COLUMN ONE : Nature’s Tiny Killers Are Back : Once thought to be a problem on the wane, infectious diseases are resurging. Modern lifestyles and mutating microbes have combined to form the global threat.
After decades of complacency, with many experts thinking humanity’s age-old struggle against infectious disease was all but won, scientists now fear that unexpected worldwide outbreaks of deadly diseases signal that the war is far from over.
The worldwide AIDS epidemic may be the most extreme example of what some medical experts see as a resurgence of dangerous viruses and other microorganisms. But scientists say that it is by no means the only one.
As further evidence of the new threat, they point to the growing prevalence in several U.S. cities of tuberculosis that is resistant to many drugs, a cholera epidemic in Latin America that has been moving northward and a rampage of malaria through parts of Africa, Asia and South America.
Almost as troubling to medical, public health and scientific specialists as the epidemics themselves is the fact that many of the microorganisms causing these dangerous outbreaks of disease have long been recognized by scientists and were thought to have been brought under control.
“In truth, we think nothing is new--only ‘newly recognized,’ ” says Dr. David Ho, head of the Aaron Diamond AIDS Research Center in New York City. “Most of these (organisms) have been around for a long time. But something happens and they grow to epidemic proportions.
“Legionnaires’ (disease), for example--in retrospect, there had been many outbreaks of Legionnaires’ previously reported in journals and scientists didn’t know what it was,” Ho said.
When the Legionnella bacterium was identified after an outbreak of the mysterious disease at an American Legion convention in Philadelphia in the late 1970s, “a lot of things made sense” that had happened previously, Ho said.
Inventive creatures that the disease-causing agents can be, many have simply found innovative and sometimes deadly new ways to attack human beings by taking advantage of a changing society. This often occurs while the attention of scientists, medical professionals and public health experts has been elsewhere.
Dr. Theodore Tsai, a federal epidemiologist who tracked the origins of the mysterious “new” disease that made 182 Legionnaires ill in Philadelphia--philosophically summed up the phenomenon this way: “Epidemics are experiments of nature.”
Or in the more recent words of Dr. Robert T. Schooley, who heads the infectious-diseases department at the University of Colorado Health Sciences Center: “Life is a competition--and we compete with microbes.”
“Although we would like to move toward a steady state where the system isn’t perturbed,” Schooley said, “we are living in a society that is perturbing the system more and more. When that happens, new diseases will clearly come forth.”
As if to underscore the thought, a report by the Institute of Medicine, part of the prestigious National Academy of Sciences, said recently that “infectious diseases remain the major cause of death worldwide and will not be conquered during our lifetimes.”
“Beginning in the late 1950s and continuing into the 1980s, the attention given to acute infectious disease . . . began to wane and a shift in focus to chronic, degenerative diseases occurred,” the report said.
“The conventional wisdom was that science, medicine, public health and an improved standard of living brought most of these diseases under control,” it added.
With those assumptions clearly challenged by recent outbreaks of disease, experts are now calling for a concerted global effort to better prepare themselves to ferret out and combat brewing epidemics before they explode on an unsuspecting public.
The task, they acknowledge, is awesome.
“The uncertainty is: Can you ever truly be fully prepared?” asked Dr. John La Montagne, director of the division of microbiology and infectious diseases for the federal government’s National Institute of Allergy and Infectious Diseases.
“I don’t know how you can totally anticipate every eventuality,” La Montagne said. “One of the things to do is try to follow what Pasteur once said: ‘Chance favors a prepared mind.’ His argument was that the more education and knowledge you had, the better you could interpret something that was happening by chance.”
Scientists say they believe that such preparedness might have helped them recognize or grapple sooner with a host of afflictions:
* Legionnaires’ disease, for example, was a strain of known water-borne bacteria that, under some circumstances, was able to flourish in the damp environment of the massive air-conditioning systems used in big buildings.
* Toxic-shock syndrome, which struck dozens of otherwise healthy young women in the early 1980s, was caused by a poison produced by a long-known bacterium that was nurtured by the materials in super-absorbent tampons.
* Lyme disease is caused by a known bacterium that was able to gain a stronger foothold as more housing spread into rural areas.
* The AIDS-causing human immunodeficiency virus, although still mysterious to scientists, may be a new version of a long-existing harmless strain, according to some speculation. Other experts have theorized that the virus might have jumped from one species, where it did not cause sickness, to another--from primates to humans, perhaps--with a lethal result.
Not all outbreaks involve new opportunities for old organisms. In some cases, a long-recognized organism changes to survive, becoming more dangerous. Viruses and bacteria may evolve or mutate to fend off drugs or other weapons used against them, or to adapt to new environments.
In addition to the possibility that such a change might be responsible for the AIDS virus, the “new” form of streptococcal bacteria that killed famous puppeteer Jim Henson in May, 1990, is believed to be either an old microbe making a comeback or a bacterial mutation of a benign strep into a highly virulent one.
Particularly frustrating to medical experts has been the resurgence of an old enemy--tuberculosis--that had long ago been subdued. Once again the disease is on the rise in the United States, in part because of increasing poverty, homelessness and AIDS. Multidrug therapy, administered over at least six months, is necessary to cure the infection, which is caused by a bacterium. When treatment is inappropriate, or not completed, resistance to one or more of the drugs often develops.
Indeed, the increasing use of antibiotics--in some cases to prevent, rather than to treat illness--has resulted in many strains of bacteria developing such resistance.
Often, when outbreaks are small and isolated, they can go unnoticed--as is often the case with food-borne illnesses. Unless people die, as was the case with restaurant hamburgers tainted with a strain of E. Coli bacteria, or somebody famous becomes ill, they can escape the attention of health officials.
“If the Minnesota Vikings had not gotten sick, we’d have missed that outbreak entirely,” said Dr. Michael T. Osterholm, state epidemiologist for Minnesota, who investigated a 1988 outbreak of shigellosis caused by contaminated food served on a flight by a Minnesota-based airline.
Even food-borne illnesses, although not thought of as “new,” have undergone changes in their epidemiology because of changes in the production and distribution of food. As a result, they are often tougher to catch.
“The classic food-borne outbreak in the 1950s was 200 or 300 people getting sick eating grandma’s potato salad at a church picnic,” Osterholm said. “That’s easy to pick up because you’ve got 50% to 60% of the people getting sick in one place. Today, we’ve got attack rates of 2% and 3%, but they affect thousands of people because the products are mass-produced and distributed widely.”
Osterholm said he blames the food-distribution system and Americans’ new eating habits.
“In the 1950s the average grocery store had about 300 items. Today, the average grocery store has 30,000 to 50,000 items,” he said.
“Along with that, you have the globalization of the food supply and the change in America’s diet. The old diet of meat and potatoes went by the wayside with cardiovascular disease and has been replaced by fresh fruits and vegetables. The problem with the new American diet is that it isn’t always beneficial to the gastrointestinal tract,” he said.
The majority of fruits and vegetables are imported to the United States from developing countries. “When travelers go to Mexico, they are told to peel the fruit before eating it,” he said. “But when you go into a modern American store, you could be buying the same fruit that had been sitting in a Mexican field two days before.”
“If we let down our guard, these bugs are very clever and can get around a lot of what we put in front of them,” said Dr. Ruth Berkelman, deputy director of the Center for Infectious Diseases, part of the federal government’s Centers for Disease Control and Prevention.
“We have to keep up with them,” Berkelman said. “We have to be there to put another obstacle in front of them. We’re very naive if we think we can conquer the microbial world. They are much too clever.”
The cornerstone of an effective defense against the microbial world is better surveillance, public health experts say. It is the key to quickly recognizing new or emerging infectious diseases and to tracking the prevalence of more established ones. Otherwise, small outbreaks can burgeon into epidemics--even pandemics.
“It’s a nuts-and-bolts thing,” La Montagne said. “You have to have a better surveillance mechanism to be able to pick these problems up early and start identifying the disease.
“One of the things about AIDS, for example, that people don’t appreciate is that it only became an obvious problem when a strange disease started in clusters among healthy homosexual men,” he said. “If it had started in drug abusers--who are generally not otherwise healthy--it might not have been picked up for a long time.”
In hindsight, some experts say that sharper surveillance could have detected AIDS as much as five years earlier--that the clues were obvious had public health officials been more vigilant about what was happening.
Once AIDS had been recognized as a new epidemic, health authorities conducted a “look back” and found several hundred cases, starting in 1976, of individuals seeking access to a then rarely used drug that was in limited supply.
The drug, pentamidine, is a treatment for pneumocystis carinii pneumonia, a life-threatening respiratory infection that is now known to be common to people suffering from AIDS. Before AIDS, however, the condition was virtually unheard of, except in organ transplant recipients. Transplant recipients, who must take immune-suppressing drugs to prevent organ rejection, are vulnerable to pneumocystis. But those seeking the drug in 1976 were not transplant recipients.
“These were people who shouldn’t have needed it,” said Schooley, who now devotes most of his time to AIDS research. “In retrospect, they were clearly AIDS cases. We probably could have detected AIDS by 1977 or 1978--long before that small cluster of cases in 1981--if we had been more alert. A lot of people who became infected wouldn’t have if we had known then.”
Recently, officials at the CDC’s Center for Infectious Diseases announced that they were drafting a major new plan to combat future epidemics. The centerpiece of the new approach is an enhanced system of surveillance both in the United States and abroad.
Currently, domestic surveillance involves voluntary cooperation by state health departments--which are frequently financially strapped, the CDC says--and only limited surveillance for microbial drug resistance is conducted. International surveillance is no more than “rudimentary,” the agency adds.
The CDC plan calls for a network of 15 sites around the world, each with epidemiologists and laboratory personnel. They would be responsible for studying and identifying infectious-disease problems in those regions. The CDC says it will also need more infectious-disease experts, citing a 12.5% decline in the number of those specialists during the last decade, except in the area of AIDS research.
The plan recommends that the CDC work with the National Institutes of Health to expand research efforts in order that scientists can better understand new or newly identified organisms.
The CDC has not estimated the cost but acknowledges that the proposals will require more money.
“To do everything that needs to be done will take more resources,” Berkelman said. “But the more you put in, the more you get back--and the more you save.”
But even the most optimistic experts concede that outright victory over infectious diseases will still remain beyond reach.
“We’re very smart and have good organizations and a lot of capabilities, but I’d be the last one to tell you our capabilities will be up to the capacity of the microbes to fool us,” La Montagne said.
“I think we will be better prepared and will be able to identify things more readily, and I think it is something we must do,” he said. “It hasn’t been something we have focused on until recently because, quite frankly, most people felt infectious diseases were a thing of the past. They never will be.”
