found what I was looking for at the WHO site, the whole article is here:http://www.who.int/e...oemczoo973.html
CATEGORIES OF INFECTIVITY IN BOVINE TISSUES AND BODY FLUID
(Based on relative scrapie infectivity of tissues and body fluids from naturally infected suffolk sheep and goats with clinical scrapie)
CATEGORY I High infectivity
Brain, spinal cord, (eye)*
CATEGORY II Medium infectivity
Spleen, tonsil, lymph nodes, ileum, proximal colon, cerebrospinal fluid, pituitary gland, adrenal gland, (dura mater, pineal gland, placenta, distal colon)
CATEGORY III Low infectivity
Peripheral nerves, nasal mucosa, thymus, bone marrow, liver, lung, pancreas
CATEGORY IV No detectable infectivity
Skeletal muscle, heart, mammary gland,milk, blood clot, serum, faeces, kidney, thyroid, salivary gland, saliva, ovary, uterus, testis, seminal testis, foetal tissue, (colostrum, bile, bone, cartilaginous tissue, connective tissue, hair, skin, urine).
*Tissues in brackets were not titrated in the original studies (8,9) but relative infectivity is indicated by other data on spongiform encephalopathies.