The most blatant source of pressure was the host’s immune system. In most cases the microbial advantage might look like virulence because the host’s disease progressed badly, but from the microbe’s point of view what was transpiring could better be described as escape. Microbes had discovered a long list of ways to escape the immune system, including disguise, Trojan Horse-like use of immune system cells as modes of entry and avoidance, constant mutation of genes coding for their outer surfaces so that the immune system failed to recognize them, and manipulation of immune system chemicals to set off false alarms that would occupy the system while the microbes slipped into safe hiding places.126
Theorists were busy trying to determine whether the balances between human immunity and microbial virulence were tipped by any particular identifiable contemporary factors. Nobel laureate Dr. Thomas Weller expressed concern that the ever-increasing numbers of severely immunosuppressed people on the planet posed a real threat for emergence of new disease problems. Cancer patients treated with high doses of chemotherapy or radiation, people infected with HIV, and individuals undergoing transplant operations all represented potential breeding sites for new or mutated microbes. Weller worried about a possible “piggyback†effect, with one microbial population taking advantage of severe immunodeficiencies produced by another microbe or medical treatment.127
Another population of immunosuppressed individuals consisted of those suffering from chronic malnutrition. Wherever a significant percentage of the Homo sapiens population was starving was likely to be a spawning ground for disease.128
Vaccines, where available, protected people against disease, but not against infection. Microbes could enter the body, but even highly virulent organisms found themselves facing an immune system that was primed and ready to mass-produce antibodies. Battles ensued; the invader was vanquished. 129 If a sufficient number of Homo sapiens in a given area possessed such immunity it would be possible to essentially eliminate the microbe. Unable to find a Homo sapiens host in which it could replicate, the microbial population would nearly disappear. Nearly. In this state, known as herd immunity, humans (or livestock animals) never suffered disease, though they might be infected, unless the necessary level of immunity in the overall population slacked off. For that reason, schoolchildren vaccine campaigns had to reach a critical threshold of successful completion or the unvaccinated children would be a great risk for disease.130
Herd immunity faced tough challenges in the age of air travel because individuals who carried microbes to which they were personally immune could fly into geographic areas where herd immunity was extremely low. Under such circumstances, even organisms not generally thought to be particularly virulent could produce devastating epidemics.
The best example of the phenomenon was the estimated 56 million American Indians who succumbed to disease following the arrival of Europeans—and their microbes. That die-off continued 500 years later, into the 1990s, as Old World microbes reached the Xikrin, Surui, and other Amazon Indians.
Yale University epidemiologist Francis Black argued forcefully in the 1990s that the terrifying death toll among New World natives was not a straightforward question of their having naive immune systems that hadn’t previously been exposed to the European microbes. Such an explanation was, he said, overly facile and flew in the face of evidence that new diseases commonly afflicted other populations of peoples without exacting such horrendous tolls. For example, new diseases were also introduced into sub-Saharan Africa by European explorers, and though they claimed many lives, nowhere were there wholesale microbial genocides, as were witnessed in South America.
Black’s theory was that what did in the American Indians was their own lack of biodiversity. Since all Amerindians were descended from two fairly small waves of migration from Asia, their gene pool was small. For the microbes this meant that the range of genetic diversity, not only in immune response but also in a host of other factors that affected the appearance and behavior of target cells in the Homo sapiens, was very limited. The microbes were, therefore, able to adapt swiftly to the very narrow set of obstacles before them, attacking the American Indians with unusual ferocity.
Black calculated that as the microbe was passed from Amerindian to Amerindian, it had a 32 percent chance of encountering a human with the same immune system genetics (major histocompatibility complex) as its prior host had possessed.131
A contemporary example of such a biodiversity mechanism at work was discovered by Michel Garenne and Peter Aaby during measles studies in Senegal. Aaby and Garenne noticed that measles became steadily more lethal as the microbe spread from one child to another, biologically related child. This was true for cousins as well as siblings. Mortality rates rose so markedly from child to child that they couldn’t possibly be ascribed to chance or random immunity. It wasn’t the children’s immune systems that varied, it was the measles virus, which adopted ever more acute virulence capabilities as it passed from one genetically similar person to another.
The virus, in short, evolved to become a tailor-made killer for particular extended Homo sapiens families.132
Overall, that seemed to argue that increased mixing of Homo sapiens, both through intermarriages across racial lines and through travel and immigration, would eventually bolster the collective Homo sapiens immune response. That was the good news. But microbiologist Avrion Mitchison, director of Berlin’s Deutsches Rheuma Forschungszentrum, was less than convinced that greater biodiversity in the human race could guarantee success over the microbes, particularly if the overall Homo sapiens population size did one day exceed ten billion.
“Even old pathogens invent new tricks,†Mitchison wrote in a Scientific American article entitled, grimly, “Will We Survive?â€133 He continued: “Recently evolved drug-resistant strains of the tuberculosis bacillus have been plaguing industrial urban centers. Will such developments change the comfortable deadlock? Will Homo sapiens and the microbes continue to coexist, or will one side win?â€
The answer, Mitchison concluded, was not at all clear.
Human activities that didn’t seem amenable to positive change were, by the 1990s, playing significant roles in the spread and possible creation of emerging diseases. Between 1980 and 1989, for example, the number of refugees fleeing natural disasters, wars, famine, or oppression increased by 75 percent every year. By the end of 1992, according to the United Nations, 17.5 million Homo sapiens were refugees, most of them living in squalor in the world’s poorest countries.
Thirdworldization had set in all over the globe. Millions of abandoned children roamed the streets of the world’s largest cities, injecting drugs, practicing prostitution, and living on the most dangerous margins of society. Western European unemployment soared, from less than 3 percent in 1970 to more than 11 percent in 1993, and a sense of hopelessness cast a pall over much of the continent.134 Civil war in the horribly overcrowded nation of Rwanda broke into inconceivable carnage during the spring of 1994. Serb invasions of Bosnia devolved into little more than slaughter of civilians.
Conservative Harvard University political analyst Samuel P. Huntington opined that the world had entered a stage of conflict that superseded nationstates, economic competition, and ideologies, becoming something far more insidious: cultural conflict. Wars and battles were fought over religion, over historic enmities that in some cases traced back to slights that had transpired between opponents more than 2,000 years ago.
In such a context, it seemed difficult to discuss E. coli virulence mutation probabilities. If men in the former Yugoslavia considered multiple acts of gang rape of civilian women justified acts of war, how could there be rational discussion of probabilities of sexual transmission of disease?
Still, the scientists pushed on, determined to remain cool in the face of global disarray, perhaps because of the chaos which threatened to abet the microbes. Studies demonstrated the rapid sprea
d of disease among refugees and the emergence of antibiotic-resistant bacteria and drug-resistant parasites in such clusters of humanity.135 The health risks of famine were carefully tallied.136
A concern shared by all public health observers was the shift globally from low-intensity geopolitical nuclear confrontation to high-intensity local conflicts. While the former had posed the threat of thermonuclear war, little actual conflict occurred. With the fall of the Berlin Wall dawned an era of extremely high-intensity conventional and guerrilla conflict which took a tremendous toll on civilian populations: direct losses of life, homelessness, refugee migrations, demolition of basic infrastructures, destruction of hospitals, and, in some cases, pointed deliberate assassinations of health providers.
When such conflicts occurred in developing countries, they created new possibilities for reemergence of old scourges such as typhus, cholera, tuberculosis, and measles—the classic wartime opportunists. Where sex became an economic component of strife, microbes that could exploit sexual transmission emerged. And along the peripheries of human battle and despair lurked the unexpected. In the flora and fauna of remote ecospheres they resided, human events affording them ever-greater opportunities for jumping from their ancient hosts to the warring Homo sapiens.
17
Searching for Solutions
PREPAREDNESS, SURVEILLANCE,
AND THE NEW UNDERSTANDING
I don’t even recognize the CDC anymore. It’s a bunch of politicized pencil-pushers who make all the decisions without ever hitting the ground, never going into the field, never seeing things up close. I’m sick of it. I quit.
—Joe McCormick, March 1993
Joe McCormick? I’m not familiar with that name, and I’ve asked around—nobody around here has ever heard of him. You’re the first reporter I know of who’s ever asked for him. Are you sure he works at CDC?
—a public relations spokesperson for CDC, January 1993
The lesson I learned in Cairo still applies. The only way to deal with bureaucrats is with stealth and sudden violence.
—United Nations Secretary-General Boutros Boutros-Ghali, 1993
On April 6, 1994, an airplane was shot down over Rwanda during the final leg of its flight from Tanzania to the Rwandan capital, Kigali. Aboard the plane were Rwandan President Juvénal Habyarimana and President Cyprien Ntaryamira of Burundi.
Three weeks later the carnage following the deaths of the two heads of state was staggering. Long-standing ethnic, economic, political, and cultural hatreds between the two nationalities living in the region, the better-educated Tutsis and the far more numerous and historically less advantaged Hutus, erupted in Rwanda and threatened the stability of neighboring Burundi. Tutsi rebel forces, reportedly backed by the Museveni government of Uganda, surged toward Kigali. The Hutu-dominated government forces and gangs of Hutu thugs responded by slaughtering Tutsi civilians living in the capital in a manner so wanton and barbaric that the global community was flabbergasted. Images of young Rwandan men filled television newscasts: men who grabbed innocent children, slashed off their heads with machetes, and then turned unashamedly to international camera crews, grinning and shouting in triumph.
The Tutsi rebel forces retaliated with equally brutal massacres of Hutu civilians living in the Rwandan countryside.
By April’s end, with the carnage still continuing, the United Nations estimated that anywhere from 100,000 to 500,000 civilians had been slaughtered, and more than a million had fled their homes in search of safe havens. On April 29 more than a quarter of a million Rwandan refugees poured across the corpse-laden Kagera River into Tanzania during a twenty-five-hour period, making it the largest short-term refugee migration in world history. Tens of thousands more made their way to Zaire, Uganda, and Burundi.
In international relief tents they awaited their uncertain futures, huddled against the rain upon muddy hillsides located less than two degrees below the equator.
In 1989 the HIV infection rate among young adults living in Kigali exceeded 30 percent, and WHO observers were certain that it had continued to escalate radically over the four subsequent years. In rural Rwanda, however, HIV rates were below 10 percent. The lines between urban and rural Rwandans blurred with the refugee exodus, however, and the people poured into areas of Tanzania and Uganda that ranked as the most hard-hit rural AIDS centers in the entire world. International health officials made an anxious prediction: if the populations remained uprooted for weeks or months on end, and refugee poverty promoted prostitution, another explosive surge in the Lake Victoria region’s already horrendous AIDS epidemic would ensue. Before that could transpire, however, cholera would come, spread as people drew their water from rivers clogged with rotting corpses.
What else lurked in the refugees’ new environs? If a novel epidemic appeared, was the international public health community prepared to handle the crisis?
Five years earlier, just before Christmas 1989, some 800 tropical disease experts gathered in Honolulu for the annual meeting of the American Society of Tropical Medicine and Hygiene. They staged an extraordinary war games scenario, envisioning a horrendous epidemic in a mythical African region. The hope was that such a role-playing scenario would reveal weaknesses in the public health emergency system that could later be corrected.
What transpired was an event eerily prescient of the Rwandan crisis. And an event that proved disheartening.
In the war games scenario three mythical equatorial African countries, designated Changa, Lubawe, and Basangani, were interlocked in a crisis that threatened Homo sapiens worldwide. Civil war inside Changa had devolved into brutal, high-intensity struggle, with both sides in the ethnically divided dispute venting their hatred upon innocent civilians. Over six months’ time an estimated 125,000 civilians had been slaughtered, virtually the entire national infrastructure destroyed, and about a quarter of a million people had fled into neighboring Lubawe and Basangani.
Most of the refugees were in a squalid encampment in Basangani, less than a mile from the Changa border. Conditions were atrocious, with drug-resistant malaria, malnutrition, and tuberculosis rampant. Some 25 percent of the adult refugees were HIV-positive. An international relief effort was under-way, with physicians, nurses, and advisers from all over the world treating the ailing refugees. In addition, a United Nations peacekeeping force, comprised of military personnel from the U.S., France, Italy, Finland, the U.K., and Malaysia, was guarding the Basangani and Lubawe borders, protecting the refugees from possible Changan attacks.
As key scientists played their roles in Honolulu, a terrible epidemic unfolded among the refugees, multinational health providers, and UN forces. Before it was even noticed, ailing individuals infected with a mysterious microbe had traveled to the U.S., the Philippines, Thailand, Germany, and neighboring African countries.
And although every imaginable effort was made to swiftly identify and control the mysterious microbe, within a month a global pandemic of what appeared to be an airborne, nearly-100-percent-lethal virus was underway.
Antibody tests were positive for Ebola, and Karl Johnson, who took part in the war games scenario, declared, “You say this might be a mutant strain of Ebola that is respiratorily transmitted. Well, if that is the case, it would be very close to Andromeda†(named for the Michael Crichton medical thriller The Andromeda Strain). “You may say ‘ridiculous,’ but I don’t think we can disregard that possibility,†Johnson said. “It was, and still is, a potential.â€
Audience members in Honolulu began murmuring to one another. Though all knew it was only a scenario, tension was high because it bore such a close resemblance to past disease emergences.
Ebola was a particular sticking point for infectious disease experts in December 1989 because just a month prior to their Honolulu gathering the virus broke out in a primate colony located in Reston, Virginia. Ebola, the scourge of Yambuku a
nd N’zara, had surfaced in the United States.
Fortunately the Reston Ebola outbreak involved a strain of the virus that, though highly lethal to monkeys, was harmless for Homo sapiens. Nevertheless, there had been a few tense days in Virginia when scientists weren’t sure what they had on their hands, and fear ran high.
Ebola, therefore, was very much on the minds of the 800 experts gathered in Honolulu. Though the tropical sun and Waikiki beaches beckoned, nobody left the cavernous hotel conference room. The Reston outbreak had shocked these experts into taking the question of readiness very seriously.
Unfortunately, what the war games revealed was an appalling state of nonreadiness. Overall, the mood in Honolulu after five hours was grim, even nervous.1 The failings, weaknesses, and gaps in preparedness were enormous.
There were no prepackaged infectious disease hospitals anywhere in the United States or at WHO in Geneva that were ready at a moment’s notice to be airlifted into an epidemic. Virtually no civilian hospitals in the United States were equipped to handle a highly contagious, lethal microbe, either in patients or inside petri dishes in their laboratories.
Only one permanent maximum-containment facility existed inside the U.S. Public Health Service system, and the vast network of overseas high-security laboratories that had been run by the Rockefeller Foundation and the CDC no longer existed. The Public Health Service and WHO would, therefore, be forced in such an epidemic crisis to choose between two unsavory options: deploying all security research capabilities and personnel to the epidemic site, thus putting large numbers of personnel at risk; or shipping all the patients, blood samples, and tissue biopsies to the CDC’s P4 laboratory, the Institut Pasteur, and Fort Detrick, risking the chance of civilian exposure should samples break open during transport.
The Coming Plague Page 92