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For European colonizers, Africa’s forests held the promise of untold riches – ivory, rubber and minerals. But unknown to the fortune seekers, those forests also held a virus that would claim over 30 million lives since the global spread of the HIV epidemic.

Craig Timberg and Dr. Daniel Halperin say European rule in Africa led to a number of social and economic changes that facilitated the spread of the virus. They're the authors of a new book on the origins of rearch of virus called Tinderbox: How the West Sparked the AIDS Epidemic and How the World Can Finally Overcome It.

Researchers say the AIDS virus originated in wild apes in Cameroon and then spread to hunters who killed the animals and marketed the meat. (Photo Luc Gnago / REUTERS)

Halperin is a medical anthropologist and epidemiologist at the University of North Carolina and until recently the Harvard School of Public Health. He also worked in AIDS-prevention programs in Africa under the administration of President George W. Bush.

The search for the virus

Timberg and Halperin write that genetic researchers have traced the origins of human immune deficiency virus (HIV) to the jungles of southeastern Cameroon.

Timberg, who is the former Johannesburg bureau chief for The Washington Post, said researchers compared the most prevalent and deadliest form of HIV to SIV, simian immune-deficiency virus, found in local chimpanzees.

He described their efforts at a recent lecture at the Foreign Policy Research Institute in Philadelphia.

"They set up collection stations across the range of where these chimps were in southern Cameroon and collected their waste," he explained.

"Chimp feces carried remnants of the virus, and they could compare the particular chimpanzee viruses to the dominant form of HIV…. What they found [are areas where the viruses] are close at the genetic level, particularly in the southeastern corner (of Cameroon). You almost can’t tell the chimp virus and dominant human virus from one another, they are so almost perfectly identical.

Timberg said even today, not many people live in southeastern Cameroon, an area with its dense jungles that's difficult to access. Through much of history, he said, there weren’t many opportunities for humans and chimps to interact.

Economic, cultural changes

That changed with the arrival of railways, roads and steamships. They carried goods from trading stations along Africa’s most powerful river, the Congo, and its tributaries reaching into the rainforests.

"African men and women became laborers, carrying goods back and forth from the jungles to pay colonial taxes.," said Timberg. "Others were forced to work as porters. Local communities then, as today, killed chimps to sell as “bush meat.”

Scientists say it’s likely the virus made the leap to humans when a hunter cut himself while handling an infected animal. New transportation routes meant the hunter and the virus were no longer confined to a remote and sparsely populated area, where both were likely to eventually die.

"There is an old porter path that’s now a highway...a dirt road today," explained Timberg, "that came within about a mile of where the scientists collected the chimp waste that’s had the virus that’s virtually identical to the version of HIV that’s killed almost everybody who’s died of AIDS.

Other elements were added to the “tinderbox” that would make a once-localized illness combust.

Changing customs made it easier to spread the virus. The colonial powers discouraged polygamy, which medical anthropologists say tended to create what they call a “closed circuit” that tended to limit sex to married partners. By contrast, younger generations under the influence of Christianity may have married a single partner, but also had ongoing relationships with others.

Younger men also were less likely to participate in initiation rituals including circumcision, a widespread tradition in much of Africa that scientists have found largely protects men from HIV. The practice removes the foreskin of the penis, a vulnerable point of entry for the virus.

A growing urban population led to the spread of sexually transmitted diseases, or STDs, in densely populated Leopoldville, now Kinshasa.

"The historical record is clear," said Timberg. "You have an explosion of STDs, things that were not a major problem before the Europeans arrived. Suddenly they are at epidemic levels.

"The Belgian colonialists are actually complaining to each other, asking why are birth rates plummeting, how [they can] make a colonial economic machine without labor for from high birth rates. They thought it had to do with polygamy. But it had to do with STDs – the women were sick. What we now know is that HIV was one of the STDs moving about in that part of the world at a low level but in a persistent way for decades.

Timberg said with modern rail, ship and airlines, it was only a matter of time before the virus became widespread. Different subtypes moved toward East Africa and to Southern Africa. One made the leap across the Atlantic Ocean.

The leap to New World

Today, he said, scientists believe the introduction of the virus to the Americas probably happened in the 1960s and 1970s, through Haiti.

At the same time as Congolese independence, thousands of Haitians were fleeing the dictatorship of Francois “Papa Doc” Duvalier. Some were officially encouraged to take part in a UN-sponsored program recruiting francophone professionals to serve in Congo, which lacked sufficient university-educated civil servants and civic leaders.

"The U.N. brings in French-speaking ex-patriots from Haiti and other countries as nurses, doctors, teachers and technocrats, " said Timberg. "It looks very much as though one of them contracts HIV in Kinshasa, flies back to Haiti and every single strain of HIV they now contract in Europe or the Americas can be traced back to that single original infection in Haiti.

Five years ago, a group of international scientists at the Fourteenth Conference on Retroviruses and Opportunistic Infections in Los Angeles confirmed this theory. They presented their conclusions based on genetic analysis of HIV samples. They said the strain found in Haiti had probably been brought from Africa in 1966.

Haiti was also center of blood donations shipped to the US to make products for hemophiliacs. And, it was a popular holiday destination for gay men from North America. It’s thought they probably facilitated the spread of the disease in the US and Europe through anal sex.

Disproved allegations

Scientific research has disproved other theories of the origins of HIV, including the idea that it was spread mainly by mass inoculations for polio in the 1950s, in part through unclean syringes. Timberg says the parts of Africa where the inoculations were performed do not have especially high rates of HIV infection. This is in contrast to areas with low circumcision rates, which do.

Others say HIV was created by Western intelligence agencies or began in the gay community in San Francisco in the 1970s. But tissue and blood samples kept by medical officials in Congo have been found to contain the virus in or around Kinshasa as early as 1959. And, recent research puts the birth of the virus in the forests of Cameroon to about a century ago.

A few years ago, University of Arizona epidemiologist Michael Worobey traced HIV to the beginning of the 20th century. He created a genetic family tree for the virus by comparing two 50-year-old lab samples found in the Congolese capital. Timberg explains they had similar genetic structures, linking them to a common ancestor.

"For quite some years, there has been a piece of historical virus from 1959 Kinshasa (Leopoldville) in some old blood samples. What Michael Worobey did," explained Timberg, " was dig up a second piece of historic virus from the biopsy of lymph nodes of a woman living in Kinshasa in 1960.

"Once you had two pieces of virus that old in the same basic time frame, you can then determine if they are very similar or not. He determined they were dissimilar enough that they could not be from [a recent] ancestor: in fact, to get the mutations they could see in the genome, it had to have been many decades earlier. The time frame he put together from his research was from sometime between 1884 and 1924 [for] a common ancestor, a common virus, in the Congo River Basin that was the grandfather of all of this.

Understanding the origins of the virus and the environment in which it developed, say the authors, is essential to improving efforts to fight the epidemic. They say the effects of colonialism can still be felt today – in solutions to the epidemic in Africa devised largely by the West.

They say curbing the spread of HIV on the continent should not rely solely on large sums of money and the latest biomedical tools. The effort must also include an understanding of cultural subtleties and behaviors that can mean the success or failure of the war against the disease.