Epidemic Situation

Year: Week:


Week 06.02.2017-12.02.2017

Influenza and ARI morbidity data

Epidemiological data show increase of influenza and other ARI registration in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (88.8 per 10 000 of population) was abow than the national baseline (69.7) by 27.4%.

ILI and ARI epidemic thresholds were exceeded in 16 of 59 cities collaborating with two WHO NICs in Russia.

Exceeding of morbidity epidemic thresholds for overall population
 
- No data - less 20% - 20 - 49% - 50% and more


Cumulative number of diagnosed influenza cases

Cumulative results of influenza laboratory diagnosis by different tests were submitted by 53 RBLs and two WHO NICs. According to these data as a result of 4529 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 27.2%, including 0.1% for A(H1N1)pdm09 virus, 19.7% for influenza A(H3N2) virus, 0.3% for influenza A and 7/1% for influenza B virus

Results of influenza diagnosis
 
- No data
- No detection
- H1pdm09
- H1pdm09+H1
- H1pdm09+B
- H1pdm09+B+H1
- H1pdm09+H3
- H1pdm09+H3+H1
- H1pdm09+H3+B
- H1pdm09+H3+H1+B
- H1
- B
- B+H1
- H3
- H3+H1
- H3+B
- H3+H1+B


Influenza Virus Isolation



  - B - A(H1N1) - A(H3N2) - A(H1N1)pdm09  


Influenza Virus Antigen Detection by Immunofluorescence Assay (IFA)



  - B - A(H1N1) + A(H1N1)pdm09 - A(H3N2)  
  - PIV - AD - RS  


Influenza Virus RNA Detection by RT-PCR



  - B - A(H1N1) - A(H3N2) - A(H1N1)pdm09  
  - PIV - AD - RS    


Table 1. Influenza Virus Isolation
Base lab. Number of
investigated
patients
Number of viruses isolated
H1 H3 B H1pdm09 Untyped
virus
Total
BL of RII32303590044
(%) 0,010,82,80,00,013,6
BL of IV117011100021
(%) 0,09,48,50,00,017,9
TOTAL440046190065
(%) 0,010,54,30,00,014,8

Table 2. Influenza Virus Antigen Detection by Immunofluorescence Assay (IFA)
Base lab. Number of
investigated
patients
Influenza Parainfluenza AD RS Total
H1+H1pdm09 H3 B I II III
BL of RII138311082723224811270411
(%) 0,077,82,01,71,63,58,15,129,7
BL of IV232041406612117123
(%) 0,017,717,22,62,65,24,73,053,0
TOTAL161511496729286012377534
(%) 0,069,24,11,81,73,77,64,833,1

Table 3. Influenza Virus RNA Detection by RT-PCR
Base lab. Number of
investigated
patients
Influenza PIV AD RS
A
(not subtyped)
H1 H3 H5 B H1pdm09
BL of RII268213 / 26820 / 1155646 / 25330 / 1079217 / 26825 / 189224 / 165738 / 164685 / 1646
(%) 0,50,025,50,08,10,31,42,35,2
BL of IV4620 / 4620 / 27100 / 4620 / 2758 / 4620 / 633 / 2052 / 2053 / 205
(%) 0,00,021,60,012,60,01,51,01,5
TOTAL314413 / 31440 / 1182746 / 29950 / 1106275 / 31445 / 195527 / 186240 / 185188 / 1851
(%) 0,40,024,90,08,70,31,52,24,8

Table 4. Cumulative number of diagnosed influenza cases
Base lab. Number of
investigated
patients
Number of diagnosed influenza cases
H1 H1+H1pdm09
(IFA)
H3 A
(not subtyped)
B H1pdm09 Total
BL of RII3937017611323461014
(%) 0,00,0319,30,35,90,225,8
BL of IV592001290880217
(%) 0,00,021,80,014,90,036,7
TOTAL4529018901332261231
(%) 0,00,0219,70,37,10,127,2

Conclusion

Influenza and ARI morbidity data. Increased influenza and other ARI reporting was registered in traditional surveillance system in Russia during the week ending 11.02.2017. The nationwide ILI & ARI morbidity level (86.9 per 10 000 of population) exceded the baseline by 27.4%.

Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples positive for influenza  was estimated as 27.2%, including 0.1% for A(H1N1)pdm09 virus, 19.7% for influenza A(H3N2) virus, 0.3% for influenza A and 7.1% for influenza B virus.

Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 19.6% of investigated patients by IFA and 8.5% by PCR. 

In sentinel surveillance system Clinical samples from 57 SARI patients were investigated by rRT-PCR. Among them 23 (40.4%) cases were associated with influenza, including 20 A(H3N2) cases and 3 influenza B cases. A total 68 ILI/ARI cases were investigated and 21 (30.9%) influenza cases were recognized, among them 17 influenza A(H3N2) and 4 influenza B cases. 

Antigenic characterization. One influenza A(H1N1)pdm09 strain was similar to A/California/7/2009 virus. 69 influenza A(H3N2) strains were antigenically related to influenza A/Hong Kong/4801/2014 virus. 49 influenza B viruses belonged to Victoria lineage and were like influenza B/Brisbane/60/2008 virus.

Genetic characterization7 influenza A(H3N2) viruses were characterized. 2 of them belonged to genetic subgroup 3C.2a1 and were like A/Bolzano/7/2016 reference-strain. 5 influenza A(H3N2) viruses belonged to genetic subgroup 3C.2a and were like A/HongKong/4801/2014 virus.