Epidemiological data show increase of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (68.5 per 10 000 of population) was lower than the national baseline (69.5) by 1.4%.
ILI and ARI epidemic thresholds were exceeded in two of 61 cities collaborating with two WHO NICs in Russia.
Cumulative results of influenza laboratory diagnosis by different tests were submitted by 54 RBLs and two WHO NICs. According to these data as a result of 2160 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 0.3%, including 0.2% for influenza A(H3N2) virus and 0.05% for influenza type A virus.
Influenza and ARI morbidity data. Increased influenza and other ARI activity was registered during the week 50.2017 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (68.5 per 10 000 of population) was lower than the national baseline by 1.4%.
Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples tested positive for influenza was estimated as 0.3%, including 0.2% for influenza A(H3N2) virus and 0.05% for influenza type A virus. Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 24.0% of investigated patients by IFA and 15.6% by PCR.
Antigenic characterization. Five influenza A(H3N2) strains were antigenically related to influenza A/Hong Kong/4801/2014 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 referens 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/HongKong/4801/2014 referens virus.
In sentinel surveillance system clinical samples from 137 SARI and ILI/ARI patients were investigated by rRT-PCR. Only one influenza A(H3N2) case was detected among ILI/ARI patients.
