The Authors reply

Abstract

We appreciate Potterat et als interest in our study which described a clear association between number of sexual partners and HIV prevalence but also noted that 41% of HIV-positive females reported no history of sexual activity. They suggest that unsafe medical injections rather than sexual transmission are responsible for the high rate of HIV infection that we observed. We acknowledged the possibility of nonsexual transmission in our article but the survey we analyzed was conducted prior to the debate about transmission and did not ask about injection history. Potterat et al mention a study in Zambia in which unsafe medical injections were found to be associated with HIV prevalence but other studies including a literature review led by the World Health Organization have concluded that there is no compelling evidence that unsafe injections are a predominant mode of HIV transmission in sub-Saharan African. If injections were a major source of transmission one would expect high rates during childhood when children receive most preventive vaccinations and many health care visits. Yet a study of mother-child dyads in public health facilities in South Africa found only 1.4% of HIV-positive children aged 2-9 years had HIV-negative mothers. While this study needs to be replicated in other settings it does not indicate that injections play a major role in transmission among children. (excerpt)