It is thought to have entered America "primarily as a scourge claiming the lives of sons and brothers who voyaged to the West Indies," the nation"s principal trading partner (Rush pp).

             Yellow fever is recognized in historic texts stretching back some four hundred years (Yellow-2 pp). The term "yellow" is comes from the jaundice that affects most patients (Yellow-2 pp). The first outbreak occurred in the New World in 1648 (Yellow-4 pp). Yellow fever is a member of the flavivirus family, group B arborvirus, the genus of which is comprised of more than sixty-eight arthropod transmitted viruses, thirty of which are known to cause human disease (Yellow-4 pp). Other flaviviral infections include "dengue, Japanese encephalitis, and tick-borne encephalitis" (Yellow-4 pp). "It is important to consider this group of viruses in the clinical differential of CNS infection, hemorrhagic fever, and acute febrile illnesses with arthropathy" (Yellow-4 pp). A vaccine has been available for sixty years, yet during the last two decades, the number of people infected has increased and the disease is once again a serious public health issue (Yellow-2 pp). .

             The virus remains silent in the body for an incubation period of three to six days, then there are two disease phases (Yellow-2 pp). Although some infections have no symptoms, the first, "acute" phase is generally characterized by "fever, muscle pain with prominent backache, headache, shivers, loss of appetite, nausea and/or vomiting.the high fever is paradoxically associated with a slow pulse" (Yellow-2 pp). Usually after three to four days most patients improve and the symptoms disappear (Yellow-2 pp). However, 15 percent enter a "toxic phase" within 24 hours, when fever reappears and several body systems are affected (Yellow-2 pp). Patients rapidly develop jaundice and complain of abdominal pain with vomiting, and bleeding can occur from the mouth, nose, eyes and/or stomach with blood also appearing in the vomit and feces (Yellow-2 pp).