After years of research, a robust picture has started to emerge about Maricopa County inmates.

More than 30 percent tested positive for marijuana or methamphetamine, nearly 30 percent have been told by a professional that they suffer from a mental illness, and they are 50 to 80 percent more likely to be infected with gonorrhea than the general population, according to a new study.

The trick now is figuring out what to do with the data Arizona State University researchers are developing on Maricopa County inmates.

Health officials hope the STD research will become a model for developing programs to test and treat inmates for ailments they bring with them or acquire in jail.

It's difficult to get the general public to care about or understand what diseases afflict inmates, medical experts say. But with 130,000 people booked into Maricopa County jails each year for stays that average less than a month and can frequently be only 48 hours, an inmate's health problems can quickly become a public-health problem.

Inmates are often from the same population that requires assistance through Arizona's Medicaid program, the Arizona Health Care Cost Containment System, said Dr. Jeff Alvarez, medical director at Correctional Health Services, the taxpayer-funded county agency that provides constitutionally required care to inmates.

"Whether they're outside or in here, if you look at it from a public-money standpoint, it's still tax dollars," Alvarez said. "It's hard to help taxpayers understand we are paying for this. Even if you don't think of the good that we're doing for people, it's still cheaper for you to take care of this now."

The research on STDs among county inmates is the most recent in a series of studies from ASU's Center for Violence Prevention and Community Safety that focus on Maricopa County residents in the criminal-justice system.

The inmate population presents a chance for researchers to work with people prone to problematic behavior who might not otherwise seek treatment for medical problems, said Charles Katz, the center's director.

"People involved with the criminal-justice system, we know, are at extremely high risk for problem behavior," Katz said. "By focusing on this population, it affords us the opportunity to be engaged in intervention activities."

The most recent study came after doctors began noticing higher-than-normal rates of chlamydia and gonorrhea through a separate data-collection effort funded by a federal grant to test women under 35 for STDs due to the diseases' potential to affect fertility.

Testing young women only seemed to scratch the surface of the problem, Alvarez said.

"The female didn't give it to herself. If this grant was intended to help fertility rates in females, it's not just treating their infection, it's treating whoever else might be infected, too," Alvarez said, citing the public-health cycle of testing and treating that many STD patients endure until their partners are cured.

"Are they really helping women in the big picture unless you're treating men?" he said.

The survey was ultimately expanded to include inmates of all age ranges and both genders who volunteered for the study.

Nationally, the Centers for Disease Control and Prevention reported gonorrhea rates were the lowest ever recorded in 2009, the most recent year with data available, and the spread of chlamydia was coming under control, although minority groups still report excessively high infection rates.

Now, armed with an independent study that shows gonorrhea- and chlamydia-infection rates of 5 to 10 percent among inmates, public-health officials are seeking solutions.

The main roadblock, according to health-care officials, comes with the costs of testing for STDs.

Both chlamydia and gonorrhea are treated with intense doses of antibiotics that could be administered during most county-jail stays longer than a day, Alvarez said, and the drugs are cheap.

The costs of testing inmates for STDs can be prohibitive, however, with per-test charges averaging about $18 through the grant-funded program and topping out at $95 for tests without a grant.

County health-care officials are working with the CDC to develop a cost-benefit analysis to determine the real value of the tests.