In the May 2003 issue of the British Journal of Obstetrics and Gynaecology we present evidence for widespread transmission of HIV through health care exposures (1). Unlike many studies which use small convenience samples, the South African Human Sciences Research Council (HSRC) conducted a national census-derived random sample survey of HIV prevalence (2). They obtained survey data and oral specimens (with the OraSure HIV-1 device) from 8840 persons aged two and over. Among 2-14 year olds the seroprevalence was 5.6%, a rate which extrapolated to all South African children yields 670,000 HIV-infected. This is not only a staggering number of infected children, it is also 2.7 times the estimate for infected 0-15 year olds in South Africa (only half of whom would be in the 2-14 year old group) that was generated by UNAIDS (3) using their sentinel antenatal surveys, and their assumptions about mother-to-child transmission, neonatal survival, and presumed negligible HIV transmission via other routes.

Two small subanalyses of data from the study shed further light on a liberal upper limit of what proportion of children’s HIV infections might be due to mother-to-child transmission. In the first, it was found that among whites in this sample, children had an HIV prevalence of 11%, but the adult prevalence was only 5.7%.

The second subanalysis involved 20 seropositive children (aged 2–11) matchable to a biological parent with a known HIV test result. Only 5 of these children had an HIV positive parent, implying that three-quarters of infections come from a source other than their mothers. The HSRC data are consistent with other African reports of seropositive children of seronegative mothers (4).

Some people have assumed that sexual exposures, voluntary or involuntary, account for all or almost all cases not due to vertical transmission (5). However, only 1.4% of 12–14 year olds in the HSRC sample reported being sexually experienced. Even assuming underreporting of sexual experience (6), the amount of sexual activity needed to produce these prevalences would need to be enormous given the inefficiency of HIV transmission even in child rape (less than 1% seroconversion in South African studies) (7), and unlikely to be overlooked by pediatricians. Furthermore, the recent large multicenter study in four African cities found that sexual behavior and lack of condom use did not differentiate cities with high, from cities with low, HIV prevalence (8, 9), and thereby offering little support for the hypothesis of significant heterosexual HIV transmission across Africa.

Instead, these data suggest frequent child-to-child transmission in pediatric health care. Examination of HIV outbreaks through pediatric clinics in Libya, Romania, and Russia has shown efficient transmission through injections, blood tests, immunization, and/or other medical procedures; for example, two hospitals in Elista, Russia, documented 89 pediatric HIV infections directly or indirectly transmitted from an index child in less than a year (10). Health care risks are not limited to children. Our other recent work has revealed the extent of the health care transmission problem in Africa. We noted sudden increases in HIV incidence associated with antenatal care and delivery (4), increasing HIV levels in Zimbabwe concurrent with decreasing sexually transmitted disease incidence and increasing condom use (11), injections for the treatment of sexually transmitted diseases being more associated with prevalent HIV than the sexually transmitted diseases themselves, and HIV incidence associated with medical injections (4, 12). Injections have been and still are quite popular among African patients, administered at the vast majority of medical visits, are frequently unnecessary, and often unsterile (13). Blood transfusions for malaria treatment are also common among children and despite efforts to assure their safety, many still go untested (14, 15).

It has not been possible to find and re-test HIV positive children and look for risk factors because the HSRC survey was anonymous. However, there are other approaches. For example, South African newspapers have reported specific instances of HIV positive children with HIV negative mothers (16). For each such case, a thorough investigation should be initiated (tracing the clinic and date for all health care received, HIV status of other children who received care in the same clinics on the same days, etc.). It is through such investigations that physicians in Russia, Romania, and Libya uncovered large-scale iatrogenic outbreaks from individual unexplained infections. The HSRC data raise serious questions about the safety of health care in South Africa, and should receive closer scrutiny by health authorities and investigators to limit iatrogenic risks.

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