STOCKTON, Calif.

AS THE 17TH INTERNATIONAL AIDS Conference wrapped up in Mexico City this summer, its 25,000 delegates had more money — including $39 billion approved in July by Congress — but no better ideas about how to spend it.

As usual, this gathering heard earnest discussions of human rights and social justice. However, from my perspective as a public-health epidemiologist, the time would have been better spent pondering the science of HIV transmission, to ensure that the huge sums will be spent on what is needed, rather than on the politically correct programs to date.

New U.S. estimates got a lot of attention last week but did not change any of these issues because the number is a small percentage of the population and does not represent any change in the overall HIV situation in the United States.

We now know that apart from a few HIV epidemics due to infected blood, epidemic HIV transmission has occurred only in populations with the highest HIV risk behaviors, principally those having multiple and concurrent sex partners within overlapping sex networks or sharing needles with other injecting drug users.

Sub-Saharan Africa has been particularly hard hit because up to 20 to 40 percent of adolescents and adults of both sexes in some countries routinely have several long-term and concurrent overlapping sex partners. While people outside Africa may have as many sex partners in a lifetime, these tend to be in a serial monogamous pattern that limits epidemic HIV spread.

Similarly, homosexual men who have multiple and concurrent partners are at high risk of epidemic HIV transmission.

From the beginning, HIV prevention programs have not focused sufficiently on these high risk groups, in part because they have been diluting their prevention efforts by trying to prevent “generalized” HIV epidemics that have not and cannot occur in any “general” heterosexual population.

For decades, UNAIDS and AIDS programs throughout the world have been operating on the politically correct but epidemiologically flawed position that virtually everyone is at risk of an HIV infection, especially the poor. This is wrong. Numerous studies in Africa have consistently shown that rich men and women have HIV prevalence rates two to three times higher than the poor, probably because the rich can afford more sex partners.

Globally, AIDS programs have wasted billions of dollars on HIV prevention directed at the general public, particularly youth, who, outside of sub-Saharan Africa, are at minimal or no risk. Workplace HIV awareness and prevention programs are too general and unless very specifically targeted (e.g., long-distance truck drivers) are a waste of time and money.

The “politically incorrect” idea that AIDS prevention should focus more on those at the highest risk now appears to be increasingly accepted by mainstream AIDS experts The head of HIV/AIDS at the World Health Organization admitted in June that “it is very unlikely there will be a heterosexual epidemic” outside sub-Saharan Africa.

However, changing high-HIV-risk behaviors remains difficult, since these are socially unacceptable and illegal in many countries. Many governments hinder efforts to prevent HIV transmission by opposing needle exchange and keeping prostitution illegal, creating unsafe conditions. In many cases they are abetted by faith-based organizations who oppose condom use.

Meanwhile, HIV-prevention programs in sub-Saharan Africa have been undermined by the politically correct myth that poverty and discrimination are the driving forces of HIV epidemics, instead of risky sex.

If we are serious about limiting HIV transmission, then the politically correct paradigm needs to be abandoned. Apart from Africa, prevention programs should exclusively target the highest HIV-risk-behavior groups: gay men, injecting drug users, sex workers and their clients. According to UNAIDS’s most recent report, HIV prevalence is high in all of these, especially gay men.

A more targeted approach is vital as it appears increasingly unlikely in the foreseeable future that there will be any magic bullet for AIDS — such as a vaccine or a cure.

Annual global HIV incidence peaked about a decade ago but the global impact of close to 30 million living with HIV still requires an unprecedented global response. AIDS will, for centuries, remain a major public-health problem that primarily affects people with the highest risk behaviors. We must confront these realities and make sure billions of dollars of goodwill are not squandered on political correctness.

UNAIDS claims to accept this but it has yet to show it can change its wasteful habits.

James Chin, M.D., a former chief of the surveillance, forecasting and impact assessment unit of the Global Program on AIDS of the World Health Organization, is a clinical professor of epidemiology at the School of Public Health at the University of California at Berkeley.