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Case 1: Discussion

Rationale for Prevention Focus on HIV-Infected Individuals

Despite recent advances in the treatment of persons living with HIV, the annual incidence of new HIV infections in the United States has not declined in recent years, remaining relatively static at a rate of approximately 55,000 new infections per year[1]. Although most HIV-infected individuals reduce risk behavior when they become aware of their HIV infection, some do not, and those who do may have difficulty sustaining behavioral change[2,3]. The increase in sexually transmitted diseases (STDs) among HIV-infected individuals in the United States[4,5,6] points out that many HIV-infected individuals continue to engage in high-risk sexual behavior, potentially placing their partners at risk for acquiring HIV infection. High-risk behavior in persons living with HIV not only contributes to the transmission of HIV to persons not previously infected, but may also result in transmission of sexually transmitted diseases (STDs), unplanned pregnancy, and transmission of new and possibly resistant strains of HIV to those who are already infected.

Prevention for Positives Initiative

Past prevention messages have primarily targeted HIV-negative individuals, but given the limited effectiveness of these efforts, health officials recognized the need for new strategies that would further reduce HIV transmission. In a collaborative effort in 2003, the CDC, the Health Resources and Services Administration, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America issued recommendations that emphasized HIV and STD prevention strategies that focused on individuals already infected with HIV--the so-called "Prevention for Positives" initiative[2]. Although busy clinicians providing medical care for HIV-infected patients may prioritize other medical issues above screening for HIV-related risk behavior, an open discussion with patients about their sexual behavior and injection practices can be performed in a time-efficient manner and can provide fruitful information. Moreover, asking about risk behavior can provide an opportunity to influence behavioral change.

High-Risk Sexual Risk Behavior in HIV-Infected Individuals

Available evidence suggests that most HIV-infected individuals in the United States remain sexually active after being diagnosed with HIV infection. Indeed, multiple studies have demonstrated that approximately 70 to 80% of HIV-infected men and women engage in some form of sexual activity[3,7,8]. Multiple factors play a role in the risk of HIV transmission with sexual activity, including the specific sexual activity involved (Figure 1), the HIV-infected person's HIV RNA level, and the presence or absence of a concurrent sexually transmitted disease. Although most HIV-infected individuals attempt to reduce the risk of sexual HIV transmission by modifying their sexual practices[10], some of these practices offer only partial protection against HIV transmission and almost no protection against STDs. In addition, many HIV-infected men and women continue to engage in high-risk sexual behavior, such as unprotected intercourse, sex with multiple partners, and sex with HIV-negative partners or partners of unknown HIV status (Figure 2).

Unfortunately, condom use among HIV-infected individuals is inconsistent: approximately one-third of HIV-infected women and heterosexual men and nearly half of HIV-infected men who have sex with men (MSM) report unprotected anal or vaginal intercourse in the prior 3 months[3]. The frequency of unprotected intercourse is even higher among drug users[12,13]. Of particular concern, several reports have noted that at least 10% of HIV-infected men and women engage in unprotected sex with HIV-negative partners or partners of unknown serostatus[3,10]. Furthermore, many HIV-infected individuals engage in sex with multiple partners. For example, one study involving HIV-infected persons revealed that 59% of MSM, 28% of heterosexual men, and 21% of women reported having more than one sexual partner in the prior 3 months[3]. In addition, 43 to 70% of HIV-infected drug users, many of whom exchange sex or money for drugs, reported multiple sexual partners within the prior 1 to 6 months[7,12,13]. Of note, a recent study performed in San Francisco determined that men and women on antiretroviral therapy who were infected with resistant strains of HIV engaged in unsafe sexual practices with the same frequency as individuals infected with non-resistant strains of HIV[11], highlighting the potential for transmission of resistant strains of HIV through unsafe sexual practices by individuals engaged in care and on antiretroviral therapy.

Factors Associated with High-Risk Sexual Behavior

Multiple factors have likely contributed to high-risk sexual behavior among HIV-infected individuals (Figure 3). First, people living with HIV may engage in "serosorting": having unprotected sexual activity only with persons whom they assume to be HIV-infected[14,15]. These assumptions, however, may not always be correct since HIV-negative persons inaccurately assumed to be infected could be exposed to HIV. Second, the use of highly active antiretroviral therapy (HAART) has improved patients' survival and well-being, and as a part of living healthy, fulfilled lives, HIV-infected individuals frequently engage in sexual relationships. Those on antiretroviral treatment may also assume that HAART eliminates the risk of transmission to their sexual partners, especially if their serum HIV viral load is undetectable[14,16]. Although one study found a threefold increase in the number of episodes of unprotected intercourse after initiating HAART[17], a large meta-analysis found that, overall, HIV-infected individuals did not increase unsafe sex practices after initiating HAART[18]. Third, certain recreational drugs increase the rate of high-risk sexual behavior. Illicit drugs, such as methamphetamine, ketamine, ecstasy, and amyl nitrate ("poppers"), have been associated with increased rates of unprotected anal intercourse among both HIV-negative MSM[19] and HIV-infected MSM[14,20]. Fourth, several studies have linked medications used to treat erectile dysfunction, such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra), with an increased risk of unprotected sexual intercourse among HIV-infected MSM[11,20,21]. Fifth, some environments where HIV-infected individuals may congregate, particularly bathhouses, parks, circuit parties, and raves, may foster high-risk sexual behavior. Internet chat rooms and dating services have also provided a cyberspace environment that facilitates meeting casual or anonymous sex partners, and the increased use of these services has probably played a major role in the increased rates of STDs among HIV-infected MSM[22,23]. Finally, some HIV-infected individuals may experience "prevention fatigue" after a period of risk modification and lapse back into high-risk sexual behavior[14].

High-Risk Injection Drug Use Behavior

Some HIV-infected injection drug users practice high-risk injection practices, such as borrowing (receptive sharing) or loaning (distributive sharing) injection equipment. Reusing syringes or borrowing others' used syringes places HIV-infected injection drug users (IDUs) at risk for acquiring infectious agents that may cause abscesses and serious endovascular infections. When HIV-infected IDUs loan syringes and other injection equipment to other drug users, they risk transmitting HIV to their injection partners. Unfortunately, many HIV-infected drug users continue to practice such high-risk behavior (Figure 4). One study demonstrated that although 83% of HIV-infected IDU in San Francisco used syringe exchange, 57% of them still reused syringes[13]. In addition, more than half of HIV-infected IDUs report sharing drug paraphernalia at some point after their diagnosis of HIV[7]. In multiple studies, 12 to 40% of HIV-infected IDUs acknowledged receptive and distributive syringe sharing in the prior 6 months[3,7,13,24,25]. Although some HIV-infected users may attempt to share equipment with only HIV-infected partners, others choose not modify injection behavior based on the serostatus of their injection partners. Indeed, in one study from Connecticut, 92% of the injection partners of HIV-infected IDUs were HIV-negative or of unknown serostatus. Sharing of drug paraphernalia by HIV-infected individuals is strongly associated with "prevention fatigue"[16].

Case Summary

Our case patient, like many HIV-infected individuals, practices a blend of lower risk and high-risk sexual and injection behaviors. For example, he uses condoms to reduce his risk of HIV transmission to his primary HIV-negative sexual partner, but he still practices unprotected sexual intercourse with multiple sexual partners at the bathhouse, potentially transmitting HIV to these partners, as well as placing himself and his partner at risk for acquiring sexually transmitted diseases. His assumptions about the serostatus of his sexual partners at the bathhouse, his use of sildenafil, and his use of methamphetamine all increase the risk associated with his sexual activity. Similarly, although he attempts to reduce his risk of infection from IDU by using clean syringes obtained through a needle exchange program, he places others at risk for HIV infection by occasionally sharing his injection equipment. A detailed discussion regarding screening for high-risk behavior is presented in Screening for High-Risk Behavior in this same Prevention for Positives module.

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    Figure 1. Type of Sexual Activity with an HIV-Infected Person and Relative Risk of Acquiring HIV

    This figure is based on data from Varghese B, Maher JE, Peterman TA, Branson BM, Steketee RW. Reducing the risk of sexual HIV transmission: quantifying the per-act risk for HIV on the basis of choice of partner, sex act, and condom use. Sex Transm Dis. 2002;29:38-43.

    Figure 1
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    Figure 2. Sexual Risk Behavior Among HIV-infected Individuals

    Sexual risk behaviors during the prior 3 months as reported by HIV-infected MSM, women and heterosexual men in Los Angeles, Milwaukee, New York City, and San Francisco interviewed between June 2000 and January 2002.

    This figure is based on data from Weinhardt LS, Kelly JA, Brondino MJ, et al. HIV transmission risk behavior among men and women living with HIV in 4 cities in the United States. J Acquir Immune Defic Syndr 2004;36:1057-66.

    Figure 2
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    Figure 3. Factors Associated with High-Risk Sexual Behavior

    Figure 3
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    Figure 4. Drug-Related Risk Behavior

    Percent of HIV-infected IDU entering a methadone maintenance program who reported risk behavior within the prior month.

    This figure is based on data from Avants SK, Warburton LA, Hawkins KA, Margolin A. Continuation of high-risk behavior by HIV-positive drug users. Treatment implications. J Subst Abuse Treat 2000;19:15-22.

    Figure 4