Occurrence of influenza B/Hong Kong-Like strains in Brazil, during 2002

RESUMO

Through the influenza virus surveillance from January to October 2002, influenza B/Hong Kong-like strains circulating in the Southeast and Centre East regions of Brazil have been demonstrated. This strain is a variant from B/Victoria/02/88 whose since 1991 and until recently have been isolated relatively infrequently and have been limited to South-Eastern Asia. A total of 510 respiratory secretions were collected from patients 0 to 60 years of age, with acute respiratory illness, living in the Southeast and Centre East regions of Brazil, of which 86 (17.13 percent) were positive for influenza virus. Among them 12 (13.95 percent) were characterized as B/Hong Kong/330/2001; 3 (3.49 percent) as B/Hong Kong/1351/2002 a variant from B/Hong Kong/330/2001; 1 (1.16 percent) as B/Sichuan/379/99; 1 (1.16 percent) as B/Shizuoka/5/2001, until now. The percentages of cases notified during the surveillance period were 34.88 percent, 15.12 percent, 15.12 percent, 4.65 percent, 15.12 percent, 13.95 percent, in the age groups of 0-4, 5-10, 11-15, 16-20, 21-30, 31-50, respectively. The highest proportion of isolates was observed among children younger than 4 years but serious morbidity and mortality has not been observed among people older than 65 years, although B influenza virus component for vaccination campaign 2002 was B/Sichuan/379/99 strain. This was probably due to the elderly protection acquired against B/Victoria/02/88. In addition, in influenza A/Panama/2007/99-like (H3N2) strains 22 (25.58 percent) were also detected, but influenza A(H1N1) has not been detected yet