By Anita Manning, USA TODAY

This year's record-setting outbreak of West Nile virus is likely to get much worse in the next few weeks and could affect as many as 1,000 people, a federal health official said Thursday.

This Culex quinquefasciatus mosquito is proven to be a vector associated with transmission of the West Nile Virus. Reuters

Already, at least 156 people in eight states and Washington, D.C., have been infected, the "vast majority" hospitalized with brain infections meningitis or encephalitis, said Lyle Petersen, a West Nile virus expert at the Centers for Disease Control and Prevention. Nine people have died of the virus so far this year, equal to last year's total.

Governors of Louisiana and Mississippi, where the bulk of the human illnesses have occurred, declared states of emergency. Louisiana Senators Mary Landrieu and John Breaux have requested help from the Air Force to spray pesticides to kill the mosquitoes that carry West Nile virus, a request that has yet to be worked out with local mosquito-control agencies.

In previous years, West Nile virus outbreaks have not peaked until the last week of August or the first week in September. "It's safe to assume we can expect more cases, and potentially a lot more cases," Petersen said in a routine press briefing. If the epidemic follows the pattern of previous years, he said, it could cause 1,000 serious illnesses and 100 deaths.

West Nile is a mosquito-borne virus that was unknown in North America until it appeared in New York City late in the summer of 1999. It has spread across the Mississippi River to 37 states, and "it's quite clear to us that we expect the virus will go coast to coast," Petersen said. "It's just a matter of time."

Why Louisiana, which has reported 85 human cases this year, has been hit so hard is not entirely clear, he said, though it's warm, wet climate and abundance of mosquitoes that could spread the virus are factors.

Only one in five people who are infected have any symptoms, and most suffer only mild fever that goes away on its own after three to six days, he says, but one in 150 who are infected develop the severe form of the disease.

Although younger people have developed the severe form, the risk is greatest for people over age 50. "The older you are, the more likely you are to develop severe West Nile virus disease," Petersen says.

There is no vaccine and no anti-viral medicine to treat it. In severe cases, doctors treat the patient's symptoms until the patient's immune system is able to defeat the virus. People who become infected once develop immunity.

But those who develop the severe form of the disease may have long-term problems. Studies of people infected in previous years show that most of those who were most seriously affected suffered some degree of brain damage that persists even a year after their illness, he says.

Mosquito-control efforts in Louisiana, where most cases have occurred, could have a "major blunting effect on this epidemic," he says, but in some states, such mosquito-control programs have languished.

"This is a classic case of an ignored problem that has now resurfaced," Petersen says. "Over the last few decades, mosquito-borne disease was not thought to be a problem anymore."

-- Anonymous, August 16, 2002

Answers

Veterinarians gear up to fight West Nile virus

By KAY LEDBETTER kledbetter@amarillonet.com

Veterinarian clinics across the area are dealing with large requests for the West Nile virus vaccine after four cases in horses were reported Tuesday and another three tested positive Thursday.

Suzan Norwood with the Canyon office of the Texas Department of Health, Zoonosis Control, said the confirmed cases of the mosquito- borne virus in horses include two in Swisher County, two in Briscoe County, one in Deaf Smith County, one in Floyd County and one in Roberts County.

The proximity of the manufacturer for the vaccine, Fort Dodge, Kan., allows for the shelves to be restocked within a day, so clients don't wait long for the vaccine, area vets said. However they've all had to restock the shelves.

Patty Brooks, secretary at the Wheeler Veterinarian Clinic, said the clinic had about 80 doses Thursday morning and they were gone that afternoon.

"I'm waiting for more to come in now," Brooks said, adding that she has already started a waiting list.

Amarillo veterinarian David Hodges said he has had a lot of calls since the news broke.

"Now that they have some cases close, they want to get the vaccination. I had a ranch call me that wanted to vaccinate 50 head and we had to order that," he said. Each horse must receive a shot now and another in three weeks to complete the vaccination process.

"Another ranch got enough doses for 20 horses two days ago. If ranches are starting to vaccinate, they may start depleting the clinics," Hodges said. "But we can get it from Fort Dodge in a day."

He said that earlier in the year, the vaccine was on back order for a couple of months, but at this point, the manufacturer has geared up for the greater demand.

"We reminded all our clients who had horses as they came in to vaccinate for West Nile virus during the winter when we got the vaccine and they did. But it's pretty tough to make a decision to vaccinate a lot of horses at one time," Hodges said.

"Nobody really knew that much about it when they were doing their annual vaccinations, and now they don't want to do it unless they have to," he said. "It's pretty evident now it's necessary."

Canyon veterinarian Gregg Veneklasen said he sold 700 doses of vaccine on Wednesday and received another 1,200 doses on Thursday to fill a list of 600 requests waiting.

He is treating a stallion, middle-aged and in great shape, at his clinic east of Canyon that is one of the confirmed cases made Thursday. The horse from Swisher County exhibited classic signs of encephalitis, including stiffness in the front end, and then the hind- end goes and the lips start to twitch, Veneklasen said.

"But today (Thursday) he's prancing around, so the prognosis is good," he said.

The horse was treated with anti-inflammatory drugs to relieve the swelling. Veneklasen said only in severe cases, where the horse is down and it is a last-ditch effort, will vets use steroids.

Norwood reported that all but one of the horses appears to be recovering from the virus. A horse in Lockney was euthanized earlier this week.

Hereford veterinarian Les Mayes said he, like many other veterinarians, sent clients information letters on the virus earlier this year and that has eased some pressure.

But now with the publicity and the cases locally, everyone is getting concerned about their horses and coming in to request the vaccine, Mayes said.

The vaccine price can range anywhere from $16 to $25 per shot depending on the veterinarian who is administering the shot, Mayes said. But a veterinarian doesn't always have to give the shots, he said.

"The folks we know can handle the vaccine correctly and who know how to administer it are able to give their own vaccine," he said, such as ranchers and feedlot workers.

All the veterinarians stress the most important thing any horse owner and the general public can do is control the mosquito population.

"People can't get this virus from horses. It's important they understand that and not panic," Veneklasen said.

Mayes said he is recommending fly spray and keeping the horses up at night and away from ponds and lagoons. He also recommends getting with local pest exterminators and having barns sprayed for flies and mosquitoes. The larger areas, such as feedlots or large horse farms, can have a crop duster spray or use a larger sprayer to treat the area.

"And we recommend the vaccination for the horses," he said.

Hodges said there also are larvacides that keep the mosquitoes from growing in areas that are wet all the time.

The veterinarians all said, however, that the human population also must use mosquito repellent to keep from contracting the virus. It is spread through mosquitoes, not by contact with infected horses or birds, so the mosquito population also must be controlled around homes.

-- Anonymous, August 16, 2002

An Aging Epidemic By Charles Murtaugh 08/16/ As if skin cancer and wildfires weren't enough to worry about, the past few years have given Americans a new summertime fear, one whose name conjures up the very dangers of the dark continent. In its characteristically cautious style, New Scientist recently warned that "West Nile virus will sweep across whole US," and National Review Online's John Derbyshire mentioned the virus in a gloomy column on the prospect of future "plagues". Even the chief of the Centers for Disease Control had described the virus as an emerging "epidemic".

When you look closer, though, West Nile appears a lot less scary. Since it first appeared in this country, in 1999, it has killed less than 30 people, while the flu kills 20,000 Americans every year. Also unlike the flu, West Nile virus is not communicable between people: it is spread by mosquitoes, but can only form a reservoir in birds. Since humans are a dead-end, rather than a host, West Nile is not subject to the sort of selective pressures that would enhance its virulence in humans. This may explain why only about one in ten infected individuals even feel ill, and fewer still seriously ill. Between its relatively low virulence, and its indirect mode of transmission, West Nile poses little threat of becoming an epidemic.

Does this mean that John Derbyshire is wrong to worry, and that infectious disease is a vanquished foe? Not necessarily. One thing that West Nile virus has in common with flu is that it is most dangerous to the elderly, and as America's population ages, it provides an increasingly target-rich environment to infectious disease.

Consider a fascinating paper published this spring in Science, documenting the steady increase in life expectancy that has occurred in the industrialized world over the past century. (Follow the link and you can read the full text, including the very provocative figures.) Contrary to almost innumerable predictions, the steady pace of this increase shows no sign of slackening. On this scale, even truly awful disease outbreaks such as the 1918 Spanish flu show up only as blips. But when this increase in life expectancy is combined with a decline in fertility, the result is the famous "graying" of the population that already worries Social Security reformers.

Perhaps unsurprisingly, the little news coverage that the Science paper received focused on its negative implications for pension programs. For pension program administrators, apparently, life can't be nasty, brutish and short enough; for the rest of us, the report ought to be rather cheering. For one thing, it casts some doubt on the oft-heard claim that we are choking ourselves on pollution, pesticides, and microwaves: if so, where's the impact on lifespan? (I see bad arguments on behalf of the environment the way Thomas Aquinas saw bad arguments on behalf of God: they do more harm than good, because they give unbelievers an opportunity to laugh.)

The authors of the Science report, Jim Oeppen and James Vaupel, are particularly struck by the smooth upward slope of the curve describing maximum average life expectancy across countries, which they describe as perhaps "the most remarkable regularity of mass endeavor ever observed." Much of that curve derives from advances that are unlikely to be reversed, such as improved nutrition and hygiene, and that contribute enormously to our societal residence to epidemics. As a species, humanity has reason to be proud of its success in postponing death, but it has contributed to a looming demographic irony: we are dying later, but more and more of us are dying every day.

When people get older, they tend to stop working: hence the looming Social Security crisis. They also, unfortunately, tend to die, and as the elderly make up increasing proportion of the population, so will the dying. Even if the rates of death due to infectious disease do not change, the result will be a net increase in the number of people dying of exotic and frightening diseases like West Nile virus or vancomycin-resistant bacteria, as well as of much more common killers like pneumonia or flu.

Could the result be a return to a simpler time when people faced death forthrightly, when death and the dying were central to social customs rather than shut behind closed doors? I rather doubt it. Instead, we are likely to be greeted with more and more hysterical coverage of exotic and rare bacterial and viral illnesses, each one deemed the latest threat to mankind's continued survival.

What will be the actual public health impact? The age bulge will put more buying power in the hands of senior citizens, who will spend it to combat their own ailments. This is all to the good: today, the lifespan trend is probably being driven more and more by investments in health care for the elderly. On the other hand, our long lives today owe much to childhood vaccine programs, established over the past century. If the vaccination network continues to fray, especially due to a misplaced public-health focus on rare but scary diseases like West Nile, such diseases will hardly be needed to fulfill John Derbyshire's worries. Measles and diphtheria can do the job nicely.

-- Anonymous, August 16, 2002