"When we saw the first group of cases, I sent a notice to the local hospitals, clinics, clinical laboratories, and local area physicians, indicating that a cluster of four cases had been identified and reminding them that the board of health should be notified immediately of any additional cases. Of course, before we got too carried away counting cases, we had to decide on a case definition."

"All four of the first cases had a typical clinical picture (jaundice, fever, nausea, vomiting, fatigue, loss of appetite), and they also had blood tests that showed elevated concentrations of bilirubin and liver enzymes. They also had anti-hepatitis A IgM antibodies.

"The symptom complex of jaundice, fever, nausea, vomiting, fatigue, loss of appetite was useful for finding potential cases, but the ultimate determination of whether someone was a 'case' or not depended on the lab test to see if they had elevated IgM for HAV."