Science / Medicine : BATTLING THE THE BEAST WITHIN US : If it’s February, it must be the big, bad flu season
It begins simply enough: a few aches and pains, perhaps a sore throat and headache, all the symptoms that might suggest a cold. But within hours, the fever ascends, the chills, joint pains and malaise start and the cough takes hold--a dry, sometimes gut-wrenching hack that makes it seem as if the lungs and throat have been scraped with sandpaper.
Influenza. It is expected in February--as sure a thing each year as death and taxes. And it peaks just about this time every year, although indications are that this year’s flu epidemic may be slightly milder than other years, according to the Centers for Disease Control, the federal agency responsible for monitoring outbreaks.
Lest that news lull anyone into complacency, consider this:
* By the time this winter is over, influenza will still infect one in every four to five Americans.
* About three-quarters of those infected will get sick. Half of them will see a doctor for their symptoms.
* A quarter of a million Americans will be hospitalized and 40,000 to 50,000 will die this year, making influenza the sixth-leading cause of death in the United States.
* Influenza epidemics cost $10 billion annually in direct medical costs and lost wages, according to CDC estimates.
“Influenza is still a major disease, although it gets pushed into the background by other viruses such as herpes and AIDS,” said Peter Palese, chairman of the microbiology department at Mt. Sinai School of Medicine in New York.
Public health officials used to think that flu epidemics occurred in cycles: Some medical textbooks still report that physicians can expect epidemics of influenza A, the more virulent form of the virus, every two to three years and epidemics of influenza B every four to five years. But 15 years of close surveillance of viruses by Baylor College of Medicine’s Influenza Research Center in Houston has taught researchers that “there is no such thing as a non-epidemic influenza year,” said Dr. Robert Couch, the center’s director. It’s just that some years are more virulent than others.
Flu-like illnesses have been reported since the 15th Century, and the disease also has been found in birds, pigs and seals. But it wasn’t until 1933 that scientists first determined that influenza was caused by a virus. Influenza viruses are some of the fastest-changing viruses in the world, a fact that makes it “unlikely that the virus will be done away with in our lifetime,” Couch said. “Our target is to simply knock the tops off the epidemics.”
Influenza epidemics typically begin in schoolchildren, then move like wildfire through their families and fan out from there to the rest of the population. “About 50 million people are at risk for influenza,” said Dr. John LaMontagne, director of the infectious disease and microbiology program at the National Institute of Allergy and Infectious Diseases.
Among those at greatest risk for the fatal complications of influenza are people already weakened by other illnesses, particularly those with heart and respiratory diseases, cancer patients and people who have had organ transplants. Those 64 and older also are at risk.
Pregnant women are vulnerable as well, particularly during the third trimester because blood volume peaks at that time and the heart is under the greatest stress. A case of flu can be enough to push a woman’s cardiovascular system over the edge.
For this reason, Couch and his colleagues at the Influenza Research Center are now conducting a study to determine the safety and efficacy of giving pregnant women flu shots.
First reports about the flu this year show that the outbreaks have been of three strains; most have been a type B influenza, known as Victoria, said Dr. Alan Kendal, director of the CDC’s Influenza Branch. The rest have been a combination of two different types of influenza A.
The pattern “seems to be the reverse of what we had last year,” he said.
The suggestion that this year’s epidemic may be slightly less severe than usual is no reason to avoid being immunized. And it is still not too late to be protected.
“Even at the beginning of a flu epidemic, it’s not too late to be immunized,” said Dr. Edwin D. Kilbourne, distinguished service professor at Mt. Sinai School of Medicine. The reason: It can take three to four weeks for an epidemic in one location to peak, but it is possible to “get substantial immunity from flu shots within 10 days or so,” Kilbourne said.
About 12 million to 15 million Americans get flu shots each year, but that is only about a quarter of the population in the greatest risk of dying of influenza complications like pneumonia. “The national objective is to keep increasing this percentage to the 50% to 60% mark (of those at risk),” Kendal said.
The vaccine costs about $3 per dose and supply is a problem. “We are perpetually undercovered by vaccine,” LaMontagne said. “We don’t have enough to go around.”
In part, this is a problem of production. Only three companies manufacture influenza vaccines in the United States: Connaught, Parke-Davis and Wyeth Laboratories.
But another problem that hampers production is simply figuring out which vaccine to produce. In 1957, for example, the Asian flu virus was late in being identified and there wasn’t enough time to immunize a substantial number of people. As a result, 70,000 people died of influenza and its related side effects that year.
Those who get flu shots can usually count on good protection. About half the times, the vaccine mix is right on the mark for a given year’s epidemic, Kendal said. (This year, so far, has been one of those years.)
The rest of the time, the degree of error can range “from minimal to total.” But Kendal said there “are very, very few cases when we feel that a vaccine would not have a beneficial effect.” The worst that will happen is that the vaccine won’t protect completely against infection, but what it always does is to protect against the extreme effects of influenza. For instance, the incidence of pneumonia and other side effects of flu are cut by about 50% to 70% by the vaccines, Kendal said.
The older someone is, the less likely that the vaccine will prevent the flu. But even if a person gets sick, the trade-off for losing significant protection against simple infection, Kendal said, “is that we may be able to keep them out of the hospital and alive.”
Influenza spreads through the air via the sneezes and coughs that ricochet everywhere during flu season. Anywhere people have close contact is a potential hotbed for the virus, but one of the best illustrations of how easily flu can spread is on airplanes.
Epidemiologists once traced an outbreak of flu to a single infected woman who sat in the back seat of the plane. The air inside the cabin recirculated as the plane sat waiting for takeoff. Later, 75% of the passengers came down with the flu, simply from breathing the contaminated air that the sick woman exhaled.
When an epidemic gains a foothold (in Northern climates it usually occurs sometime between mid- and late-December), the influenza viruses tend to overwhelm all other respiratory viruses for the next eight to 12 weeks.
The same pattern is repeated during the winter season in the Southern hemisphere. “There is no place to my knowledge that is flu-free,” LaMontagne said. “You will find flu even in tropical areas if you look for it.”
Influenza viruses move around the world the way birds migrate--a pattern that seems to be more than coincidental. It appears that wild birds, which do not become sick from influenza, provide the perfect reservoir and transportation for the virus.
Flu shots, which are made up of viral material, are designed to protect people from a particular strain of influenza virus. In the United States, the only flu shots approved for use by the Food and Drug Administration contain killed influenza virus--that is, virus deactivated so that it can’t cause an infection.
But a new generation of vaccines containing live virus is coming. These new vaccines are under investigation in the United States and are already being used in the Soviet Union and other European countries.
New and improved flu shots may soon involve a combination approach--one that takes advantage of certain important proteins produced by the flu virus. One of these proteins, called neuraminidase, allows the virus to enter and exit cells. The idea would be to inject humans with neuraminidase, which would theoretically alert the immune system to the presence of the virus.
Alternative routes are also under investigation for administering the live vaccine. At UCLA and at Baylor’s Influenza Research Center in Houston, studies are examining the effectiveness of nose-drop vaccines.
How do you know if you have the flu? Detecting the virus is virtually impossible, unless you have a laboratory test that is usually too time-consuming for all but the Centers for Disease Control to use.
This means that most cases of flu are diagnosed by symptoms that could be caused by a range of respiratory infections. The thinking is that if you come down with flu symptoms at the time an epidemic is moving through your area, you probably have the flu, although your doctor might take a throat culture to rule out a strep infection.
Classic flu signs are a bad cough, fever, chills and joint pain. But the real giveaway is an overwhelming feeling that you’re really sick and the only place you can possibly survive is in bed.
If you find yourself prone for a few very miserable days, hold onto this happy thought: the sicker you are, the better the immunity that you develop, at least to that strain of flu virus. Provided that there are no drastic changes in virus strains, your immunity will last four to five years.
In the meantime, the best treatment for most cases of flu is what Dr. Mom always prescribed: bed rest and plenty of fluids.
