The number of partners and the probability of HIV infection.

This paper analyses the probability of contracting the AIDS virus in relation to the number of sexual contacts and the number of different partners. It is shown that in the case of a fixed number n of sexual contacts there is the following ranking from least risk to greatest risk: 1. a monogamous relationship with a non-infected partner; 2. a monogamous relationship with a randomly selected partner; 3. a relationship with more than one randomly selected partners; 4. n randomly selected partners; 5. a monogamous relationship with an infected partner.