Friday, October 28, 2016

The Origins of AIDS

This is a draft of the first part of an abandoned two-part book review I wrote a while back about three books about the origins and spread of the HIV virus. They were Tinderbox: How the West Sparked the AIDS Epidemic and How the World Can Finally Overcome It, by Craig Timberg and Daniel Halperin; The Origins of AIDS, by Jacques Pepin; and The Chimp and the River: How AIDS Emerged from an African Forest, by David Quammen.

Early in the 20th century, in the southeastern corner of Cameroon in central Africa, a hunter killed and butchered a chimpanzee for meat, nicking himself in the process. That event, as trivial as a papercut, set in motion one of the greatest catastrophes in human history: The global AIDS pandemic, which has killed 30 million people to date and continues to infect two million more each year. (The only disasters that exceed it in scale are the Black Death of the 14th century, the 1918 Spanish flu, and World War II.) At each step in the spread of the disease entirely contingent circumstances came into play, many the result of well-intentioned humanitarian initiatives, that amplified the pandemic when it might have burned itself out. These books tell two stories: One is the story of the origin and global spread of the Human Immunodeficiency Virus (HIV); the second is the story of the dedication, ingenuity and sheer good luck of the scientists who figured it all out.
AIDS, like the flu or smallpox, is zoonotic, that is, it passes from animals to humans. Variants of the Simian Immunodeficiency Virus (SIV), from which HIV derives, have circulated for millennia among the primates inhabiting the tropical rainforests of west and central Africa. In fact, on at least at least eight separate occasions in the 20th century a far less transmissible strain of the virus, the HIV-2, passed to humans from a species of monkey called the sooty mangabey. The mangabey, memorably described by science writer David Quammen as looking like an “elderly chimney sweep of dapper tonsorial habits,” inhabits the canopies of coastal west Africa, some two thousand kilometers from where the vastly more dangerous strain of the virus, HIV-1, emerged.
HIV-1 has also infected humans on multiple occasions—at least four that we know of, three times via chimpanzee and once via gorilla. By far the most lethal variant is known as HIV-1 Group M--with “M” as in main. This is the strain responsible for 99 percent of AIDS deaths worldwide, and because its simian counterpart is concentrated among the chimpanzees of southeastern Cameroon, scientists believe it almost certainly originated there. Figuring that out took intrepid work. Chimpanzees are an endangered species: Killing or even tranquilizing them to secure blood samples is unacceptable. Scientists had to develop new ways of testing urine and faeces to determine if they contained SIV antibodies. Early on, a distinguished AIDS researcher wounded himself in the forest chasing down the animals’ excrement and died of malaria after he was medivac’ed to England.  (Incidentally, it was once thought that chimpanzees had evolved a tolerance for the virus, as the mangabeys have. In fact, research at Jane Goodall’s Gombe ape preserve would later show they sicken and die from the virus as humans do.)
HIV-1M in turn has spawned an array of subtypes that have become endemic to different regions of the world. That there are so many global variants of HIV is a function of the speed with which the virus reproduces and the frequency with which it errs in doing so. The virus evolves a million times faster than animals, meaning that in a mere decade it recapitulates the ten million years since humans, chimpanzees and gorillas last had a common ancestor.

We can only speculate about the hunter who was the real Patient Zero. (In the early years of the epidemic the popular press designated a promiscuous French Canadian airline steward as Patient Zero, for his putative role bringing the disease to North America. That account is now thought almost certainly false.) Did he cut himself, say on the tip of his spear, or did the chimp, a powerful and aggressive animal, wound him? Did he snare the animal with a forest vine and then use an iron-bladed machete to finish him off—or did he take him down with a poisoned dart? Both methods of hunting are widely prevalent. It might have depended on whether he was a Baka pygmy, who often provide bushmeat to their Bantu neighbors in return for agricultural staples and trinkets, or one of the more recent inhabitants of the region—the Mpiemu or Kao or Bakwele. Whatever the case, over the millennia that humans have hunted game in the region, this cannot have been the first time a cross-species spillover of HIV-1M occurred. In the past, infected hunters might have spread the disease to a wife or girlfriend in a closed loop of sexual contact: An epidemiological dead end. This time was different. This time a spark was lit. And the tinderbox that set it aflame was the arrival of colonialism.
Then, as now, the most important city in central Africa was Leopoldville, today known as Kinshasa. Leopoldville is the last navigable port on the southern side of the Congo River, before a series of cataracts known as Livingstone Falls breaks up the river’s steady flow and makes it impossible to descend any farther to the ocean. Leopoldville was first settled by Europeans in 1881, and by 1898 they had completed construction of a railroad to Matadi, on the Atlantic Coast, bypassing the falls and knitting the vast interior of Congo to the global marketplace. By the turn of the century, Leopoldville was a booming town of 10,000 people.
It’s believed the hunter—or one of the handful of people he might have infected—made it to Kinshasa in the first decade of the 20th century. He might have been drawn by the prospect of construction work. He may have had meat, elephant tusks, or rubber to sell. Quammen spins an elaborate tale about a person he calls the Voyager (in contrast to the Hunter) involving a hunt, a fortuitous discovery, multiple lovers and a murder, that is so vivid in its detail it can be hard to remember it’s entirely hypothetical. We do know it would have been a long (500 kilometer) voyage, but not especially grueling. The southern tip of Cameroon is part of the vast Congo River basin, and two tributaries of the Congo, the Ngoko and the upper Sangha, drift from there languorously southward into the mighty river.
Scientists have several reasons for believing that Kinshasa was the crucible for the disease. For one, Kinshasa hosts a greater diversity of HIV-1M variants than anywhere else. The longer a disease is present in a given area, the more chance it has to mutate and recombine. Second, the two oldest samples of HIV-1M ever found are both from Kinshasa. One is from a vial of blood dating from a 1959 study of red blood cell diseases, found abandoned in a freezer in 1986. The other, discovered two decades later, is from a 1960 lymph node biopsy preserved in a fingernail-size chunk of paraffin wax discovered in a dusty cabinet at the University of Kinshasa. Painstaking efforts showed that these two variants are only 88 percent alike, suggesting that they diverged some 50 years earlier, in about the year 1910. There are other reasons Kinshasa is thought to be ground zero. For example, retrospective readings of patient case studies from Kinshasa in the late 1960s are clearly suggestive of AIDS; also, a small percentage of blood samples taken from young mothers in a 1970 study reveal the presence of HIV antibodies.
Like many incubations, it took a long time before the pandemic began to take the shape we know it as. That reflects the nature of the disease. Contrary to conventional wisdom, sex is actually a poor way to transmit the virus; a healthy, circumcised man has a low risk of picking up the disease from an infected woman, short circuiting the chain of transmission. Circumcised men are many times less likely to be infected than their intact brethren. By luck, most men of that region are circumcised, often as part of manhood rituals; further east and in southern Africa they are not. Had AIDS migrated there first, it would have emerged sooner and with far greater ferocity. 
Craig Timberg, a reporter for the Washington Post, and AIDS-researcher Daniel Halperin provide the best overview of the rising colonial enterprise and how it shaped the prospects of the local people. The brutal era of “Red Rubber” would have just concluded, as King Leopold, buckling to international pressure, ceded his territory to the Belgian government. Determined to put paid to Leopold’s reputation, the Belgians made it their mission to build up the country’s trade, services and infrastructure. Unlike the French, who saw their mission as bringing the glories of French civilization to Africa, or the British, who were largely content to govern through indirect rule, the Belgians conceived of their colonial project in an intensely paternalistic way. In some ways, it was very effective: By the time the country achieved independence, it could boast 85,000 miles of roads, 5,000 miles of rail, and 70 airstrips.
All that construction required a lot of manpower. Pepin observes that in 1910 Leopoldville was little more than a labor camp, controlled by its Belgian administrators and inhospitable to families, where the male-female ratio was ten to one. Twenty years later the ratio was still four to one. Travel in the countryside and entry into Leopoldville were restricted, especially for women. Even the men were considered temporary employees rather than urban settlers and encouraged, after a time, to return to their native villages.
Of course, there is nothing more conducive to prostitution than bringing together large numbers of young men. Prostitution would take root and flourish during the colonial era. But it is important to understand that prostitution meant something else—or rather, a variety of other things—than it does to us now. At one end of the scale were women who serviced up to a thousand men a year, in down-market brothels that were little more than shacks. (But even at this low end the women rarely had pimps to bully them and skim off their earnings.) At the upper end were women who attached themselves to wealthy men, formed mutual aid societies, and were known as “vedettes” or “basi ya kilos” because they could afford to buy consumer goods by the kilo. In the middle were “femmes libres,” or free women, who took on a lover or three, and who provided him with conversation, domestic services (including cooking and laundry), and sex, in a transient approximation of marriage. A survey in 1928 found that nearly half the 6,000 women in the city were “mainly living in the prostitution.” Only 328 of the women were married.
It is at this point that the stories the books tell begin to diverge. Timberg and Halperin insist that sexual relations, including prostitution, were the primary vector through which the virus spread, in the context of growing urbanization and the development of transport routes:  “Western powers were key actors in turning a localized outbreak into a sprawling epidemic as bustling new trade routes, modern colonial cities, and the rise of prostitution sped the virus across Africa,” they write. In their account, cities bred prostitution, which bred STDs (including syphilis, probably introduced by the colonists), which increased the likely transmission of HIV.  Pepin, the epidemiologist, puts the emphasis not on sex, but on unsterilized needles, and specifically on the intensive public health campaigns undertaken by the colonial regime against STDs, malaria, yaws, and sleeping sickness. It is agonizing to think that a symbol of mid-century medicine, the glass syringe, could have been the prime, early vector of AIDS, but Pepin’s deep dive into the colonial medical archives brings to light persuasive evidence that it was.
Pepin himself was a general practitioner in Zaire for four years in the 1980s. From a “rather primitive” hospital 500 kilometers northeast of Kinshasa, he supervised 20 or so rural health centers, some reachable only by dugout canoe. He realizes now that he inadvertently might have helped spread the virus. In theory, syringes and needles were sterilized by the hospital autoclave, but power outages could last two months, forcing the staff to resort to more rudimentary methods of cleaning the equipment. In truth, he says, “I did not pay too much attention to how long the [syringes and needles] were boiled by nurses between patients.”  
The difficulty Pepin faces in proving that the early spread of the virus was due to public health measures is that the infected would have died within 15 years of being jabbed, and nothing about their deaths would have inspired any particular attention. So like a medical Hercule Poirot, he assembles a circumstantial case from a variety of sources. First he shows that diseases have been spread in past public health programs:
  • In Egypt from the 1940s to 1980s, more than a fifth of the population was unknowingly infected with Hepatitis C to control the shistosomiasis endemic to the Nile Delta.
  • In French Equatorial Africa, the “mother of all diseases” was sleeping sickness, spread by tsetse fly, which in some areas killed more than all other diseases combined. From an outpost in Oubangi-Shari from 1917-1919, one legendary doctor examined 90,000 people  and diagnosed and treated over 5,000 cases of the disease, using only three microscopes and six syringes.
  • In separate outbreaks in 1980s Romania and 1990s Libya, hundreds of sick children and orphans were infected with HIV by unsterilized needles.
Then comes a closer look at the crime scene: the colonial healthcare system. The Belgians’ paternalism extended to medicine. By the 1950s, 10 percent of the  budget went to building and maintaining the colony’s 96 district hospitals and nearly 3,000 dispensaries and maternity wards. Together, these boasted some 85,000 hospital beds--more than the rest of Africa put together. The work paid off: The number of sleeping sickness cases went from 36,000 in 1930 to 1,200 in 1958.
The effort was not entirely humanitarian: The aim of many of the disease control initiatives implemented during the colonial era was to protect Europeans by decreasing the reservoir of pathogens in the African population. Pepin drily observes that this investment in tropical medicine and disease control eventually paid off: By 1940, the mortality of Europeans living in the Congo was only marginally higher than for their kin in Belgium.
Finally for Pepin comes the identification of the culprit. In 1926, the Red Cross established a Dispensaire Antivenerien in Leopoldville. With their tight control over the population, the colonists required all unmarried women to show up for regular exams and have their health card stamped. Most of the “free women” of the city visited the clinic a few times a year. In the belief that it was better to keep prostitution hygienic than to fail at banning it altogether, the Belgians aggressively treated any indication of venereal disease. In the 1930s and 1940s, the clinic was giving 50,000 injections per year. (In a cruel irony, most of these treatments were useless: wrong diagnoses and ineffective drugs.) In the 1950s, after the advent of penicillin, the number of injections per year shot up to 150,000. The medical community knew very little about viruses then, but in 1952 a doctor bemoaning the spread of “inoculation hepatitis,” complained about the dispensary’s sterilization efforts: “Every day, local nurses give dozens even hundreds of injections in conditions that make sterilization of the needle impossible…. At the Dispensaire Antivenerien de la Croix Rouge, an average 300 injections are administered each day. The used syringes are simply rinsed, first with water, then with alcohol and ether.”
In short, and taking in the usual caveats, this is the most plausible scenario: The Voyager—most likely the original, infected hunter—traveled to Kinshasa, where he got work building up the city’s aqueducts, houses or roads and carried on relationships with one or more of the city’s femmes libres, eventually sparking a tiny outbreak of a wasting disease that would have struck no one at the time as particularly remarkable. At some point he—or perhaps one of his lovers—presented himself to the venereal clinic, where he received a false positive diagnosis for syphilis. He was treated with a prolonged course of an arsenic-based drug. During one or more of those visits, microscopic droplets of blood remained in the needle tip used in his injection, which was then reused a half dozen times before the remnants of the virus were washed away. Now the virus had spread to a handful of women who would have been having concomitant sex with several men. From then on it is impossible to establish what combination of sex and dirty needles kept the virus alive. But for a long time it survived more as an ember than a flame. Mathematicians estimate that until the early 1950s, there may have been no more than a hundred or so HIV-infected individuals in the city at any given time.  It would take another major historical event for the pandemic to mushroom outward in a chain reaction to launch the pandemic’s rise. That event was the collapse of the Congolese state.
Congo’s implosion following its independence in 1960, emphatically punctuated by the assassination of Patrice Lumumba early the following year, was in part engineered by Belgium and in part reflected the fragility of the new state. More than the other African states that won independence in the late 1950s and early 1960s, the Congo was dependent on its European labor force. The Belgians’ paternalistic approach to colonialism meant that they occupied virtually every position of consequence in the bureaucracy and private industry. At independence, the Congo had only 17 native college graduates. Thus when continued upheaval prompted the Belgians to bolt, they took with them the middle-class expertise necessary to keep the country running. One year after independence, for example, the number of doctors in country had dwindled to 270—in a country, it should be remembered, the size of Western Europe.  The UN responded to this crisis by shipping in thousands of black French-speaking professionals from Haiti, themselves eager to flee the depredations of the Duvalier regime. Among them were nurses, postal administrators, agronomists, police officers and so on. At one point, half the country’s teachers were Haitian. Most of them were single or had left their families behind. And of course, they were only human.
In the end, it took just one. Epidemiological reconstructions show that a single strain of the virus, HIV-1M subtype b, migrated via one individual host back to Haiti, sometime in 1966-67. Even then, the virus might have met an epidemiological dead-end, had it not been for a joint-venture set up by a Miami businessman and a Haitian politician, Luckner Cambronne, the leader of the TonTon Macoutes.
Haiti at that time was a gay tourist destination, and had been known as such since the late 1940s. The Spartacus travel guide for gay men praised Haitians as “handsome, well endowed, uninhibited and affectionate” and asserted (without any evidence) that most of the population was bisexual. Tours organized out of San Francisco and New York promised a land of “sun, sand and duty free sex,” and maintained walled enclaves for those with deep pockets. Because of that connection it was not clear at first whether the disease had been brought to Haiti by gay Americans or transmitted to Americans in the rough trade. The first evidence of HIV in Haiti dates from approximately 1969 and in the US from 1971. Given the margin of error in these dates, it’s possible either predated the other.
In the event, the debate was moot: It wasn’t sex but rather a new medical procedure developed to increase the stock of plasma, the liquid component of blood, that initially amplified the incidence of the virus. The procedure, called plasmapheresis, entails drawing blood, filtering out its cells and platelets, and then transfusing those cells back into the bloodstream. The liquid component of blood, plasma was used in surgery to expand intravascular volume, mined for its anti-coagulant factors, used in tetanus shots and transfusions. The great advantage of the procedure over simply donating blood is that it can be done once or twice a month without putting the donor at risk of anemia. This plasmapheresis center set up in Port au Prince by the dictator’s henchman went under the name Hemo-Caribbean. It was a thriving business: The plasma bought off poor Haitians for five dollars a donation could be sold in Miami for $35. By 1971, Hemo-Caribbean was exporting 6,000 litres of plasma to the US each month, in cargo planes full of blood. (Another plasmapheresis center in Panama was owned by dictator Anastasio Somoza; Managuans started referring to blood as el oro rojo, the red gold.)

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