Slightly confused after doing some reading online.

I have been doing some reading online about hiv transmission.  I have a few questions.  About what is the total population of the USA that has hiv or aids (it looks to be relatively small though large for the seriousness of the disease)?  How much of that is heterosexually transmitted?  When looking at the data they refer to heterosexual transmission as high risk behavior.  Do they mean just unprotected or many partners or with people know to have hiv. I hope this makes sense because it is somewhat confusing to me.

[H. Hunter Handsfield, M.D.]

Welcome to the forum.

The CDC data on HIV and AIDS in the US are available to anyone at http://www.cdc.gov/hiv/topics/surveillance/index.htm

Off the top of my head, having not looked at the statistics for a few months:  About 1.1 million US residents are HIV infected; 576,000 people have died (through 2007); there are about 56,000 new infections each year.  Of the new infections, about 55% are in men who have sex with men (which reflects a very dramatic elevated risk, since this means 2-3% of the population accounts for more than half the infections).  About 10-15% are acquired by shared injection equipment, leaving around one third of cases acquired heterosexually.  Among the heterosexually aquired cases, the large majority are in particularly high risk groups, such as non-white populations in the southeast.  (Overall rates are 10 fold higher in African Americans than in whites.)

The term "high risk" does not have a precise definition and never will.  A person having heterosexual exposure with a commercial sex worker is at high risk compared to a heterosexual without such exposure, but still miniscule compared to gay men with multiple partners or injection drug users.  And of course it's much higher risk from sex with known infected partners than partners not known to have HIV.  The large majority of those who acquire HIV heterosexually are the regular partners of infected persons.  One-off exposures are exceedingly rare sources of new HIV infection.

The bottom line is that the average white heterosexual single person is exceedingly unlikely to ever catch HIV in the US, assuming s/he avoids sex with known injection drug users, bisexal men, and others at particularly high risk, such as immigrants from HIV endemic countries (e.g. southern Africa).  That's even without condoms -- and of course if condoms are used consistently, as they should be, the risk is essentially zero.

I hope this helps.  for more information, spend some time on the CDC surveillance website.

Regards--  HHH, MD