[Analysis on the aetiology of influenza in children in Tianjin].
OBJECTIVE
To analyse the pathogen of child patients with influenza in Tianjin area.


METHODS
The influenza virus isolation was performed by MDCK cells and embryonated eggs. The identification of the isolates was carried out with hemagglutination (HA) and hemagglutination inhibition (HI) tests.


RESULTS
Two hundred and thirty-eight throat swab specimens from children with influenza-like illness were collected in Tianjin area from Oct. 2001 to Mar. 2002 and 64 strains (26.9%) of influenza virus were isolated. Data showed that there were 42 strains (65.6%) of A (H3N2) subtype, 13 strains (20.3%) of A (H1N1) subtype and 9 strains (14.1%) of B type in these positive isolates. All the isolated viruses grew very well in MDCK cells and hemagglutinated with human "O" red blood cells, and most (62/64 strains) of them were able to multiply in embryonated chick eggs. However, there were only 3 isolates with HA positive in inoculating embryonated eggs with the specimens. Meanwhile, it was revealed that out of 55 strains of A type viruses, 53 strains (96.4%) were from O to D phase, 2 strain of A (H3N2) were D phase characters and all B type isolated viruses being D phase properties.


CONCLUSIONS
There were three endemic types of influenza viruses-A (H3N2), A (H1N1) and B type in Tianjin area, with A, the main type.
Guo
Xiao-hua
XH
Tianjin Centers for Disease Control and Prevention, Tianjin 300011, China.
Duan
Wei-ping
WP
Wang
Shi-rong
SR
Zhang
Hua
H
Li
Ying
Y
Chen
Jin-ying
JY
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D014644:Genetic Variation; D006385:Hemagglutination Inhibition Tests; D006386:Hemagglutination Tests; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus / Q000145:classification / Q000302:isolation & purification*; D009981:Influenza B virus / Q000145:classification / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology / Q000209:etiology* / Q000821:virology*; D008297:Male