Low prevalence of hepatitis C virus antibodies in HIV-endemic area of Zimbabwe support sexual transmission as the major route of HIV transmission in Africa

Medical injections have recently been suggested to cause a large proportion of African HIV infections. If this hypothesis is true, high prevalences of other infections transmitted by injections should be expected. In a cohort of 145 HIV-negative and 124 HIV-positive individuals from a rural area of Zimbabwe with a high HIV prevalence we only found one with antibodies to hepatitis C virus. This does not support injections playing a major role in HIV transmission in sub-Saharan Africa. The fast-growing HIV epidemic in sub-Saharan Africa has become a major threat to health and development on the continent. The general concept has been that the African HIV epidemic is driven by heterosexual spread, with mother-to-child transmission as the second most important transmission mechanism. This paradigm has recently been challenged in a series of papers authored by Gisselquist and colleagues [1–3] and Brewer et al. [4]. They suggested that medical injections have contributed far more to African HIV transmission than previously recognized [1–4]. The papers have received considerable interest [5], and their hypothesis has tremendous importance for the design of HIV preventative efforts in the developing world. If medical injections have been a major contributor to the African HIV epidemic, more effort needs to be placed on safe practices when providing medical injections. However, if medical injections have only had a minor effect on the dramatic spread of HIV, recent papers may risk disturbing or perhaps even derailing many of the well-designed preventative efforts focusing on the sexual spread of HIV. This could create very unfortunate repercussions for current programmes targeting the HIV/AIDS pandemic in the region. Hepatitis C virus (HCV) has shown a remarkable capacity for spreading by unsafe injections. This includes large epidemics of HCV among intravenous drug users, in which more than half of the tested populations are often HCV seropositive in both developing and developed countries [6]. However, unsafe medical care, including unsterile syringes and HCV-infected blood products have also caused large numbers of HCV infections in different settings [6]. Most notable has been a large HCV epidemic in Egypt associated with parenteral antischistosomal therapy [7]. Although HIV is also spread by unsafe injections, HCV seems to transmit at least as effectively as HIV by unsafe injections [8]. The average incidence of anti-HCV seroconversion after accidental percutaneous exposure from an HCV-positive source is estimated to be 1.8%, whereas the risk of HIV seroconversion is estimated to be 0.3% [8]. Furthermore, the prevalence of HCV in sexually highly active populations is lower than the prevalence among intravenous drug users [6]. Having multiple sexual partners in the previous 3 months, being homosexual or bisexual, and engaging in receptive anal intercourse are factors not clearly associated with the spread of HCV [9]. Although epidemiological results cannot exclude a role for the sexual transmission of HCV, they do suggest that even in sexually very active populations, the sexual transmission of HCV occurs infrequently, and that HCV may be largely associated with parenteral exposure [9]. With a hypothesis of injections as a major cause of African HIV transmission, one must expect high prevalences of other diseases transmitted by injections. Accordingly, Brewer et al. [4] also suggested that to accept medical injections as a major cause of African HIV transmission, the epidemiological data for other bloodborne pathogens should be consistent. A very simple confirmation of the hypothesis is therefore a similar or even higher HCV prevalence in HIV-endemic areas in Africa. Consequently, does a low HCV prevalence in an HIV-endemic area strongly suggest that injections are not a major HIV transmission route in that region. We are presently studying the interaction between HIV and schistosomiasis in the Mupfure Schistosomiasis and HIV cohort. The study is conducted in Mupfure, a rural area in Mashonaland, Central Province of Zimbabwe. The area where the study is conducted has a high prevalence of HIV, with 31.7% of the 2281 individuals screened for inclusion in the cohort being anti-HIV positive. In order to account for factors that may cause co-morbidity, study subjects were retrospectively tested for anti-HCV and anti-HIV by enzyme-linked immunosorbent assay performed according to company instructions (Ortho HCV 3.0 and HIV-1/HIV-2 Ab-capture ELISA test system; Ortho-Clinical Diagnostics, Neckargemünd, Germany). Confirmatory tests for anti-HCV were performed according to company instructions by a strip immunoblot assay (Chiron RIBA HCV 3.0 SIA, Chiron Corporation, Emeryville, CA, USA). Complete data were available on 269 individuals: 145 HIV negative and 124 HIV positive. One individual was confirmed positive with anti-HCV out of 124 patients infected with HIV [0.8%, 95% confidence interval (CI) 0.0–4.9] (Table 1). No individuals were confirmed positive with anti-HCV out of 145 patients not infected with HIV (0.0%, 95% CI 0.0–3.0%) (Table 1). Seventeen of the total population reported previous blood transfusions, 11 HIV positive and six HIV negative (Table 1). The HCV-infected patient, a 31-year-old woman, did not report previous blood transfusion.Table 1: Prevalence of anti-HIV and anti-hepatitis C virus antibodies in the study population.The estimated overall prevalence of HCV in Africa is 5.3% [10], and it is suggested that medical injections are the main reason for this high prevalence [11]. Zimbabwe has an extended child vaccination programme, including 10 injections covering the following diseases: tuberculosis, polio, tetanus, diphtheria, measles and hepatitis B [12]. At the last survey in 1998, a coverage of 79–88% of the individual vaccines were reported [12]. Substantial HIV transmission by medical injections has been reported in countries such as China, Russia and Romania. However, these countries are at an earlier stage in their HIV epidemic with much lower HIV prevalences. Furthermore, has HIV transmission in these countries been accompanied by an even higher transmission of HCV. The fact that injection-transmitted HCV infection is present, albeit at a low prevalence in our cohort, does indicate that medical injections cannot account for the high prevalence of HIV in the same cohort. A higher HCV prevalence in HIV-positive individuals has been described in Ethiopia [13]. However, in a recent review [11] it was concluded that published studies generally do not find any association between HCV and HIV in sub-Saharan Africa. It was also noted that the sub-Saharan African countries with the highest prevalence of HIV had the lowest prevalence of HCV [11]. Our data are thus in accordance with previous findings, and strongly support the dominating opinion that HIV in sub-Saharan Africa is mainly sexually transmitted. The data do not support the suggestion that medical injections contribute substantially to the present African HIV epidemic. This conclusion is paramount both with regard to continuous support for current HIV preventative campaigns and in order to retain the confidence in the efforts of health authorities on the continent.