A comeback for whooping cough 


Мы поможем в написании ваших работ!



ЗНАЕТЕ ЛИ ВЫ?

A comeback for whooping cough



When she was 5 /2 months old, Traci Cohn of Rockville, Md., developed a 104 °F fever and cried inconsolably for three days. Ever since that illness Traci, now 17, has been mentally retarded. Her family and one of her doctors believe that the fever and subsequent mental damage were the direct result of the pertussis, or whooping cough inoculations that she received in the first months of her life.

Whooping cough, named for the distinctive sound made by its victims as they gasp for air between bouts of violent coughing, was until the 1940s a major killer of children. Caused by a bacterial infection that increases the amount of mucus in the lungs, the disease sometimes results in convulsions and death. Over the past four decades, however, pertussis has been largely subdued in developed nations by mass inoculations with a vaccine made from killed pertussis bacteria. Now doctors annually pump :some 18


million doses of the vaccine into U.S. children — usually in the form of a D.P.T. shot, so called because it also provides protection against diphtheria and tetanus. Some 40 states require children to have D.P.T. inoculations before they are allowed to enter school.

Despite these efforts, the Center for Disease Control in Atlanta reports that the incidence of whooping cough is increasing; the latest figures show that the number of U.S. cases has nearly doubled in the past three years, from 1895 in 1982 to 3275 in 1985. Meanwhile, health officials are concerned that more and more parents, aware. of cases like Traci's, will refuse to allow their youngsters to be inoculated.

Minor reactions to the vaccine, such as redness and swelling, are common. Permanent brain damage, according to one study, occurs only once in about every 300000 inoculations, death even less frequently. Researchers suspect that these severe complica­tions — which can include convulsions, shock, loss of muscle control and fever — are caused by bacterial toxins. Still, most doctors insist that the shots are worth the risks. Martin Smith, president of the American Academy of Pediatrics, calculates that the chances of suffering serious damage from whooping cough are ten times.greater than having damaging side effects from the vaccine. Says Dr. Peter Patriarca of the CDC's immunization division: "There is no question that the vaccine has more side effects than any other vaccine. But it's a matter of risk vs. benefits".

However, many parents of children stricken by the vaccine complain that they were unaware of the risk. "Doctors don't sit down with parents and talk about the vaccine", says Washington Attorney Jeff Schwartz, whose daughter Julie died of apparent vaccine-related seizures at age three. "It's shocking to us that this information is not routinely provided". In other nations, fear of the vaccine's potential dangers has had tragic results. After two children died from side effects in 1974 and 1975, Japan banned use of pertussis vaccine for two months. Many parents were so alarmed that even after it was reinstated, they refused to inoculate their children. Between 1977 and 1979, as a result, 28000 Japanese children contracted whooping cough, and 93 died. (By comparison, between 1972 and 1974 Japan reported only 1024 cases and 6 deaths.) In Britain, more than 100000 cases of pertussis and 36. deaths occurred between 1977 and 1979, after reports about side effects were broadcast on television. A similar epidemic struck in Sweden after the government decided to withdraw the vaccine. Says Swedish Pediatrician Patrick Olin, who is testing an alternative to the still banned shot: "The fact that we have no mass vaccination is the clear reason for the rapid increase".


Hit by a number of liability lawsuits, the pharmaceutical industry is acting defensively. Lederle Laboratories of Wayne, N. J., announced that it is boosting the price per shot of its vaccine to $11.40 (it was only 45 cents in 1982), holding back 8_of that amount for what company calls its "liability reserve".

Meanwhile, researchers are scrambling to purge the vaccine of its harmful effects. In its current form, pertussis vaccine is made by killing pertussis bacteria with heat or chemicals and grinding them up, toxins and all. When the resulting mixture is injected, several of the toxins stimulate an immune response that protects the recipient from attacks by live pertussis bacteria. But some of the toxins in the vaccine apparently cause the side effects as well.

Researchers in Japan have brewed what they hope is a safer vaccine by separating out the most dangerous toxins produced by the bacteria, leaving only four to stimulate the immune response. U.S. scientists at the National Institute of Health and the Public Health Service have gone one step further: they announced that they had determined the genetic code of the bacterial gene that orders production of one of the toxins. They hope to alter the gene so that it signals the production of only the part of the toxin that stimulates the immune response, then to use this partial toxin as an essential ingredient of a safe vaccine.

Until a safer vaccine is available in the U.S., the CDC has advised parents to watch carefully for these symptoms in children receiving D.P.T. shots: 1) severe allergic reaction like a rash or troubled breathing; 2) a fever of 105°F or higher within 48 hours of a shot; 3) the onset of shock, which is characterized by clamminess and a rapid pulse; 4) persistent crying that lasts for three hours or more, or unusual high-pitched cries; 5) seizures, fits or convulsions within three days of a ■ shot; 6) dulling of mental function within seven days of a shot. "If any one of these symptoms occurs", says the CDC's Patriarca, "no further doses of the vaccine should be given", and the child should be taken immediately to a doctor, clinic or hospital.

VACCINES FOR ADULT DISEASES

When the flu and pneumonia season arrives, shortly a surprising number of Americans will be caught with their antibodies down, (or no good reason. Around 48 million adults should consider being vaccinated against influenza or pneumonia, medical authorities say. Another 4 million ought to be vaccinated against hepatitis В, а sometimes fatal liver infection that is spreading at an alarming rate: there were 50 percent more new cases in 1986 than in 1981,


according to the Federal Centers for disease control. All told, Health officials estimate, infections for which vaccines already exist kill 70000 Americans a year and strike hundreds of thousands more — costing tens of billions of dollars in medical care and lost work.

It is curious that while Americans are more fussy about their health than ever before, they're neglecting the most powerful preventive measure in medicine. Shots have saved countless lives since childhood vaccines became widely used. There were 200000 U.S. cases of diphtheria reported in 1921 — none in 1986. Paralytic polio struck around 57000 in 1952 — only two last year. But even in light of such well-known medical triumphs, researchers say, no more than one in five adults whose life would be jeopardized by a vaccine-preventable infection gets immunized against it. "Historically, we've thought of immunization as something for children", says Dr. Alan Hinman, director of the CDC's division of immunization. "But it's an adult thing to do".

Are you unprotected? Whether you should prime your disease-fighting antibodies depends on your age and medical history and the probability of direct infection. For final advice, consult your doctor. So that you can take stock of your bodily defenses, here is a survey of the most threatening diseases for which vaccines are available.

Influenza: In a typical year, influenza kills 10000 to 40000 Americans. In the 1984/85 epidemic, a CDC official estimates, the toll was at least 50000. Influenza costs the nation $3 billion to $5 billion annually in productivity losses and health care, says Dr. David S. Fedson of the University of Virginia, head of the immunization task force of the American College of Physicians. In an epidemic year, he says, the expense is about S12 billion. The CDC now recommends the vaccine for persons over 65, for sufferers of chronic lung and heart disease and for adults living with such high-risk persons, ft is also advised for any adult who wants to lower the odds of getting the flu. The vaccine, which prevents infection in 60 to 70 per cent of recipients and lessens its severity in many others, is reformulated annually and should be taken every fall.

Doctors and patients shun flu shots today partly because of fears stemming from the swine-flu controversy of 1976, in which some 500 of the 45 million people given the vaccine mysteriously developed a neurological disease. Since that episode, says Leonard Kurland, a neurologist and epidemiologist at the Mayo Clinic, flu shots have caused no additional cases of Guillain-Barre syndrome. Today's highly purified flu vaccines, researchers say, "rarely" cause the feverish aches that plagued recipients of the first flu shots 30 years ago.


Pneumonia: Between 20000 and 40000 Americans die annually of pneumonia caused by pneumococcal bacteria. Like the flu shot, the pneumococcal vaccine is advised for the elderly and the chronically ill and those with whom they live.- The once-in-a-lifetime vaccine is the only preventive measure of any kind that Medicare covers.

A Veterans Administration study published in the "New England Journal of Medicine" last fall has caused some physicians to lose faith in the vaccine. The VA researchers studied 2295 men (mostly over 55) with chronic illness such as diabetes and alcoholism; the 1145 men who received vaccine, the researchers found, had no fewer cases of pneumococcal infection than men who didn't. But the oft-mentioned study is "invalid", some researchers say. For instance, Fedson says, too few subjects were tested for the vaccine's benefits to become apparent, and subjects who received vaccine were by chance more feeble than the controls. Neither the U.S. Public Health Service nor the CDC has changed its vaccine recommendations in the wake of the VA study. Experts still say it prevents infection in two out of three recipients who would otherwise become infected.

Hepatitis B: Following the do-as-l-say-and-not-as-l-do medical dictum, most physicians fail to immunize themselves against hepatitis B. Since the virus is transmitted via blood and blood products as well as semen and saliva, health-care workers are urged to get a vaccination: Yet, Hinman says, no more than 30 percent of physicians and 40 percent of dentists have done so. Others at high risk are gay men with multiple partners and i.v. drug abusers who share needles. The CDC also says that heterosexuals with more than one sex partner should consider the vaccine; of the 300000 or so people who became infected last year, says CDC epidemiologist Gary Schatz, about 120000 got it from heterosexual contact.

A major purpose of the vaccine is to stem the tide of virus carriers — now at 500000 to 1 million Americans and rising. About 10 percent of infected persons can't get rid of the hepatitis В virus and become chronic carriers; a fraction of them die of cirrhosis or liver cancer. But the vaccine, which is administered in three doses over six months and is thought to spur lifelong immunity, is not likely to become more popular until it's more convenient and much cheaper.

% Time to bring your immune system up to date? For those who received a tetanus or diphtheria vaccine, researchers recommend a booster every 10 years. And as many as 20 percent of Americans in their 20s and early 30s are susceptible to measles; either they didn't get the disease in childhood, and so have no natural immunity,


or they received a weak measles vaccine. As a result, measles outbreaks have lately occurred on college campuses, prompting some schools to require students t6 prove their immunity or roll up their sleeve. Another immunity gap is rubella, or German measles. About 15 percent of women of childbearing age are susceptible to rubella, which can cause birth defects.

While several once dreaded diseases are disappearing, influenza and pneumonia and hepatitis В are flourishing, relatively unchecked by vaccines. Fear of shots isn't the problem. Repeated surveys show that when physicians advise high-risk patients to get a vaccine, most of them follow doctor's orders.



Поделиться:


Последнее изменение этой страницы: 2017-02-19; просмотров: 270; Нарушение авторского права страницы; Мы поможем в написании вашей работы!

infopedia.su Все материалы представленные на сайте исключительно с целью ознакомления читателями и не преследуют коммерческих целей или нарушение авторских прав. Обратная связь - 3.144.172.115 (0.007 с.)