Running the numbers

Came across an article recently that provided the following information:

ATLANTA - One in five sexually active gay and bisexual men has the AIDS virus, and nearly half of those don't know they are infected, a federal study of 21 U.S. cities shows.

Experts said the findings are similar to earlier research, but the study released Thursday is the largest to look at gay and bisexual U.S. men at high risk for HIV. More than 8,000 men were tested and interviewed, and 44 percent of those who had the virus didn't know they had it.

Overall, less than half of 1 percent of Americans have the AIDS virus, according to a calculation by the Kaiser Family Foundation, a research and policy organization in Washington, D.C.

But gay and bisexual men continue to be infected at much higher rates, said Jennifer Kates, Kaiser's director of global health and HIV policy.

Two numbers in this article made me wonder. The first was the rate of infection amongst homosexual males. The second was the overall infection rate amongst the American population. It just didn't seem to make sense.

Conventional wisdom says that 10-12% of the human population is homosexual.

So if you were to look at the US, using a population of 300 million and 10% of those being homosexual, the homosexual population of the US should be 30 million.

Now assuming that there is no gender bias concerning homosexuality, 15 million of those are men.

We are told that "one in five sexually active gay and bisexual men has the AIDS virus."

So that means that 3 million homosexual men in the US have AIDS.

That is 1% of the US population and doesn't take into account the heterosexual community of 270 million people.

However the Kaiser Family Foundation (a research and policy organization in Washington, D.C.) says that "overall, less than half of 1 percent of Americans have the AIDS virus."

So just one small portion of the US population (homosexual men equaling 5% of the US population) already outpace this calculation.

Concerning HIV infection routes:

The World Health Organization estimates that [U]heterosexual transmission has accounted for 75% of the HIV infections in adults world-wide[/U]. The remaining 25% are primarily due to the use of contaminated blood and blood products, needle sharing by intravenous drug users, and homosexual/bisexual transmission. Heterosexual intercourse has been the dominant route of transmission in Africa, Asia, South America, Central America and the Caribbean. Indeed, in the United States, AIDS ceased being primarily a disease of gay men in the early 1990s. Data from the United States Centers for Disease Control and Prevention show that the proportion of new cases reported among homosexual/bisexual men decreased from 47.3% in 1993 to 43.3% in 1994. While the rate of AIDS among American gay males decreases, there has been a recorded increase among women and minority groups. Women accounted for 18.1% of total AIDS cases in 1994, up from 16.2% in 1993. In the same years, the number of American Blacks with AIDS increased from 36.1% to 39% of total new cases, while Hispanics with AIDS increased from 17.7% to 18.7%.

So if heterosexuals account for 3 times as many infections as homosexuals, what are we looking at?

So 20% of homosexual men have contracted AIDS. Women are infected at a lower rate so a safe estimate might be a 1% infection rate amongst homosexual females (iv drug use and other transmission vectors) which would add 150,000 to the AIDS infected homosexual community.

So the estimated total for those infected with AIDS amongst the American homosexual community would be 3.15 million people.

Now if there are three heterosexual people who have AIDS for every one infected homosexual person (based on WHO numbers) we are left with a total infected population of 9.45 million heterosexual people. Add in the homosexual community numbers and you get a total of 12.6 million. This is greater than 4% of the US population and far far above the listed the "less than half of 1% of the US population" as stated by the Kaiser Family Foundation.

So what should one believe?

Then comes this study from Britain which says:

More than 480,000 people or one per cent of the UK's adult population regard themselves as gay or lesbian while a further 245,000 or 0.5 percent say they are bisexual, according a study published by the Office for National Statistics.

The data has been collected by the new Integrated Household Survey (IHS), which is the largest social report ever produced for the ONS.

The 450,000 individual respondents to the survey provided the biggest pool of UK social data after the national census, the statistics service said.

So if we do away with the conventional wisdom of 10% and use this more recent 1% estimate, the numbers would break down like so:

Members of the homosexual community: 3 million
Number of AIDS infected gay men: 300,000
Number of AIDS infected gay women: 15,000
Total: 315,000
Number of AIDS infected heterosexual people: 945,000
Total number of infections: 1,260,000

This infection rate would be much more in line with the "less than half of 1% of the US population" (1% of 300,000,000 = 3 million, 0.5% = 1.5 million) as stated by the Kaiser Family Foundation.

So it would seem that either AIDS infection rates are far far more than estimated (1000% more) or the percentage of homosexual humans is far less than commonly assumed.

Just interesting to look at the numbers.