[Seroepidemiological data on the circulation of influenza virus in Moldova in 1991-1992]

1. To establish the predominant circulating antigenic subtypes of influenza viruses in the epidemic season (19911992). 2. To evaluate the efficiency of seroepidemiological method in determining the circulating antigenic subtypes and its practical consequences.

Our study consist of 1082 patients with acute respiratory disease or their contacts. Antigens prepared at "Cantacuzino Institute", C.D.C. Atlanta and from viral strains isolated in our laboratory were used. Hemagglutination-inhibiting Test was preceded by the elimination of the unspecific inhibitors with IO4K M/90. Significant titers were considered those > 1/10.

Were assessed by determining the number of antibody carriers, their ratio and geometrical mean of the reciprocal value of H.I. antibody titers.

1. In the winter of 1991 and 1992 A/H3N2 infections and in the spring 1991 and 1992 A/H1N1 virus prevailed, while B virus circulated by the end of spring 1992 epidemic season. 2. The decrease in 1992 of A/Iaşi/1/69 (H3N2) activity at the same time with high titers against A/Iaşi/1/76 (H3N2) and A/Iaşi/1/80 (H3N2) suggests a marked antigenic drift occurring in this interval 3. Serological method for determining the presence of hemagglutination inhibiting antibodies seemed enough and compulsory for detecting the etiological agent of acute respiratory disease, and an epidemic outbreak. 4. The circulation of three distinct antigenic subtypes determines the options for composition of anti-influenza vaccine.