All specimens were collected over a one year period (Sept 2008 to Aug 2009). A total of 110 bovine liver samples, 14 ovine spleen samples and 9 ovine liver samples were collected from local food markets with the assistance of the Veterinary Public Health Section, the Food and Environmental Hygiene Department, and the Agriculture, Fisheries and Conservation Department, the Government of Hong Kong Special Administrative Region (HKSAR). It should be noted that ovine liver and spleen samples were not uniformly sampled throughout the study period due to supply issues. All animals from which the specimens had been obtained have passed the relevant health inspection to certify its meat and other products as fit for human consumption. Precautions taken to avoid cross contamination include the use of disposable scalpels during tissue dissection and the collection of samples only from the centre of each tissue block after surface decontamination. Disposable protective gloves were also used and changed after processing each tissue sample.