Revisiting the condom riddle: solutions and implications.

Author:Munoz, Karen

Introduction: Male Condoms

A male condom is a thin sheath worn over a the penis during sexual intercourse to reduce the risk of acquirement and transmission of Human Immunodeficiency Virus (HIV), Sexually Transmitted Infections (STIs), and to prevent pregnancy. Since its first appearance in the 16th century, the male condom, has evolved and as current paradigms suggest, using them consistently and correctly provides protection against the aforementioned conditions (World Health Organization, 2010).

Today, condom availability and use continue to be widespread, especially in developed parts of the world, and play a significant role in public health interventions and outreach efforts, as HIV and other STIs continue to burden communities and societies (Moran et al., 1990). This paper aims to critically examine the "condom riddle", initially proposed in 1978, and provide alternative solutions with existing paradigms in order to promote safe sexual practices through condom use.

The Age Old Condom Riddle and Existing Solution

The condom riddle first appeared in an article entitled "An Algorithm prevents the Propagation of Certain Diseases at Minimum Cost". It was published in 1978 in conference proceedings appropriately titled "Interfaces Between Computer Science and Operations Research" (Lenstra, Rinnooy Kan, & van Emde Boas, 1978). The challenge in the riddle is as follows: If a man were to have sexual intercourse with three women consecutively, but only has two condoms, how would he do so without exposing himself or any of the women to diseases. Dr. Ilan Vardi, a Professor of Computational and Applied Mathematics at Stanford University, proposed a mathematical solution to the problem and published it in his book "Computational Recreations in Mathematica" in 1991(Vardi, 1991). His solution was later translated into a non-mathematical module (Vardi, 1993). The proposed and universal solution to this riddle is as follows: The man in question uses condom "A" and "B" at the same time to have sexual intercourse with woman #1. Then, he takes off condom "B" to have sexual intercourse with woman #2 using condom "A" only. Finally, the man turns condom "B" inside out and places it back on top of condom "A" to have sexual intercourse with woman #3. Through this process, he has sexual intercourse with all three women with two condoms and reduces the risk of exposing himself and the women to STIs as the exchange of bodily fluids is theoretically less. To facilitate understanding of this process, we have provided an illustration of the solution (Figure 1), which has been discussed at length on message boards, blogs, forums, personal websites, books, and University websites (OCF, 2004).

Public Health Implications of Posted Solution

The condom riddle may not be as unrealistic as many would think. A study of sexual behaviors in Puerto Rico identified a 2% self-reported prevalence of group sex activities, with this group possibly more vulnerable to the acquisition and transmission of HIV and STIs (Ortize et al., 2011). The current solution for the riddle does not provide the most effective and safe method of reducing the spread of infection among the four sexually active individuals. In this section, we examine some of the problems associated with the proposed solution from a public health perspective.

Condoms Are Not One-Hundred Percent Effective

As with any form of protection, condoms are not 100% effective. An observational study carried out in the southern United States showed that used condoms ripped during intercourse for 3% of participants, and the rate of a condom ripping was found to be higher for first time users (Hollander, 2005). Other studies indicate that slippage and condom ripping during use may range from 1.0% to 3.6% (Fitch, Stine, Hager, Mann, Adam, & McIlhaney, 2002). Thus, a condom cannot be regarded as a flawless method of reducing the risk of acquisition and transmission of STIs and pregnancy prevention. The solution to the riddle, therefore, does not account for the margin of error in ripping, breakage, and other mechanical problems.

Using Condom A and B Together

In order for...

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