health

After an incubation* period of three to six days, the yellow fever virus begins
to produce symptoms. An early phase of disease occurs, which includes
fever, headache, muscle aches, and vomiting. The infected person may have
a slower heartbeat than that expected with a high fever. After a few days,
most of the symptoms disappear. Many people recover from yellow fever at
this point without complications. However, about 15 percent of patients
develop a second, toxic phase of the disease, in which fever reappears and
the disease becomes more severe. Inflammation* of the liver occurs, along
with jaundice, stomach pains, and vomiting. The mouth, nose, eyes, and
stomach can bleed uncontrollably, with blood present in vomited material
and bowel movements. The kidneys may begin to fail, and patients may go
into a coma (an unconscious state in which a person cannot be awakened).