The cycling of inmates in and out of prisons and jails around the world contributes significantly to the global epidemics of HIV, viral hepatitis and tuberculosis, according to new research from the Johns Hopkins Bloomberg School of Public Health.

Inmates typically suffer from higher rates of those diseases, which spread more readily in crowded correctional facilities and then get passed to others on the outside when the inmates are released, the study found.

The study, “Global burden of HIV, viral hepatitis, and tuberculosis in prisoners and detainees,” was published July 17 in The Lancet as part of a series of studies on HIV and prisoners.

Although the study was global in its focus and did not examine individual nations, let alone cities, the findings could have important implications for Maryland, and particularly Baltimore, which has one of the highest rates of HIV infection among U.S. metro areas. Inmates from Baltimore make up more than a third of the state's prison population.

Andrea Wirtz, a co-author of the study and assistant scientist at the Bloomberg School of Public Health, said the results were important, considering the racial and economic disparities in the jail and prison population from Baltimore.

“By having this disparity in imprisonment in the city, are we increasing peoples' risk of HIV and other infectious diseases?” Wirtz said. “We can say this is part of the bigger picture of the HIV epidemic.”

Nearly 32,000 Marylanders were living with the disease in 2013, according to the Centers for Disease Control and Prevention. Many of those reside in Baltimore — 12,435 that same year, according to the Baltimore City Health Department.

In the United States, HIV is a bigger problem among people moving in and out of prison than hepatitis and tuberculosis, said Bruce L. Gilliam, an associate professor of medicine at the University of Maryland School of Medicine.

The study found that of the estimated 10.2 million people incarcerated worldwide on any given day in 2014, 3.8 percent had HIV, 15.1 percent had hepatitis C, 4.8 percent had hepatitis B and 2.8 percent had tuberculosis. In less wealthy countries, between 10 percent and 20 percent of prisoners have HIV.

The authors reached their conclusions by analyzing nearly 300 scientific papers written about prisoners and infectious diseases by scientists around the world during the past 10 years. They also requested research data from United Nations organizations and from prison officials in countries such as China and Russia. Officials in 17 countries turned over their data.

The researchers believe transmission of HIV within U.S. prisons is fairly low due to the availability of antiretroviral drugs there, but the risk of transmission rises once prisoners are released due to difficulties accessing continuing care.

Hepatitis C can spread through prison tattooing, the researchers found, and tuberculosis can thrive in unsanitary conditions in some correctional facilities.

The study authors said corrections officials ought to do more to improve how they combat the spread of infectious diseases, including offering condoms, needle exchanges and other services to address the public health issue.

“We knew from a lot of the literature that HIV would be higher in the prisons,” Wirtz said. “But while there are improvements in jails and other detention centers, there is a higher rate of HIV and other infectious diseases globally, even when there are improvements.”

The authors blamed prisons' role in the spread of disease around the world on laws, policies and policing practices that don't ensure a continuity of medical treatment for inmates in detention, during imprisonment and after release. Interventions to treat HIV, tuberculosis and hepatitis are required by international law but are not commonly available, the authors wrote.

“There is a global standard that says that prisoners deserve the same standard of health care as the communities they come from,” Chris Beyrer, a professor of public health and human rights at the Bloomberg school and another co-author of the study, said in a statement.

“But in country after country, this standard is not being met, and our failure to handle the post-release linkage to care and services is the single most important thing that has to change. The idea that we can ignore these epidemics among prisoners is bad public health.”

With HIV, there are steps prison officials could take to stem its spread ,Gilliam said, but what's more difficult is overcoming the social stigma associated with HIV.

Someone entering prison with HIV may decline to be tested and not tell prison officials about it because they're ashamed, he said. That helps drive the spread of the disease.

The system to get treatment for HIV in prison also can be difficult to navigate for inmates, but Gilliam said the state and Baltimore City have launched numerous programs within the last 15 years to help guide former inmates through the process.

“When I got here 15 years ago there was a huge problem with this continuation of care, and the state realized it, the city realized it, and I think we're a lot better off then we were then,” Gilliam said.

This study, he said, “reinforces why that is important.”

Prisoners also face a stigma upon release that can make it difficult for them to access health and social support services, the study found.

Even in Maryland, many former prisoners face difficulties getting access to health care after they are released, not only jeopardizing their own health but also public health.

The study found many former prisoners infected with HIV don't get adequate care or receive medication when released, making them more infectious and contributing to the disease's spread among those who haven't been in the criminal justice system, including their sexual partners or those with whom they share needles for injecting drugs.

David C. Fathi, director of the American Civil Liberties Union's National Prison Project, said prison officials and the general public should take note of the issues raised by the study.

“Many people don't think about prisons at all, and those who do, many of them don't care about prisoners and think that prisoners deserve whatever happens to them,” he said. “But I think what this study shows is that we have that attitude at our peril, and we can't have good public health without having good prison health.”

cwells@baltsun.com