Since reports of emergence and spread of the human immunodeficiency virus (HIV) in the United States between the 1970s and 1980s, the HIV/AIDS epidemic has frequently been linked to gay, bisexual, and other men who have sex with men (MSM) by epidemiologists and medical professionals. It was first noticed after doctors discovered clusters of Kaposi's sarcoma and pneumocystis pneumonia in homosexual men in Los Angeles, New York City, and San Francisco in 1981. The first official report on the virus was published by the Centers for Disease Control (CDC) on June 5, 1981, and detailed the cases of five young gay men who were hospitalized with serious infections. A month later, The New York Times reported that 41 homosexuals had been diagnosed with Kaposi's sarcoma, and eight had died less than 24 months after the diagnosis was made. By 1982, the condition was referred to in the medical community as "gay-related immune deficiency" (GRID), "gay cancer", and "gay compromise syndrome". It was not until July 1982 that the term Acquired Immune Deficiency Syndrome (AIDS) was suggested to replace GRID, and it was not until September that the CDC first officially used the AIDS acronym. Scientists and physicians now know that HIV/AIDS does not only affect MSM and can infect anybody, regardless of sex and sexual orientation. Nonetheless, MSM are still considered a "key population" globally, meaning they have high rates of HIV and are at high risk for acquiring it. Gay, bisexual, and other men who have sex with men are a small percentage of the U.S. population, but are consistently the population group most affected by the HIV/AIDS epidemic in the United States, and are the largest proportion of American citizens with an AIDS diagnosis who have died. The United Nations estimates the global median HIV prevalence among MSM at 7.7%.
MSM as a behavioral category
Men who have sex with men (abbreviated as MSM, also known as males who have sex with males) are males who engage in sexual activities with members of the same sex, regardless of how they personally identify themselves. Many MSM choose not to (or cannot for other reasons) identify as homosexual or bisexual. Similarly, the label excludes men who identify as gay or bisexual, but who have never had sex with another man, including many gay teenagers. The terms "men who have sex with men" (MSM) and "women who have sex with women" (WSW) have been used in medical scholarship and research since at least 1990. But, the term has been attributed to Glick et al., because their usage in a 1994 study solidified the concept in medical terminology. MSM is often used in medical literature and social research to describe such men as a group for research studies without considering issues of self-identification because it offers better behavioral categories for the study of disease-risk than identity-based categories (such as "gay", "bisexual", or "straight"), because a man who self-identifies as gay or bisexual is not necessarily sexually active with men, and someone who identifies as straight might be sexually active with men.
Demographics Determining the number of men who have ever had sex with another man is difficult worldwide. The World Health Organization estimates that at least 3% and as high as 16% of men have had sex at least once with a man. Their estimate includes victims of sexual abuse in addition to men who regularly or voluntarily have sex with men. The United Nations estimates that 6-20% of men worldwide have sex with other men at some point during their lifetime. A recent study using social media platforms to estimate the global population of MSM resulted in much higher estimates than those reported by the UNAIDS.
MSM in the United States
Estimates about the U.S. population of men who have sex with men (MSM) vary. The Centers for Disease Control and Prevention estimate that men who have sex with men (MSM) represent about 2% of the American population. A 2005 study estimates that among U.S. men aged 15 to 44, an estimated 6% of have engaged in oral and/or anal sex with another man at some point in their lives, and about 2.9% have had at least one male partner in the previous 12 months. A 2007 study estimated that there are 7.1 million men who have sex with men (MSM) in the United States, or 6.4% of the overall U.S. population. The percentage of men who have sex with men varied by state, with the lowest percentage reported in South Dakota (3.3%) and the highest in the District of Columbia (13.2%). However, the same study found that 57% of men who have sex with men identified as heterosexual or bisexual. A 2010 study estimated that 2.6% of the male population in the United States had engaged in same-sex behavior in the past year, 4.0% in the past five years, and 7.0% at any point in their lifetime.
"Down-low" subculture among Black MSM
Down-low is an African-American slang term specifically used within the African-American community that typically refers to a sexual subculture of Black men who usually identify as heterosexual but actively seek sexual encounters and relations with other men, practice gay cruising, and frequently adopt a specific hip-hop attire during these activities. They generally avoid disclosing their same-sex sexual activities, and often have female sexual partner(s), and may be married or single. In medical research, the term down-low is used to identify sexual identity-behaviour discordance among men who have sex with men (MSM). According to a study published in the Journal of Bisexuality, "[t]he Down Low is a lifestyle predominately practiced by young, urban Black men who have sex with other men and women, yet do not identify as gay or bisexual". In this context, "being on the down-low" is more than just men having sex with men in secret, or a variant of closeted homosexuality or bisexuality—it is a sexual identity that is, at least partly, defined by its "cult of masculinity" and its rejection of what is perceived as White American culture (including what is perceived as White American LGBT culture) and terms. A 2003 cover story in The New York Times Magazine on the down-low phenomenon explains that the American Black community sees "homosexuality as a white man's perversion." It then goes on to describe the down-low subculture as follows:
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