Monday, December 05, 2011

Five notes from Jacques Pepin's The Origins of AIDS

My response to World AIDS Day on Friday was a post at my blog reacting to the new book by doctor and Université de Sherbrooke professor Jacques Pepin, The Origins of AIDS. This book is a detailed examination of the origin of AIDS, piecing together the chain of events that allowed HIV to transition from minor zoonotic transfer that killed only a relatively few chimpanzee hunters and their intimates to being a global pandemic with tens of millions of dead and infected.

The mechanics behind the transfer of HIV from chimpanzee hosts to humans infected by blood during hunting and butchery are simple enough, while modern surveillance of the epidemic from the early 1980s on gives us a knowledge of how the disease is transmitted into new populations, how it takes hold and how it can be stopped. But how did HIV manage to make the transition from minor zoonosis to aspirant global epidemic?

Pepin argues that HIV wouldn't have seeded a global pandemic had it not been for a perfect storm of events occurring under colonial rule in Central Africa, of which two of the most important are the widespread use of unsterilized hypodermic needles to (among other things) inoculate French colonial subjects against local pandemics and patterns of urban migration in the Kinshasa-Brazzaville conurbation that encouraged the growth of a sex trade suited to accelerating the virus' spread. (For Pepin's purposes, "central Africa" comprises several discrete groups of territories: French Equatorial Africa, a federation of four colonies later countries (Gabon, Republic of Congo, Central African Republic, Chad), the French Cameroons that began as a German colony, later became a French mandate under the League of Nations, and eventually dominated; the Belgian Congo produced by the 1908 nationalization of the Congo Free State founded by royal génocidaire Léopold II on his own initiative; and, the non-Francophone anomaly of Equatorial Guinea, at one point the only Spanish holdings in sub-Saharan Africa.)

Pepin's book is all about populations, not only how they die and grow sick but how they live and structure their lives in very challenging situations. A few of the points that Pepin made struck me as worth sharing with Demography Matters' readership.

1. The relatively small populations of central Africa compared to central Africa's colonizers

One thing that jumped out at me when I opened Pépin's book was the ratio between the populations of colonized central Africa and its European colonizers. Central Africa was very sparsely populated.

While the quality of historical demographic data in central Africa is not very high at all, it is fair to suggest that for every person living in central Africa in the 1920s, perhaps four people lived in France and Belgium. The ratio was particularly low in French Equatorial Africa, a region of some two million square kilometres that was estimated in the late 19th century to have had a population of some five million people, more recent estimates suggesting a population that may have been half that. The former German colony of Cameroon had a population somewhere between two and three million people. Even the Belgian Congo, a veritable "subcontinent" as Pépin called it, in the 1920s had a population roughly the same size as its Belgian colonizer of seven or eight million people.

The difference in terms of population densities was vaster still, since central Africa's land area of some 4.7 million square kilometres is eight times the 582 thousand square kilometres of metropolitan France and Belgium combined. Central African populations, well into the lifetimes of many of the people reading this post, were small and (on average) widely dispersed.

Things have changed hugely. Now in 2011, central Africa has approximately twice the population of its colonizing region in Europe, and this ratio of central African population to Franco-Belgian is certain to continue to increase sharply to the relative advantage of the former region. I don't think it's at all speculative to suggest that this change in population ratios has much to do with the end of the French and Belgian empires in this vast area, since imperialism over a vast territory is easier if there isn't a vast population living on it that might contest the imperium's claims.

2. The vulnerability of central African populations to external forces

The small size and very low density of central African populations before the 20th century, and their very rapid growth after that point reflects the terrible vulnerability of populations in the region to outside forces.

Slavery had a hugely negative impact on the region, whether the transatlantic slavery of the European trade directed towards the New World or the Arab trade directed towards northern Africa and the Indian Ocean. Pépin cites estimates that eight hundred thousand slaves may have been taken by European slavers from the central African areas of his study; he doesn't provide estimates for the numbers taken by African slavers. This massive forced migration, sustained over centuries, had demographic impacts apart from the direct one of people leaving their lands of birth. The long-term effects of the central African slave trade included the destruction of much of the human and social capital necessary for the formation and maintenance of large-scale trading networks and polities, this in turn limiting the carrying capacity of central Africa relative to other world regions. The Kingdom of Kongo was destabilized over the long term by the export of people via the Portuguese based in neighbouring Angola and São Tomé and Príncipe.

The formation of European colonial empires in central Africa was also associated with terrible mortality. Much of this mortality was intentional, most famously in the Congo Free State where in the space of a generation the population shrunk by perhaps half from twenty to ten million, produced by a combination of very elevated death rates caused by mass killings, overwork, and their second-tier consequences (famine, disease, migration) and the lowered birth rates of potential parents who opted not to become parents in a country that amounted to an open-air extermination camp. A similarly sharp population decline also occurred in French Equatorial Africa as a result of the region's conquest and its sequelae.

To the best of my knowledge, central Africa is one of the few areas of the world in the modern era where populations consistently declined. Empire can be blamed for this.

3. The vulnerability of central African populations to disease

In my post last December on the dire demographics of the Roman Empire (and by extension, all pre-modern cultures), I followed Vaclav Smil in his identification of central Africa as the closest contemporary proxy for the Roman Empire's high birth rates and almost equally high death rates. In the early 21st century, such an analogy is somewhat strained, since although the region's health indicators--life expectancy, maternal mortality, and the like--lag world norms considerably they've considerably in advance of pre-modern standards.

A century ago? Not so much. Even now, Sub-Saharan Africa generally suffers from a higher burden of endemic disease than other low-income world regions, this substantially a consequence of sub-Saharan African environments. Consistently high temperatures and humidity support the mosquitos that sustain malaria, for instance. What one source identifies as "neglected tropical diseases", a broad collection of parasitical and protozoan diseases generally not present elsewhere in the world or not present to the same degree, seriously hinder the health and economic development of the region's peoples. Central Africa, a region that then as now had comparatively little developed health infrastructure, is and was especially vulnerable.

Tsetse fly-borne trypanosomiasis was the biggest threat to central African populations. Becoming especially widespread in central Africa over the 19th century following the intensified migrations and trade associated with colonial conquest, trypanosomiasis seems to have threatened the depopulation of large regions, with outside observers claiming that the populations of some regions like lowland Uganda or parts of the Congo basin were halved by the parasitic disease.

In Pepin's account, the French responded to this existential threat to the populations by establishing a fairly thorough compulsory medical program relying heavily on the use of hypodermic needles as delivery mechanisms for medicines. Most unfortunately, the hypodermic needles used were not sterilized, the idea of viral contamination of syringes only becoming known in central Africa until after the Second World War. This, Pepin suggests, may have been the thing that took HIV from being a rare zoonotic infection of chimpanzee hunters to being a plague with the potential for far wider spread. In his 2010 paper "Iatrogenic Transmission of Human T Cell Lymphotropic Virus Type 1 and Hepatitis C Virus through Parenteral Treatment and Chemoprophylaxis of Sleeping Sickness in Colonial Equatorial Africa", Pepin's study of a population in the Central African Republic that had received treatment for trypanosomiasis more than sixty years previously revealed that only a small fraction of the people who had been treated and expected to survive to the present actually did: "From historical data, we predicted that 59% of Mbimous 65 years and older would report treatment for trypanosomiasis before 1951; only 11% did so." Why? Noting that the rapid progression of human beings from infection with HIV to death in the space of a single decade made his hypothesis impossible to confirm, Pepin noted that use of unsterilized needles in the region was quite common--"In 1917–1919, of 89,743 individuals screened in Oubangui-Chair (now Central African Republic), 5347 were diagnosed as having trypanosomiasis and treated (mostly with subcutaneous drugs) using only 6 syringes."--and that other viruses known to be transmitted via the same routes as HIV, including Hepatitis C and HTLV-1, were present among the survivors.

HIV may have started as a zoonosis, but Pepin argues that it's only the widespread use of needles in the medical campaigns of France that allowed the rapid transmission of the virus beyond the relatively enclosed networks of kinship that once would have contained the virus. HIV could plausibly have been transmitted to very large numbers of people, some of whom who eventually would make their way to the cities of central Africa.

4. The role of unbalanced sex ratios, specifically, and anti-family sentiments generally, in the amplification of STDs

Central African cities are generally young, often founded as outposts by European colonizers and only seeing rapid growth after the Second World War, when rural-to-urban migration (only sometimes triggered by humanitarian catastrophes) and economic growth made urban life more appealing. In the case of central African cities, rural-to-urban migration was something undertaken mainly by men, as economic actors who (unlike women) had the autonomy as individuals necessary to move. Particularly in the Belgian Congo, migration by women was restricted in a vain effort to prevent the formation of families in urban areas and the entrenchment of urban living as a viable alternative. (This Belgian policy might be best considered as one of a clutch of policies, including the limitations on higher education of Congolese subjects, aimed at keeping the colony firmly under the control of the metropole.)

With the populations of Central African cities being composed disproportionately of young men with active sexual appetites, the unbalanced sex ratio created an opportunity for women to establish lucrative careers as sex workers. Pepin identifies numerous different trends in the sex trade, everything from women who had stable and lucrative relationships with a limited number of people to less fortunate women who exchanged sex anonymously with large numbers of people for pittances. As the economy of independent Congo deteriorated over the 1960s, the latter practice became more common. The formation of large open-ended sexual networks created a perfect environment for HIV's rapid spread. It didn't help that, as Pepin notes, Belgian medical policy in the future Kinshasa for STDs made full use of the coercive power of the state to provide medical treatment for anyone possibly infected with a STD, even the many people infected with yaws and thus providing a false positive for syphillis tests, and that the main medical centre also used unsterilized needles.

It's not a coincidence at all that this model of rural-to-urban migration, encouraging the migration of working-age men to urban centres but discouraging the migration of women and children to same in the hope of limiting permanent urban settlement, is exactly the same model of rural-to-urban migration instituted in southern Africa under apartheid that led to the current stratospheric rates of HIV prevalence throughout the wider region. Belgium echoed South Africa's sustained underinvestment in the human capital of its non-white subjects, and AIDS reaped the benefits.

5. The potential novelty and superficiality of migration-related links

(This principle applies to viruses and human beings alike.)

We could, if we really wanted, blame the HIV/AIDS epidemic outside of sub-Saharan African on la francophonie. After Belgium's hasty withdrawal from the Congo, in the 1960s the country was left without the trained professionals necessary to run the Congolese state. In order to fill the gap while Congo's own higher education system came online, the United Nations recruited thousands of French-speaking Haitian professionals and their dependents, fleeing the dictatorship of Duvalier. Many stayed; some few were infected with HIV; one unfortunate Haitian brought the virus back to his homeland sometime around 1966, as shown by the 2007 research of research of Worobey et al.. From Haiti, HIV made its way to the United States in 1969 and eventually seeded the epidemic in the North Atlantic world that led to the disease's recognition in the developed world a decade, perhaps, after it had become a major killer in central Africa. In the early 1980s in North America, in fact, AIDS was strongly associated in the popular imagination with Haitians, who formed a disproportionate number of the first diagnosed AIDS cases, especially in Québec and Florida where the Haitian immigrant diaspora was most visible. (Randy Shilts' book on the early epidemic, And the Band Played On, quotes a bathhouse owner in Florida who went so far as to say that AIDS was nothing gays in Florida had to be concerned with.)

How did all this happen? The chance historical events that established central Africa as a collection of territories run by Francophone powers, the ill fortune in Haiti that made emigration--not only to obvious destinations in the North Atlantic world, but even to remote central Africa--a good life choice, and the shared use of French in both the sending and the receiving country. Yes, as Paul Farmer noted in his generally quite good take on the Haitian AIDS epidemic, AIDS and Accusation, neither Haiti nor Congo (then Zaire) are as Francophone as France (as France now, at least; Eugen Weber's 19th century France was quite different), but neither had to be. In Haiti, French remained a socially more prestigious and internationally useful language than Haitian Creole; in Congo, a very complex language situation with four regional languages of note and official standing dozens of local languages did give French a privileged position as an official language. That shared language made Haiti and Congo appear in the perspective of the other.

The shape of the modern AIDS epidemic was chance, at many levels. The unfortunate Haitian who seems to have transferred the virus out of Africa might not have been infected, or might have died without transmitting the virus further. In that case, the transmission of HIV outside of Africa could have been delayed by decades, and by the 21st century AIDS would be seen as an overwhelmngly African disease, with the chance associations of the epidemic with gay men and Haitians not coming up. Conceivably, differences in colonial policy towards urbanization and public health, or maybe heightened concern for the possibility of medical contamination, could have slowed down or even aborted the epidemic. If different colonial powers had been active--perhaps the Portuguese, building on the long history connecting between the Portuguese and their Angolan colony with Congo--then even if the same sorts of things that caused the AIDS epidemic occurred it would have progressed in different directions. (Angola and Brazil are both quite lucky to have avoided the large epidemics often predicted for them, and the misuse of improperly sterilized hypodermic needles in Guinea-Bissau under Portuguese rule does seem to have unleashed HIV-2, the less lethal and much rarer variant of HIV, on the world.) Ubangi Shari --> Kinshasa --> Port au Prince --> New York City was not an inevitable trajectory for AIDS, nor was the size or shape of the epidemic to date.


Anonymous said...

The most interesting stuff I've read so far today... Hats off!

beobob said...

Pepin calls his book "Origin of AIDS," but he doesn't actually enter the fray. His one contribution to the origins debate is to calculate how unlikely it is that the virus originated in Cameroon and migrated to Kinshasa. Despite all the convenient (for the medical industrial complex) denials, the oral polio vaccine theory is still the most likely origin of the AIDS pandemic. If it can be proved that batches of the experimental vaccine given to almost a million people in Africa in the late 1950s were prepared using chimpanzee kidneys, as appears to be the case, then all the theoretic dating means nothing as it necessarily assumes there was no punctuated deviation from the genome evolution.

Randy said...


As I understand it, vials of the experimental vaccine have been tested. Not only was HIV not found, but the vaccines weren't even made from chimpanzees! At any rate, the HIV virus in humans is most similar to the SIV found in chimpanzees on the western shore of the Congo, i.e. not in the Belgian Congo where Koprowski et al worked. Et cetera.

Hooper's flight into conspiracy theories does his good work elsewhere no good.