On July 3 Johnson and MacKenzie were some twenty miles outside of San Joaquin gathering ticks from the bushes around a chaco, or small cattle ranch. They suspected the virus might be carried by insects and were collecting samples to take back to their field lab for analysis.
When they began the long trek back to San Joaquin, the shorter Johnson kept having to slow down to avoid outpacing his usually athletic, longlegged colleague.
By the time they reached the river and started to canoe downstream to San Joaquin, Johnson noticed he was pulling most of the weight.
“I feel lousy. Really lousy,†MacKenzie said as he staggered off to bed.
The next morning Peace Corps nurse Rose Navarro, who had been sent in to help with translating, took one look at MacKenzie and pronounced his condition serious. She also noticed that Angel Muñoz, a Panamanian lab technician who had recently arrived from MARU to assist Kuns, had similar symptoms.
Johnson and Kuns contacted Panama through a cumbersome radio relay system, and a USAF C-130 flew in that day—the Fourth of July—to evacuate the two ailing researchers.
As he waved goodbye to MacKenzie, Johnson felt a feverish chill come over his body and thought, “Damn! I should have been on that plane too!â€
Over the next four days Johnson slowly hitchhiked his way, plane to plane, across Bolivia, Peru, and Colombia, finally reaching the Gorgas Hospital in Panama.
And now here he was, bleeding to death. To his left lay MacKenzie, on the right Muñoz. Johnson could imagine his brief obituary: “promising young research physician, born in Terre Haute, Indiana, 1929. Dead, age 34. Unmarried.â€
He knew there were two ways the virus could kill him. He’d seen it in San Joaquin. He might soon develop neurological symptoms, getting tremors and losing control of his muscles; eventually, he would have a grand mal seizure and die. Or the sheer volume of blood hemorrhaging from his capillaries would become so devastating that his body would go into shock and he’d die of cardiac arrest. Either death could strike in a matter of hours, or days.
In any event, there was no cure, no antitoxin. There was just lying and waiting.
After several more days of agony all three men showed signs of improvement, thanks largely to the efforts of an Army doctor flown in especially for them from Washington, D.C. Though he had never treated this particular ailment, the doctor had handled dozens of cases of another viral hemorrhagic disease called Seoul Hantaan, which first came to the attention of Westerners when 121 trench-bound American soldiers fighting in the Korean War died bleeding deaths that were not unlike the one threatening Johnson. (Nearly 2,500 U.S. soldiers suffered the Hantaan disease from 1951 to 1955.)2 Nobody had yet identified the Hantaan virus and it wasn’t clear how the disease was transmitted, but U.S. Army doctors had discovered that patients’ chances of recovery were greatly enhanced by careful supervision of their electrolytes and fluids. In all hemorrhaging diseases, as the capillaries leaked out precious fluids and proteins, the delicate chemical balances of vital organs such as kidneys, hearts, livers, and spleens were severely disrupted. Long before the immune system had a chance to mount a counterattack against the Hantaan virus, the organs would cease functioning and the patient would either convulse or go into shock.
Also in from Bethesda was Pat Webb, Johnson’s petite fiancée. Born in England and trained in both medicine and virology, Webb was doing research at NIH and had planned to move to Panama soon to join Johnson. Short, thin, and prematurely graying, Webb had an often caustic, opinionated style of speech. But for those who persevered, knowing Webb meant experiencing a woman possessed of a profound sense of humanity that infused her medical and research work.
Now she sat beside her future husband and caressed, kissed, or embraced him whenever he could tolerate the pain of being touched. By deliberately touching Johnson to illustrate there was no danger, she hoped to allay the fears of the frightened hospital staff.3 Webb’s fear was not the virus, but that Johnson would die, and a couple of times his condition seemed so grave she was convinced he wasn’t going to make it.
The Army physician’s efforts, however, paid off. Johnson survived.
As soon as he was up and about, Johnson started studying samples of the San Joaquin virus brought back to Panama with MacKenzie and Muñoz. He was able to confirm in the sophisticated MARU facilities what had tentatively been discovered in his glove-box contraption on the Bolivian frontier: the disease was caused by a virus that was similar to, but not the same as, Junin and Tacaribe.
With Johnson safely recuperating, Webb headed back to Washington in late August. It had been two weeks, the worst was over, and it was time she got back to work. On board the plane she was suddenly seized by a pounding headache, muscle pains, and waves of shaking chills. The symptoms escalated until Webb knew that, despite all her protestations to the Gorgas nursing staff, she had gotten the virus from kissing and embracing her fiancé. She was treated at the NIH hospital and, after ten distressing days, had recovered enough to go home. A few weeks later, Webb moved to Panama and eagerly joined in the detective work.
Though they had no way of knowing whether their painful illnesses had actually made them immune to the virus, Muñoz, MacKenzie, and Johnson made the journey back to San JoaquÃn in September, traveling now aboard USAF planes. They were quite naturally nervous, even fearful, but they felt compelled to return to the danger zone. The men shared a powerful scientific curiosity that pushed both doubt and fear aside, replacing them with a sleuthing urge every bit as powerful as that of a detective hunting down a serial killer. They needed to find out how the virus was transmitted in order to stop its spread.
On the way, Johnson and MacKenzie reviewed all the possible ways the three of them could have become infected. Since the infections seemed to have been simultaneous, it was unlikely they were due to accidents or carelessness in their primitive field laboratories. The window screens and DDT had probably protected them from any virus-carrying insects that might lurk in San JoaquÃn. And the fact that many family members who tended to dying relatives were not ill seemed to rule out person-to-person transmission of the virus. Of course, Webb’s illness forced an opposite conclusion.
The only experience the three had shared shortly before becoming ill was the town party. But what possible association could there have been between the party and their near-deaths?
In their absence Kuns had remained in San JoaquÃn, painstakingly capturing samples of every species of insect and mammal—from bedbugs to teeth-baring bats and slithering anacondas—he could get his hands on, all the while aware of the need to handle the animals with extreme care. As the wild rats tried to claw at him, or mosquitoes dove for his vulnerable flesh, Kuns deftly manipulated the creatures.
“I understand the ways of animals,†Kuns told his Bolivian assistants. He had a Ph. D. in veterinary sciences, specializing in the study of diseases that affected both humans and animals, and he had minored in wildlife ecology studies. Kuns was a details man; his training reinforced a natural tendency toward searching for answers by tediously sifting through mountains of minutiae. He and Johnson—the impatient man of action—were a study in contrasts. While the rest of the MARU team recuperated in Panama, Kuns organized forty San Joaquin men to assist in the capture of local creatures. All the men were volunteers who believed they had already had the strange disease and their survival presumably rendered them immune. Over a year’s time Kuns and his volunteers would collect some 10,000 mammals of dozens of species, all of which had to be identified and studied for viral contamination. Even more insects were amassed, and Kuns pored over microscopes, used field texts to figure out just what species each and every creature represented, and trained his assistants to do the same. When identity was impossible to ascertain, Kuns shipped samples to the Smithsonian in Washington, D.C., or the Field Museum of Natural History in Chicago, where experts made th
e final judgment calls.
In coming months Kuns would complete one of the most exhaustive ecology surveys ever conducted in South America, all done in the pressure-cooker atmosphere of an epidemic. Having flown bombing missions over Germany in World War II, Kuns had no trouble staying cool, though he never forgot that any insect or animal he held in his hands might carry the deadly virus.
The team went to enormous lengths to find the culprit. A typical rectangular thatched/wattle house was purchased and meticulously deconstructed pole by pole, every insect and animal scraped off and analyzed. By night Kuns and MacKenzie, wearing miner’s headlamps, waded into knee-deep water to collect nocturnal animals such as vampire bats and night mosquitoes. Even though they tried to maintain a modicum of nonchalance on such occasions, MacKenzie couldn’t help but feel chills when he would turn suddenly and spot beady red eyes staring at him. After a few nights on such forays, Kuns and MacKenzie figured out that the eyes belonged to giant constrictor snakes, anacondas, one of which they measured at over eighteen feet in length.
The townspeople were anxious to help, and Kuns had to warn people not to handle the animals unless they had already survived the disease. One afternoon the leader of Kuns’s volunteer ecology army, Einar Dorado, held a big gray mouse in his hands while Merl tried to jab the beast with a needle in order to withdraw a blood sample. The angry animal squirmed, bit Dorado, and urinated over his hands.
Two weeks later Dorado was dead. His prior ailment had probably been the flu and he was not immune to the mysterious virus.
Kuns thought about that large gray mouse—a type of rodent that was pervasive throughout San Joaquin. He remembered visiting a small home in the middle of town and spotting a six-year-old girl asleep atop a cowhide laid across the dirt floor. When the girl awoke, Kuns lifted the hide and dozens of those same big gray mice raced out of a nest in the floor.
As soon as Johnson and MacKenzie arrived in San Joaquin, the team spread word that they would give money to anybody who captured sick wild animals. Despite the strong monetary incentive, villagers were able to bring in only five sick animals over the next ten months, all large gray mice. The rodents were of a wild Calomys species normally found in the bush. Three of the animals died, suffering symptoms similar to those seen among the people of San Joaquin. The other two recovered and became virus carriers. The mysterious virus, which the team had dubbed Machupo after the local river, was found in the blood, spleens, or brains of the five animals.
The team hypothesized that the disease was carried the same way as the plague: by insects that inhabited the fur of the rodents. An alternative idea held that mosquitoes or ticks that fed on the mice might, in turn, feed on human blood and thereby spread the virus. In either case, an insect carrier had to be found.
From September 1963 to November 1964, the team, now including Webb, made numerous frustrating trips back and forth between San Joaquin and their Panama laboratories. They captured thousands of insects, ranging from tiny fleas and mites to larger ticks and mosquitoes. The insects were mashed up and their extracts scoured for Machupo virus.
None was found.
Night after late night in the Panama laboratory Johnson complained to Webb, “I can’t tell what the hell is going on. I’m running out of ideas here.â€
After having solved the first parts of the mystery with awesome speed, the team was now mired in confusion. Kuns was convinced that better insect traps and more extensive forays in the foothills around San Joaquin would eventually smoke out the culprit, but Johnson was dubious.4 Some villagers in San Joaquin were downright fed up with the investigation, and the Americans became targets of wholesale theft of critical supplies, such as the diesel fuel for their generator. Things became so unstable that the Bolivian government declared martial law in the area, flying in fifty-five soldiers to maintain order. Thirty-seven of those soldiers eventually got the disease.
The team’s work was further delayed by angry anti-American uprisings in Panama that erupted into full-scale riots, forcing closure of the Canal Zone airport and delaying return trips by Johnson, Webb, MacKenzie, and Kuns.
One hot June day in 1964 Johnson and Webb were going over their laboratory records in Panama and noticed an odd disease pattern among the hamsters they had infected experimentally. If they injected the virus into baby hamsters, the animals almost always died and the adult hamsters would eat the bodies. The adults would then become infected at a low level, but would survive. The adults, however, would pass on lethal infections to previously disease-free baby hamsters. How had these babies become infected?
Johnson and Webb, now married, happily spent long hours together in the laboratory, isolating viral samples from hamster blood. There were no shortcuts, no ways to get around the long tedious hours and days of work required to get a tiny pellet of viruses from thousands of hamster cells. Once the infected animal red blood cells were grown in petri dishes, the virus had to be purified out by a series of fractionization techniques. First, they mixed the hamster cells and blood with ammonium sulfate, which created a salted-out layer of gunk that sat at the bottom of a test tube. The fluid was poured off, and the virus-contaminated mass at the bottom was mixed with an alcohol, creating another layering. The virally infected layer, now smaller and purer, was spun about at low speed in a centrifuge; objects in the test tube migrated under spin to various positions according to their weights. The garbage—extraneous bits of hamster cells—formed a visible band in the tube, which was removed. Then the tube was spun again, this time at a very high speed, adequate to separate objects that differed only slightly in weight.
A pellet would be left, at long last, at the tube’s bottom—a nearly pure sample of concentrated, deadly Machupo viruses.
Johnson and Webb discovered that the adult hamsters were shedding virus in their urine. They then bred wild mice from San Joaquin and found the same thing—the animals actively urinated Machupo virus. The baby rodents had become infected because they were caged in an atmosphere of wood chips and sawdust drenched in Machupo virus.
Johnson felt the archetypical cartoon lightbulb flash above his head and heard himself shout, “Aha!â€
He returned to San Joaquin and did a very simple experiment: He divided the town in half. On one side he set five-cent mousetraps throughout houses and corn storage areas. The other half of San Joaquin was left alone. One woman living in the trap side of town begged Kuns to give her as many traps as possible; he could only spare three. In a single night she caught twenty-two mice in her home, proudly presenting them all to an astonished Kuns the following morning.
Within two weeks the difference was obvious. While the epidemic continued at the same pace on one side of town, no new Machupo virus cases occurred where mousetraps had been set. Two weeks later, having set traps throughout San Joaquin, Johnson’s team stopped the Machupo epidemic.
“This is unbelievable,†Johnson proudly said to himself. “Within just eighteen months we isolated the virus, discovered its mechanism of transmission, and stopped it cold.â€
Between 1962 and 1964 over 40 percent of the residents of the San Joaquin region were sick with Machupo virus; some 10 to 20 percent of the villagers died of the disease. If the region hadn’t been so sparsely populated, the impact could have been devastating. As it was, for the people of San Joaquin, Magdalena, and the surrounding area, Machupo virus was a scourge that claimed at least one member of every family and was carried aboard mouse-infested supply carts to remote parts of the eastern frontier. Its impact on people’s lives would not soon be forgotten.
Over the next three years the Panama-based researchers would fill in some of the remaining pieces of the Machupo puzzle, and successfully stop a second outbreak of the disease deeper in the Bolivian savannas.5
Johnson put together a best-guess history of Machupo virus, and together with MacKenzie, Kuns, and Webb published several scientific paper
s between 1964 and 1966 describing most aspects of the virus. He decided the epidemic’s roots lay in Bolivia’s social revolution of 1952, when the people of the San Joaquin area suddenly found themselves without an employer or steady source of food supplies. In their haste to grow corn and other vegetables, they chopped down dense jungle areas of the alturas and bandas wherever the land naturally formed a relatively flat mesa above the Machupo River flood line. In so doing, they unwittingly disrupted the natural habitat of the Calomys field mouse and provided the rodent with a superior new food source: corn.
The mouse population swelled during the 1950s and the rodents literally invaded the town of San Joaquin in the early 1960s.
By the time the first cases of Bolivian hemorrhagic fever (as the disease was now dubbed) surfaced, the mice could be found anyplace the townspeople stored food and grain.
And each night while the mice nibbled away at the humans’ food supplies, they urinated.
The virus could be eaten or inhaled or could gain entry through cuts in the skin; in any event, Machupo could be lethal.
Johnson noticed that there was a ritual common to every household in San Joaquin. Before dawn the mothers and grandmothers would awaken and quietly prepare breakfast for the men and children. While pots boiled, the women would sweep their dirt and clay floors.
The Coming Plague Page 4
