An epidemic is a disease that kills the privileged. In normal times, germs recognize the boundaries that separate the poor from the rich; they respect the entitlement to vigorous health that good food, clean housing, and a carefully tutored immune system bestow upon the better off. The confluence of infectious disease with poverty is tolerated perhaps because it implicitly validates social hierarchies. It is as if the debilitating infections and untimely deaths of the lower orders were nature’s way of ratifying the judgment of economy and history in conferring wealth and power on a select few. But in time of plague unforeseen and agonizing death strikes the rich along with the poor, the industrious along with the dissolute, the robustly youthful along with the decrepit elderly. By scrambling the correlations between social status and health, an epidemic nullifies the acknowledged rules about who should live long and who should not, and thus undermines civilization’s most basic function: to predict and regulate the survival of its members. For this reason the dislocations of an epidemic are among the most severe a community can undergo; ever since Moses led the Hebrews out of Egypt, pestilence has been associated with the overthrow of public order and the eclipse of old gods.

Efforts to rationalize the chaos of an epidemic are essential both in coping with disease and in preserving respect for established authorities, who’ve often blamed outbreaks on the unwanted incursions of the poor and other social outcasts–Jews in the 14th century, gay men in the 20th–into the public sphere. New theories of contagion that arose in Europe starting in the 16th century emphasized the importance of person-to-person contact in the spread of disease, and led to the development of quarantine measures to identify and isolate likely carriers. These measures met with uneven success in suppressing epidemics–the most dreaded pestilence of that era, bubonic plague, is transmitted mainly by rat-borne fleas, not by humans–but quarantine played a larger role as an instrument of social control.

Rarely applied to members of the upper classes, quarantine regulations drastically constrained the physical movements and public presence of the poor, often imprisoning them in their homes or in municipal pesthouses and banning street festivals, social gatherings, even funerals. By these measures officials sought both to prevent the spread of infection and forestall the sort of assemblies where panic might be transmuted into rebellion. As historian Paul Slack has noted, elites viewed the lower classes as dangerous reservoirs of infectious disease and political disorder, an attitude that reflected the “contempt of the respectable for the masses who presented a threat to their health, their social position, and their peace of mind.”

A more ecological approach arose in the 1880s, when the advent of the germ theory of disease unmasked the bacteria and viruses that cause infection. Insights from the new sciences of microbiology and immunology led to revolutionary public health programs–water purification, sewage treatment, mass immunization–that sought to protect the community as a whole from the incursions of pestilence. These advances and the steady improvement in the diets and living standards of the poor have greatly diminished, although not erased, the class bias of infectious disease in industrialized countries. Then after World War II miraculous new vaccines and antibiotics that prevented or cured previously untreatable infections–“magic bullet” therapies, the crowning achievements of the germ theory–obscured the social and economic dimensions of infectious disease. Despite their natural histories as systemic disorders rooted in hunger, overcrowding, and bad sanitation, epidemics could instead be viewed as a series of isolated duels between patient and germ, each one resolved by the intervention of a medical priesthood armed with supernaturally powerful drugs.

This paradigm unraveled when it confronted AIDS, a monster that can’t be slain with magic bullets. Condoms may block the exchange of bodily fluids, but our fears about AIDS have led us back to the age-old impulse to erect social barriers to the spread of disease, to rope off the “carriers”–gays, drug addicts, prostitutes, Haitians–and prevent their contact with “innocents.” One of the most crucial boundaries, one that amplifies America’s racial and class antagonisms and projects them onto a global scale, is the line that separates the famished, untreated third world from the well-fed, overmedicated first. The rift between “advanced” and “underdeveloped” has long been represented as a contrast between the incompatible disease regimens of infection and decay–malaria and cholera at one pole, heart disease and Alzheimer’s at the other. AIDS threatens this dichotomy: it links Africa’s shantytowns with America’s metropolises, and reminds us just how fragile the barrier between them really is.

Richard Preston’s recent best-seller The Hot Zone reflects our current obsession with policing the borders between ourselves and the virus. The Hot Zone is not about AIDS, but about a nightmare version of AIDS: the Ebola virus, a germ that kills 50 to 90 percent of the people who catch it and “does in ten days what it takes AIDS ten years to accomplish.” Preston, a journalist who has won several awards for his science reporting, tracks the virus from its first local outbreaks in central Africa in the 1970s to its sudden emergence in 1989 in the Washington suburb of Reston, Virginia. Ebola’s journey from dank rain forest to blithe suburbia thus recapitulates the horrifying intrusion of AIDS into American consciousness.

Ebola belongs to a family of hemorrhagic fever viruses that seem to have been genetically engineered by a B-movie producer. In Ebola all the destructive capacities of radiation exposure, demonic possession, and alien hatchlings are rolled up into one malevolent little strand of DNA. Ebola and its sister viruses derive their name from their ability to destroy the interior lining of blood vessels and cause massive hemorrhages. As the disease progresses, blood dribbles out of every orifice in the body, even from the nipples and the pores of the skin. The victim’s eyeballs turn ruby red and bulge from their sockets as they fill up with blood. The virus eats away the connective tissues that anchor the facial muscles to bone; the face sags into an expressionless, zombielike mask. Meanwhile blood clots drift through the body and lodge in the brain, causing strokes and brain damage. Dementia sets in–patients have been known to tear off their clothes and stagger grotesquely out of the hospital. As the infection reaches its climax, victims vomit up blood mixed with rotting tissue and long coils of virus particles and thrash about in epileptic convulsions, spattering bystanders with tainted gore. Internal organs often die several days before the heart stops beating, so the corpse decomposes with astonishing speed, like a staked vampire that compresses a century’s worth of decay into a few minutes.

One might think that such cinematic flourishes would make for a gripping tale, but Preston’s book reads like a bad screenplay. Instead of adding any substantive material to the original account he published in the New Yorker, he has larded his story with the portentous banality of a Stephen King novel. We slog through whole chapters full of the daily routine of disease-control experts: they make lunch for the kids, pet the dog, drive back and forth to work–somehow never suspecting that a new virus is poised to strike. More space is taken up with tedious descriptions of lab procedures and tidbits of germ-warfare folklore like “the puke factor” (“a sudden urge to throw up when you find yourself unprotected in the presence of a Biosafety Level 4 organism”). Occasional Ebola-hunting expeditions to Africa allow Preston’s prose to oscillate between bad Hemingway (“He gave money to his women friends and they, in turn, were happy to love him”) and worse Conrad (“It seemed to emerge out of the stillness of an implacable force brooding on an inscrutable intention”). Inevitably the puke factor comes into play once again when we come across sentences like “The team had discovered the red chamber of the virus queen at the end of the earth.”

The payoff finally comes when army scientists detect the Ebola virus in a colony of monkeys shipped to Reston from the Philippines. The Pentagon reacts with its customary finesse: seal off the area, put on space suits, kill everything. Here Preston is in his element; with chapter headings like “The Mission: 1630 hours, Wednesday” he deploys the terse hysteria of military jargon to impart a sense of urgency to the operation. You would think that a struggle between the U.S. Army and a group of caged monkeys would be a walkover, but here the warrior veterinarians and their simian adversaries are pretty evenly matched. These monkeys are preternaturally truculent; if you even look at them the wrong way, they spit at you and pelt you with virus-laden feces. Then they go for the face, slashing at your eyes with their enormous canines. The soldiers trudge from cage to cage euthanizing the monkeys, carefully avoiding eye contact–until one animal escapes, grabs a syringe, and races toward a young private who hadn’t expected to die that day. (Don’t worry, it’s just one of the many dream sequences Preston feels compelled to throw in.) Anyway, we get the picture: Monkeys are bad news. After reading The Hot Zone, we want to stay away from them, as well as any continents they happen to be living on.

But for Preston Ebola is an emblem of deeper mysteries. Contemplating the horror of Ebola is like “staring into a discolored alien sun.” Some people, like Ebola expert Karl Johnson, spend so much time staring at the sun that they become mesmerized and begin to say things like “A virus can be useful to a species by thinning it out.” Aphorisms like this one bring out the armchair nihilist in Preston, who wonders whether Ebola might not be a corrective mechanism, a way of restoring the balance of nature: “In a sense, the Earth is mounting an immune response against the human species.” What these ruminations really signify is Preston’s deep-seated anxiety over the uncontrolled interpenetrations between modern life and the old, primitive, septic world that Ebola represents. Contact between first world and third is creepy, dangerous, unnatural, a symptom of an infection that calls forth an immune response. As civilization builds highways through the jungle, it opens itself up to avenging pathogens that scuttle out and hitch a ride to the nearest airport. In The Hot Zone the all-important thing is to secure the perimeter; dramatic tensions always hinge on the possibility that technological barricades may fail, that some invisible tear in the space suit may let in a lethal bug.

In the end Preston decides to travel back to the heart of darkness: a cave on Kenya’s Mount Elgon in whose dark recesses an Ebola-like virus is said to lurk. Shuffling along in his space suit, Preston descends into a maelstrom of promiscuously mingling species, a place where the normal barriers have all broken down. Elephants, leopards, rats, bats, spiders, nameless insects that feed on the fungi lining the walls–they all gather in Kitum Cave, heedlessly swapping blood, saliva, guano, and viruses. The cavern puts him in mind of a similar cesspool, this one a little closer to home, another place where America meets Africa, where the evolved meets the primitive, where alien life-forms slither together, jostling and biting one another: “Kitum Cave is Mount Elgon’s equivalent of the Times Square subway station.”

The Hot Zone’s iconography of space suits and decontamination chambers derives in large part from Michael Crichton’s 1969 novel The Andromeda Strain. But Preston’s outlook is also shaped by broader currents of paranoia and victim blaming that mark the pervasive Crichtonization of American cultural discourse. Just as sexual harassment is really a stratagem of boardroom sluts who prey on family men, and the health-care crisis is really caused by undeserving patients who abuse emergency-room doctors, so modern-day plagues are really caused by the eruption of third world squalor into the aseptic domains of the West.

Ironically, the factual history of Ebola that Preston sketchily recounts demonstrates just the opposite. The worst outbreak on record occurred in Zaire in 1976, when a villager infected with the virus showed up at a missionary hospital to get a shot of antimalarial medication. The hospital couldn’t afford disposable syringes, so the Belgian nun who gave him his shot then used the same unwashed needle to inject upwards of a hundred other patients, who carried the infection back to some 55 surrounding villages. Hundreds died before traditional quarantine measures set up by the villagers themselves finally extinguished the outbreak. The pattern is typical. In Africa Ebola epidemics are usually either caused or exacerbated by the use of Western medical technology without an adequate economic base to support it.

But what about the Reston outbreak? Well, four animal handlers did indeed catch the virus–and lived to tell about it. It turns out that the monkeys carried a strain of Ebola that’s perfectly harmless to humans.

For a savvier treatment of these issues we can turn to The Coming Plague, Laurie Garrett’s massive treatise on contemporary developments in infectious disease. Garrett, a journalist who has reported on science for National Public Radio, combines a comprehensive overview of evolving patterns of disease with a firm grasp of the social, economic, and political dynamics that shape them. While she avoids Preston’s histrionics, she paints a picture that in many ways is more frightening.

In her introduction, Garrett acknowledges her intellectual debt to the historian William H. McNeill, whose 1976 book Plagues and Peoples is a landmark in the historiography of disease. McNeill’s study looked at profound and largely unperceived historical processes that inscribe themselves in bodies instead of books: the intertwined evolution of human demographics and disease virulence. For McNeill humans exist in a precarious balance between the forces of macroparasitism, the exploitation of ordinary people by governments and other forms of elite rule, and the forces of microparasitism, the inescapable feasting of microbes upon human flesh.

McNeill showed that the course of imperialism–the ultimate form of macroparasitism–has often been critically altered by the accompanying dynamics of microparasitism. The diseases that the Spaniards brought to the New World unleashed epidemics that killed off 90 percent of the native inhabitants–a holocaust that proved the decisive factor in the European conquest of the Western Hemisphere. On the other hand, tropical diseases have sometimes thwarted European colonial ambitions, as in 1802 when a yellow-fever epidemic wiped out the 33,000-man army Napoleon sent to restore Haiti to French rule. The outcome of military campaigns has historically hinged more on the vicissitudes of plagues than on the skills of generals. Army camps are ideal breeding grounds for germs, and during 19th-century wars epidemics typically knocked off five to ten times as many soldiers as battlefield wounds. The development of sanitation procedures and mass inoculations at the turn of the century finally banished epidemic disease from the trenches; indeed the vast bloodlettings of World War I owe less to the deadliness of modern weapons than to the success of modern medicine in keeping soldiers alive long enough to be killed by the enemy.

Like McNeill’s, Garrett’s goal is to elucidate the link between the workings of microbes and the workings of the economy and the state. She gathers a mountain of evidence demonstrating that infectious disease is overwhelmingly a problem of poverty and exploitation, foisted on the third world by the utter indifference of the first, and her demonstration has the precision of an account ledger. According to the former director of the Centers for Disease Control, of the 14 million children who died of infectious disease in 1989, 9 million could have been saved by the simplest of medical provisions–sterile syringes, vitamin supplements, vaccinations–at a cost of about $3 billion. At the same time the third world exports a net of $118 billion a year in debt repayments to Western banks. With figures like these, Garrett makes a convincing case that the macroparasitism of the privileged upon the dispossessed plays a critical role in the microparasitism of disease.

Unfortunately, Garrett’s account ledger is rather hard to decipher. The Coming Plague was apparently rushed into print to compete with The Hot Zone, and it suffers from hasty editing and a disjointed structure. Crucial facts and statistics are jumbled amid a mass of geopolitical musings and extraneous details about the exploits of heroic epidemiologists. Many readers may lack the patience required to sift through 620 pages of fragmented, repetitious narrative, but it’s worth the effort because her insights are both provocative and compelling.

One troubling conclusion is that the Western model of high-tech interventionary medicine is inadequate when it comes to dealing with emerging epidemics. Magic-bullet antibiotics have lost their stopping power against new generations of drug-resistant bacteria. The speed with which microbes evolve resistance has almost caught up to the pace of drug development; even if scientists stay one step ahead, replacement drugs are often so costly as to be beyond the reach of the impoverished countries that need them most. In the United States a host of old microbes that doctors had previously thought vanquished–scourges like tuberculosis and streptococci–have resurfaced, more virulent than ever and impervious to almost any drug. Vaccine development is still a promising approach, but it’s no panacea; some microbes–the HIV virus prominent among them–mutate so rapidly that vaccines against them become obsolete in a matter of months.

Garrett argues that we must combine sophisticated medicine with a focus on the social and economic circumstances that foster epidemics. Improvements in diet, water quality, and medical infrastructure are indispensable, but they demand political stability. The AIDS catastrophe in central Africa has ridden on the wings of decades of warfare and migrations that disrupted traditional ways of life and drove thousands of impoverished women into prostitution. Here in the United States efforts to stop the spread of AIDS are also hampered by severe sociopolitical dysfunctions. Racism, homophobia, and religious conceptions of AIDS as a form of divine punishment against life-style deviants all continue to block needed public-health measures like condom distribution and needle exchange.

In many other ways America seems uniquely unready to confront the microbial threats that loom on the horizon. After Hillary’s insurance-reform debacle and the ascent of the Republicans, discussion of the government’s role in health care has been pushed off the agenda by weightier topics like space colonies. But our private health-care system is disastrously unsuited to the task of funding and organizing public-health programs, which rely on dogged investment in unprofitable chores like vaccinating underprivileged schoolchildren and building water-treatment plants. Childhood vaccination rates in the United States have already slipped below those of Mexico and Albania. By its nature, free-market medicine caters to private interests at the expense of the general welfare; indeed its invisible hand is largely responsible for the upsurge in drug-resistant bacteria, thanks to the profligate overprescription of antibiotics to dose every ache and sniffle.

One of the most unsettling things that Garrett brings to light is the typical germ’s insouciant disregard for boundaries and distinctions that we take for granted–stale old categories like “species” and “sex.” We think of our own chromosomes as being immutable, indelibly etched with a genetic blueprint that only eons of evolution can alter. But bacteria can reproduce a new generation every 20 minutes; a human year is the equivalent of 525,600 E. coli years. So if the human genome is a stone tablet, the microbial genome is more like an Etch-A-Sketch, constantly mutating into new and often deadlier configurations. This process is greatly accelerated by a prodigious ability to accrete new genes from the outside. Microbial sex is a remarkably indiscriminate affair; bacteria will mate, couple, and swap chromosomes with improbably distant species, taking on any number of useful drug-resistance genes in the bargain. Sometimes they dispense with the niceties and simply gobble up any random piece of DNA that drifts their way. Processes like these can turn a harmless bug into a ravening predator in the blink of an eye.

Indeed at a genetic level we ourselves may be more virus than human. As the Nobel-winning biologist Joshua Lederberg has noted, our chromosomes are cluttered with vast stretches of useless DNA that codes for nothing at all. These introns may actually be the genetic remains of ancient viruses that became so perfectly attuned to their hosts that they simply inserted themselves right into our chromosomes. Passing silently along from generation to generation, they bear witness to the uneasy truces our ancestors had to make with epidemics long past.

The sinister, queasy interconnectedness of life is an aspect of the world that humans cannot afford to ignore. And in this context our continuing efforts to build artificial barriers separating the healthy from the sick seem especially perverse. California’s Proposition 187 breaks new ground in inaugurating the medical apartheid state by denying government health-care services to undocumented immigrants and their children, a move that will cut a sizable portion of the state’s population off from the screening and vaccination programs necessary to prevent new epidemics. It’s hard to foresee the effects of these policies. America is already a quarantined society, stratified economically and geographically into hermetic suburbs and inescapable ghettos. Perhaps the gated luxury enclaves and private security forces can keep the new plagues at bay. But if we do succeed in confining the ravages of disease to the poor and the powerless, it will be at the expense of our own humanity.

The Hot Zone by Richard Preston,

Random House, $23.

The Coming Plague by Laurie Garrett, Farrar, Straus and Giroux, $25.

Art accompanying story in printed newspaper (not available in this archive): illustration/Russ Ando.