National influenza surveillance 1997.

In 1997 information from several sources was combined to detect trends in influenza activity in Australia. Data was included from laboratories, general practitioners and a national employer. Laboratory surveillance documented two consecutive outbreaks, influenza B in July followed by influenza A (H3N2) in August. Some of the influenza A (H3N2) viruses isolated, represented by the A/Sydney/5/97 strain, showed significant antigenic drift from the A/Wuhan/359/95 vaccine strain. Influenza activity was also reflected in the consultation rates recorded by sentinel general practitioner reporting schemes. The peak consultation rate recorded by the Australian Sentinel Practice Research Network was higher and later than in recent years, occurring in early August. Tropical Influenza Surveillance in the Northern Territory demonstrated an early outbreak in March followed by a second rise later in the year. There was no rise in absenteeism rates recorded by a national employer.