Background
Materials and methods
Sample collection and outbreak definition
Detection of viruses using real-time RT-PCR
RT-PCR for norovirus genotyping
PCR for the partial RdRp and VP1 regions of norovirus strains
Data analysis
Statistical analysis
Results
Outbreaks due to viral AG
Season | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Total | 2007–2008 | 2008–2009 | 2009–2010 | 2010–2011 | 2011–2012 | 2012–2013 | 2013–2014 | 2014–2015 | 2015–2016 | 2016–2017 | ||
Total of AG outbreaks | 1459 | (100%) | 114 | 103 | 93 | 171 | 122 | 161 | 162 | 139 | 135 | 259 |
Virus | ||||||||||||
Norovirusa | 1327 | (90.9%) | 104 | 93 | 90 | 155 | 110 | 150 | 150 | 123 | 118 | 234 |
RVA | 73 | (5.0%) | 5 | 6 | 1 | 7 | 4 | 3 | 9 | 8 | 10 | 20 |
Sapovirus | 49 | (3.4%) | 1 | 3 | 2 | 8 | 6 | 8 | 3 | 8 | 6 | 4 |
RVC | 10 | (0.7%) | 4 | 1 | 0 | 1 | 2 | 0 | 0 | 0 | 1 | 1 |
Setting | ||||||||||||
K/Nsb | 504 | (34.6%) | 11 | 18 | 11 | 59 | 31 | 43 | 67 | 46 | 67 | 151 |
PSsb | 413 | (28.3%) | 40 | 46 | 45 | 54 | 27 | 27 | 40 | 30 | 32 | 72 |
NHsb | 256 | (17.6%) | 30 | 24 | 17 | 21 | 36 | 60 | 25 | 22 | 14 | 7 |
Restaurants | 143 | (9.8%) | 16 | 5 | 10 | 19 | 14 | 16 | 13 | 19 | 14 | 17 |
Welfare facilities | 42 | (2.9%) | 1 | 4 | 5 | 3 | 6 | 4 | 7 | 8 | 1 | 3 |
Hospitals | 31 | (2.1%) | 10 | 1 | 2 | 5 | 4 | 4 | 3 | 2 | 0 | 0 |
Junior and senior high schools, universities | 16 | (1.0%) | 5 | 1 | 3 | 1 | 0 | 1 | 0 | 2 | 0 | 3 |
Othersc | 54 | (3.7%) | 1 | 4 | 0 | 9 | 4 | 6 | 7 | 10 | 7 | 6 |
Repeated AG outbreaks reported at the same facilities
K/Nsa | PSsa | NHsa | Welfare facilities | Hospitals | Restaurants | Junior and senior high schools, universities | Others | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Total outbreaks | 504 | 413 | 256 | 42 | 31 | 143 | 16 | 54 | ||||||
Facilities | 353 | 255 | 215 | 37 | 28 | 143 | 16 | 52 | ||||||
Frequency | ||||||||||||||
1 | 259 | 160 | 186 | 33 | 25 | 143 | 16 | 50 | ||||||
2 | 66 | (KN2-1–KN2-66) | 55 | (PS2-1–PS2-55) | 20 | (NH2-1–NH2-20) | 3 | (WF2-1–WF2-3) | 3 | (HP2-1–HP2-3) | 0 | 0 | 2b | (OT2-1, OT2-2) |
3 | 16 | (KN3-1–KN3-16) | 24 | (PS3-1–PS3-24) | 7 | (NH3-1–NH3-7) | 1 | (WF3-1) | 0 | 0 | 0 | 0 | ||
4 | 5 | (KN4-1–KN4-5) | 13 | (PS4-1–PS4-13) | 1 | (NH4-1) | 0 | 0 | 0 | 0 | 0 | |||
≥ 5 | 7 | (KNo5-1–KNo5-7) | 3 | (PSo5-1–PSo5-3) | 1 | (NHo5-1) | 0 | 0 | 0 | 0 | 0 |
Combination type | Number of facility | Number of facility (Number of settinga) | Interval between outbreaks (Month) | ||
---|---|---|---|---|---|
Average | Maximum | Minimum | |||
Total | 149 | 32.3 | 107 | 0 | |
Same virus (Norovirus + Norovirus) | 120 | 32.8 | 107 | 0 | |
Same genotype | 23 | 36.1 | 83 | 0 | |
GII.2 | 2 | (2 K/Ns) | 41.5 | 83 | 0 |
GII.3 | 1 | (1 PS) | 22 | – | – |
GII.4 | 19 | (3 K/Ns, 14 NHs, 1 hospital, 1 other) | 34.9 | 83 | 0 |
GII.6 | 1 | (1 PS) | 61 | – | – |
Different genogroup or genotype | 97 | 32.0 | 107 | 2 | |
Different genotype | 71 | 31.3 | 107 | 2 | |
GII.2 + GII.3 | 8 | (5 K/Ns, 3 PSs) | 24.1 | 72 | 2 |
GII.2 + GII.4 | 14 | (9 K/Ns, 4 NHs, 1 warefare) | 32.9 | 71 | 10 |
GII.2 + GII.6 | 4 | (2 K/Ns, 2 PSs) | 34.0 | 35 | 32 |
GII.2 + GII.14 | 5 | (1 K/N, 4 PSs) | 29.0 | 53 | 13 |
GII.2 + GII.17 | 2 | (1 K/N, 1 PS) | 19.5 | 30 | 9 |
GII.3 + GII.4 | 13 | (12 K/Ns, 1 NH) | 36.0 | 66 | 13 |
GII.3 + GII.5 | 1 | (1 K/N) | 24 | – | – |
GII.3 + GII.6 | 2 | (1 K/N, 1 PS) | 30.0 | 35 | 25 |
GII.3 + GII.14 | 3 | (2 K/Ns, 1 PS) | 22.0 | 30 | 13 |
GII.3 + GII.N.D.b | 1 | (1 K/N) | 54 | – | – |
GII.4 + GII.6 | 6 | (5 K/Ns, 1 NH) | 21.0 | 23 | 4 |
GII.4 + GII.14 | 4 | (1 K/N, 3 PSs) | 29.5 | 95 | 2 |
GII.4 + GII.17 | 5 | (3 NHs, 1 hospital, 1 other) | 48.8 | 107 | 28 |
GII.6 + GII.14 | 2 | (2 PSs) | 35.5 | 53 | 18 |
GII.6 + GII.17 | 1 | (1 PS) | 14 | – | – |
Different genogroup (GI + GII) | 26 | 33.9 | 93 | 2 | |
Different virus | 29 | 30.2 | 72 | 0 | |
Norovirus + Other virus (Sapovirus or RVA or RVC) | 27 | 31.1 | 72 | 0 | |
RVA + Sapovirus | 2 | 18.5 | 33 | 4 |
Repeated AG outbreaks during the same season at the same facilities
Settinga | AG Season | Dominant norovirus genotypeb | Facility name | AG virus or norovirus genotype (variant) caused the outbreak | ||
---|---|---|---|---|---|---|
1st | 2nd | 3rd | ||||
K/Ns | 2008–2009 | GII.3, GII.4, GII.6 | KN2-49 | GII.3 | GI.4 | |
2009–2010 | GII.2, GII.4, GII.3 | KN4-5 | RVA | GII.3 | ||
2010–2011 | GII.3 | KN4-3 | GII.3 | GII.4 (Den Haag 2006b) | ||
KNo5-2 | GII.4 (Den Haag 2006b) | GII.3 | ||||
KN2-62 | GII.3 | Sapovirus | ||||
2011–2012 | GII.4, GII.14 | KNo5-6 | GI.6 | RVA | ||
2013–2014 | GII.6, GII.4 | KNo5-4 | GII.4 (Sydney 2012) | GI.7 | ||
KNo5-7 | GII.3 | RVA | GII.6 | |||
KN2-58 | RVA | GII.6 | ||||
KN2-18 | GII.6 | GII.4 (Sydney 2012) | ||||
2014–2015 | GII.4, GII.3 | KN4-4 | GII.4 (Sydney 2012) | GII.3 | ||
KNo5-4 | GII.4 (Sydney 2012) | GI.2 | ||||
KNo5-5 | GII.17 | RVA | Sapovirus | |||
2015–2016 | GII.3, GII.4 | KN2-48 | GII.4 (Sydney 2012) | GI.6 | ||
KN3-10 | GI.3 | GII.4 (Sydney 2012) | ||||
KNo5-5 | GII.3 | GI.6 | ||||
KNo5-7 | GII.2 | Sapovirus | ||||
2016–2017 | GII.2 | KN3-3 | GII.3 | GII.2 | ||
KN3-2 | GII.2 | GII.4 (Sydney 2012) | ||||
KNo5-6 | GII.2 | RVA | ||||
KN2-2 | GII.2 | GII.2 | ||||
KN3-16 | GII.2 | GII.4 (Sydney 2012) | ||||
PSs | 2007–2008 | GII.2, GII.14 | PS2-4 | GII.4 (Den Haag 2006b) | GII.14 | |
PS2-28 | GI.3 | GII.2 | ||||
2009–2010 | GII.2 | PS3-7 | GII.2 | GII.6 | ||
2010–2011 | GII.3, GII.2 | PS4-7 | GII.3 | GII.3 | ||
PS3-24 | Sapovirus | GII.2 | ||||
PS2-3 | GII.2 | GII.3 | ||||
PS4-13 | Sapovirus | GII.3 | RVA | |||
PSo5-1 | GII.2 | GII.12 | ||||
2011–2012 | GII.14 | PS4-9 | Sapovirus | Sapovirus | ||
PSo5-3 | GII.12 | GI.6 | GII.14 | |||
2012–2013 | GII.4 | PS3-11 | GI.6 | GII.7 | ||
2013–2014 | GII.6 | PS4-2 | GII.6 | GII.6 | ||
PS4-8 | GII.6 | GI.6 | ||||
PS4-4 | GI.3 | GII.6 | ||||
2014–2015 | GI.3, GII.17 | PS4-6 | GI.2 | GI.3 | ||
PS4-2 | GI.3 | GI.3 | ||||
2015–2016 | GII.17 | PS3-5 | GI.3 | GI.3 | ||
2016–2017 | GII.2 | PS3-1 | GII.2 | GII.2 | ||
PS3-18 | GII.2 | Sapovirus | ||||
PS3-22 | GI.4 | RVA | ||||
PS4-3 | GII.6 | GII.2 | ||||
NHs | 2011–2012 | GII.4 | NH2-20 | GII.4 (New Orleans 2009) | RVA | |
NHo5-1 | GII.4 (Den Haag 2006b) | GII.4 (Den Haag 2006b) | ||||
2012–2013 | GII.4 | NH2-3 | GII.4 (Sydney 2012) | GII.4 (Sydney 2012) | ||
NH3-7 | GII.4 (Sydney 2012) | Sapovirus | ||||
Welfare facility | 2012–2013 | –c | WF2-3 | GII.4 (Sydney 2012) | Sapovirus |
Repeated norovirus outbreaks due to the same genotype at the same facilities
Number of combination | Interval between outbreaks (Month) | |||
---|---|---|---|---|
Average | Maximum | Minimum | ||
Total | 49 | 31.2 | 90 | 0 |
Genotype | ||||
GI.3 | 2 | 4.0 | 7 | 1 |
GII.2 | 13 | 43.2 | 90 | 0 |
GII.3 | 5 | 47.2 | 75 | 1 |
GII.4 | 20 | 18.6 | 47 | 0 |
GII.6 | 6 | 41.2 | 67 | 2 |
GII.14 | 3 | 35.0 | 51 | 6 |
Settinga | ||||
K/Ns | 17 | 36.4 | 83 | 0 |
PSs | 20 | 35.7 | 90 | 0 |
NHs | 11 | 16.8 | 40 | 0 |
Hospital | 1 | 13 | – | – |
Facility name | Outbreak strain name | Interval (month) | VP1 | RdRp region | Epidemiological information | |||
---|---|---|---|---|---|---|---|---|
Genotype (variant) | Amino acid identities (%) | Domaina with amino acid differences (Number of difference) | P–type | Predominant group of infection | Scale (patients/ enrollment) | |||
PS3-5 | y15-V1226-3 | 1b | GI.3 | 100 | No difference | GI.P3 | 6th grade, 3rd and 4th grade | 30/696 |
y15-V1256-1 | 1st grade | 13/785 | ||||||
PS4-2 | y14-V1098-1 | 7b | GI.3 | 87.2 | Shell (8), Protruding (62) | GI.P3 | 5th grade, 6th and 2nd grade | 18/134 |
y15-V1215-1 | No data | No data | ||||||
KN2-2 | y16-V1450-1 | 0b | GII.2 | 99.8 | Shell (1) | GII.P16 | 4-year-old class | 7/60 |
y16-V1509-2 | 0-year-old class | 11/74 | ||||||
NH2-3 | y12-V863-1 | 0b | GII.4 (Sydney 2012) | 100 | No difference | GII.P31 | Residents on the 1st floor | 7/37 |
y12-V881-1 | Residents on the 2nd floor | 11/37 | ||||||
NHo5-1 | y11-V657-2 | 0b | GII.4 (Den Haag 2006b) | 98.9 | Protruding (6) | GII.P4 | Residents on the 2nd floor | 28/214 |
y11-V689-2 | Residents on the 3rd floor | 43/214 | ||||||
PS3-1 | y16-V1355-2 | 0b | GII.2 | 100 | No difference | GII.P16 | 4th grade, 1st, 5th and 6th grade | 87/1028 |
y16-V1387-1 | 1st grade, 5th and 6th grade | 17/1028 | ||||||
PS4-7 | y10-V426-3 | 1b | GII.3 | 99.8 | Protruding (1) | GII.P12 | No data | No data |
y10-V486-1 | No data | No data | ||||||
PS4-2 | y13-V1056-4 | 2b | GII.6 | 100 | No difference | GII.P7 | Whole school | 71/601 |
y14-V1086-3 | 1st to 5th grade | 55/563 | ||||||
KNo5-1 | y12-V797-1 | 24 | GII.4 (Sydney 2012) | 99.4 | Protruding (3) | GII.P31 | 0 to 5-year-old | 18/82 |
y14-V1131-5 | 0 to 5-year-old | 15/66 | ||||||
NH3-2 | y12-V840-1 | 13 | GII.4 (Sydney 2012) | 99.4 | Shell (1), Protruding (2) | GII.P31 | Whole facility | 8/160 |
y14-V1129-1 | Whole facility | 5/130 | ||||||
NH3-3 | y12-V902-8 | 22 | GII.4 (Sydney 2012) | 99.8 | Protruding (1) | GII.P31 | Dementia unit | 14/50 |
y14-V1145-1 | Dementia unit | 21/50 | ||||||
PS3-2 | y07-V195-2 | 48 | GII.14 | 99.3 | Protruding (4) | GII.P7 | No data | No data |
y11-V717-4 | 1st grade | 60/758 |