Summary of evidence that the foreskin and
lysozyme may protect against HIV infection

By George Hill

This file contains a summary of the evidence that the foreskin and the sub-preputial wetness under the foreskin (prepuce) may protect against human immunodeficiency virus.

Lysozyme is an enzyme with anti-bacterial action that is found in body fluids. (An enzyme is a protein or conjugated protein produced by a living organism and functions as a biochemical catalyst.1) Lysozyme breaks down cell walls and kills bacteria.

Prakash and others reported in 1983 that sub-preputial wetness contains lysozyme2 and Lee-Huang finds lysozyme in human urine.3 Lee-Huang et al. report that lysozyme is also an effective agent for killing HIV in vitro.3

Laumann et al. report that about 77 percent of adult American males are circumcised. 4 Thus, these circumcised males have no sub-preputial wetness and no lysozyme protection. Laumann finds that circumcised men are slightly more likely to have both a bacterial and a viral STD in their lifetime.4

World Health Organization data show that the incidence of HIV infection in the United States is four or more times greater than in any other advanced industrial nation.5 Other advanced nations either do not circumcise males or have a very low incidence of circumcision compared to the United States.6

Chao reports that a circumcised husband is a risk factor for HIV infection amongst pregnant women in Rwanda.7 Grosskurth et al. find a higher incidence of HIV infection in circumcised men in Tanzania.8

The high incidence of HIV in the United States and its correlation with the high rate of circumcision has been noted by Storms9 and Nicoll. 10 Furthermore, Tanne reports a general epidemic of STD, including chlamydia and HIV, in the United States.11

Moreover, Fleiss and others report that the increased friction and more vigorous and prolonged thrusting required to achieve orgasm with a circumcised penis may be more likely to cause "breaks, tears, microfissures, abrasions, and lacerations through which HIV in semen can enter the receiving partner's bloodstream."12

More research is needed to verify the protective effect of lysozyme and the foreskin in vivo.


  1. The American Heritage Dictionary of the English Language, 3rd edition. Houghton Mifflin Company, Boston: 1992.

  2. Prakash S, Rao R, Venkatesan K, et al. Sub-preputial wetness--its nature. Ann Nat Med Sci 1982:18:109-112.

  3. Lee-Huang S, Huang PL, Sun Y, et al. Lysozyme and RNases as anti-HIV components in beta-core preparations of human chorionic gonadotropin. Proc Natl Acad Sci (U S A) 1999 (Mar 16);96(6):2678-2681.

  4. Laumann EO, Masi CM, Zuckerman EW. Circumcision in the United States: prevalence, prophylactic effects, and sexual pratice. JAMA 1997;277:1052-1057.

  5. World Health Organization. The Current Situation of the HIV/AIDS Pandemic, Quarterly Report. World Health Organization, Geneva: July 3, 1995.

  6. Wallerstein, E. Circumcision: the uniquely American medical enigma. Urologic Clinics of North America 1985;12(1):123-132.

  7. Chao A, Bulterys M, Musanganire F, et al. Risk factors associated with prevalent HIV-1 infection among pregnant women in Rwanda. National University of Rwanda-Johns Hopkins University AIDS Research Team. Int J Epidemiol 1994; 23:371-380.

  8. Grosskurth H., Mosha F, Todd J, et al. A community trial of the impact of improved sexually transmitted disease treatment on the HIV epidemic in rural Tanzania: 2. Baseline survey results. AIDS 1995;9(8):927-934.

  9. Storms MR. AAFP fact sheet: a need for updating. Am Fam Physician 1996;54:1216,1218.

  10. Nicoll A. Routine male neonatal circumcision and risk of infection with HIV-1 and other sexually transmitted diseases. Archives of Disease in Childhood (London) 1997;77(3):194-195.

  11. Tanne JH. U.S. has epidemic of sexually transmitted disease. BMJ 1998;317:1616.

  12. Fleiss P, Hodges FM, Van Howe RS. Immunological functions of the human prepuce. Sex Trans Inf 1998;74(5):364-367.

19 March 1999

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