In 1985, with the AIDS crisis in full swing, the US Centers for Disease Control (as the agency was called at the time) recommended that all blood and organs donated in the country be tested for HIV. But because the virus can lurk in cells for up to six months before detection, in 1994 the CDC (now with ‘Prevention’ tacked on to its name) added additional guidelines to help clinicians identify those organ donors at high-risk for infection that merit further screening.

HIV transmission through organ donation dropped precipitously in the intervening years. However, infection rates of other viruses — most notably hepatitis B and C — have gone up. To better screen for these pathogens, researchers developed PCR-based testing methods that can catch viruses within a smaller time window after infection compared to serological culturing approaches. Yet despite this benefit, a 2008 survey revealed that only around half of the US’s 58 organ procurement organizations used the more accurate testing method. As a result, dozens of infections have slipped through the cracks.

In response, the CDC yesterday issued its new draft guidelines for how donated organs should be screened to include tests — preferably PCR-based tests — for HIV and hepatitis.

Under the new guidelines, organs infected with hepatitis B or hepatitis C will be set aside but not automatically get tossed. There are far more people on the organ waitlist than there are available donors, the guidelines note, and thus it has become “acceptable medical practice” to transplant an infected organ on a case-by-case basis. Infected organs can be offered to recipients who already have the infections, for example, or even to uninfected recipients “in rare circumstances… where benefit is deemed to outweigh risks.” However, according to federal law HIV-positive organs cannot be used, even in HIV-infected recipients, except in Illinois, which passed its own bill in 2004 allowing the practice.

Current testing technologies still aren’t perfect, though. PCR-based tests can give false negative results, and sometimes the infection is just too recent for tests to pick up. Blood suppliers are grappling with the same dilemma, and are similarly moving towards PCR testing despite the higher price tag. All the more reason to keep working towards engineering organs in the lab.

Image: from the US Library of Medicine, in the public domain