Letter to Lancet in response to the WHO
This letter rejected by Lancet
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Schmid et al (Lancet, February 7) claim that "the major mode of spread of HIV-1" in Africa is sexual in adults and mother-to-child transmission (MTCT) in children. Although their evidence is consistent with such claims it cannot be considered proof.
 MTCT should be approximately the same in both sexes. Yet according to Fig.1 in children up to the age of 4 years transmission appears restricted to girls.
 In support of sexual transmission they cite epidemiological evidence of the existence of a parallel between HIV-1 and herpes simplex virus type 2 (HSV-2) seropositivity, the age distribution of HIV-1 seropositivity and concordant seropositivity amongst couples.
 A parallel age distribution between HIV-1 and HSV-2 seropositivity does not prove that HIV-1 like HSV-2 is sexually transmitted. Sexual behaviour intervention reduces incidence of HSV-2, acute syphilis, gonorrhoea, and unprotected casual sex but has no effect on HIV incidence. This means that the mode of HIV-1 acquisition is not the same as HSV-2.1. In fact no correlation exists between the prevalence of HIV and any of the STDs.2 Biggar et al3 were the first to report the age distribution of HIV-1 seropositivity. They also showed that "The age curve for the prevalence of antibody against" HIV-1 parallelled that of antibodies against P. falciparum, a non sexually transmitted microbe. This means that from the age distribution no conclusions can be drawn regarding the route of transmission. Similarly, concordances among couples does not prove sexual acquisition. Sexual partners exhibit concordances for several common cancers which are not sexually transmitted.
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Sexual transmission can be proven epidemiologically only by following infected individuals and their negative partners in prospective studies in which the possibility of HIV acquisition by other means is excluded. There are many such studies both in gay and heterosexual partners but for some unknown reason Schmid et al did not mention any of them. All these studies show that like pregnancy, a positive antibody test can be sexually acquired but not sexually transmitted.4-6The difference is that while pregnancy can be acquired by a single act of sexual intercourse, for AIDS to appear a very high frequency of receptive anal intercourse over a long period is necessary.
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In the best prospective study in heterosexuals Padian et al found no seroconversions even after 6 years of follow-up.7. In the largest study in African heterosexuals the authors concluded: "The probability of HIV transmission per sex act in Uganda is comparable to that in other populations…", that is, comparable to that found by Padian et al in their cross-sectional study, very low.8 In other words, there is no more heterosexual transmission of HIV in Africa than anywhere else including the USA, Australia and Europe. This means that alternative explanations must be found for the exceedingly high seropositivity reported from Africa.
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Eleni Papadopulos-Eleopulos Biophysicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
Valendar F. Turner Consultant Emergency Physician, Department of Emergency Medicine, Royal Perth Hospital, Perth, Western Australia
John M Papadimitriou Professor of Pathology, University of Western Australia, Perth, Western Australia
Helman Alfonso Lecturer, School of Public Health, Curtin University of Technology
Perth, Western Australia
Andrew Maniotis Department of Pathology, Anatomy and Cell Biology, and Bioengineering, University of Illinois at Chicago, Chicago, USA
Christian Fiala Specialist in Gynaecology, Vienna, Austria
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Correspondence to EPE
Email vturner@westnet.com.au
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REFERENCES
Kamali A, Quigley M, Nakiyingi J, et al. Syndromic management of sexually-transmitted infections and behaviour change interventions on transmission of HIV-1 in rural Uganda: a community randomised trial. Lancet 2003;361:645-52.
Chitwarakorn A. Sexually Transmitted Diseases in Asia and the Pacific. Chiang Mai, Thailand: Ministry of Public Health, AIDS Division, HIV/AIDS Situation in Thailand, 1998.
Biggar RJ, Gigase PL, Melbye M, et al. Elisa HTLV retrovirus antibody reactivity associated with malaria and immune complexes in healthy Africans. Lancet 1985;ii:520-523.
Caceres CF, van Griensven GJP. Male homosexual transmission of HIV-1. AIDS 1994;8:1051-1061.
Brody S. Sex at Risk:Â Lifetime Number of Partners, Frequency of Intercourse, and the Low AIDS Risk of Vaginal Intercourse. New Brunswick NJ: Transaction Publishers, 1997.
Group ES. Risk factors for male to female transmission of HIV. British Medical Journal 1989;298:411-414.
Padian NS, Shiboski SC, Glass SO, Vittinghoff E. Heterosexual transmission of human immunodeficiency virus (HIV) in northern California: results from a ten-year study. American Journal of Epidemiology 1997;146:350-357.
Gray RH, Wawer MJ, Brookmeyer R, et al. Probability of HIV-1 transmission per coital act in monogamous heterosexual, HIV-1 discordant couples in Rakai, Uganda. Lancet 2001;357:1149-1153.