The war against infectious disease often requires multiple weapons. Chlorinated water, sewage treatment plants, and surface disinfectants for hospital use contribute to the control of bacterial disease. These sanitation measures are probably much more important than antibiotics in terms of the number of people who die of infection.
Viral diseases present their own challenges. The smallpox virus was eradicated by a worldwide vaccination program, but many other viruses mutate too fast for this approach. Flu shots, for example, have to be repeated every year because new strains of influenza virus emerge. The HIV virus that causes AIDS is even worse: it rapidly develops resistance to anti-viral drugs, and it has escaped efforts to develop a vaccine for almost 30 years.
Male circumcision is one tool to slow the spread of HIV. According to a recent review in the medical literature, this procedure reduces the risk of female-to-male transmission of the virus by 60 percent. It does not appear to change the risk of male-to-male transmission, so the mechanism is not clear. But it does work, to some extent, and is believed to provide life-long partial protection.
So is it a good idea to circumcise all men? A team of researchers from the Joint United Nations Programme on HIV/ AIDS (UNAIDS), the World Health Organization (WHO), and the South African Centre for Epidemiological Modelling and Analysis (SACEMA) presented results from mathematical modeling studies. There are two major cautions:
1. Risk compensation: if circumcised men think they are safe from AIDS, they may engage in more risky behavior. The studies reported so far do not indicate this as a problem among men who receive intensive health education along with circumcision.
2. Cost: Circumcision programs may take funds away from other health programs, such as education and condom distribution. Thus the authors recommend starting with areas of high HIV prevalence, and with men at high risk. This generally includes the age group 15 to 34 years old. Circumcising babies is lower cost and provides long-term population benefits, but it may not be the most cost-effective solution if a vaccine is developed within the next 20 years.
The models cited all show that male circumcision is not enough to stop the HIV epidemic, but it can make a difference. For areas with low rates of male circumcision and high rates of HIV infection, the prediction is that one HIV infection can be prevented for every five to 15 circumcision procedures.
UNAIDS/WHO/SACEMA Expert Group, “Male Circumcision for HIV Prevention in High HIV Prevalence Settings: What Can Mathematical Modelling Contribute to Informed Decision Making?”, PLoS Medicine 2009 September; 6(9): e1000109. Epub 2009 Sep 8.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.