Epidemic Situation

Year: Week:


Week 31.12.2018-06.01.2019

Influenza and ARI morbidity data

Epidemiological data show decrease of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILIand ARI morbidity level (33.2 per 10 000 of population) was lower then national baseline (72.6) by 42.4%.

ILI and ARI epidemic threshold was exeeded in one of 61 cities collaborating with two NICs of 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 36 RBLs and two WHO NICs. According to these data as a result of 847 patients investigation 91 (10.7%) respiratory samples positive for influenza were detected including 55 influenza A(H1N1)pdm09 cases in 9 cities, 28 influenza A(H3N2) cases in 12 cities, 1 influenza type A case in 1 city and 7 influenza type B cases in 3 cities.

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 RII53010506
(%) 0,01,90,09,40,011,3
BL of IV0000000
(%) ------
TOTAL53010506
(%) 0,01,90,09,40,011,3

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 RII2070266912111561
(%) 0,01,02,92,94,35,85,37,229,5
BL of IV10000000101
(%) 0,00,00,00,00,00,010,00,010,0
TOTAL2170266912121562
(%) 0,00,92,82,84,15,55,56,928,6

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 RII6081 / 6080 / 026 / 3280 / 632 / 60855 / 5064 / 3076 / 3077 / 307
(%) 0,2-7,90,00,310,91,32,02,3
BL of IV370 / 370 / 01 / 90 / 40 / 371 / 90 / 271 / 272 / 27
(%) 0,0-11,10,00,011,10,03,77,4
TOTAL6451 / 6450 / 027 / 3370 / 672 / 64556 / 5154 / 3347 / 3349 / 334
(%) 0,2-8,00,00,310,91,22,12,7

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 RII7990027175590
(%) 0,00,03,40,10,96,911,3
BL of IV480010001
(%) 0,00,02,10,00,00,02,1
TOTAL8470028175591
(%) 0,00,03,30,10,86,510,7

Conclusion

Influenza and ARI morbidity data.  Decreased influenza and other ARI activity was registered during the week 01.2019 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (33.2 per 10 000 of population) was lower than the national baseline (72.6) by 42.4%.

Etiology of ILI & ARI morbidity. 91 (10.7%) respiratory samples positive for influenza were detected including 55 influenza A(H1N1)pdm09 cases in 9 cities, 28 influenza A(H3N2) cases in 12 cities, 1 influenza type A case in 1 city and 7 influenza type B cases in 3 cities.

Antigenic characterization. 17 influenza viruses were characterized antigenically in Moscow and Saint-Petersburg NICs including 10 influenza A(H1N1)pdm09, 6 influenza A(H3N2) strains and 1 influenza type B strain. All influenza A(H1N1)pdm09 viruses were related to influenza A/Michigan/45/2015 vaccine strain, all influenza A(H3N2) viruses were like to A/Singapure/INFIMN-16-0019/2016 vaccine strain, one influenza B virus belonged to Victoria lineage and antigenically related to B/Colorado/06/2017 vaccine strain.

Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 24.9% of investigated patients by IFA and 6.0% by PCR. 

In sentinel surveillance system clinical samples from 28 SARI and ILI/ARI patients were investigated by rRT-PCR. No influenza associated SARI cases were detected. Among ILI/ARI patients 2 (9.1%) influenza A(H3N2) cases were detected.