Thanks to expanding HIV testing within the prison systems, it's clear that HIV is being kept at bay for now.

The estimated number of state and federal prisoners known to be HIV-positive is at its lowest since 1991, according to a report called "HIV in Prisons, 2015," released by the Bureau of Justice Statistics.

The report shows that in 1991, 17,680 prisoners were known to be HIV-positive. At its peak, that number reached 25,980 in 1998.

Now, the recent statistics show that in 2015, the number of state prisoners living with HIV decreased significantly to 15,610. As far as federal prisoners, within a span of 17 years (between 1998 and 2015), the number of people with HIV grew by only 470 — from 1,066 to 1,536.

The number of AIDS-related deaths also decreased significantly — from 73 deaths in 2010 to around 45 deaths in 2015, according to data from BSJ’s Deaths in Custody Reporting Program.

A number of reasons might be given credit for the significant drop, but BSJ acknowledges that both state and federal prison systems have been administering various HIV testing practices with prisoners: during their admittance, while incarcerated, and as part of their release process.

In fact, 15 states reported to have tested incoming prisoners despite their consent; and 17 states say all the prisoners in their prisons are offered HIV tests, though they may choose to opt out. One of the most common forms of testing in prisons is by request of the prisoner themselves, BSJ notes.

Other important findings within the study showed that by 2015, 15,920 male prisoners and 1,220 female prisoners were HIV-positive. This was down from 2014, which showed 16,410 male and 1,330 female prisoners to be living with the virus.

Between 2010 and 2015, the number of HIV-positive male prisoners declined by 14 percent, while the number of HIV-positive female prisoners declined by 31 percent.