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Food quality is an important public health issue. However, a number of repugnant animal and plant products are permitted in our food. The FDA's ‘Defect Levels Handbook’ (1) delineates the ‘maximum levels of natural or unavoidable defects in foods for human use’. It specifies acceptable detection levels of insect fragments, animal filth (excreta), hair, rot and other unappetizing elements in food that are processed and distributed. These standards assume that food availability is abundant and that discard is acceptable. With scarcity, different rules apply to stave off hunger and death.

Viral diseases are in the population. In this AJT issue, three articles compare conventional serologic testing and nucleic acid based testing (NAT) to detect blood borne pathogens. The methodologies employed to address the problem differs. In two articles by Kucirka, meta-analysis of available literature calculates the differential detection of HIV (2) and HCV (3) through either antibody based assays or NAT in populations identified by the 1994 Public Health Service (PHS) high-risk behavior for HIV. The third article by Ellingson compares clinical antibody results for HCV and HIV with NAT from potential donor sera performed at reference laboratories (4). To no surprise, all found that detection of HCV and HIV is more sensitive using NAT. The Kucirka articles demonstrate that HIV and HCV frequency differs between ‘high-risk’ behavior groups. Commercial sex workers, IV drug users, men who have sex with men and the other risks have different frequencies of these viruses. The Ellingson article illustrates that deceased individuals have a higher prevalence of HCV and HIV compared to live blood donors and that individuals with unknown or high-risk behavior have an even higher rate of detection.

However, the question at hand is what detection techniques for HIV and HCV are best suited for screening the nation's organ donors? These policies are established by HRSA/OPTN/UNOS and CMS. A simplistic summary of the current policy is ‘an adequate donor sample must be tested in approved clinical laboratory using FDA approved screening tests prior to the transplantation’.

Should policy be changed? All three manuscripts address concerns about the failure of serology-based technology to detect infectious virions during the time (window) prior to the generation the antibody response. It is implied that replacing serologic testing with NAT (or its addition to existing testing) would significantly decrease risk for recipients with few consequences. This needs a discussion. A basic assumption in these manuscripts is that a history of ‘high-risk’ behavior/donor is reliable and that first-person and third-party historians are equivalent. All people take secrets to the grave. In a Gift of Hope (Illinois) analysis of organ donors after the 2007 transmission of HIV and HCV (a seronegative donor), 553/3959 (14%) donors were characterized as ‘high-risk’ (Smith and Mozes, personal communication, March 2011). Of these, 85% were identified by incarceration (355) or ‘fever, nodes, weight loss, etc.’ (115). The remaining 83/553 (15%) high-risk donors were identified as homosexual men, IV drug users, customers of/or commercial sex workers or other variables identified by the PHS. True? The deceased organ donor cannot give a history. One should question whether the first-person identification literature used in Kurcika's papers applies to the deceased donation process that is dependent upon third-person historians.

All NAT results are not the same. Ellingson's manuscript states that NAT results came from three reference labs, whereas serologic results were performed by local convention. Reference labs typically put samples into batch runs, done after sufficient samples have accumulated to make the process reliable and cost effective. Time constraints mandate that organ donation uses small (often single) runs performed by technicians that may do the test infrequently. In the latter scenario, the NAT reliability would likely differ from that found in the Ellingson paper.

No one wants to eat rodent excreta and no one wants diseases to be transmitted through organs. However, if one has to eat or have an organ transplant to survive, both will occur. Policy should minimize adverse events and maximize the availability of organs. In times of shortage, one cannot discard precious, life-giving resources. Current policy requires that HCV and HIV serologic donor testing occur and a positive result excludes (HIV) or diminishes organ utilization (HCV). A recent consensus conference on donor testing concluded that the introduction of NAT to standard donor screening would result in more deaths from organ discard after false positive tests than prevention through disease transmission (5). The risk of not detecting HIV or HCV in a donor must be balanced by deaths in people that declined organs because of a false positive test. The establishment of such risk threshold should not be the sole domain of any one group, rather one of public policy that includes those on the waitlist.

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The author of this manuscript has no conflicts of interest to disclose as described by the American Journal of Transplantation.

References

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