Alcohol's Role in HIV Transmission and Disease Progression

Article excerpt

Alcohol use has negative effects on HIV disease progression through several mechanisms, including transmission, viral replication, host immunity, and treatment efficacy. Research with animal models has explored the effect of alcohol intake on several aspects of simian immunodeficiency virus (SIV) disease progression. Data suggest that the increased SIV levels observed in alcohol-consuming animals may represent an increase in virus production as opposed to a decrease in host defense. Results also suggest that changes in nutritional balance and metabolism, as a possible consequence of a proinflammatory state, together with increased virus production in animals consuming alcohol, accelerate SIV and possibly HIV disease progression. Further studies using the animal model are necessary. KEY WORDS: Alcohol and other drug (AOD) use, abuse, and dependence; AOD effects; disease factor; disease complication; immune system; human immunodeficiency virus (HIV); HIV infection; acquired immune deficiency syndrome; antiretroviral therapy; simian immunodeficiency virus; animal models; rhesus macaques

Human immunodeficiency virus (HIV) infection continues to be a major global health prob-lem, with an estimated 33 million peo-ple infected as of 2007. In the United States, more than 1.1 million people are infected with HIV (Centers for Disease Control and Prevention 2009). Although effective treatment of HIV infection has substantially decreased HIV-related mortality, HIV still is the sixth leading cause of death for adults aged 25-44 in the United States (http:// www.cdc.gov/hiv/topics/surveillance/ resources/slides/mortality/slides/ mortality.pdf).

Recent data indicate that new HIV cases have not decreased in recent years and may actually be increasing in men who have sex with men, a trend observed both in North America and in Asia (http://www.unaids.org/ en/KnowledgeCentre/HIVData/Glob alReport) (Hall et al. 2009).

Alcohol is the most commonly abused substance in the United States, and people with HIV are more likely to use alcohol than the general population. Whereas the rate of alcohol abuse is approximately 4.6 percent in the general U.S. population (Grant et al. 2004), 8 percent of HIV-infected individuals in U.S. cohorts can be classified as heavy drinkers (Galvan et al. 2002). The prevalence of hazardous drinking in HIV-infected U.S. veterans is 20 percent, with 67 per-cent considered to drink "too much" at some point by their health care providers (Conigliaro et al. 2003). The rate is even greater among homosexu-al/bisexual men (41 percent) (Lefevre et al. 1995). Heavy drinking in HIV patients correlates with illicit drug use (cocaine and heroin), lower educational status, and male gender (Galvan et al. 2002).

Given the high prevalence of sub-stance abuse in the HIV population, deciphering the effects of alcohol and other drugs on HIV transmission, disease progression, and treatment response is a high research priority. This article will review evidence showing that excessive alcohol con-sumption is detrimental to the HIV- infected patient in several aspects (see figure 1). Topics discussed include the effect of alcohol abuse on HIV transmission, viral replication, host immune system, and efficacy of treatment to keep HIV levels low (i.e., antiretroviral [ARV] therapy [ART]). The article also will present data showing the effect of alcohol intake on simian immunodeficiency virus (SIV) pathogenesis in rhesus macaques, the animal model of choice for HIV infection. Finally, the article will discuss potential research avenues in nonhuman primate (NHP) animal models that can be used to further our understanding of the role of the alcohol in the natural history of acquired immune deficiency syndrome (AIDS).

ALCOHOL'S ROLE IN HIV TRANSMISSION

As stated above, alcohol intake increases the rate of HIV transmission through multiple mechanisms, as reviewed below and shown in figure 2.

Behavioral Effects

Alcohol use causes disinhibition and diminished perception of risk, which increase the likelihood that a person would put him or herself (or his/her partner) at risk for HIV infection by engaging in unsafe sexual practices, such as having multiple sex partners, unprotected intercourse, sex with high-risk partners (e. …