That was just the beginning. The day Kinfumu died, a nurse and a nun who had cared for him fell ill. The nun was evacuated to another town 70 miles to the west where she died–but not until the contagion had spread to at least three of her fellow nuns. Two have since died. In Kikwit, the disease raged through the ranks of the hospital’s staff. Inhabitants of the city began fleeing to neighboring villages. Some of the fugitives carried the deadly illness with them. Terrified health officials in Kikwit sent an urgent message to the World Health Organization. The Geneva-based group summoned expert help from around the globe: a team of experienced virus hunters (box) composed of tropical-medicine specialists, microbiologists and other researchers. They grabbed their lab equipment and their bubble suits and clambered aboard transport planes headed for Kikwit.
Except for a handful of patients too sick to run away, the hospital was almost abandoned when the experts arrived. While the team went to work, the Zairean government tried to cordon off the city to prevent more inhabitants from spreading the contagion across the countryside-possibly even to the sprawling slums of Kinshasa, the capital, where most of its 4.5 million people live in squalor and destitution. The quarantine was mostly a hollow announcement; it’s been years since there was a functioning government in Zaire. The international doctors sent people with bullhorns through the streets pleading with residents to stay home. And they managed to get a preliminary death toll–at least 58 of 76 confirmed sufferers have now died–and rush 16 blood samples to the Atlanta-based Centers for Disease Control and Prevention for analysis. Last week the CDC announced it had linked the outbreak to to a virus. It wasn’t just any virus. As many experts had feared all along, it was Ebola. If the word doesn’t make your hair standon end, it should. Discovered just 19 years ago, when similar outbreaks killed more than 400 people in Zaire and neighboring Sudan, the Ebola virus remains a gruesome mystery. No one knows where the virus resides in nature, how human epidemics get started or why they’re so rare. We know only that the virus can spread from person to person through body secretions, and that 50 to 90 percent of the victims die in a matter of days. The first flulike symptoms typically appear within three days of infection. Then, as the virus starts replicating m earnest, the victim’s capillaries clog with dead blood cells, causing the skin to bruise, blister and eventually dissolve like wet paper. By the sixth day, blood flows freely from the eyes, ears and nose, and the sufferer starts vomiting the black sludge of his disintegrating internal tissues. Death usually follows by day nine.
Ebola is a potent emblem of the microbial world’s undiminished power over us. But it’s not the only one. New viruses have emerged with terrifying regularity in recent decades. Most are still obscure tropical menaces with names like Machupo and Oropouche. But because they are vital menaces, they’re largely untreatable. And the AIDS epidemic has shown us what an obscure tropical menace can make of itself when the circumstances are right. Fifteen years ago, it was unimaginable. By the end of this decade, the global number of HIV infections should reach 40 million. And despite billions of dollars spent on years of intense research, AIDS is still a death sentence.
Scientists agree that AIDS won’t be the last viral scourge, and that message has finally registered with the masses. Movie-makers have already churned out thrillers like “Robin Cook’s Virus” (a made-for-TV movie) and “Outbreak,” in which an airborne Ebola variant strikes a california town and threatens tO wipe out the nation in 48 hours. And bookstores were already well stocked with nonfiction titles like Laurie Garrett’s “The Coming Plague” and Richard Preston’s “The Hot Zone,” a novelistic account of earlier Ebola outbreaks that’s been out less than a year and is already in its 21st printing. Obviously there is more at work here than concern for people in Kikwit or Kinshasa. We want to know whether Ebola is headed our way. Could it reach critical mass in a Third World capital, then engulf the globe? And what if Ebola somehow mutated into an airborne form? Could coughs and sneezes become the agents of mass death?
Not likely. Viruses are the ultimate parasites. Unlike bacteria, they have no life of their own. Bacteria absorbs nutrients, excrete waste and reproduce by dividing; viruses are simply shreds of genetic information, encoded as DNA or RNA, that can integrate themselves into a living cell and use its machinery to run off copies of themselves (chart, page 51). Their purpose is not to cause harm, just to replicate and spread. When a virus is more abundant in a person’s saliva, for example, it stands a better chance of infecting the next person who comes into contact with that secretion, in a kiss or on a shared glass. But as Amherst College evolutionary biologist Paul Ewald has shown, microbial life involves trade-offs. If the virus multiplies too aggressively, immobilizing or killing the person carrying it (the host), it takes itself out of circulation. Viruses that can survive outside the host’s body don’t have to be so considerate. Once sneezed onto a tabletop, for example, they can sit and wait for another host to come along. Similarly, a virus that can travel from host to host by way of a “vector,” such as a mosquito or rodent, has no stake in a particular host’s well-being.
Man isn’t Ebola’s natural host. The virus occasionally infects people, but the adventure is ultimately suicidal–the victims die too quickly to infect many others. Within the walls of a Zairean hospital, an Ebola victim may be close enough to others to spread the infection. But if the hospital can employ strict infection-control measures-such as wearing gloves, gowns and masks–trans-mission can be thwarted. And contrary to the terrifying twist in “Outbreak,” there’s no reason to think that a virus normally transmitted only through body fluids would suddenly mutate and start traveling by air. In any case, even if it did become airborne, Ebola wouldn’t survive more than a few minutes in the atmosphere: ultraviolet light destroys it. As deadly as it is, Ebola is ill equipped to go global, and humanity is well equipped to stop it.
Until recently, most experts thought of new vital diseases as accidents of genetic mutation. But of late, they have become less fearful of random genetic change–and more terrified by the effects of human social change. Consider the emergence of HIV-1 from sub-Saharan Africa. Many experts now assume the virus was present for decades or even centuries before it swept the globe in the 1970s and ’80s. Until the 1960s, it would have had a hard time escaping the continent’s isolated rural villages. But trucking and tourism brought the outside world to the countryside during that decade, while war and commerce drew villagers out into the world. Prostitution thrived along truck routes and in newly teeming cities, and for a sexually transmitted virus, the supply of hosts was suddenly limitless.
Sometimes it takes nothing more than a change in the weather to unleash a killer. In 1993, an exceptionally mild winter in the American Southwest caused an explosion of the region’s native field mice population. More people were exposed to the rodents. And consequently, some were stricken by a mouse-borne hanta virus that had never before been noticed on this continent. Fifty-five have since died, but the hanta-virus story is an exception. More often, says Stephen Morse, a virologist at Rockefeller University, human activities–from farming to urbanization and jet travel–are what speed the movement of viruses. “The primary problem,” he says, “is no longer virological but social.”
One way to stir up trouble is simply to encroach on a microbe’s habitat. As more families have moved into rural areas of Wisconsin, for example, encephalitis from the once obscure La Crosse virus has become increasingly common among children. It’s not just that the new exurbanites have placed their kids in the paths of the virus-carrying mosquitoes, says University of Wisconsin pathobiologist Thomas Yuill. They’ve done more than that. By sawing off hardwood trees – and letting new trunks sprout from the stumps–the newcomers have created countless small basins for the mosquitoes to breed in. Larger ecological disruptions can have more dramatic effects. Argentina’s campesinos started plowing under grasslands and replacing them with cornfields after World War II. As a result, a field mouse known as Calomys musculinus thrived. And so did a virus called Junin, which survives in the rodents’ urine and droppings and is easily inhaled on dust particles. By 1953, thousands of farmers were stricken with Junin each year, developing hemorrhagic fevers that kill one victint in five.
Urbanization has placed unprecedented numbers of people in close contact, making way for ever larger outbreaks. Without cities, we wouldn’t even have diseases like measles. (To sustain a chain of transmission, the common measles virus requires access to at least 250,000 potential hosts.) And the trend toward urbanization continues unabated. At the beginning of this century, only 10 percent of the world’s population lived in cities. By 2000, 50 percent will be city dwellers. “Since most of the mega-cities are in the developing world, where sanitation and health care are primitive,” virus tracker Gerald Myers of Los Alamos National Laboratory warns, “we can expect a lot more trouble.”
The cities of Zaire are a ease in point. Some 44 percent of the country’s estimated 43 million people live in towns and cities. Yet only 14 percent have access to clean water. The nation’s urban hospitals remain breeding grounds for infection. New syringes are in short supply; sanitation is often inadequate. At the university hospital in Kinshasa, several patients share a single bed. And corpses have piled up for months in the morgue of the city’s larger Mama Yemo Hospital; administrators lacked the funds to dispose of them. It’s no coincidence that two of central Africa’s three Ebola outbreaks have occurred in hospitals.
But who’s to stop the factors contributing to viral emergence? When building a dam is the only way to grow crops, is the prospect of a new mosquito-borne illness more daunting than of famine? What experts agree on is this: by paying more attention to the openings we create for new viruses-and by keeping closer track of unusual disease outbreaks–we can wrest some control over our fate.
A first step would be to create a network of surveillance posts to monitor local health problems. If local health workers could quickly report anomalous illnesses to an international agency–and the agency had the means to respond swiftly–the next AIDS might be detected and contained before it went global. Unfortunately, local health systems are a shambles in many of the regions where surveillance is needed most. And developed countries are making little effort to pick up the slack. The U.S. military, as part of its effort to keep soldiers alive, maintains a small worldwide network of laboratories. But no U.S. agency is directly responsible for monitoring public health beyond U.S. borders.
To fill this perilous gap, Donald Henderson of the Johns Hopkins School of Public Health proposes that the United States and other developed countries spend $150 million a year to fund 15 surveillance clinics, located near rain forests and on the outskirts of large tropical cities, along with 10 state-of-the-art virology labs. That may sound expensive, but it is no more than the world spent to eradicate smallpox, and it’s a small fraction of what a new global epidemic could cost. “We just haven’t learned our lessons very well,” says Dr. Joe McCormick, one of the CDC physicians who investigated the 1976 Ebola outbreaks in Zaire and Sudan. “We’re going to pay now or pay later.”
in the past decades, more than a dozen threatening viruses have emerged. Wheather they are due to people encroaching on untouched land, faster travel or reasons still unknown, these infections are taxing an already depleted global health network. Some better–known cases:
The virus that causes AIDS has infected 13 million people around the world since the epidemic began. By 2000, that number could reach 40 million.
Transmitted in the same manner as HIV but less deadly, it causes fata T-cell leukemia in only 1 percent of its victims. The virus is thought to be present on all continents.
Dot indicates significant viral outbreak
(filovirus) With a fatality rate of up to 90 percent, it killed hundreds in Zaire and western Sudan in 1976 and 1979. A new outbreak in Kikwit, Zaire, has killed scores.
(filovirus) Closely related to Ebola, this virus was identified in 1967 when 31 people were infected in West Germany and Yugoslavia by Ugandan green monkeys. 7 died.
(arenavirus) First identified in 1953 near the Junin River in northern Argentina. Spread by field mice, it kills 20 percent of its victims.
(arenavirus) This new virus was identified in 1990 in Sao Paulo, Brazil. Last year a Yale scientist accidentally infected himself and survived.
(arenavirus) This rodent-borne virus re-emerged last year in norther Bolivia when 7 family members were infected in Magdalena; 6 died.
(arbovirus) Identified in 1961 after causing flulike symptoms in 11,000 residents of Belem, Brazil. Transmitted by the biting midge, or sandfly.
(arbovirus) In the 1950s, this mosquito-borne virus was recognized in northern Kenya. An epidemic occurred in Egypt’s Nile River delta in 1977, with more than 10,000 infected.
A new form of this East Asian, rodent-borne virus appeared in the southwestern U.S. in May 1993, taking 12 lives; 106 cases, more than half fatal, have since been reported in 23 states.
(arenavirus) The virus that causes African hermorrhagic fever infects 200,000 to 400,000 annually in West African, killing approximately 5,000.
Severe strains of this mosquito-borne tropical virus have emerged in Asia and Latin America since the mid-’70s. There were 116,000 infections in Latin America alone 1990.
Source: World Health Organizational, Pan American Health Organization; Graphic by Lisa Mangano, Research by Brad Stone– Newsweek
Get all the shots recommended for the locale.
Bring all those you already take, and any your doctor recommends for diseases endemic to your destination.
Have your doctor prescribe a disposable supply.
Not advised in remote places.
Consider taking out a supplemental policy that includes air transport to a high-quality medical facility. Some policies will fly you only as far as the nearest English-speaking hospital– not a guarantee of high standards.
Find out which ones the U.N., the Peace Corps or U.S. corporations use.
Major American teaching hospitals like New York’s Columbia-Presbyterian are opening up clinics abroad.
If it’s safe to wait, you should–until you are flow to a country with a higher standard of medical care.
