The Origins of AIDS
By Jacques Pepin
Cambridge University Press, 2011

Most sexually transmitted diesases go back thousands of years. Gonorrhea, for example, was first described by a Greek physician in A.D. 150, and pubic lice have been evolving right along with us since before we became Homo sapiens. This might have been one reason why it was such a shock when a strange new virus came to our attention in the early 1980s. We soon discovered that it was transmitted sexually and through infected blood, but where did it come from?

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We have intriguing evidence that HIV as we know it has been in existence since at least the 1930s.

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HIV has been around since before the 1980s, though it remained unnoticed and unidentified by medical science. The earliest confirmed case of HIV was in 1959, the proof found in a sample of blood from the Belgian Congo, saved in a freezer for decades and later analyzed for the virus. Other early cases of HIV infection that have retrospectively been confirmed include that of a Norwegian sailor, who must have been infected while visiting African ports in the early 1960s. He, his wife, and his child (who was apparently congenitally infected) all died in 1976, and their tissues were tested 12 years later and found positive for HIV.

Jacques Pepin — a professor and microbiologist, not to be confused with the chef of the same name — does some serious detective work to find the most plausible explanation for HIV’s origins. While he doesn’t skimp on the science, the story of AIDS’ origins can’t be told without getting into the history of Europe’s colonization of Africa in the 20th century. This period, followed by the era of post-colonization, found many societies in upheaval. Urbanization, unemployment, and migration facilitated the spread of HIV in Africa during much of the 1900s, and once it left the continent it was able to hitch a ride from host to host, traveling the world.

A chimpanzee immunodeficiency virus, called SIV_cpz, might have arisen from a recombination of other strains of SIV originally infecting red-capped mangabeys, moustached guenons, and mona monkeys — all of which are hunted by the chimpanzee. A chimpanzee infected with these related simian viruses could have incubated them in its cells, allowing the pieces of genetic material to recombine into what is now known as SIV_cpz — which has been estimated to have come into existence just a few hundred years prior to its move to humans in the 1900s. A human hunter could have become infected with this chimpanzee virus, probably through a wound incurred while hunting the chimpanzee for its meat. In fact, it is possible that people occupying the same areas inhabited by the chimpanzee have been periodically infected with these simian immunodeficiency viruses for hundreds of years, developing AIDS-like symptoms but not transmitting the virus beyond their villages. These infections led only to epidemiological dead-ends, at least until the geopolitical circumstances favored the virus’ worldwide spread.

While we don’t have definite proof, we have intriguing evidence that HIV as we know it has been in existence since at least the 1930s. Back then, a French colonial physician named Léon Pales, based in Brazzaville (now of the Republic of the Congo), documented a mysterious disease that he called Cachexie du Mayombe. This illness, characterized by extreme weight loss, afflicted African railroad workers who were forced to live in squalid conditions. After Pales ruled out other common fatal ailments such as tuberculosis and malnutrition, he noted unusual conditions during his autopsies of those who succumbed: cerebral atrophy and lymphadenopathy, which are now known to be very common among AIDS patients. Without tissue samples we can only speculate, but the records Pales kept correspond to what genetic analysis tells us: that HIV probably arose sometime around 1921. Since it takes about a decade for HIV infection to develop into AIDS, it is interesting that Cachexie du Mayombe arose in the 1930s, in the same geographical location from which HIV was later determined to have arisen.

The twin cities of Brazzaville and Léopoldville (then nicknamed Léo and now known as Kinshasa), which were a 20-minute ferry ride apart on opposite sides of the Congo River, are the likely birthplace of HIV-1, the principal — and more virulent — type of HIV. From 1921 to 1951 they experienced explosive population growth: 7,000 to 80,000 people in Brazzaville and 16,000 to 222,000 people in Léo. Additionally, these new urban centers had very lopsided male-to-female ratios, as colonial policies encouraged the migration of male workers into the cities while expressly discouraging female migration. Strangely, such policies were in place to keep prostitution rates low, though in reality they only drove prostitution by increasing demand for such services. At this time, HIV could have simmered unnoticed by physicians for decades.

In the past, it has been hypothesized that HIV was initially spread by a contaminated oral polio vaccine, which was distributed widely in the Belgian Congo during the 1950s. This idea has since been debunked — old vials of the vaccine in question were recovered and tested, and other details didn’t add up. Pepin does, however, make the case that it was almost certainly spread via other well-meaning medical interventions. Firstly, in response to the high rate of prostitution, Léo opened high-volume STD clinics to serve both sex workers and their clients. Additionally, all new arrivals to town were required to be examined at these clinics. Needles and syringes were not sterilized properly and were regularly reused. Secondly, colonial medicine initiated countrywide campaigns to eliminate sleeping sickness, a horrific and fatal disease endemic to the region. While the effort was successful by some measures, in hindsight the improper sterilization of IV equipment and its rampant reuse could have spread HIV much more quickly than it would have spread otherwise — we already know that hepatitis B was inadvertently spread by IV equipment in the same region during the 1950s.

In the 1960s, during a time of particularly dramatic social upheaval in the newly independent Democratic Republic of the Congo, the country faced a shortage of physicians and teachers. The UN arranged for assistance to come from around the world; thousands of technicians came from Haiti, many of whom were employed as teachers. It is thought that at least one Haitian, having become infected with HIV while in the Congo, returned home to the Caribbean, where HIV could spread in this new location. At the time, Haiti was a popular destination for American and Canadian sex tourists, and in the late ’60s or early ’70s HIV is thought to have moved into North America.

Like most books published by academic presses, the prose in The Origins of AIDS can be quite dry at times, but the underlying story is fascinating and the information Pepin presents is thorough. It’s amazing — and unsettling — that the convergence of events was such that this antique simian virus was able to cross over into human hosts and set off a worldwide pandemic over the course of just a few decades.