Genetic predisposition to latent influenza A virus in children with blood type B(III) as a possible cause of new epidemiologic strains in the countries of South-Eastern Asia]

Regular clinical and epidemiological surveys of two groups of healthy 14-16-year-old boys were carried out for 3 years from September 1989 to May 1992 to investigate the latent circulation of influenza A viruses in the human population. Once or twice a quarter clinical materials were laboratorily studied to detect virus antigens, virus-specific NA-sequences and to determine changes in humoral immunity. The latent circulation of influenza A viruses might be identified in 10-20% of cases long before (2-4 months) the onset of epidemic development. The incidence of epidemic isolations was found to reach 33-36%, gradually decreasing from 29 to 9 or 3.5% in the postepidemic period. The long-term persistence (for 5 months) of virus antigens was reported among healthy children who had chiefly blood group B(III). The new hypothesis that the genetic predisposition of children with blood group B(III) to latent persistence of influenza A viruses may be a possible cause of the emergence of new epidemic strains in the South-East Asian countries has been forwarded.