Spillover: Animal Infections and the Next Human Pandemic (59 page)

Gimble was a well-known member of one of the famed Gombe families; his mother had been Melissa, a successful matriarch, and his brothers included Goblin, who rose to be the community’s alpha male and lived to age forty. Gimble’s life and career would be different—and shorter.

Soon after getting the results on Gimble, Beatrice Hahn wrote a long email to Jane Goodall, explaining the context and the implications. Goodall herself had trained as an ethologist (she earned a PhD at Cambridge), not as a molecular biologist, and the realm of western blot analysis for antibodies was as alien to her as field sampling had been to Hahn. Goodall’s work on chimpanzees began back in July 1960, at what was then the Gombe Stream Game Reserve, on the east shore of Lake Tanganyika, and which later became Gombe National Park. She established the Gombe Stream Research Center in 1965, based in a small concrete building near the lake, and continued her study of chimps in the hilly forest for another twenty-one years. In 1986 Goodall published an imposing scientific opus,
The Chimpanzees of Gombe
,
and then ended her own career as a field scientist because, appalled by the treatment of chimpanzees in medical labs and other captive situations around the world, she felt obliged to become an activist. The study of Gombe’s chimps went ahead in her absence, thanks to well-trained Tanzanian field assistants and later generations of scientists, adding decades of data and precious continuity to what Goodall had started. She remained closely connected to Gombe and its chimps, both personally and through the programs of her Jane Goodall Institute, but she wasn’t often present at the old research camp, apart from stolen interludes of rest and reinvigoration. Instead she traveled the world, roughly three hundred days a year, lecturing, lobbying, meeting with media people and schoolchildren, delivering her inspirational message. Hahn understood the intensity of Goodall’s protectiveness toward chimps in general, toward Gombe’s chimps in particular, and of her wariness toward anything that might put them in more jeopardy of exploitation, especially in the name of medical science. At the end of the long email, Hahn wrote:

Let me finish by saying that finding SIV
cpz
in the Gombe community is a virologist’s DREAM-COME-TRUE. Given the wealth of behavioural and observational data that you and your colleagues have collected over decades, it is the IDEAL setting to study the natural history, transmission patterns and pathogenicity (or lack thereof) of natural SIV
cpz
infection in wild chimpanzees. Moreover, all this can be done entirely non-invasively. AND there certainly are funding opportunities for such a unique study. So, the virologist’s dream-come-true does not have to be the primatologist’s nightmare, although I am sure it will take some time before I can convince you of that.

Eventually she did convince Goodall, but not before another nightmarish discovery emerged from the work.

Earlier in her email, Hahn had written: “With respect to the chimpanzees, it is probably safe to say that SIV infection will NOT cause them to develop immunodeficiency or AIDS.” On that point, she would prove herself wrong.

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J
ane Goodall described her own concerns when I caught up with her during one of her stopovers. We knew each other from previous adventures—among chimps in the Congo, among black-footed ferrets in South Dakota, over single-malt scotch in Montana—but this was a chance to sit down quietly at a hotel in Arlington, Virginia, during a paralyzing snowstorm, and talk about Gombe. The fiftieth anniversary of her own chimp study was approaching, and I had been assigned by
National Geographic
to write about it. After we discussed her childhood influences, her dream of becoming a naturalist in Africa, her mentor Louis Leakey, her early days in the field, and her time as a PhD student at Cambridge, she herself mentioned genetics and virology. At that point I turned the conversation to SIV.

“I was really, really apprehensive about Beatrice Hahn’s research,” Jane volunteered. “We were, a lot of us, really nervous about the result of what might happen if she found HIV/AIDS.” She had met Hahn, talked with her, and was reassured by the force of Hahn’s concern for the chimps’ welfare. “But still. I still have this unease because, even though she cares, once these results are out, as they are now, other people can use them in different ways.” For instance? What sort of dangers, I asked, did Jane have in mind? “That this would start a whole new flurry of research on captive chimps in medical labs.” The news of chimps with AIDS, she feared, would sound like a promising opportunity to learn more about AIDS in humans, never mind the chimps.

What about the impact of the virus at Gombe itself? We both knew that Hahn
had
found something resembling AIDS, and by now Gimble was dead. What about the prospect that other members of the Gombe community might die of immune failure? “Yeah, exactly,” Jane said. “That’s a very scary thought.”

As scary as it was, though, she realized from the start of her conversations with Hahn that such a finding could be taken two ways. On the one hand, Jane said, there was a possible consolation: If people heard that wild chimps carry an AIDS-causing virus, they might stop hunting and butchering and eating them. “Because they’ll be afraid. That was one side of it. Then the other side of it was, well, people will say, ‘All these creatures are really dangerous for us, so let’s kill them all.’ It could have gone either way.” Jane is a perspicacious woman. She has the aura of a secular saint but is actually quite human, grounded, savvy, and capable of ambivalence. As things have transpired so far, she noted, neither of the extreme outcomes has occurred.

Briefly we discussed Hahn’s noninvasive sampling methodology: Urine might contain antibodies, and feces could yield viral RNA. Jane allowed that that part was reassuring, not having to knock out chimps and jab them with needles. “Don’t need blood,” she said. “Just need a bit of poo.” Amazing what they can do from a bit of poo, I agreed.

So she had given her consent for Hahn’s study, and the work proceeded. At the end of November 2000, Hahn’s lab in Alabama received the first batch of material, which included three fecal samples from poor Gimble. Hahn’s grad student Mario Santiago did the screening, and again all three of Gimble’s samples tested positive. Santiago then amplified a viral RNA fragment and sequenced it, confirming that Gimble’s virus was indeed SIV
cpz
. It seemed to be a new strain, distinct enough from other known strains that it might be unique to East Africa. This was significant on several counts. Yes, the chimps of Gombe were infected. No, they couldn’t be source animals for the human pandemic. The variants of SIV found by Martine Peeters in western Africa (this was before Hahn’s own findings from Cameroon) more closely matched HIV-1 group M than the Gombe virus did.

In mid-December, another email from Hahn’s computer went out to Richard Wrangham, Jane Goodall, Martin Muller, and others. Under the subject line
GOOD NEWS AT LAST
, Hahn described the findings from Gimble and the position of his strain on the SIV family tree. Then, with her characteristic penchant for uppercase exuberance, she wrote: “THIS IS A HOME RUN!”

105

T
hat was just the beginning. For nine years the study continued. Fieldworkers at Gombe collected fecal samples from ninety-four different chimpanzees, each of which was known by name and, in most cases, by its individual character and family history. Beatrice Hahn’s people did the analyses, finding that seventeen of those ninety-four chimps were SIV-positive. As time passed, some chimps died. Others disappeared in the forest and were presumed dead when they failed to reappear. Death is often a private matter for wild creatures, including chimpanzees, especially when it comes upon them by slow and painful degrees. They tend to go absent from the social group, if there is a social group, and meet the end alone. Gimble last showed himself to trackers on January 23, 2007. His body was never found.

Back in Birmingham, there was turnover of a different sort, as grad students and postdocs cycled through Hahn’s lab. Mario Santiago departed, heading off for the next stage of his career, and Brandon Keele arrived. Samples continued coming from Gombe, in occasional batches, and those samples were analyzed—a slow and laborious process. Much of the work fell to Keele, though even for him this was “a backburner project.” Keele described to me, during my visit with him at Fort Detrick, the moment of recognition that occurred near the end of his postdoc period, bringing that project to the front burner.

“I was trying to leave and finish up. I said to myself, ‘I wonder what’s happening with these chimps?’ ” He was aware that the number of known SIV-positives at Gombe had increased as the sampling stretched on, and that there was evidence of vertical transmission (mother to infant) as well as sexual transmission accounting for new infections. He thought the study might yield an interesting, undramatic paper about how a harmless virus spreads through a population. “And then we started compiling the data,” he told me. That meant bringing in a dimension of behavioral observations from the field. So he contacted collaborators at the Jane Goodall Institute’s research headquarters in Minnesota and, asking about one individual after another, heard a drumbeat of unsettling news.

“Oh, no, that chimp is dead.”

“No, that chimp is dead. He died in 2006.”

“No, that chimp is dead.”

Keele recalled asking himself: “What the hell is going on?” Part of the answer, revealed when he saw an updated mortality list, was that a wave of untimely deaths had been sweeping through SIV-positive members of the Gombe population.

He and the team at Hahn’s lab had lately written an abstract for a talk he planned to give at a meeting, which would lead in time to a journal publication. The draft abstract, by Keele’s recollection, contained a sentence such as: “It doesn’t really seem that there is a death hazard to infection in these chimps.” They had sent the draft to their partners at Gombe, who responded quickly with news of seven additional chimpanzee deaths, about which Keele hadn’t even known. He scrapped the abstract, thought again about what he was doing, and began working more closely with Gombe and Minnesota to assemble a more complete set of data. Then they would see where it led.

Around the same time, spring of 2008, Keele also heard about some unusual pathology results on tissues from one dead Gombe chimp. The chimp was known as Yolanda, a twenty-four-year-old female. She sickened in November 2007, of an unknown ailment, and came down from the mountains to languish near the research center. People tried to feed her, but Yolanda didn’t eat. She sat in the rain amid thick vegetation, weakened and miserable, and then died. They put her body in a freezer. Two months later, it was thawed for necropsy.

The necropsy was performed by Jane Raphael, a Tanzanian veterinarian working at the Gombe Stream Research Center and specially trained for the task. Not knowing whether Yolanda had been SIV-positive or not, Raphael took the stipulated precautions. She wore a full Tyvek suit, two layers of gloves, an N95 respirator mask, a face shield, and rubber boots. She split open Yolanda’s belly, cut through the ribs, and spread them wide to see what she could see.

“The main problem was in the abdominal cavity,” Raphael told me, two years later, as we sat in her small office just up from the shore of Lake Tanganyika. “There was something like abdominal peritonitis. The intestines were very much adhered together.” Raphael, a quiet woman, wearing a neat cornrow hairdo and a flowered print dress, chose her words carefully. She described separating the glommed guts with her gloved hands. “It was unusual,” she said. She seemed to remember it all vividly. “The muscles underneath the pelvis were very much inflamed. Red. And they had some blackish spots.” What caused the inflammation? Cautious of going beyond her data, Raphael said she didn’t know.

Her inspection done, she snipped out tissue samples from virtually every organ: spleen, liver, intestines, heart, lungs, kidneys, brain, lymph nodes. For the SIV-positive cases, she said, lymph nodes were especially important. Yolanda’s lymph nodes appeared normal to the eye, but histopathology would later penetrate that illusion. Some of the samples, preserved in RNAlater, went off to Beatrice Hahn. Others, pickled in formalin, were destined for a pathologist in Chicago. When the results came together, this case would challenge prevailing ideas about SIV in chimpanzees. “Previously it was said, they are infected but they don’t come down with the disease,” Raphael told me. “Yolanda made us to start thinking otherwise.”

I followed the pickled samples to Chicago, where the pathologist who had examined them, Karen Terio, welcomed me to a glimpse of the evidence. Terio had trained as a veterinarian, at one of the country’s best vet schools, and then did a residency and a doctorate in pathology, specializing in diseases transferred between animals of different species. She worked for the University of Illinois and consulted for the Lincoln Park Zoo, which helps run a health-monitoring project at Gombe. Hence the lymph nodes and other bits of Yolanda came for her expert scrutiny. Terio cut up the tissues, sent them to laboratory technicians for mounting and staining, and sat down for a look at the slides. “It was striking because I couldn’t find any lymphocytes,” she told me. “When I saw the first lymph node, I thought, ‘Hmm, this is weird.’ ” She asked her boss to have a look through the microscope. He did, and agreed there was something very wrong. She phoned a colleague at the Lincoln Park Zoo, Elizabeth Lonsdorf, who leads the zoo’s work on behalf of wild African apes, including the health project at Gombe.

“We have a problem,” Terio told Lonsdorf. “She doesn’t have any lymphocytes.”

“Does that mean what I think it means?”

“Yes. The lesions in this animal look like an end-stage AIDS patient.”

Together she and Lonsdorf made a call to Beatrice Hahn. Hahn’s first question was, “Are you sure?” Terio was indeed sure, but she quickly emailed images of the slides so that the others could judge for themselves. Brandon Keele was by now in the loop. Terio sent actual slides to another collaborator, an expert on immune-system pathology, to refine the diagnosis. Everyone agreed and, with the sample code broken, everyone knew how these pieces fit together: The chimp Yolanda, dead at age twenty-four, had been SIV-positive and suffering immune deficiency.