On reaching Mugunga Dr. Roberts went directly to the MDM cholera treatment center. After two months of compiling the death toll from the unfolding disaster in Rwanda, he would finally have a chance to intervene. The faceless numbers had not prepared him for what he found. More than a thousand cholera victims were crammed into an open area the size of a baseball diamond. Every five minutes, one of them would die. Desperate aid workers moved among the diseased, trying to help those that could be saved with the meager and entirely inadequate resources at hand.
The treatment for cholera under these conditions is simple and remarkably effective. Cholera is a disease that kills by dehydration. The vast quantities of watery diarrhea produced by its victims can sap more than a liter of fluid an hour from their bodies, often leaving a shriveled corpse within twenty-four hours of the first symptoms. Oral rehydration therapy requires only that the victim drink a mixture of water and salts in sufficient quantities to replace the lost fluids. Before the development of this simple treatment just over thirty years ago, cholera killed between 30 and 60 percent of those with disease. Proper application of oral rehydration can reduce this fatality rate to less than 5 percent.
Oral rehydration requires clean water. One of the organizers of the aid effort, Dr. Jacques de Milliano, president of Médecins Sans Frontières (MSF, or Doctors without Borders), estimated that they needed 3 million gallons to provide for the refugees. On the day that Les Roberts arrived in the camp, fifty thousand gallons of water were delivered to Goma.
In the morning of that day, the MDM cholera treatment center had taken delivery of a bladder containing thirteen hundred gallons of water. Within two hours it was gone. Most had gone not to the cholera victims, but to thirsty refugees armed with guns and machetes. By afternoon aid workers had little more than sentiment to offer the afflicted. Les Roberts watched as cholera drained the life from those around him. As he stood there amid the horror of the epidemic, a feeling of utter helplessness overwhelmed him. In that moment, he realized that he had come to “the worst place on earth.”
By the end of the day, more than a third of the people in the treatment center had died. The scene repeated itself at similar centers in this camp and at the other two camps around Goma. Worse yet most of the victims never made it to the rehydration tents. Many days would pass before the situation improved. On July 24 six thousand of the refugees would die in a single day. The disaster was just beginning.
Roberts and the other aid workers who had converged on Goma had prepared themselves for the challenge of delivering medical care for diseased, wounded, and malnourished refugees. What set Goma apart from other refugee operations was the overwhelming task of managing the dead. For weeks on end, refugees hired by the aid agencies drove along the camp’s makeshift network of roads, removing corpses and stacking them like cordwood in the backs of pickup trucks. The trucks unloaded their grisly cargo at one end of the camp, where excavating equipment borrowed from the French military labored from dawn to dark, digging endless trenches to receive the steady flow of bodies.
At the treatment center where Dr. Roberts worked, MDM had hired four refugees who spent the entire day removing the dead. A fifth refugee moved from corpse to corpse attending to cholera’s most brutal consequence. She did not remove the dead; she collected the living. She lifted hundreds of infants and children from the arms of their dead mothers and arranged for the care of cholera’s orphans.
In the crush of desperate and dying refugees, the walls and barriers that define civilization disappeared. The lines that separate one person from another, one space from the next, life from death, faded. Only the tightly packed bodies of the diseased and the dying together with the presence of medical workers and their supplies delineated the location of the cholera treatment center. One morning the physician managing the center assigned Dr. Roberts and another aid worker to establish a perimeter around the center. If it were to serve as more than a collection point for the dead, they would need to define its boundaries. In particular, they needed to protect the tent’s water supply. As they set about putting up a fence, they immediately discovered that they could not drive a single post into the ground. Throughout the camp, just below the surface, an impervious layer of solid volcanic rock made digging impossible. Each post required not a posthole, but a pile of rocks to hold it in place.
They labored for hours under the equatorial sun, making their way past the desperate and the dead, trying to create an island of order amid the chaos, piling rocks around one fence post after another. At one point that afternoon, as Dr. Roberts stepped back to stretch the fabric between two posts, the ground beneath him seemed to give. He pulled back reflexively and turned to look down. The dead body he had stepped on stared back at him. Dr. Roberts adjusted the fence line and moved on. Survival in Goma demanded well-defined borders.
In addition to being an epidemiologist, Les Roberts is an environmental engineer. He understood all too well that treating cholera victims, no matter how well it was done, would not solve the problem. The cholera outbreak in Goma was a monster storm beyond anything in recent memory. The center of the storm was Lake Kivu, the area’s only adequate source of drinking water.
It is routine practice at refugee camps to drill wells at locations throughout the camp and carefully protect the wellheads from contamination. At Goma the volcanic rock that made setting fence posts so difficult made digging wells impossible. Bringing water into the camps was not feasible. The trucks and roads available in Zaire could not begin to provide the thousands of truckloads of water required by the refugees. Air transport could only bring in a trickle. To the thirsty refugees, the answer was simple. Lake Kivu contained an inexhaustible supply of water.
When the hurricane of weak and hungry refugees collided with the nor’easter of Goma’s geography and geology, the superstorm of infectious disease that followed was almost inevitable. With a single water supply, a slight microbial breeze could set the storm in motion. One can only speculate as to the source of that first wind. Perhaps one of the refugees picked up the disease from a source in Goma and then contaminated the lakeshore. Perhaps cholera was hiding in those clear blue waters even before the first refugees arrived.
Once cholera found its way into the crush of refugees that blanketed the vast hillside above Lake Kivu, the storm began to take shape. The frozen lava beneath their feet that had defied efforts to dig postholes and wells made the construction of latrines impossible. Instead, the excrement from hundreds of thousands of people, including tens of thousands of cholera victims, flowed steadily down the hillside and into the lake. As the disease took its toll on the refugees, even their dead bodies began to appear in the lake.
From the first day that they began to arrive, refugees crowded the shores of the lake, filling whatever container they could find. They had no alternative. They could not afford to be concerned about the vast numbers of bacteria seeping into the lake. A strong enough thirst makes any water clean enough to drink.
Under other circumstances, trucks with automatic chlorinators would be used to transport, treat, and distribute the lake water, but they were simply not available in adequate numbers. With no way to purify the water, nothing stood between the disease and its victims.
Dr. Roberts was death’s accountant. Each day, he and half a dozen other epidemiologists set out to estimate how many people in the camps were well, how many were sick, and how many had died. Each time he came to Lake Kivu, he had a sense of tremendous futility. He envisioned an effort to enlist refugees to simply add a chlorine solution to buckets of water at Lake Kivu rather than waiting for chlorinator trucks. He went to his superiors at the WHO and asked that he be relieved from his other duties to organize this effort. They insisted that he attend to his primary task, which was to assemble a body count.
Reluctantly he continued with his grim tally as the cholera epidemic ran its course. After cholera had made its way through the camp, shigella, another waterborne killer, moved in. Shigella is a bacteri
a that shreds the lining of the gut, causing bloody diarrhea and in many cases death. The counting continued. When Roberts and the other epidemiologists from Goma generated the official estimate of deaths, the result was staggering. More than sixty thousand people had died in less than one month, most of them in just two weeks.
Goma was horrific for its scale and suddenness, but little Gomas happen every day all around the world. Tomorrow, between the time you wake up and the time you eat lunch, diarrheal diseases will have killed more people than Hurricane Katrina. In the next ten days, they will kill more people than all the automobile accidents in the United States in an entire year. In less than two months, the count of their victims will surpass the death toll from the Indian Ocean tsunami. Within one year 1.8 million people worldwide will die from diarrheal diseases. The World Health Organization estimates that 88 percent of those deaths derive from unsafe water and inadequate sanitation and hygiene. Children under five will account for 90 percent of the victims.
Around the world 1.1 billion people lack access to improved water sources and 2.6 billion people lack access to improved sanitation. In the words of former U.N. secretary general Kofi Annan, “We shall not finally defeat AIDS, tuberculosis, malaria, or any of the other infectious diseases that plague the developing world until we have also won the battle for safe drinking water, sanitation and basic health care.” The problems facing the drinking water supplies of industrialized countries of the world might seem far removed from the desperate struggle for clean water in the developing world. But as we swarm over the planet in ever-increasing numbers with ever-increasing speed, the protection afforded by distance and oceans is an illusion. Disconnection is no longer possible.
On January 29, 1991, just a year before the outbreak in Goma, the General Office of Epidemiology, Ministry of Health (MOH), in Lima, Peru, received reports of an increase in gastroenteritis in an area of the Pacific coast just north of Lima. The MOH responded immediately and within days microbiological samples from the victims were sent to labs in Peru and to labs at the CDC. The results startled public health officials throughout the Americas. For the first time since the nineteenth century, cholera was on the loose in the Western Hemisphere.
One of the laboratories that received samples belonged to Dr. Eugene Rice at the U.S. EPA Drinking Water Research Laboratory in Cincinnati. As the EPA expert on disinfection, his job was to determine the concentration of chlorine needed to purify drinking water in Peru. His first job, however, was not to kill the cholera, but to grow more. Within days billions of bacteria were flourishing on agar plates in the tropical warmth of the culture room.
When Dr. Rice examined the culture plates, he noticed something unusual. As he expected, most of the plates were coated with smooth disks like drops of wax, each one representing a colony containing millions of bacteria. Then he noticed that a few of the colonies were different. Not smooth at all, these colonies had a rough, tortured surface. When he examined these colonies under a microscope, the bacteria from the rough colonies hung together in clumps of tens or even hundreds of cells. By comparison bacteria from the smooth colonies were evenly dispersed. On a hunch he chose to test cells from the two different cultures separately. When he exposed the two groups of cells to chlorine, the results were chilling.
As expected, chlorine killed the bacteria from the smooth colonies rapidly and effectively. Within ten seconds hundreds of thousands of bacteria were reduced to a handful of survivors. Then Dr. Rice exposed cells from the rough or rugose colonies to chlorine. When he examined samples after thirty seconds, thousands of viable bacteria were floating in clumps in the solution. Even after two minutes, these hardy clusters of bacteria were still present.
The rugose strain, it turned out, produced a gooey slime that caused the bacteria to clump together. Chlorine might kill some of the cells on the outer layers of these clusters, but it could not reach into the core. The cells on the outside had sacrificed themselves to protect their bacterial brethren against the chlorine.
In the developed world, the threat posed by chlorine resistance lies more in the possibilities it raises than in any immediate hazard. The cholera outbreak in Peru did ultimately reach the United States, where 102 people fell seriously ill and one died, but these introduced cases never exploded into an epidemic as they did elsewhere. The universal use of water filtration and sewage treatment coupled with the relatively high level of sanitation limited the experience of the United States to a small number of isolated cases. However, the fact that this sort of resistance can occur raises the possibility that cholera or other pathogens could develop the capacity to circumvent the systems we use to treat our water.
When we take technological aim at a microbe, our target is not only moving, but it is also redefining itself to confound our aim and our weapons. When you look at the world from the perspective of a pathogen, human success in beating back most infectious diseases from the industrialized world has created a vast, underexploited ecological niche. A pathogen that can find its way past the detergents, filters, disinfectants, and antibiotics that we throw up in front of it has hit the mother lode. In terms of evolution, this means that a pathogen with the characteristics necessary to get around these barriers will have the greatest chance of reproducing and infecting others. In other words, when we place a barrier in front of a pathogen, we simply redefine the criteria for success.
The emergence of chlorine-resistant pathogens such as cryptosporidium or toxoplasma as agents of waterborne disease provide clear evidence that treatment-resistant organisms can and will emerge. The appearance of a strain of cholera that exhibits a degree of chlorine resistance suggests that even an old and fearsome waterborne nemesis may have the capacity to reinvent itself.
Filters, too, can be defeated. Regulators and treatment plant operators take comfort in the fact that modern filtration plants can remove 99 percent or more of the cryptosporidium flowing into the plant. Clearly reducing the number of oocysts entering the plant by a factor of a hundred or a thousand will dramatically reduce health risks, but it is essential to recognize two things. First, under conditions that are not unusual, millions if not billions of oocysts could flow into a typical treatment plant, and thousands if not millions will flow out to the consumers. Second, the average oocyst flowing out will not be the same as those flowing in. The filter will remove those oocysts most susceptible to removal, that is, the largest oocysts, leaving behind the oocysts that are best suited to passing through filters.
Just as the emergence of antibiotic resistance has put us in a pharmacological arms race with pathogens, so the emergence of cryptosporidium as a significant human pathogen signals the beginning of a new era in the provision of safe drinking water that will challenge us to develop new strategies for source water protection and drinking-water treatment. Perhaps the most appropriate way to view cryptosporidium is as a microbial “proof of concept.” Nature can indeed build an organism that we cannot control with chlorine, which, for almost a hundred years, has been the big gun in our water treatment arsenal. Variants of cryptosporidium or other chlorine-resistant pathogens may emerge that are smaller, more infectious, or more virulent. More important, there is no reason to assume that other pathogens will not develop similar capacity to resist disinfection if they have not done so already.
In the world of public health, diseases caused by newly evolved organisms are referred to as emerging infectious diseases. The CDC devotes an entire journal to their study. Twenty-five years ago, neither cryptosporidium nor E. coli O157:H7 would have made its way onto the list of existing human pathogens. Many other pathogens have joined that list and new ones are added every year. Some of them are also waterborne. It is entirely possible, perhaps even likely, that a pathogen with the durability of a cryptosporidium oocyst and the deadly effects of E. coli O157:H7 could emerge in the not too distant future.
In the spring of 2003, a previously unknown viral infection was killing people in Hong Kong. The disease came to be known as Se
vere Acute Respiratory Syndrome (SARS) because the overwhelming and often fatal lung infection struck with such devastating speed. SARS appears to have moved from pigs to humans and became the subject of a massive global public health effort to contain it. For weeks the evening news carried pictures of workers in their germ warfare suits at hospitals in Hong Kong and Toronto as they struggled to comprehend and contain this terrifying new disease. Less widely publicized were the results of studies showing that human feces could spread the disease. The worst local outbreak in the entire epidemic occurred because a man with the disease stayed in an apartment building with poorly vented toilets. In other words one of the deadliest diseases to emerge in recent years showed that it had the potential to become waterborne.
Simple compassion demands that the developed world take action to improve the water supply of the world’s poor. Few actions will have a greater impact on global health. Enlightened self-interest makes this call to action even more urgent. It is no coincidence that deadly diseases from SARS to avian flu began in the developing world. Communities in which water and sewage is untreated or inadequately treated and humans live in crowded conditions and in close proximity with animals provide an ideal setting for the emergence of waterborne pathogens. When that happens, distance will provide limited protection.
Two hundred years ago, mere mountain ranges could hold cholera at bay, and when the deadly disease finally escaped from Calcutta, it took more than five years to travel just five thousand miles. Today we are all next-door neighbors. The stunning speed with which avian flu has spread should remind us how easily new and deadly pathogens could reach us in our shrinking world.
The Blue Death Page 27
