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New York Times
October 17, 2011
Chimp to Man to History Books: The Path of AIDS
By DONALD G. McNEIL Jr.
Our story begins sometime close to 1921, somewhere between the Sanaga River in Cameroon and the Congo River in the former Belgian Congo. It involves chimps and monkeys, hunters and butchers, “free women” and prostitutes, syringes and plasma-sellers, evil colonial lawmakers and decent colonial doctors with the best of intentions. And a virus that, against all odds, appears to have made it from one ape in the central African jungle to one Haitian bureaucrat leaving Zaire for home and then to a few dozen men in California gay bars before it was even noticed — about 60 years after its journey began.
Most books about AIDS begin in 1981, when gay American men began dying of a rare pneumonia. In “The Origins of AIDS,” published last week by Cambridge University Press, Dr. Jacques Pépin, an infectious disease specialist at the University of Sherbrooke in Quebec, performs a remarkable feat.
Dr. Pépin sifts the blizzard of scientific papers written about AIDS, adds his own training in epidemiology, his own observations from treating patients in a bush hospital, his studies of the blood of elderly Africans, and years of digging in the archives of the European colonial powers, and works out the most likely path the virus took during the years it left almost no tracks.
Working slowly forward from 1900, he explains how Belgian and French colonial policies led to an incredibly unlikely event: a fragile virus infecting a small minority of chimpanzees slipped into the blood of a handful of hunters, one of whom must have sent it down a chain of “amplifiers” — disease eradication campaigns, red-light districts, a Haitian plasma center and gay sex tourism. Without those amplifiers, the virus would not be what it now is: a grim pilgrim atop a mountain of 62 million victims, living and dead.
In the early 1980s, Dr. Pépin was a young doctor fighting a sleeping sickness epidemic at a hospital in Nioki, in what was formerly the Belgian Congo, then Zaire, and is now the Democratic Republic of Congo. The virus was then unknown in Africa, but his work gave him clues that would later help him on its trail.
In retrospect, he says in his book, he may have inadvertently infected some of his patients. Ideally, the glass syringes used in Nioki were sterilized in the hospital’s autoclave. But with the electricity often out, nurses boiled them instead. “And I did not pay too much attention to how long they were boiled,” he said in an interview.
Later, he worked in Guinea-Bissau on H.I.V.-2, which is related to H.I.V.-1 but causes a milder and harder-to-transmit form of AIDS that some victims live with for decades. Noting that cases were more common among older people, he concluded that it was dying out. If sexual transmission among young people was not keeping it alive, he reasoned, some other route must have first made it so widespread among the elderly. He suspected the aggressive campaigns that colonial doctors waged against syphilis, yaws, leprosy, tuberculosis and other ills until independence arrived in the 1960s. They all used injections, since pill versions of many antibiotics did not exist or were costly.
In 2005, Dr. Pépin began field studies. By sampling the blood of Africans 55 and over, he showed that those who had many injections in their youth or had undergone ritual circumcision, in which many boys were cut with the same blade, often had antibodies to hepatitis C or HTLV, a little-known virus that, like H.I.V.-1, comes from chimps and infects the CD4 cells of the immune system, but is harmless.
That was hard evidence that blood and syringes had spread other viruses.
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In brief, his recounting of the epic journey is this:
In nature, only about 6 percent of troglodytes chimps are ever infected. Within a troop, each female mates with many males, but mating with outsiders is rare, so most troops are untouched while a few are heavily infected.
H.I.V.-1’s four genetic groups, M, N, O and P, show that it made the chimp-human jump at least four times in history. But group M accounts for more than 99 percent of all cases.
Why did only one spread?
Molecular clock dating shows that M reached humans somewhere near 1921. Chimpanzees are too big and agile to be hunted with anything but guns, which until the 20th century were almost entirely in white hands.
Using colonial census data, surveys of how modern bush-meat hunters butcher kills, and infection rates among nurses stuck by dirty needles, Dr. Pépin calculates that, in the early 1920s, a maximum of 1,350 hunters might have had blood-to-blood contact with troglodytes chimps. Only 6 percent of the chimps — about 80 — would have been infected, and fewer than 4 percent of the scratched hunters probably could have caught it. That would suggest only three infected hunters at most.
Given how inefficient most sexual spread is — in some cases, a husband and wife can have sex for months without passing H.I.V. — sex alone would not have let three hunters, or even a dozen, pass on their virus to today’s millions, he argues. There must have been an amplifier.
Studies among heroin addicts — he cites examples from Italy, New York, Edinburgh and Bangkok — show that blood transmission is 10 times as efficient.
In the 1920s, machine-made glass syringes replaced expensive hand-blown ones, and the Belgians and French attacked many diseases in their colonies, both out of paternalism and to create herd immunity to protect whites. Patients might get up to 300 shots in a lifetime. Other diseases have spread this way; an Egyptian campaign against schistosomiasis ended in 1980 after giving more than half its “beneficiaries” hepatitis C.
Thus, one hunter’s group M infection could have become dozens. Then Dr. Pépin’s focus shifts to the twin cities facing each other across the Congo: Leopoldville (now Kinshasa) on the Belgian side, Brazzaville on the French.
They are the epidemic’s cradle; viral diversity is highest there, and the earliest positive blood sample, from 1959, was found there.
... until 1960, brothels were rare. Most of the women were “femmes libres” — escapees from rural polygamy who typically had only three or four clients for whom they also cooked and did laundry.
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Since femmes libres had few partners, viral spread was probably sluggish, although occasional hepatitis outbreaks were noted at clinics where prostitutes got penicillin shots for syphilis — suggesting amplification by needle there, too.
... when whites fled the chaos of independence, economies collapsed. Poverty was rampant.
... competition forced desperate women to have sex with up to 1,000 clients a year, and venereal disease treatment dried up. There must have been a viral explosion like the one that happened 20 years later in a closely studied band of prostitutes in Nairobi: In 1981, 5 percent of them had the virus; three years later, 82 percent did.
The next link was Haiti. ...
Once again, Dr. Pépin argues that rapid expansion through sex alone is mathematically impossible and that there must have been an amplifier. He believes the culprit was a Port-au-Prince plasma center called Hemo-Caribbean ...
Hemo-Caribbean’s co-owner was Luckner Cambronne, leader of the feared Tontons Macoutes secret police. Nicknamed the “Vampire of the Caribbean,” Mr. Cambronne, who died in 2006, bled 6,000 sellers who were paid as little as $3 a day and exported 1,600 gallons of plasma to the United States each month, according to an article in The New York Times.
... Dr. Max Essex, chairman of the AIDS Initiative at the Harvard School of Public Health, ... said. “This is very scientifically hard, objective scholarship.”
Dr. Allan Ronald, a University of Manitoba AIDS expert who began the Nairobi prostitute study, also read an early version and called Dr. Pépin “one of the unsung heroes of AIDS research.”
While others had speculated that syringes amplified the virus, he said, “Jacques did the studies among elderly people that were needed.”
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