A new guidance document released by the US Food and Drug Administration (FDA) calls for changes to the way human cells, tissues and cellular and tissue-based products (HCT/Ps) are tested for the presence of treponema pallidum, better known as syphilis.
HCT/P donations are already subject to a battery of tests to ensure they are not contaminated with any serious diseases. At present, those tests include ones to detect hepatitis B and C, HIV-1/2, the West Nile virus, Chagas disease, human T-lymphotropic virus (HTLV), and syphilis.
Syphilis is a sexually transmitted bacterium that undergoes three distinct stages. During the first stage, a patient will experience visible sores lasting between three and six weeks. In the second stage of the disease, the initial sores heal, but the disease causes skin rashes and sores to emerge in other areas. In the final and latent stages of the disease, syphilis can cause dementia, blindness, paralysis and organ damage, sometimes not for decades after the initial infection.
In previous guidance documents on the subject, FDA has observed that the transmission of syphilis through the blood supply is a relatively rare event, with just 324 cases detected by The Red Cross in 2007-08. However, because the disease can exist in a latent stage in patients, it can be more difficult to detect than other diseases, necessitating the use or serological screening on each donation of blood.
FDA's newest guidance document borrows that approach, extending its reach from blood products to HCT/P products as required under 21 CFR 1271.45(b), thus updating the previous recommendations under the 2007 Donor Eligibility guidance.
"When the 2007 Donor Eligibility guidance was issued, few screening tests for evidence of T. pallidum infection in donors were licensed, cleared, or approved.," FDA explained. However, there are now several cleared serological tests available.
"We believe that the technology for donor screening tests has evolved such that FDA-licensed, approved, or cleared test systems with an indication for use in donor screening to test for evidence of T. pallidum infection are now widely available, and that laboratories now are proficient in their ability to utilize such systems," regulators wrote.
The guidance thus makes three clarifications:
- FDA intends to require the use of appropriate, FDA-licensed, -approved or -cleared donor screening tests to test for syphilis. As such, FDA will end the use of its previous enforcement discretion.
- The use of pre-amendments devices (i.e. on the market prior to the Medical Device Amendments of 1976) are not acceptable for use as a donor screening test for evidence of infection with T. pallidum.
- The new testing requirements will apply to all HCT/Ps.
Comments on the guidance will be accepted through 3 February 2014.
Draft Guidance for Industry: Use of Donor Screening Tests to Test Donors of Human Cells, Tissues and Cellular and Tissue-Based Products (HCT/Ps) for Infection with Treponema pallidum (Syphilis)