When the first cases of AIDS were discovered, few virologists could have foreseen that it would develop into a global scourge capable of bringing nations to the brink of ruin. It is extremely difficult to predict how new illnesses will evolve over time, and the latest disease to spread quickly -- severe acute respiratory syndrome (SARS) -- is no exception. The virus could end up following any number of trajectories; it is impossible to tell at this stage which path it will take. But one thing that epidemiologists generally agree on is that SARS is only the beginning: The world will likely face numerous global epidemics like SARS -- and far worse ones -- in the near future.
Several factors have conspired in recent years to significantly magnify the likelihood of disease outbreaks. The rapid growth of urban areas -- on average, 160,000 people around the world move from the countryside into cities each day -- is bringing diverse populations into close proximity and creating new opportunities for microbes to find susceptible hosts. And the environmental changes -- from paving roads to damming rivers -- that accompany urbanization alter the natural habitats and reproductive patterns of disease-bearing animals, such as mosquitoes, mice and rats. What's more, the explosion of international travel and global commerce is accelerating the movement of pathogens across national boundaries. Each year, 1 billion people travel by air, and 700 million go on transnational trips. (Indeed, all it took for SARS to jump from China to Canada was for a single infected person to step on a plane.) And global trade in produce has grown by 30 percent in the last 10 years, with the United States now importing 70 percent of its fruits and vegetables. "We're seeing a big increase in the movement of viruses, both geographically, from one place to another, and cross species," notes former Centers for Disease Control and Prevention epidemiologist Clarence Peters. "There are more and more things that are favoring the emergence of new organisms."
And while the threat of new epidemics mounts, familiar diseases are recrudescing in more virulent forms. Of the 9 million new cases of tuberculosis reported each year, 5 percent are resistant to one or more antibiotics. Though still primarily a problem in developing countries, where cases of the disease are rising by up to 10 percent each year, tuberculosis could easily begin to overtake the developed world if current trends continue. It has already made some frightening inroads. An outbreak of resistant tuberculosis in New York City during the early 1990s, for example, cost nearly $1 billion to contain. "It's like watching SARS in slow motion," notes Nils Daulaire, president of the Global Health Council. "It could certainly re-emerge to become a disease not just of the poor but of everybody." Resistant strains of other major diseases, including malaria, AIDS and cholera, are also spreading, while common illnesses are increasingly showing immunity to conventional treatments. Ninety-five percent of staphylococcus infections -- and many variants of streptococci (which causes meningitis), pneumococci (which causes pneumonia) and gonococci (which causes gonorrhea) -- are impervious to "first-line" antibiotics, such as ampicillin and erythromycin. Penicillin, once a silver bullet against almost any bacterial infection, is now useless in all but a few cases.
Unfortunately, this pattern shows no signs of abating, and unless considerable progress is made in the development of new medicines, benign ailments could once more become the life-threatening illnesses they were in the 19th century, prior to the discovery of antibiotics. "We are very much used to assuming that everything is going to be OK if we go to the doctor, but that's not always going to be the case," notes Peters. "It's just going to get worse. We're going to see more and more difficulty in being able to treat common infections."
With the SARS virus, which replicates quickly and spreads easily, the medical options are even more limited. No human vaccine exists for the class of virus (known as the coronavirus) to which SARS belongs, and it will likely take three to five years to produce one -- a long time considering that the disease managed to travel across continents within a matter of weeks. "The time it takes modern technology to respond to SARS is significantly slower than the virus can move and cause a pandemic," notes University of California, Irvine virologist Luis Villarreal.
And this problem is not unique to the SARS virus, or to coronaviruses in general. Even wealthy nations have drugs for only a small fraction of known virus types, and because viruses mutate much faster than bacteria, anti-viral drugs become outdated sooner. (Hence the need to engineer a new flu shot each year.) This is especially worrisome considering that, by most estimates, another major outbreak of viral influenza is long overdue. In fact, one of the characteristics of SARS that has epidemiologists spooked is that it resembles -- in its mobility and deadliness -- the brutal 1918 "Spanish Flu" virus, which killed 20 million people worldwide, including 650,000 Americans. "SARS has all the characteristics of the 1918 influenza," notes Villarreal, "such as the respiratory spread, the high death rate, and no immunity or reagents against it." SARS may well be a portent of what's to come. According to many experts, the next Spanish Flu could be just around the corner. As a recent National Academy of Sciences (NAS) report on infectious diseases notes, "The precursor virus(es) of the 1918 virus still exist in nature, and there is nothing to prevent it or a virus of similar virulence from re-emerging."
Yet despite all the warning signs, the United States and the rest of the developed world have done shockingly little to prevent or prepare for new outbreaks. For one thing, the U.S. government and the pharmaceutical industry have made only nominal efforts to develop new anti-microbial agents. Only four major drug companies have antibiotics research programs, and not one has a new type of antibiotic in advanced development. In the last 30 years, only two new classes of antibiotics have been discovered, and one of them was obsolete before it hit the market. Vaccine production is little better. Drug manufacturers nearly failed to meet demand for influenza vaccines during the last two years -- the mildest cases of the illness in decades -- and the 11 companies worldwide that manufacture the vaccine cannot produce enough for a U.S. outbreak, let alone a global one. In addition, doctors continue to prescribe antibiotics in cases where they are not needed -- such as for minor viral infections like bronchitis, otitits and the common cold -- thus encouraging the growth of anti-microbial resistance. "We throw them around, so antibiotic resistance emerges rapidly," notes Peters.
Public-health infrastructures have also been allowed to deteriorate in recent years. U.S. hospitals lack the capacity to accommodate a massive influx of patients, adult immunization rates in America have fallen below optimal levels, and disease surveillance systems for tracking new contagions have become fragmented and outmoded. On top of that, over the last two decades the U.S. government has significantly curtailed funding for research on contagious diseases in favor of nontransmittable illnesses, including cancer and heart disease, and it has decommissioned many disease-monitoring stations throughout the world. "There's been a long period of disinvestment in the kinds of public-health infrastructure that identifies, reports and responds to diseases," explains Daulaire. "Meanwhile, as far as the bugs are concerned, they keep chugging away, and sooner or later they come up with something that breaks through our defenses."
The collective disregard for the threat of communicable diseases is largely a byproduct of the many extraordinary victories achieved during the 20th century in the fight against germs. With the advent of antibiotics, vaccines, improved sanitation and more accurate diagnostic tools, among other things, the annual death toll from microbial illnesses in the United States fell by 95 percent from 1900 to 1980, and the average life expectancy rose by nearly 30 years. Epitomizing the widespread euphoria generated by these many brilliant successes, the Surgeon General famously proclaimed in 1969, "The war against pestilence is over." But soon after, the pendulum began swinging in the other direction. Since 1980, the infectious disease mortality rate has climbed an average of 1 percent each year in America, and evidence suggests that, in the absence of a major public-health effort, things will only get worse. "We need a public-health paradigm shift," notes Joia Mukherjee, medical director of Harvard Medical School's Partners in Health. "We either do something real or massive numbers of people are going to die."
The NAS report likens the threat of global outbreaks to an encroaching hurricane of unparalleled magnitude. "A transcendent moment nears upon the world for a microbial perfect storm," the authors write. But unlike the meteorological perfect storm, which occurs only once in a long while, the microbial storm will happen again and again. The last two decades have already seen a dramatic surge in the number of new epidemics -- including AIDS, West Nile Virus, Ebola and hantavirus -- as well as a steady proliferation of drug-resistant microbes. SARS is the latest hallmark of this rising peril. "SARS is a case in point," explains Daulaire. "It's a concrete example of what many of us have been talking about in the past decade in terms of the risk that the world is facing." The only question is whether the world will heed the warning before it's too late.
Alex Stone is a reporter-researcher at The New Republic.
