Re-Emergence of HIV Infection and Syphilis Among Men Who Have Sex with Men

Sexual activity has been shown to be the primary mode of transmission for several important viral and bacterial infections among men who have sex with men (MSM) throughout the world and therefore sexually transmitted infections (STIs) are still one of major public health problem worldwide. Since the earliest days of the human immunodeficiency virus (HIV) epidemic MSM have been profoundly affected by the disease; by the time the first AIDS cases were reported in the early 1980s, HIV had already spread widely among homosexual and drug-user communities. In western Europe, has been estimated that HIV incidence peaked around 1983 among MSM and in 1987-88 among injecting drug users, with 120.000 homosexual/bisexual men infected by 1985, and 144.000 injecting drug users infected by 1989 (Downs et al., 2000). MSM account for a substantial proportion of HIV infections and compose a “bridging group” for transmission to heterosexuals because of the high frequency of reported bisexuality. Widescale behavioural modification in response to the emerging HIV/AIDS pandemic saw dramatic reductions in the incidence of many acute STIs in the late 1980s (WHO, 2007). However, these have not been maintained and many states are now observing increases in rates of diagnosed STIs; then the proportion of homosexual men reporting “unsafe sex”, often measured as unprotected anal intercourse (UAI) with casual partners, has increased since the mid-1990s (Prestage et al., 2005). In western Europe, among MSM, HIV diagnoses increased in 2002 (22%, from 2757 in 2001 to 3371 in 2002) after a slow decline in the previous years. Increased high risk sexual behaviour and migration of HIV-infected people from sub-Saharan Africa have contributed to the rise in the incidence of STIs since 2000 (Hamers & Downs, 2004). On the other hand, antiretroviral treatment, which lowers the viral load, may reduce the likelihood that an HIV infected person infect a partner during unprotected sexual intercourse. Mathematical modelling suggests that the effect of antiretroviral treatment on lowering transmission at the population level could be offset by an increase, even modest, in risk behaviour, and the net effect of these opposing forces on HIV incidence has been much debated (Katz et al., 2002).