Rapid Laboratory Diagnosis of an Outbreak of Influenza.

The specific diagnosis of an outbreak of acute febrile disease in a sanatorium ward was made rapidly by examining sera from the nine patients for antibodies to a series of likely viruses. All eight convalescent cases had high antibody levels to Influenza A2 (Asian) virus and the case at the acute stage had none. This serological diagnosis provided the first information that influenza was present in the area. Later, Influenza virus Type A2 was grown from the acute case.