Both Kinshasa and the rest of DR Congo also enjoyed some protection against an explosive epidemic from the great distances between population concentrations and the difficulty of travel where transport had widely broken down and much violence and insecurity prevailed, these factors together preventing the linking of sexual networks that commonly fostered epidemics. The falsity of the common belief that ‘war creates the perfect conditions for the spread of AIDS’42 was also demonstrated at this time in neighbouring Angola, where national antenatal prevalence after nearly 40 years of warfare was found by a survey in 2004 to be only 2.8 per cent, with the lowest figures in central provinces ‘that have been more protected by the effect of war,’ as the Vice-Minister of Health put it.43 By contrast, the two countries registering modest epidemic growth during the 1990s, Gabon and Cameroun, were the most peaceful in the region.
The limited capacity for expansion shown by the western equatorial epidemic during the 1990s had as its counterpart the survival there – perhaps especially in the countryside – of a diversity of HIV subtypes and recombinant forms far greater than anywhere else in the world. A more explosive epidemic might well have swamped this diversity by a single dominant strain more like those created by founder effects elsewhere. Yet it was from this region that the various forms of the virus were carried to the rest of the continent and the world. The most spectacular illustration was the transmission of the circulating recombinant form CRF01_AE from its hearth in the northern DR Congo and the neighbouring Central African Republic, where alone it was common early in the epidemic, to become the major strain of HIV in South-East Asia, although the means of this transmission are unknown.44 A less dramatic example was the other major circulating recombinant, CRF02_AG, which provided 60 per cent of HIV-1 strains in Cameroun during the 1990s, especially in the north, and some 54 per cent in Gabon. Its ancestors probably lay in the DR Congo – one of them was a virus collected at Yambuku in 1976 – but CRF02_AG itself was rare in both Congos during the 1990s and appears therefore to have taken shape in the Cameroun-Gabon region, whence it was carried northwards to become the dominant form of the virus throughout West Africa.45 By contrast, the subtypes (as distinct from CRFs) of HIV-1 transmitted to other parts of the continent appear to have been carried directly from the DR Congo. Subtype A was the most common form there, especially in the north, and was carried into East Africa, where it shared predominance with subtype D, itself rare elsewhere except in the DR Congo.46 Less certainly, subtype C, which came to dominate southern Africa (and Ethiopia), was common only in the south of the DR Congo, whence it may have been carried southwards.47 The history of this radiation from the equatorial region is the next issue to consider.
4
The Drive to the East
Eastern Africa was probably the first region to which HIV was carried from its western equatorial origin, along several different routes that cannot now be traced in detail. The virus entered a region divided historically into two contrasting natural and social environments: the well-watered, densely peopled kingdoms around Lake Victoria and on the Ethiopian plateau, and the less centralised societies in the drier savanna country where population clustered only on highland outcrops, in colonial cities along transport routes, and on the Indian Ocean coast. This framework gave HIV/Aids in eastern Africa its distinctive contrast between explosive epidemics in the Lake Victoria basin and the capital cities, on the one hand, and slow penetration into the remainder of the region, on the other. Varying relationships between cities and countryside were especially important in the process, as were the mobile groups linking them together and the factors – widespread labour migration, male predominance in urban populations, low status of women, lack of circumcision, and prevalence of sexually transmitted diseases – that bred higher levels of infection than in western equatorial Africa.
The virus first entered the Lake Victoria basin bordering the DR Congo. Patients from Rwanda and Burundi were seen alongside Congolese in European hospitals during the late 1970s and early 1980s. They not only led expatriate researchers to visit Kigali as well as Kinshasa in 1983 but encouraged observers of the epidemic to believe that Rwanda, Burundi, and perhaps even Uganda had been simultaneous or even earlier places of origin alongside western equatorial Africa. The location of the chimpanzee host makes this unlikely, however, as does the distribution of HIV-1 subtypes, for there is no indication in the Lake Victoria basin of the diversity of strains found in the DR Congo. Until well into the epidemic, the A and D subtypes dominated the region.1
In Rwanda the first probable case recorded was a mother who displayed characteristic opportunistic infections in 1977 and subsequently tested positive for HIV along with her husband and three children.2 A retrospective study found that by 1982 some 12 per cent of blood donors in Kigali were infected. The team visiting the hospital there a year later identified symptoms of Aids in 26 patients.3 The virus had apparently established itself during the 1970s and reached epidemic proportions by the early 1980s. The evidence from Burundi is even stronger, for 658 blood specimens taken during a study of haemorrhagic fever there in 1980–1 later revealed an HIV prevalence of 4.4 per cent, reaching 7.6 per cent in Bujumbura and 2.8 per cent in the countryside, at a time when Kinshasa’s antenatal prevalence was only 3 per cent. During 1983 cryptococcal meningitis, Kaposi’s sarcoma, tuberculosis, and other opportunistic infections became increasingly common in Bujumbura and doctors suspected Aids, which was confirmed serologically in 1984.4
Map 2 Eastern Africa
Bujumbura’s epidemic grew remarkably fast during the early 1980s. By 1986 some 16.3 per cent of women tested at antenatal clinics were infected. Thereafter growth slowed temporarily, rising only to an urban prevalence of 18.3 per cent in 1992, which nevertheless implied a high incidence of new cases.5 One reason for the epidemic’s virulence may have been its close association with tuberculosis, long prevalent in Burundi. In 1986, 55 per cent of tuberculosis cases treated in Bujumbura were HIV-positive, while tuberculosis cases in Burundi as a whole increased between 1985 and 1991 by 140 per cent. The epidemic’s most striking feature, however, was its urban concentration. While urban antenatal prevalence in 1992 was 18.3 per cent, it was only 5.2 per cent in semi-urban and 1.9 per cent in rural areas.6 Rwanda’s first rough sample survey of people of all ages in 1986 showed a similar contrast between 17.8 per cent prevalence in towns and only 1.3 per cent in the countryside. The highest rates among pregnant women were in Kigali, where they rose even more quickly than in Bujumbura, reaching 33 per cent in 1993.7
The rapid infection of Kigali and Bujumbura took place in countries where sexual behaviour among the overwhelmingly Christian general population was remarkably strict. In a survey conducted during the late 1980s, only 10 per cent of men and 3 per cent of women aged 15–19 in Burundi reported sexual intercourse during the last twelve months, compared with 51 per cent and 30 per cent respectively in the Central African Republic.8 The result was a different epidemic pattern, dominated not by widespread partner exchange but by commercial sex. Sex workers had long been Africa’s urban witches, blamed for all manner of social ills, so that there is a danger of stereotyping their role in the epidemic. Yet everywhere in eastern Africa, except Uganda, they were the first focus of infection. In 1984 a study of 33 sex workers in Butare, Rwanda’s second town and home to a military base and university, found 29 infected with HIV, along with 28 per cent of their clients, who frequented a median number of 31 sex workers a year. Of 300 Aids patients in Bujumbura in 1987–9, 106 of the 184 men had frequented sex workers and 21 of the 116 women had themselves been sex workers.9 Both countries were overwhelmingly monogamous, with exceptional numbers of unmarried women. In the early 1990s Kigali had 50 per cent more men than women aged 20–39. Fifteen years earlier the city also had an estimated minimum of 2,000 femmes libres, many of them uprooted by the destruction of Tutsi power since the revolution of 1961.10