The African AIDS Epidemic. John Iliffe

adult prevalence of 8 per cent in 1991, while spreading at roughly half that level to Ouesso in the north, Pointe-Noire in the west, and the rural Niari region neighbouring the capital, although expansion into the sparsely-populated countryside elsewhere was slow.²⁴ By contrast, in Gabon, further to the north-west, an epidemic emerged more slowly. The first evidence of HIV there dated from 1983 and antenatal prevalence in the main towns of Libreville and Franceville rose only slowly to less than 2 per cent between 1986 and 1994, with even lower levels in the countryside.²⁵ Cameroun had a different but equally unspectacular experience. Perhaps because it was probably a site of early HIV evolution, the disease there remained scattered, much as it had been in the DR Congo until the later 1970s. Between 1986 and 1988 researchers in Cameroun found only 23 cases distributed among a dozen towns. This excluded the two main cities, Yaoundé and Douala, but neither played Kinshasa’s role in breeding an epidemic. In 1992 each had an antenatal prevalence only slightly over 2 per cent. Instead, Cameroun’s highest HIV concentrations at that time were on its eastern border with the Central African Republic.²⁶

      This was because the CAR experienced an epidemic more striking than Kinshasa’s, expanding more rapidly both in the capital and to the rest of the country. Doctors in Bangui began to suspect Aids in 1982, confirmed it late in 1983, and came to think that they had seen it some years earlier in cases of cryptococcosis, tuberculosis, Kaposi’s sarcoma, diarrhoea, and wasting. HIV must certainly have reached the region by the 1970s. Prevalence in Bangui’s general population aged 15–45 rose from 2.3 per cent in 1985 to 7.8 per cent in 1987. By 1993 prevalence among antenatal women there had reached 16 per cent.²⁷ French doctors blamed the epidemic on sexual behaviour in a rapidly expanding town dominated by unmarried young people from a countryside with traditions of considerable sexual freedom. In 1987, 58 per cent of respondents aged 15–44 had had a child before the age of 20, 54 per cent reported extra-marital sex, 81 per cent had suffered a sexually transmitted disease, and only 34 per cent had used a condom. The epidemic was not primarily due to prostitution – not more than 21 per cent of Bangui’s sex workers were HIV-positive during the later 1980s – but to rapid partner change, averaging between 20 and 40 partners a year according to a group of 56 men and 49 women examined in 1983–5, 60 per cent of whom were HIV-positive. Many poor young women engaged in sporadic subsistence sex. Multiple injections – eight a year on average for those with both HIV and tuberculosis in 1985–8 – added to the risk.²⁸

      From about 1985, when prevalence began to grow rapidly in Bangui, the epidemic also spread more widely. By 1990 some provincial towns in close communication with the capital had adult prevalence rates of 8 per cent. Two years later similar levels were recorded at Berberati and Gamboula, truck-stop towns near the Cameroun border with ties to diamond diggings that attracted many young people, while at Mbaimboum, where Cameroun, Chad, and the Central African Republic met, the prevalence among women in 1993 was 22.8 per cent. In parts of the DR Congo bordering the CAR Aids was known as ‘Bangui’.²⁹

      This account of the epidemic’s origins in western equatorial Africa has indicated distinctive circumstances that both enabled HIV-1 to establish itself as a human epidemic and constrained its growth within the region. Two circumstances were especially important. One was the mobility fostering the rapid spread of disease among young urban immigrants, truck drivers, alluvial miners, and their female partners, although constrained everywhere in the region by distance, insecurity, transport difficulties, and sparsity of population. The other was the rapid urbanisation that had begun in the later colonial period and escalated amidst postcolonial conflicts. Kinshasa had some 400,000 inhabitants when the earliest infected blood was collected there in 1959 and four times as many when indications of an epidemic first appeared in the mid 1970s. Once known as Kin la Belle (Kinshasa the Fair), it had become Kin la Poubelle (Kinshasa the Dustbin). Its decaying modern core was ringed by unserviced squatter settlements. The real value of its official minimum wage fell by 75 per cent during the first sixteen years after independence in 1960. Unemployment exceeded 40 per cent for men in 1980 and was much higher for women, who made up only 4 per cent of the country’s formal urban labour force.³⁰ While the numbers of men and women in the city were roughly equal and nuclear families predominated, only 70 per cent of adult women were married in 1984, while their lack of economic opportunity other than petty trade, together with a formerly polygynous culture in which young unmarried people had much sexual freedom and gifts were a normal part of love-making, led a proportion of young women to depend on sexual relationships with men either for survival or for otherwise unobtainable goods.³¹ Full-time prostitution was probably less important than in some eastern African cities where women did not trade and men heavily outnumbered them. In 1988 Kinshasa’s sex workers averaged only 8.6 clients a week, compared with 35 among lower-class sex workers in Nairobi in 1987. Their 27 per cent HIV infection in 1985, although horrifying, contrasted with 61 per cent in Nairobi. It was estimated in 1988 that to eliminate all prostitution from Kinshasa would reduce HIV transmission by only 25 per cent.³²

      The bulk of transmission was rather among a minority of vulnerable individuals in wide networks of ephemeral sexual relationships in which the men were often significantly older and wealthier than the women. In an illuminating contrast with Rwanda that would have applied to the whole western equatorial region, Michel Caraël observed that ‘Kinshasa, with its bars, its precocious, free, and joyous sexuality despite immense poverty, its litany of bureaux (concubines)’ was ‘light years away’ from the ‘austere Catholic town’ of Kigali, where men had extra-marital relations chiefly with sex workers and then infected their wives, so that HIV was most common in the age range 25–35, whereas in Kinshasa the disease was more widespread among older men and younger women.³³ Kinshasa’s sexual pattern raised HIV to epidemic proportions, but not the explosive proportion seen in Kigali. This was reinforced by the fact that over 90 per cent of men in the western equatorial region were circumcised, which probably provided some protection because the foreskin was especially liable to viral penetration, and that sexually transmitted diseases – although closely associated with HIV infection – were relatively rare, including the incurable genital ulcer disease caused by herpes simplex virus 2 (HSV-2) that was spreading throughout the world in synergy with HIV. A later comparison was to show that, thanks chiefly to these two advantages, Yaounde had significantly lower HIV prevalence than Kisumu in Kenya or Ndola in Zambia, despite high levels of extra-marital sex.³⁴

      These constraints help to explain the most remarkable feature of the HIV epidemic in western equatorial Africa: its failure to expand during the 1990s beyond the levels of prevalence reached early in the decade, although those levels were often at or above the threshold 3–5 per cent prevalence commonly thought to trigger exponential growth. In Brazzaville city, for example, prevalence at antenatal clinics fell between 1991 and 1996 from 8 to 5 per cent, suggesting, together with a peak prevalence in older age groups (men of 35–49 and women of 25–30), that this early epidemic had reached maturity at a modest prevalence.³⁵ The epidemic in Bangui, similarly, stabilised between 1993 and 1998, although at a level of 16 per cent that could be sustained only by a high incidence of new cases.³⁶ In Gabon and Cameroun, where the epidemic had begun later, there was more growth during the 1990s, but to adult levels below 7 per cent.³⁷ The most striking illustration was the DR Congo, often considered ‘a risk environment par excellence’,³⁸ where, however, the long-predicted epidemic explosion did not happen. In Kinshasa, for example, HIV prevalence among pregnant women declined between 1985–8 and 1992 from 6–7 per cent to 5 per cent and then remained at or below that level for the remainder of the decade.³⁹

      Analysts struggled to explain this surprising stability. Some suggested that the HIV strains evolved so early in this region might be less virulent than those elsewhere, but there was no hard evidence to support this. Others thought that poverty might have reduced the rate of sexual partner exchange.⁴⁰ More convincingly, it was pointed out that in Kinshasa, as in Bangui, the epidemic, having begun so early, had reached a stage of maturity at which a stable prevalence concealed a balance between deaths among older groups and a substantial incidence of new infections, chiefly among the young. Between 1986–7 and 1989–90 in Kinshasa, for example, prevalence among pregnant women under 25 nearly doubled, while among older women it fell slightly. The investigators estimated that the annual incidence of new infections in pregnant