To the Editor:
Viewing HIV as a sexually transmitted, rather than sexually transmissible, infection blinds investigators to other important routes such as transmission through needles or contaminated sharps. In his analysis of HIV transmission dynamics O’Farrell, 1 like most researchers studying HIV transmission patterns in developing countries, assumes that transmission is exclusively sexual, not to mention that he naively believes denials of anal intercourse, the quintessential sexual vector. 2 He writes: “Possible factors include the high numbers of male sexual contacts with FSW [female sex workers], genetic diversity of HIV, genetic and immunologic host factors, sexual practices, condom use, stage of HIV disease (early or late), male circumcision status, and concomitant STIs [sexually transmitted infections].”1 Such a view precludes factoring confound introduced by transmission due to contaminated sharps, especially in settings where contaminated syringes and needles are reused. The reader retains the nagging feeling that high HIV prevalence may be fueled by seeking medical care, for which there is accumulating evidence. 2,3 Painful as it may be to investigate such a possibility, the fact remains that the association of HIV transmission with STI could also be a consequence of STI treatment, routine vaccination, or perhaps antenatal care. Until empirical studies are conducted to investigate this possibility without turning a blind eye to the politically unpalatable, conclusions about HIV transmission in developing countries and, importantly, about appropriate public health interventions, remain scientifically suspect. Indeed, O’Farrell details many anomalies in the interpretation of the contribution of specific sexual variables to observed HIV incidence and prevalence. (To his credit, he notes that reported condom use fails to distinguish between countries with high and low HIV prevalence, and considers the often overlooked importance of genital hygiene.) One wonders how many of these anomalies could be at least partially explained by unsuspected HIV transmission in medical settings. Lastly, this vector might fit the data better than sexual transmission, especially given the observation that HIV propagation does not obey the reproduction number formula he uses. 4 That this is a distinct possibility is underscored by our guess that many researchers would be concerned about receiving care involving the use of medical sharps in developing countries. From an epistemological point of view, we’re amazed that researchers don’t put two and two together and rigorously assess the possibility that inordinately high HIV prevalence in some developing countries, along with observed anomalies of sexual variables or of intervention trials, 5 may be elucidated by controlling for unexplored confound, which may also account for the democratic sex ratio reported in developing countries.
JOHN J. POTTERAT, BA,* AND
STUART BRODY, PhD†
1. O’Farrell N. Enhanced efficiency of female-to-male HIV transmission in core groups in developing countries: the need to target men. Sex Transm Dis 2001; 28: 84–91.
2. Brody S. Sex at Risk: Lifetime Number of Partners, Frequency of Intercourse, and the Low AIDS Risk of Vaginal Intercourse. New Brunswick, NJ: Transaction Publishers, 1997: 109–168
3. Holding R, Carlsen W. Fast track to global disaster: contaminated syringes kill millions each year. San Francisco Chronicle. October 27, 1998:A-1.
4. Potterat JJ, Muth SQ, Brody S. Evidence undermining the adequacy of the HIV reproduction number formula. Sex Transm Dis 2000; 27: 644–645.
5. Grosskurth H, Gray R, Hayes R, Mabey D, Waver M. Control of sexually transmitted diseases for HIV-1 prevention: understanding the implications of the Mwanza and Rakai trials. Lancet 2000; 355: 1981–1987.