Flying foxes were non-randomly sampled using mist nets and anaesthetized. Three millilitres of blood was collected from the brachial vein and stored for 24 h at 48C to allow for serum separation. The separated serum was then stored at 2208C until use. All bats were released at the site of capture after recovery from anaesthesia. Serum neutralization tests were conducted on all serum samples at the Australian Animal Health Laboratory, Geelong, Australia, under Biosafety Level 4 conditions. Details on anaesthesia and testing protocols are given in the electronic supplementary material. P.D. conceived and directed the study; P.D. and J.R.C.P. cowrote the paper with assistance from J.H.E.; J.R.C.P. designed and conducted the modelling and statistical analyses with J.D. and A.P.D., and conducted all fieldwork related to livestock; J.H.E. and S.A.R. led the bat survey work, and S.A.R. conducted some of the sample testing. M.B. collected field data on pig production during the NiV outbreak investigation. A.A.J. facilitated data acquisition and all field activities in Malaysia. A.D.H. directed sample testing. H.E.F. assisted in study design, helped direct field activities and provided veterinary input. All authors were involved in the design of the study and the interpretation of the results and commented on the manuscript. All other Do expert assessments converge? An exploratory case study of evaluating and managing a blood supply risk BACKGROUND: Examining professional assessments of a blood product recall/withdrawal and its implications for risk and public health, the paper introduces ideas about perceptions of minimal risk and its management. It also describes the context of publicly funded blood transfusion in Canada and the withdrawal event that is the basis of this study. METHODS: Interviews with 45 experts from administration, medicine, blood supply, laboratory services and risk assessment took place using a multi-level sampling framework in the aftermath of the recall. These experts either directly dealt with the withdrawal or were involved in the management of the blood supply at the national level. Data from these interviews were coded in NVivo for analysis and interpretation. Analytically, data were interpreted to derive typifications to relate interview responses to risk management heuristics. RESULTS: While all those interviewed agreed on the importance of patient safety, differences in the ways in which the risk was contextualized and explicated were discerned. Risk was seen in terms of patient safety, liability or precaution. These different risk logics are illustrated by selected quotations. CONCLUSIONS: Expert assessments did not fully converge and it is possible that these different risk logics and discourses may affect the risk management process more generally, although not necessarily in a negative way. Patient safety is not to be compromised but management of blood risk in publicly funded systems may vary. We suggest ways of managing blood risk using formal and safety case approaches. Blood is a special product, being integral to life and inside our bodies. As Chan [1] notes (following Titmuss [2] ), there is much symbolism associated with blood. As a medical solution to a health problem it depends on the gift of others. Its gift or donation is altruistic and seen as sharing what is essential to life. In Christian societies, blood is seen as having the ability to wash away sins [3] . It represents purity, intensified by its gift to others. Blood donation is a very visible connection to others, even in societies where payments are made to donors [4] . These payments remain controversial and may lead to compromises in the safety of blood products. Blood donation is indeed a two-edged sword: a lifesaver or a transmitter of disease. The struggle over successful compatibility of blood types and to combat transmissible diseases has been a long but largely successful story [5] . The hazards in receiving transfused blood were heightened by HIV/AIDS, which as Chan [1] argues, led to the blood risk being intensified by this stigmatising illness. But since the mid-1980s, screening tests for sexually transmitted infections, including HIV and, later, other transmissible diseases have been implemented in many countries worldwide. In fact, scientific risk assessments, the vigilance of existing or new federal agencies, enhanced public information and disclosure have greatly improved both the calculated and perceived risk of 'bad blood'. As we shall see, Canada is no exception but it is a jurisdiction where there is particular salience.