NR AWTJ
AU Tyshenko,M.G.
TI BSE and the safety of milk
QU The Veterinary Record 2007 Mar 10; 160(10): 347
KZ Vet Rec. 2007 Feb 17;160(7): 215-8. PMID: 17308017
PT comment; letter
VT
Your correspondent is correct in stating that there have been publications detailing the scale of the British BSE epidemic using predictive methodology.
The maternal transmission value in the recently published review paper (Tyshenko 2007) was compiled based on experimental data using various animal systems. The review intentionally did not include retrospective analysis using back calculation methods. For the back calculation methods that give maternal transmission, the temporal changes in the rate of BSE prevalence and case reporting are determined by estimates. Donnelly and others (2002) using the back calculation method affirm uncertainty exists in that the absolute level for prevalence can be estimated but not absolutely determined. Moreover, the effects of offspring culling were not incorporated into the calculation for the 0.5 per cent value due to the complexity of tracking effects through multiple generations. Donnelly and others agree that it gives a lower number, but this number remains consistent with previous estimates from dam-calf pair analysis of BSE cases.
Whether the 'true' number is 0.5 per cent (as estimated by the back calculation in Donnelly and others [2002]), 0.7 to 1.0 per cent (allowing for the offspring cull using correction factors), scaled in duration to equal six months and comparable to 5 to 9 per cent (Donnelly and others 1997) or the 10 per cent value from the original experimental data (Wilesmith and others 1997), the result for the purpose of the review paper is the same: maternal transmission was involved as a route of BSE transmission through cattle herds. Even though the degree of maternal transmission in cattle may be difficult to ascertain, it remains a route for BSE propagation based on experimental and predictive risk modelling data.
MH Animals; Canada/epidemiology; Cattle; *Consumer Product Safety; Encephalopathy, Bovine Spongiform/*epidemiology/etiology; Female; Great Britain/epidemiology; *Milk
AD Michael Tyshenko, McLaughlin Centre for Population Health Risk Assessment, Institute of Population Health, University of Ottawa, 1 Stewart Street, Ottawa, Ontario, Canada K1N 6N5.
SP englisch
PO England