What is the X in X-mas?
parvovirus par·vo·vi·rus (pär'vō-vī'rəs)
Any of a group of small viruses of the genus Parvovirus that cause disease in many vertebrates, especially mammals such as dogs and cattle.
Any of a group of small DNA viruses of the family Parvoviridae that cause disease in many vertebrates, especially a febrile infection in dogs resulting in vomiting, diarrhea, and sometimes death. In humans it commonly causes an acute contagious infection called fifth disease, marked by a facial rash.