Epidemiological data show increase of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the new national baseline (calculated in country) for 2017-2018 season (72.6) by 29.2%.
ILI and ARI epidemic thresholds were exceeded in 12 of 61 cities collaborating with two WHO NICs in Russia.
Cumulative results of influenza laboratory diagnosis by different tests were submitted by 51 RBLs and two WHO NICs. According to these data as a result of 1668 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza type A virus and 0.9% for influenza type B virus.
Influenza and ARI morbidity data. Increased influenza and other ARI activity was registered during the week 02.2018 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the national baseline by 29.2%.
Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples tested positive for influenza was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza A virus and 0.9% for influenza type B virus. Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 22.9% of investigated patients by IFA and 19.2% by PCR.
Antigenic characterization. 7 influenza viruses were characterized antigenically including 5 influenza A(H3N2) strains and 2 influenza type B strains. All influenza A(H3N2) strains were related to influenza A/Hong Kong/4801/2014 virus. All influenza type B strains were belonged to Yamagata line and were like B/Phuket/3073/2013 reference virus.
Genetic characterization. One influenza A(H3N2) virus was characterized in Saint-Petersburg NIC. Virus belonged to genetic subgroup 3C.2a1 and was like A/Bolzano/07/2016 reference virus. 4 influenza A(H3N2) strains from clinical samples were characterized in Saint-Petersburg NIC. Viruses belonged to genetic subgroup 3C.2a and were like A/Hong Kong/4801/2014 reference virus.
In sentinel surveillance system clinical samples from 87 SARI and ILI/ARI patients were investigated by rRT-PCR. 5 influenza cases were detected among SARI patients, including 1 influenza A(H1N1)pdm09 case, 3 influenza A(H3N2) cases and 1 influenza B case. Among ILI/ARI patients 5 influenza cases were detected, including 1 influenza A(H1N1)pdm09 case, 1 influenza A(H3N2) case and 3 influenza B cases.
