Regarding your questions: Coronaviruses are a specific family of RNA viruses that cause a wide variety of disease in animal species. Coronaviruses are best known for causing enteric disease in domestic species, including transmissible gastroenteritis in pigs, coronavirus diarrhea in dogs, and feline infectious peritonitis. Coronaviruses are best identified by electron microscopy of feces or tissue, and are recognizable due to the presence of peplomers (characteristic of coronaviruses) surrounding the viral particle (it resembles a crown). Coronaviruses are different in many ways from other viruses in the way that they replicate, the diseases that they cause, the tissues that they choose to infect, the receptors that are used to gain entry to cells, their ability to be grown in culture, cell cultures that may be used to grow the cells, and of course, their characteristic size and appearance. There are few viruses that can be directly treatable with drugs, and coronaviruses are not one against which there are any specific treatments. The best that we can due with coronaviruses, and other viruses that affect the intestine, is to empirically treat the symptoms and support the animal until it can support itself. The source of the coronavirus of ECE is simply another animal, which has shed infectious virus. The shedding period of ECE is considered anecdotally to be approximately 6-8 months. With kindest regards, Bruce Williams, dVM [Posted in FML issue 3397]