Epidemic Situation

Year: Week:


Week 02.01.2017-08.01.2017

Influenza and ARI morbidity data

Epidemiological data show decrease of influenza and other ARI registration in Russia in comparison with previous week as result of New Year and Christmas holidays The nationwide ILI & ARI morbidity level (51.9 per 10 000 of population) was below than the national baseline (69.7) by 21.5%.

ILI and ARI epidemic thresholds were exceeded in 23 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 44 RBLs and two WHO NICs. According to these data as a result of 1140 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 41.2%, including 0.09% for A(H1N1)pdm09 virus, 25.4% for influenza A(H3N2) virus, 15.2% for influenza A and 0.6% 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 RII42041005
(%) 0,09,52,40,00,011,9
BL of IV20000000
(%) 0,00,00,00,00,00,0
TOTAL62041005
(%) 0,06,51,60,00,08,1

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 RII21701322317211068
(%) 0,06,00,90,91,47,89,74,631,3
BL of IV580103496225
(%) 0,01,70,05,26,915,510,33,443,1
TOTAL27501425726271293
(%) 0,05,10,71,82,59,59,84,433,8

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 RII835173 / 8300 / 158251 / 8300 / 1294 / 8241 / 46615 / 53410 / 54318 / 543
(%) 20,80,030,20,00,50,22,81,83,3
BL of IV1040 / 1040 / 2638 / 1040 / 261 / 1040 / 281 / 420 / 410 / 45
(%) 0,00,036,50,01,00,02,40,00,0
TOTAL939173 / 9340 / 184289 / 9340 / 1555 / 9281 / 49416 / 57610 / 58418 / 588
(%) 18,50,030,90,00,50,22,81,73,1

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 RII10090025017361430
(%) 0,00,024,817,10,60,1042,6
BL of IV131003901040
(%) 0,00,029,80,00,80,030,5
TOTAL11400028917371470
(%) 0,00,025,415,20,60,0941,2

Conclusion

Influenza and ARI morbidity data.  Decreased influenza and other ARI reporting was registered during the week ending 08.01.2017 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (51.9 per 10 000 of population) was below than the baseline by 21.5%.

Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples positive for influenza  was estimated as 41.2%, including 0.09% for A(H1N1)pdm09 virus, 25.4% for influenza A(H3N2) virus, 15.2% for influenza A and 0.6% for influenza B virus.

Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 28.0% of investigated patients by IFA and 7.6% by PCR. 

In sentinel surveillance system clinical samples from 73 SARI and ILI/ARI patients were investigated by rRT-PCR. 31 (77.5%) influenza A(H3N2) SARI cases and 17 (51.5%) influenza A(H3N2) ILI/ARI cases were detected

Antigenic characterization. One influenza A(H1N1)pdm09 strain was similar to A/California/7/2009 virus. 14 influenza A(H3N2) strains were antigenically related to influenza A/Hong Kong/4801/2014 virus. 10 influenza B viruses belonged to Victoria lineage and were like influenza B/Brisbane/60/2008 virus.

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