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a three-part plan that includes: (1) intensifying efforts to help all infected persons learn their
HIV status; (2) establishing new prevention programs to help HIV-infected persons establish and
maintain safer behaviors, combined with improved linkages to treatment and care; and (3)
expanding highly targeted prevention programs to reach all HIV-negative persons at greatest
risk.[124]
Worldwide, heterosexual transmission accounts for the majority of cases of HIV
infection. The important factors that promote heterosexual transmission include:[125]

* More sexual partners
* Frequent change of sexual partners
* Unprotected sexual intercourse (lack of barrier precautions)
* Presence of additional sexually transmitted diseases
* Lack of male circumcision
* Social vulnerability of women and young persons
* Economic and political instability of the community

The lack of economic and political stability makes it difficult to institute programs to
change behavior, to promote condom use, to treat sexually transmitted diseases, to test for HIV
infection, and to treat HIV infection with antiretroviral therapies that reduce viral load and the
risk of transmission.[125] If HIV-infected persons have access to HIV testing, counseling, and
treatment, then the prevalence of HIV in the population will drop.[123]
Practicing "safe" sex will diminish the prevalence of HIV infection in populations where
HIV has become well established. Though transmission of HIV can be reduced, transmission
cannot completely be eliminated once it is established in a population.[16,17] Risk reduction
interventions, including education on abstinence and safer sex, are beneficial. Abstinence
intervention has a short-term effect over months, while safer sex interventions have a longer
lasting effect, particularly amongst adolescents who have previously had sexual intercourse.
These interventions appear to reduce the frequency of sexual intercourse. Promotion of the use
of condoms as a barrier precaution has also been shown to reduce the rate of HIV infection, and
is a mainstay of prevention efforts.[126] The availability of condoms has a significant effect
upon condom use and does not appear to increase rates of sexual activity.[127]
A marked increase in the number of incarcerated persons in the U.S. has paralleled an
increase in HIV infection within the prison population. Half the increase in prisoners has
resulted from convictions for drug offenses, and drug abuse fuels risk for HIV infection. It is
estimated that a fourth of HIV infected persons in the U.S. are incarcerated for at least part of
each year. in 2004, 1.8% of U.S. prison inmates were HIV positive, a rate four times that of the
entire U.S. population. Prison administrators have generally been reluctant to institute
prevention measures such as those promulgated by the World Health Organization.[128]
There are three major variables that explain the sexual transmission of HIV: (1)
transmission efficiency, (2) number of sexual partners, and (3) seroprevalence (numbers of
infected individuals in a population). HIV transmission through sexual exchange of semen or
vaginal fluids is much less efficient than transmission of either gonorrhea or hepatitis B virus.
Usually, multiple sexual exposures are necessary to increase the likelihood for transmission of
HIV from infected persons. It is estimated that gonorrhea may be transmitted in 22 to 25% of
sexual encounters involving an infected individual, hepatitis B virus in 20 to 30% of encounters,
and hepatitis C in 2% of sexual encounters. In contrast, HIV transmission occurs much less