Ghaffar, AH, Wynne, K, Field, B & Meeran, K. Imperial College Healthcare NS Trust, Charing Cross Hospital, Fulham Palace Road, London. W6 8RF.

The authors have performed detailed proteomic studies.1 Though their laboratory approach is rigorous, the interpretation of their findings is flawed. They detected prion protein in human urine-derived fertility products. They accept that with the laboratory methods used the prion protein detected could be either normal prion protein or the infectious form. Although cases of transmission of CJD have been documented from cadaveric and other tissues, no cases have been highlighted from urinary-derived products despite the use of these products for over 40 years. Horizontal transmission of CJD usually manifests over a much shorter time span than this. vCJD has an ‘incubation’ period of 10-13 years, transfusion related CJD of 6-8 years and for pituitary derived growth hormone, the incubation period was 4-36 years.2 Furthermore the authors quote rodent studies where urine has been demonstrated to be infective, however in the relevant studies the animals were inoculated either intra-cerebrally or intraperitoneally.3,4 The authors suggest that ‘the risks of urine-derived fertility products could now outweigh their benefits.’ This theoretical risk has not been borne out in reality and in our opinion, is therefore unjustified.

1) van Dorsselaer A, Carapito C, Delalande F, Schaeffer-Reiss C, Thierse D, Diemer H, McNair DS, Krewski D, Cashman NR (2011) Detection of prion protein in urine-derived injectable fertility products by a targeted proteomic approach. PLoS One 6(3): e17815.
2) Brown P, Brandel JP, Preese M, Sato T (2006) Iatrogenic Creutzfeldt-Jakob disease: the waning of an era. Neurology 67: 389-393.
3) Seeger H, Heikenwalder M, Zeller N, Kranich J, Schwarz P, Gaspert A, Seifert B, Miele G, Aguzzi A (2005) Coincident scrapie infection and nephritis lead to urinary prion excretion. Science 310: 324-326.
4) Kariv-Inbal Z, Ben-Hur T, Grigoriadis NC, Engelstein R, Gabizon R (2006) Urine from scrapie-infected hamsters comprises low levels of prion infectivity. Neurodegener Dis 3: 123-128.