From May 1 through October 31, 2009, trained local fi eld workers visited the hospital in Maela daily (Monday-Saturday). Patients whose illnesses met clinical case defi nitions for infl uenza-like illness (ILI) or pneumonia (Table  1) were identifi ed by clinic staff at the time of examination, and these patients were asked to complete an additional clinical interview. Inpatient and outpatient department cases were included in the surveillance. From July 27 through October 31, 2009, original clinical case defi nitions were modifi ed to capture each patient who had a history of fever during the current illness but who was not febrile at the clinic visit (either because of the intermittent nature of fever or self-administration of antipyretics).