Spillover: Animal Infections and the Next Human Pandemic (6 page)

In the minutes after Brownie’s death, she had changed into boots, long pants, and shoulder-length gloves and begun the postmortem exam. The owners were keen to know whether Brownie had eaten some sort of poisonous grass that might threaten their other horses too. The vet sliced opened Brownie’s abdomen and found his guts looking normal. No sign of twisted bowel or other blockage that might cause colic. In the process, “I got a couple of splashes of abdominal fluid on my leg.” You can’t do a postmortem on a horse without getting smeared, she explained. Next she looked into the chest, by way of a modest incision between the fourth and fifth ribs. If it wasn’t colic it was probably cardiac trouble, she suspected, and saw that hunch immediately confirmed. “The heart was massively enlarged. The lungs were wet and full of bloody fluid and there was just fluid right through the chest cavity. So he died of congestive heart failure. That was all I could conclude. I couldn’t conclude whether it was infectious or not.” She offered to take samples for lab testing, but the owners declined. Enough information, enough expense, too bad about Brownie, and they would simply bury the carcass with a bulldozer.

Were there bats around this property? I asked.

“There’s bats everywhere.” Everywhere throughout northern Queensland, she meant, not just at Little Mulgrave. “If you walk out the back here, you’ll see a couple hundred bats.” The entire area of Cairns and its environs: warm climate, plenty of fruit trees, plenty of fruit-eating bats. But the subsequent inquiry turned up nothing about Brownie’s situation that seemed to have closely exposed him to bats. “They couldn’t say, other than random chance, why this particular horse got infected.” Buried beneath ten feet of dirt, having left behind no samples of blood or tissue, he couldn’t even be labeled “infected” except by later inference.

Immediately after the postmortem, the vet washed her hands and arms thoroughly, wiped down her legs, and then went home to take a Betadine shower. She keeps a large supply of Betadine, the professional antiseptic of choice, for such occasions. She gave herself a good surgical scrub and got into bed, after a hard but not too unusual night. It wasn’t until nine or ten days later that she started feeling headachy and sick. Her doctor suspected the flu, or a cold, or maybe tonsillitis. “I get tonsillitis a lot,” she said. He gave her some antibiotics and sent her home.

She missed a week’s work, languishing with symptoms that felt like influenza or bronchitis: mild pneumonia, sore throat, a bad cough, muscle weakness, fatigue. At one point a senior colleague asked whether she had considered the possibility that the dead horse had infected her with Hendra virus. The young vet, trained in Melbourne (way down in temperate Australia) before she moved up to tropical Cairns, had scarcely heard Hendra virus mentioned in veterinary school. It was too obscure, too new, and not an issue in the Melbourne area. Only two of the four kinds of reservoir bats range that far south, and evidently they had yet to cause concern. Now she went to the hospital for a blood test, then another, and yes indeed: She had antibodies to Hendra virus. By that time she was back on her feet, working again. She had been infected and shaken it off.

When I met her, more than a year later, she was feeling fine, apart from a little weariness and more than a little anxiety. She knew well that the case of Mark Preston—his infection during a horse postmortem, his recovery, his interlude of good health, then his relapse—cautioned against complacency that the virus had left her forever. State health officials were tracking her case; if the headaches returned, if she felt dizzy or suffered a seizure, if her nerves tingled, if she started coughing or sneezing, they wanted to know it. “I still go and see the infectious disease control specialists,” she said. “I get weighed by the Department of Primary Industries on a regular basis.” From blood tests they charted her antibody levels, which continued to fluctuate peculiarly down and up. Lately the numbers were back up. Did that portend a relapse, or did it just reflect her robust acquired immunity?

The scariest part, she told me, was the uncertainty. “It’s the fact that this disease has been around for so little that they can’t tell me whether there’s going to be any future health risk.” How would she be in seven years, ten years? How high was the chance of recrudescence? Mark Preston died suddenly after a year. Ray Unwin said his health was still “crook.” The young vet in Cairns only wanted to know, in her own case, the same thing we all want to know: What next?

II

THIRTEEN GORILLAS

8

N
ot many months after the events at Vic Rail’s stables, another spillover occurred, this one in Central Africa. Along the upper Ivindo River in northeastern Gabon, near the border with the Republic of the Congo, lies a small village called Mayibout 2, a sort of satellite settlement just a mile upriver from the village of Mayibout. In early February 1996, eighteen people in Mayibout 2 became suddenly sick after they participated in the butchering and eating of a chimpanzee.

Their symptoms included fever, headache, vomiting, bloodshot eyes, bleeding from the gums, hiccupping, muscle pain, sore throat, and bloody diarrhea. All eighteen were evacuated downriver to a hospital in the district capital, a town called Makokou, by decision of the village chief. It’s less than fifty miles as the crow flies from Mayibout 2 to Makokou, but by pirogue on the sinuous Ivindo, a journey of seven hours. The boat wound back and forth between walls of forest along the banks. Four of the evacuees were moribund when they arrived and dead within two days. The four bodies, returned to Mayibout 2, were buried according to traditional ceremonial practice, with no special precautions against the transmission of whatever had killed them. A fifth victim escaped from the hospital, straggled back to the village, and died there. Secondary cases soon broke out among people infected while caring for the first victims—their loved ones or friends—or in handling the dead bodies. Eventually thirty-one people got sick, of whom twenty-one died: a case fatality rate of almost 68 percent.

Those facts and numbers were collected by a team of medical researchers, some Gabonese, some French, who reached Mayibout 2 during the outbreak. Among them was an energetic Frenchman named Eric M. Leroy, a Paris-trained veterinarian and virologist then based at the Centre International de Recherches Médicales de Franceville (CIRMF), in Franceville, a modest city in southeastern Gabon. Leroy and his colleagues found evidence of Ebola virus in samples from some patients, and they deduced that the butchered chimpanzee had been infected with Ebola. “
The chimpanzee seems to have been the index case
for infecting 18 primary human cases,” they wrote. Their investigation also turned up the fact that the chimp hadn’t been killed by village hunters; it had been found dead in the forest and scavenged.

Four years later, I sat at a campfire near the upper Ivindo River with a dozen local men who were working as forest crew for a long overland trek. These men, most of them from villages in northeastern Gabon, had been walking for weeks before I joined them on the march. Their job involved carrying heavy bags through the jungle and building a simple camp each night for the biologist, one Mike Fay, whose obsessive sense of mission drove the whole enterprise forward. Fay is an unusual man, even by the standards of tropical field biologists: physically tough, obdurate, free-spirited, smart, and fiercely committed to conservation. His enterprise, which he labeled the Megatransect, was a two-thousand-mile biological survey, on foot, through the wildest remaining forest areas of Central Africa. He took data every step of the way, recording elephant dung piles and leopard tracks and chimpanzee sightings and botanical identifications, tiny notations by the thousands, all going into his waterproof yellow notebooks in scratchy left-handed print, while the crewmen strung out behind him toted his computers, his satellite phone, his special instruments and extra batteries, as well as tents and food and medical supplies enough for both him and themselves.

Fay had already been walking for 290 days by the time he reached this part of northeastern Gabon. He had crossed the Republic of the Congo with a field crew of forest-tough Congo men, mostly Bambendjellés (one ethnic group of the short-statured peoples sometimes termed Pygmies), but those fellows had been disallowed entry at the Gabonese border. So Fay had been forced to raise a new team in Gabon. He recruited them largely from a cluster of gold-mining camps along the upper Ivindo River. The hard, stumbling work he demanded, cutting trail, schlepping bags, was evidently preferable to digging for gold in equatorial mud. One man served as cook as well as porter, stirring up massive amounts of rice or
fufu
(a starchy staple made from manioc flour, like an edible wallpaper paste) at each evening’s campfire, and adorning it with some sort of indeterminate brown sauce. The ingredients for that variously included tomato sauce, dried fish, canned sardines, peanut butter, freeze-dried beef, and
pili-pili
(hot pepper), all deemed mutually compatible and combined at the whim of the chef. No one complained. Everyone was always hungry. The only thing worse than a big portion of such stuff, at the end of an exhausting day of stumbling through the jungle, was a small portion. My role amid this gang, on assignment for
National Geographic
,
was to walk in Fay’s footsteps and produce a series of stories describing the work and the journey. I would accompany him for ten days here, two weeks there, and then escape back to the United States, let my feet heal (we wore river sandals), and write an installment.

Each time I rejoined Fay and his team, there was a different logistical arrangement for our rendezvous, depending on the remoteness of his location and the urgency of his need to be resupplied. He never diverted from the zigzag line of his march. It was up to me to get to him. Sometimes I went in by bush plane and motorized dugout, along with Fay’s trusted logistics man and quartermaster, a Japanese ecologist named Tomo Nishihara. Tomo and I would pile ourselves into the canoe amid whatever stuff he was bringing for the next leg of Fay’s trek: fresh bags of fufu and rice and dried fish, crates of sardines, oil and peanut butter and pili-pili and double-A batteries. But even a dugout canoe couldn’t always reach the spot where Fay and his crew, famished and bedraggled, would be waiting. On this occasion, with the trekkers crossing a big forest block called Minkébé, Tomo and I roared out of the sky in a Bell 412 helicopter, a massive 13-seater, chartered expensively from the Gabonese army. The forest canopy, elsewhere thick and unbroken, was punctuated here by several large granite gumdrops that rose above everything, hundreds of feet high, like El Capitan standing out of a green ground fog. Atop one of those inselbergs was the landing zone to which Fay had directed us. It was forty miles due west of Mayibout 2.

That day had been a relatively easy one for the crew—no swamps crossed, no thickets of skin-slicing vegetation, no charging elephants provoked by Fay’s desire to take video at close range. They were bivouacked, awaiting the helicopter. Now the supplies had arrived—including even some beer! This allowed for a relaxed, genial atmosphere around the campfire. Quickly I learned that two of the crewmen, Thony M’Both and Sophiano Etouck, had roots in Mayibout 2. They were present when Ebola virus struck the village.

Thony, an extrovert, slim in build and far more voluble than the other fellow, was willing to talk about it. He spoke in French while Sophiano, a shy man with a body-builder’s physique, an earnest scowl, a goatee, and a nervous stutter, sat silent. Sophiano, by Thony’s account, had watched his brother and most of his brother’s family die.

Having just met these two men, I couldn’t decently press for more information that evening. Two days later we set off on the next leg of Fay’s hike, across the Minkébé forest, heading southward away from the inselbergs. We got busy and distracted with the physical challenges of foot travel through trackless jungle terrain, and were exhausted (especially they, working harder than I) by nightfall. Halfway along, though, after a week of difficult walking, common miseries, and shared meals, Thony loosened enough to tell me more. His memories agreed generally with the report of the CIRMF team from Franceville, apart from small differences on some numbers and details. But his perspective was more personal.

Thony called it
l’épidémie
, the epidemic. This happened in 1996, yes, he said, around the same time some French soldiers came up to Mayibout 2 in a Zodiac raft and camped near the village. It was unclear whether the soldiers had a serious purpose—rebuilding an old airstrip?—or were just there to amuse themselves. They shot off their rifles. Maybe, Thony guessed, they also possessed some sort of chemical weaponry. He mentioned these details because he thought they might have relevance to the epidemic. One day some boys from the village went out hunting with their dogs. The intended prey was porcupines. Instead of porcupines they got a chimp—not killed by the dogs, no. A chimp found dead. They brought it back. The chimp was rotten, Thony said, its stomach putrid and swollen. Never mind, people were glad and eager for meat. They butchered the chimp and ate it. Then quickly, within two days, everyone who had touched the meat started getting sick.

They vomited; they suffered diarrhea. Some went downriver by motorboat to the hospital at Makokou. But there wasn’t enough fuel to transport every sick person. Too many victims, not enough boat. Eleven people died at Makokou. Another eighteen died in the village. The special doctors quickly came up from Franceville, yes, Thony said, wearing their white suits and helmets, but they didn’t save anyone. Sophiano lost six family members. One of those, one of his nieces—he was holding her as she died. Yet Sophiano himself never got sick. No, nor did I, said Thony. The cause of the illnesses was a matter of uncertainty and dark rumor. Thony suspected that the French soldiers, with their chemical weapons, had killed the chimpanzee and carelessly left its meat to poison the villagers. Anyway, his fellow survivors had learned their lesson. To this day, he said, no one in Mayibout 2 eats chimpanzee.

I asked about the boys who went hunting. Them, all the boys, they died, Thony said. The dogs did not die. Had he ever before seen such a disease, such an epidemic? “
No
,” Thony answered. “
C’etait le premier fois.
” Never.

How did they cook the chimp? I pried. In a normal African sauce, Thony said, as though that were a silly question. I imagined chimpanzee hocks in a peanutty gravy, with pili
-
pili, ladled over fufu.

Apart from the chimpanzee stew, one other stark detail lingered in my mind. It was something Thony had mentioned during our earlier conversation. Amid the chaos and horror in the village, Thony told me, he and Sophiano had seen something bizarre: a pile of thirteen gorillas, all dead, lying nearby in the forest.

Thirteen gorillas?
I hadn’t asked about dead wildlife. This was volunteered information. Of course, anecdotal testimony tends to be shimmery, inexact, sometimes utterly false, even when it comes from eyewitnesses. To say
thirteen dead gorillas
might actually mean a dozen, or fifteen, or simply lots—too many for an anguished brain to count. People were dying. Memories blur. To say
I saw them
might mean exactly that or possibly less.
My friend saw them, he’s a close friend, I trust him like I trust my eyes.
Or maybe:
I heard about it on pretty good authority
. Thony’s testimony, it seemed to me, belonged in the first epistemological category: reliable if not necessarily precise. I believed he saw these dead gorillas, roughly thirteen, in a group if not a pile; he may even have counted them. The image of thirteen gorilla carcasses strewn on the leaf litter was lurid but plausible. Subsequent evidence indicates that gorillas are highly susceptible to Ebola.

Scientific data are another matter, very different from anecdotal testimony. Scientific data don’t shimmer with poetic hyperbole and ambivalence. They are particulate, quantifiable, firm. Fastidiously gathered, rigorously sorted, they can reveal emergent meanings. That’s why Mike Fay was walking across Central Africa with his yellow notebooks: to search for big patterns that might emerge from masses of small data.

The next day we continued on through the forest. We were still more than a week from the nearest road. It was excellent gorilla habitat, well structured, rich with their favorite plant foods, and nearly untouched by humans: no trails, no camps, no evidence of hunters. It should have been full of gorillas. And once, in the recent past, it had been: A census of Gabon’s ape populations done two decades earlier, by a pair of scientists from CIRMF, had yielded an estimate of 4,171 gorillas within the Minkébé forest bloc. Nevertheless, during our weeks of bushwhacking, we saw none. There was an odd absence of gorillas and gorilla sign—so odd that, for Fay, it seemed dramatic. This was exactly the sort of pattern, positive or negative, that his methodology was meant to illuminate. During the course of his entire Megatransect he recorded in his notebook every gorilla nest he saw, every mound of gorilla dung, every stem fed upon by gorilla teeth—as well as elephant dung, leopard tracks, and similar traces of other animals. At the end of our Minkébé leg, he subtotaled his data. This took him hours, holed away in his tent, collating the latest harvest of observations on his laptop. Then he emerged.

Over the past fourteen days, Fay informed me, we had stepped across 997 piles of elephant dung and not one dollop from a gorilla. We had passed amid millions of stems of big herbaceous plants, including some kinds (belonging to the family
Marantaceae
) with nutritious pith that gorillas devour like celery; but not one of those stems, so far as he’d noticed, had shown gorilla tooth marks. We had heard zero gorilla chest-beat displays, seen zero gorilla nests. It was like the curious incident of the dog in the nighttime—a silent pooch, speaking eloquently to Sherlock Holmes with negative evidence that something wasn’t right. Minkébé’s gorillas, once abundant, had disappeared. The inescapable inference was that something had killed them off.