Many readers asked about the safety of milk and dairy products. Questions have also arisen about the safety of other products derived from bovine sources, such as gelatin and tallow derivatives, which find their way into a dazzling array of items eaten or used by humans. These include products as varied as jellybeans, cosmetics, and vaccines. Scientific advisory committees in many countries, including the United States, have addressed these questions and have concluded that infectivity in the tissues used as sources of these products is either low or nonexistent, and that even if existent, infectivity would in most cases be destroyed by the processes used in product manufacturing. Nevertheless, depending on estimates of risk inherent in tissue sources and use of different products, industry has been either obliged or strongly urged to ensure BSE-free status of source cattle and to include processing steps known to destroy infectivity.
Chickens are resistant to both natural and experimental infection.
The American Scene Concerns have been raised about BSE status in the United States and about the safety of foods and other products from domestic bovine sources. If true, this incidence has so far escaped detection, despite extensive recent search for cases. One oft-repeated but misguided objection to this statement is that very few apparently healthy cattle have been examined. However, if we wish to know whether or not a given disease exists in a population, we do not concentrate on asymptomatic persons, but instead on population subsets at highest risk. For example, if we wished to know whether or not cases of Alzheimer's disease occurred in a given country, we would first examine older adults, not the general population.