Livestock commodities (i.e. fresh or frozen meat, fresh eggs and milk, raw hides and any other derivatives that have not undergone further processing) including live animals are traded both nationally and internationally. Animal diseases can have an impact on trade at all levels. They can reduce the quantity and quality of animals/commodities available for sale by effects that range from catastrophic mortality to erosion of productivity. The difference in animal disease status between countries in different geographic areas and stages of industrialization is a limiting factor for trade that excludes many livestock producers in sub-Saharan Africa from higher value markets and renders the entire sub-continent uncompetitive in world markets.