Epidemic Situation

Year: Week:


Week 06.11.2017-12.11.2017

Influenza and ARI morbidity data

Epidemiological data show decrease of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (52.9 per 10 000 of population) was lower than the national baseline (69.5) by 23.8%.

ILI and ARI epidemic thresholds were not exceeded in all of 61 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 51 RBLs and two WHO NICs. According to these data as a result of 1717 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 0.2%, including 0.06% for influenza A(H1N1)pdm09 virus, 0.06% for influenza A(H3N2) virus and 0.1% for influenza type A 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 RII18000000
(%) 0,00,00,00,00,00,0
BL of IV0000000
(%) ------
TOTAL18000000
(%) 0,00,00,00,00,00,0

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 RII6420002114203230117
(%) 0,00,00,03,32,23,15,04,718,2
BL of IV147000115225447
(%) 0,00,00,07,53,415,03,42,732,0
TOTAL7890003219423734164
(%) 0,00,00,04,12,45,34,74,320,8

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 RII11892 / 11710 / 4211 / 4810 / 4150 / 11711 / 50057 / 90040 / 86542 / 845
(%) 0,20,00,20,00,00,26,34,65,0
BL of IV2150 / 2150 / 510 / 510 / 510 / 2150 / 510 / 1663 / 1660 / 166
(%) 0,00,00,00,00,00,00,01,80,0
TOTAL14042 / 13860 / 4721 / 5320 / 4660 / 13861 / 55157 / 106643 / 103142 / 1011
(%) 0,10,00,20,00,00,25,34,24,2

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 RII14320012014
(%) 0,00,00,070,10,00,070,3
BL of IV2850000000
(%) 0,00,00,00,00,00,00,0
TOTAL17170012014
(%) 0,00,00,060,10,00,060,2

Conclusion

Influenza and ARI morbidity data.  Decreased influenza and other ARI activity was registered during the week 45.2017 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (52.9 per 10 000 of population) was lower than the national baseline by 23.8%.

Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples tested positive for influenza  was estimated as 0.2%, including 0.06% for influenza A(H1N1)pdm09 virus, 0.06% for influenza A(H3N2) virus and 0.1% for influenza type A virus. Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 20.8% of investigated patients by IFA and 13.7% by PCR. 

Genetic characterizationFirst influenza A(H3N2) strain from clinical sample was characterized. Virus belonged to genetic subgroup 3C.2a and were like A/HongKong/4801/2014 referens virus. Virus have additional amino acid substitutions T135K, R150N, R261Q in HA. Substitution T135K leads to loss of potential N-glicjsilation site at position 133.

In sentinel surveillance system clinical samples from 106 SARI and ILI/ARI patients were investigated by rRT-PCR. No influenza cases were detected.