Varicella vaccine from a child with natural varicella, introduced into human embryonic lung cell cultures, adapted to and propagated in embryonic guinea pig cell cultures, and finally propagated in human diploid cell cultures. Japan was among the first countries to vaccinate for chickenpox. The vaccine was first licensed in the United States in 1995. Routine vaccination against varicella zoster virus is also performed in the United States, and the incidence of chickenpox has been dramatically reduced there (from 4 million cases per year in the pre-vaccine era to approximately 400,000 cases per year as of 2005). In Europe most countries do not
Foreign animal disease Foreign animal disease A Foreign animal disease (FAD) is an animal disease or pest, whether terrestrial or aquatic, not known to exist in the United States or its territories. When these diseases can significantly affect human health or animal production and when there is significant economic cost for disease control and eradication efforts, they are considered a threat to the United States. Another term gaining preference to be used is Transboundary Animal Disease (TAD), which is defined as "those epidemic diseases which are highly contagious or transmissible and have the potential for very rapid spread, irrespective of national borders, causing