga. "We go nowhere without them."
Horses, like humans, can recover from West Nile, which can be deadly if
it leads to encephalitis, swelling of the brain. Infections can range
from what looks like a minor flu to serious neurological illnesses; but
three racehorses that were infected with the virus last year recovered,
and, so far, two have gone on to race, according to veterinarians.
Officials at both Queens racetracks are also dropping "mosquito dunks"
made of larvicide, which kills the eggs, into other bodies of standing
water that are mosquito breeding grounds. They are also setting up
giant mechanical mosquito traps across the 430-acre Belmont property,
and the Nassau County Health Department plans to set up a
mosquito-trapping station there to catch the bugs and test them for
West Nile, officials said.
Amid all this, it is still unclear whether West Nile will reappear in
the New York City area or spread to Long Island again. Recent tests on
hibernating mosquitoes in Fort Totten, Queens, near the center of the
1999 outbreak that infected 69 people, confirmed that the virus was
still alive there.
"You wouldn't even want to think about it," said John Dowd, a trainer,
who was working with 10 horses at Aqueduct before the races there last
Thursday. Among Mr. Dowd's charges that day were some racehorses, like
Wires Crossed and Critical Thinker, worth up to $10 million.
Farm managers, particularly those on the East End of Long Island, where
the virus struck last year, and other horse breeders said they were
taking precautions similar to those at the racetracks, including using
the mosquito dunks in standing water. Several said they were planning
to stable their horses at night, spray them with pesticides and keep
them in barns at dusk and dawn, peak mosquito hours.
Jeff Raine, who manages the Big E farm in Jamesport, N.Y., where two
horses, including a thoroughbred brood mare, succumbed to West Nile
last year, said he was doing everything he could to prepare for
mosquito season. The 120-acre breeding farm is owned by Robert
Entenmann of the baked goods company, and is home to 15 horses that
serve as Mr. Entenmann's private breeding and racing stock.
"I've had nightmares about it recurring," said Mr. Raine, who had to
put to sleep the brood mare, Terroir, a retired racehorse who ran at
Aqueduct and Belmont before she was sent to the Jamesport farm to
breed.
Terroir's illness was the first confirmed case of equine West Nile in
last year's outbreak, said Dr. John Andresen, the veterinarian who
treated her and diagnosed her as having the virus. Government
scientists are using genetic material from Terroir for research on a
possible vaccine, he said.
At Belmont and elsewhere, state officials are testing the blood of
chickens, which carry the virus but do not get sick from it, for signs
of West Nile. Chickens can spread the virus to horses if mosquitoes
bite infected chickens and then bite horses. But horses, "dead-end
hosts," cannot spread the disease to other horses or species, experts
said.
A group of chicks from Belmont who were tested recently showed no sign
of exposure to the virus, said Dr. Neil Cleary, a veterinarian with the
racing association who treated one of the two Belmont racehorses who
was infected with West Nile but recovered.
State officials said that since the outbreak, they have conducted blood
tests on horses in the Riverhead area and across Long Island to
determine how many were exposed to the disease, possibly making them
immune.
Results released so far showed that of 69 horses tested in the
Riverhead area, 20 were exposed to the disease but did not get sick.
The incubation period is up to seven days, so those horses would not be
at risk for infection, veterinarians said.
It is still not known why the virus struck that cluster of Long Island
farms, 60 miles from the Queens epicenter of the outbreak. But several
experts said they suspected West Nile was carried to Riverhead, on the
tip of the island, by birds.
Dr. Andresen and other veterinarians who have studied the virus since
last year's outbreak, the first time West Nile was detected in the
Western Hemisphere, said the newness of the disease here made it
difficult to understand the risks.
"It leaves the vets in a quandary," said Dr. Howard Flynn, president of
the Long Island Veterinary Medical Association, who runs a clinic in
Medford, N.Y. . "This is brand-spanking new around here, and that's
part of the problem."
Only one other documented outbreak of the virus caused as many deaths
among horses as the Long Island one, a 1996 outbreak in Morocco.
It killed 42 of 94 horses confirmed to be infected, said Dr. Peter
Timoney, director of the Gluck Equine Research Center at the University
of Kentucky in Lexington. A smaller outbreak occurred in Tuscany,
Italy, in 1998, Dr. Timoney said.
Dr. Timoney and other veterinarians said that only a few outbreaks of
West Nile had occurred among horses since the virus was first detected,
in Uganda in 1937.
But they said they were concerned about the high mortality rate among
infected horses. Almost half the horses with confirmed cases -- 9 of 25
-- either died or were so sick they had to be put to sleep, a mortality
rate far higher than the 4 or 5 percent rate for humans.
"Statistically we haven't seen a major occurrence of this disease in
horses," Dr. Timoney said. "Still, think about the stakes: these
Kentucky Derby hopefuls. If that one animal becomes seriously infected
and dies, that's one hell of an economic loss." ut did not become ill.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lois Levitan, PhD Program Leader
Environmental Risk Analysis Program
Center for the Environment
213 Rice Hall, Cornell University
Ithaca, New York USA 14853
Phone: (607) 255-4765 Fax: (607) 255-0238
Email: LCL3@cornell.edu
Program Email: envrisk@cornell.edu
http://www.cfe.cornell.edu/risk
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
</x-rich>
Received on Wed Apr 26 11:49:10 2000
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