Epidemic Situation

Year: Week:


Week 08.01.2018-14.01.2018

Influenza and ARI morbidity data

Epidemiological data show increase of influenza and other ARI activity in Russia in comparison with previous week. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the new national baseline (calculated in country) for 2017-2018 season (72.6) by 29.2%.

ILI and ARI epidemic thresholds were exceeded in 12 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 1668 patients investigation the overall proportion of respiratory samples positive for influenza was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza type A virus and 0.9% for influenza type 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 RII46000000
(%) 0,00,00,00,00,00,0
BL of IV4000000
(%) 0,00,00,00,00,00,0
TOTAL50000000
(%) 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 RII4371209414263591
(%) 0,20,50,02,10,93,25,98,020,8
BL of IV890006287932
(%) 0,00,00,06,72,29,07,910,136,0
TOTAL526120156223344123
(%) 0,20,40,02,91,14,26,38,423,4

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 RII11791 / 11790 / 51019 / 7920 / 5029 / 11795 / 73116 / 93947 / 939125 / 931
(%) 0,080,02,40,00,80,71,75,013,4
BL of IV1730 / 1820 / 441 / 1030 / 446 / 1822 / 1030 / 1301 / 13015 / 130
(%) 0,00,01,00,03,31,90,00,811,5
TOTAL13521 / 13610 / 55420 / 8950 / 54615 / 13617 / 83416 / 106948 / 1069140 / 1061
(%) 0,070,02,20,01,10,81,54,513,2

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 RII1437012119637
(%) 0,00,071,50,070,60,42,6
BL of IV2310010629
(%) 0,00,00,40,02,60,93,9
TOTAL16680122115846
(%) 0,00,061,30,060,90,52,8

Conclusion

Influenza and ARI morbidity data.  Increased influenza and other ARI activity was registered during the week 02.2018 in traditional surveillance system in Russia. The nationwide ILI & ARI morbidity level (51.4 per 10 000 of population) was lower than the national baseline by 29.2%.

Etiology of ILI & ARI morbidity. The overall proportion of respiratory samples tested positive for influenza  was estimated as 2.8%, including 0.5% for influenza A(H1N1)pdm09 virus, 1.3% for influenza A(H3N2) virus, 0.06% for influenza A virus and 0.9% for influenza type B virus. Percent of positive ARI cases of non-influenza etiology (PIV, adeno- and RSV) was estimated as 22.9% of investigated patients by IFA and 19.2% by PCR. 

Antigenic characterization. 7 influenza viruses were characterized antigenically including 5 influenza A(H3N2) strains and 2 influenza type B strains. All influenza A(H3N2) strains were related to influenza A/Hong Kong/4801/2014 virus. All influenza type B strains were belonged to Yamagata line and were like B/Phuket/3073/2013 reference virus.

Genetic characterizationOne influenza A(H3N2) virus was characterized in Saint-Petersburg NIC. Virus belonged to genetic subgroup 3C.2a1 and was like A/Bolzano/07/2016 reference 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/Hong Kong/4801/2014 reference virus.

In sentinel surveillance system clinical samples from 87 SARI and ILI/ARI patients were investigated by rRT-PCR. 5 influenza cases were detected among SARI patients, including 1 influenza A(H1N1)pdm09 case, 3 influenza A(H3N2) cases and 1 influenza B case. Among ILI/ARI patients 5 influenza cases were detected, including 1 influenza A(H1N1)pdm09 case, 1 influenza A(H3N2) case and 3 influenza B cases.