Viral etiology of acute respiratory infections in infants and young children.

114 children with acute respiratory infections were investigated to detect the viral etiological agents. The following methods were used: the direct immunofluorescence technique for the rapid diagnosis from tracheobronchial aspirates and the serological reactions--hemaglutinoinhibition and complement fixation reaction--to determine the increase of antibodies titres. Of 55.2% respiratory infections with a viral etiology, 60.3% represent acute infections of the lower respiratory tract. Due to the influenza epidemic reported between October 1996 and February 1997 (with a higher number of cases than in the last 5 years), most viral respiratory infections were caused by influenza viruses (57.14%). The direct immunofluorescence technique proved to be sensitive and specific in detecting the viral etiological agents which caused respiratory infections. Thus, using this technique, a positive diagnosis was made in 68.2% of cases, of which 49.2% were positive by the hemagglutination and complement fixation reactions, too. The test specificity could have been higher if the pathological products had been prelevated within the first three days after the onset of the disease.

Seroepidemiological study of the circulation of influenza C virus in man.

The seroepidemiological study of the circulation of influenza C virus was achieved by testing HI antibodies in human sera collected from healthy subjects in Bucharest belonging to various age groups. The investigations were carried out over a two years period (October 1988--September 1990), using 3 influenza C virus strains: C/Taylor/1233/47, C/USSR/0303/77 and C/Moscow/1/84, the last two being antigenically similar. The analysis of the distribution of HI antibody values against the three influenza C virus strains showed that over October 1988--June 1989 the reported circulating viruses belonged to two distinct antigenic groups, one similar to the prototype C/Taylor/47 strains and the other to C/USSR/and/C/Moscow strains, whilst during the July 1989--September 1990 time interval viruses belonging solely to the C/USSR and C/Moscow antigenic group circulated. Similarly, one should note that circulation of influenza C viruses is not seasonal, it can appear anytime and even several times per year; this accounts for the relatively high and permanent antibody level in the population belonging to all age groups.

Comparative study of the immunogenicity of aqueous versus aluminium phosphate adsorbed split influenza vaccine C.I.

The antibody responses induced by the split influenza vaccine adsorbed on aluminium phosphate and the corresponding, nonadsorbed vaccine, both prepared in the Cantacuzino Institute, were studied in subjects belonging to three different age groups: 3-6, 10-15 and over 60 years of age, respectively. In all age groups the immunogenicity of the two vaccine preparations was similar, being uninfluenced by the level of preexisting antibodies. The immunogenicity of both vaccines was similar even in children considered to be non-primed. There were no differences in the persistence and specificity of antibodies induced by the two vaccines. No significant enhancement of the immunogenicity by aluminium phosphate was observed.

[Supplementary data on the theory concerning the cyclic evolution of influenza viruses]. / Date suplimentare in favoarea ipotezei privind evolutia cicica a virusurilor gripale

The distribution per age groups of antibodies to influenza viruses A/Hong Kong/1/68, A/England/837/69 and A/England/42/72 in the sera collected in 1970 demonstrates that antigenically similar strains also dominated the epidemiologic picture of influenza in the past century. The results suggest that the pandemic of 1893 and infection in persons born before 1885 were caused by a strain similar to A/Hong Kong/1/68 and in those born in 1895-1897 by the antigenic variant A/England/42/72. The anamnestic response to the A/England/69 variant, following upon vaccination with the Hong Kong strain shows that the primary infection in persons born before 1900 was caused by a strain antigenically similar to the first variant. The data obtained lend support to the hypothesis of antigenic recycling of influenza virus and of the finite character of the antigenic variation of influenza viruses.