Although influenza is recognized for its worldwide importance, little is known about the disease from tropical countries like Indonesia. From August 1999 through January 2003, a surveillance study was conducted in clinics at 6 sentinel locations. Adults (age, 114 years) and children (age, 4 14 years) presenting with respiratory symptoms suggestive of influenza were asked to enroll in the study. Nasal and pharyngeal swabs were examined by virus isolation, polymerase ...