A new study suggests that most young gay men in Mexico City would pledge to stay H.I.V.-free, attend a monthly safe-sex talk and take regular H.I.V. tests to prove they were uninfected — all in return for just $288 a year.
Most male prostitutes would make the same promise for $156 a year, the study found.
Because each person receiving H.I.V. treatment costs Mexico’s public health system up to $7,000 a year for drugs alone, payments that encourage men to stay uninfected could be a bargain, the authors argue.
The study, done by researchers from Brown University, the University of California at Berkeley and Mexico’s national public health institute, was published online by The European Journal of Health Economics.
Although other countries have tried programs that pay people for good health behavior, like taking children for checkups, the authors believe their study was the first to pinpoint a specific dollar value that would ensure cooperation from 70 percent of a risk group — in this case, young gay and bisexual men, who have very high H.I.V. infection rates and are the drivers of Mexico’s epidemic.
The researchers approached men aged 18 to 25 in gay bars, discos and the streets of the city’s red-light district. The 40-minute survey, taken on cellphone-size computers, increased or decreased the amount each man was offered until 70 percent answered yes.
When it comes to staying H.I.V.-free, prostitutes have to make difficult decisions, said the lead author, Omar Galárraga, a health economist at Brown. They are often desperate for cash, and they can charge more for sex without a condom.
“But also, they know they are high-risk, so it’s good for them to have checkups,” he said. “If you’re a man who has sex with men in Mexico City, you’re lucky if you are tested every two years, if at all.”
Although he has not surveyed gay men or prostitutes in the United States to determine how much cash would be tempting, Dr. Galárraga said the cost-benefit ratio could, in theory, be greater in the United States because drugs and hospital care are far more expensive.
However, he noted two important differences. Prostitution is not illegal in Mexico, but it is in the United States, which could hamper recruitment. Also, 9 percent of the survey takers said they would not participate at any price, and they tended to be wealthier and better educated — that is, more resembling Americans.
DONALD G. McNEIL Jr.