Influenza Surveillance in Bangkok, 1983-1993

Abstract

Influenza surveillance is an important strategy of the control of this disease. The main  objectives of surveillance are collection of influenza isolates and epidemiological information, so  that a decision can be made on which appropriate virus variants should be used for the production of influenza vaccine.

The Thai National Influenza Center, Department of Medical Sciences has isolated influenza viruses by using fertilized hensu eggs and MDCK cells. Two thousand seven hundred and ninety- nine throat swab specimens were collected from acute respiratory infection (ARI) patients in Bangkok area. Of the 622 influenza isolates during 1983-1993, 381 were of type A and 241 were of type B. The type A isolates were further identified, 94 isolates as A(H1N1) and 263 isolates as A(H3N2). Twenty—two percent of ARI patients caused by influenza viruses and 80% of them aged in the range of 0-14 years. Influenza epidemic was prevalent in rainy season. The results of antigenic characterization, comparing with the other isolates from several parts of the world, showed that during 11 studied-years, influenza viruses 25 strains were spread in Bangkok area.