Rabies can be diagnosed in humans by nuchal biopsy from the nape of the neck. Yellow fever has never occurred in the United States. Yellow fever is a member of the Flaviviridae. Yellow fever is unlikely to occur in the United states because the insect vector is not present here. A vaccine is not available for yellow fever.
Yellow fever exists in Africa in a cycle involving small mammals and fowl.
They can acquire cellular genes. They usually lack a portion of their long terminal repeat. They readily transform cells in culture. They can cause tumors in animals after a short incubation period. They usually require a helper virus for replication.