Trends in infectious diseases and the male to female ratio: Possible clues to changes in behavior among men who have sex with men

Men who have sex with men (MSM) are a priority population for HIV care and prevention programs. This report describes HIV and other sexually transmitted disease (STD) trends among MSM in metropolitan Atlanta by analyzing nine databases. We describe the use of the male-to-female (M:F) ratio, a surrogate marker for MSM in databases without standardized MSM variables that is recommended as an indirect measure of HIV risk behavior in the CDC/HRSA Integrated Guidelines for Developing Epidemiologic Profiles. During 1997 to 2001, there were increases among MSM for reported syphilis (from 9% to 17%), antibiotic-resistant gonorrhea (from 4.8% to 8.6%), and HIV seroprevalence (from 33% to 43%). During 1998 to 2001, the M:F ratio for cases peaked at 12:1 during a hepatitis A outbreak among MSM, increased for shigellosis (from 1:0 to 18:1) and giardiasis (from 1.7 to 2.1), and did not appreciably change for hepatitis B, salmonellosis, or chlamydia. HIV and several other STDs appear to have increased among MSM in metropolitan Atlanta. When standardized MSM variables are not available, an M:F ratio is useful.