Men are roughly four times more likely to be diagnosed HIV-positive than women in this country. Unique in the world, the United States HIV crisis still primarily affects gay and bisexual men, particularly young, black, gay men. In 2014, gay and bisexual men accounted for an estimated 70 percent of the 37,600 new HIV infections in the United States, according to the Centers for Disease Control and Prevention. Women, on the other hand, account for only about one in five new HIV diagnoses.

The one place where women’s HIV prevalence reaches and sometimes exceeds that of men is in our jails and prisons. Though the percentage of women in state and federal prisons with HIV has been on the decline for nearly two decades, the rates still far outpace the national averages: According to the most recent numbers from the Bureau of Justice Statistics, which collects data from inmates in state and federal correctional facilities, 1.3 percent of female inmates are HIV-positive. If that doesn’t sound high, consider that the HIV infection rate for the general female population is only 0.14 percent. That means that women in state and federal correctional facilities are over nine times more likely to be HIV-infected than women on the outside.

And those numbers don’t even account for what can be higher rates of HIV infection among women in jails. While prisons generally hold people convicted of felonies for sentences that are longer than one year, jails—the roughly 3,000 county or municipality-run detention facilities in communities across the country—temporarily hold people arrested but not yet convicted of a crime. Most incarcerated women today are in jails, and jails are transient places, with people constantly moving in and out. HIV-prevalence rates are often much higher in jails than they are in prisons—one study that reviewed jail health records from 2009–10 found that 9 percent of newly incarcerated women in New York City jails were HIV-positive.

“Jails and prisons are places where a disproportional number of HIV-infected women end up, primarily because both HIV and incarceration target those who are poor,” says Dr. Anne Spaulding, an infectious disease physician who has provided care for women and men with HIV and hepatitis C in prisons and jails for the past two decades.

What accounts for this glaring disparity? For one thing, the number of women in jail, prison, and on probation is ballooning. More women than ever before are being sent to jail and prisons, and the growth has largely impacted the most socially and economically disadvantaged: black women, Latina women, and women living in poverty.

Women in jails are now the fastest-growing incarcerated population in the country. Among women, rates of state and federal imprisonment were highest for adult black women ages 30–34 years (264 per 100,000), followed by Latina (174 per 100,000), and white women (163 per 100,000). Black women were between 1.6 and 4.1 times as likely to be imprisoned as white women of any age group. Thanks to stricter drug-enforcement laws and expanding law-enforcement efforts, the case of incarcerated women and HIV is truly one in which social, economic, racial, and gender inequity have created multiple, intersecting challenges for women who often lack robust social safety nets in the first place.

The types of activities and circumstances that are putting more women into contact with law enforcement are the same ones that are also putting them at increased risk of HIV infection. Women in state and federal prisons are more likely to be incarcerated for drug and property offenses than their male counterparts. Incarcerated women are more likely to have substance-abuse issues and report more frequent drug use and use of harder drugs compared with incarcerated men, according to the Bureau of Justice Statistics. Needless to say, substance abuse has been linked to HIV through several mechanisms, most notably through shared needles among injection-drug users.

Women who exchange sex for money, food, shelter, or drugs are also at a greater risk of being arrested, street-based workers much more so. According to one study of women in Rhode Island Department of Corrections facilities, 27 precent of respondents reported having engaged in sex work. This study found that prior sex exchange was also linked to physical abuse, injection-drug use, and crack cocaine use—all of which are associated with an increased HIV-infection rate.

Systematic inequities are therefore at the root of incarceration and HIV for women. The behaviors that lead women to incarceration and HIV are rooted in poverty, traumatic childhoods, and sexual and physical abuse at the hands of sexual partners, who are often at risk of HIV infection too. Studies suggest that illegal activity, like sex work and drug use, are often introduced by male partners in intimate relationships. According to the report by the Vera Institute of Justice, 86 precent of women in jails have experienced sexual violence in their lifetime. Black women experience elevated domestic violence rates compared with their white and Latina peers, at a rate that is 20 precent higher than white women.

Abusive partners can force low-income women to lose employment and housing through battery and harassment. With an abusive partner, it’s very difficult to negotiate a healthy sexual relationship that would prevent a sexually transmitted disease like HIV. Women who have been incarcerated are also more likely to have had sexual partners who have also been incarcerated. I was one of a team of researchers at the Centers for Disease Control and Prevention who published a study in this year’s Journal of Acquired Immune Deficiency Syndromes that found that women with a history of incarceration were more likely to have partners who had been incarcerated too.

Because we have for decades used our criminal-justice system to handle the mental-health needs of the most vulnerable Americans, our incarcerated population as a whole is disproportionately burdened with a slew of chronic diseases and mental illnesses. But women in the criminal-justice system are much more in need of mental and general health services compared with men. For women, HIV is just the tip of the iceberg of elevated rates of physical and psychiatric conditions, which several studies indicate are higher than among men. The same study that found such high rates of HIV among female inmates in New York City jails also found high rates of chlamydia (6.2 percent) and gonorrhea (1.7 percent), in which sex workers (6.5 percent of the sample) had more than twice the odds of having chlamydia.

The fact that our most disadvantaged women can be found in jails and prisons, physically and mentally ill, represents a deep failure on the part of the United States. Nearly 80 percent of women in jails and over half of women in prison are mothers—providing quality rehabilitation for women who need it most would benefit these women, their families, and their communities. “When you incarcerate a person, you’re affecting their family as well,” says Dr. Spaulding.

Unfortunately, most women’s correctional facilities are underfunded, and the type of care that inmates receive while in jail and prison varies widely from facility to facility. “Although incarcerated people have a constitutional right to health care, there are no mandatory standards of care and no mandatory oversight,” says Dr. Carolyn Sufrin, assistant professor in gynecology and obstetrics at Johns Hopkins Medicine. Sufrin, whose research focuses on reproductive-health care for incarcerated women, says that “with any health care service, including HIV care, how it is dealt with in prisons and jails depends on which prison or jail you are at. Every prison and jail has its own approach to screening, treatment, counseling, continuity, and comprehensive care.”

Many facilities are therefore increasingly abrogating their rehabilitative responsibilities, especially when it comes to assisting newly released inmates in returning to their communities.

“Some prison systems try to save money by decreasing the number of weeks of medications they provided to people with HIV at discharge—from four weeks’ worth to two weeks’,” says Dr. Spaulding. “That’s penny-wise and pound-foolish, especially in a community where the wait for a new appointment in an HIV clinic can take up to several months.”

So how do we fight this crisis? Diverting women who have experienced the unfortunate confluence of poverty, trauma, and substance abuse to mental-health and drug-treatment services can minimize their risk of being incarcerated at the outset. Providing impoverished women and their families with adequate housing and social services can mitigate the relationship between poverty and hazardous, illegal activities.

For women who are already in jail or prison, high-quality comprehensive health and education services can simultaneously promote HIV-risk reduction and treat HIV-infected women. Initiatives that promote drug and mental rehabilitation and healthy reentry into communities can reduce recidivism.

“From the perspective of virus suppression, people with HIV can do quite well when inside [jail or prison],” says Dr. Spaulding. “What needs more attention is when they get out, the transition from jail or prison back to the community—that needs more attention from public health. On a systems-level, health-care planners can think more about how health care transitions occur.”

Cooperation between community clinics and correctional facilities could facilitate healthy reentry into communities for released inmates who are HIV-infected, which can ensure they are able to continue their anti-retroviral treatment and reduce further transmission.

We can’t expect this problem to go away by continuing to lock up the vulnerable and the needy. The money we’re spending on incarcerating women would be much better spent on efforts to prevent their initial introduction to the criminal-justice system, and reduce their risk of HIV infection: adequate housing, robust responses to domestic violence, and social services that provide hope for their future.