病原微生物検出情報 Vol. 36 No.11（2015. 11）（231）

ISSN 0915-5813

IASR

Vol. 36 No. 11 November 2015
Infectious Agents Surveillance Report
http://www.nih.go.jp/niid/en/iasr-e.html

Analysis of influenza virus isolates from the 2014/15 influenza
season, Japan ..................................................................................... 202
Outbreak of influenza in a care facility for the elderly and its
affiliated hospital, December 2014-January 2015-Hiroshima
Prefecture ........................................................................................... 207
Outbreak of influenza B in a nursery home for the elderly, JulyAugust, 2015-Okinawa Prefecture ................................................... 209
Assessment of the impact of seasonal influenza on designatedsentinel hospitals, Japan ................................................................... 210
Influenza encephalopathy, 2009/10-2014/15 seasons, Japan-National
Epidemiological Surveillance of Infectious Diseases (NESID) ........ 212
Estimation of excess mortality during the 2014/15 influenza
season, Japan ..................................................................................... 213
Influenza vaccination coverage in the 2013/14 influenza season
and seroprevalence of influenza prior to the 2014/15 influenza
season, Japan-FY 2014-National Surveillance of Vaccine
Preventable Diseases ......................................................................... 214
Selection process of candidate influenza vaccine strains for the2015/16 season, Japan ....................................................................... 217
Current epidemiology of avian influenza viruses ................................ 220

National Institute of Infectious Diseases andTuberculosis and Infectious Diseases
Control Division,Ministry of Health, Labour and Welfare

Risk assessment of pandemic influenza - a recommendation by USCDC..................................................................................................... 221
Genetic analysis of A(H1N1)pdm09 isolated from a patient who
returned from Shanghai in early September 2015-MiePrefecture ........................................................................................... 223
Characteristics of AH3 influenza virus isolated from an outbreakin a nursery school, week 35-36, 2014-Aichi Prefecture ................. 224
Influenza virus isolated in the early 2015/16 influenza season-Ibaraki Prefecture ........................................................................... 225
Detection of enterovirus D68 from 8 pediatric patients including
one manifesting acute flaccid myelitis, August-September,2015-Saitama City ............................................................................ 226
Epidemic keratoconjunctivitis outbreak due to adenovirus 54 in
Fukui Prefecture, June 2015 ............................................................. 227
Epidemiology and causative viruses of hand, foot and mouthdisease and herpangina in 2015 in Shimane Prefecture ................. 228
Isolation of coxsackievirus B5 and human parechovirus 1 from an
outbreak of infectious gastroenteritis among infants whose soleclinical manifestation was diarrhea-Osaka Prefecture .................. 229
Congenital syphilis in Japan, 2011-2014–National Epidemiological
Surveillance of Infectious Diseases (NESID) ................................... 230<THE TOPIC OF THIS MONTH>
Influenza 2014/15 season, Japan
Figure 1. Weekly number of reported influenza cases/sentinel site and isolated influenza
viruses from week 18, 2013 to week 40, 2015, Japan

No. of cases/sentinel site
(National Epidemiological
Surveillance of Infectious
Diseases)

AH3
B/Victoria
B/Yamagata

3530

202020

1010

10000

18 22 26 30 34 38 42 46 50 2

2013

6 10 14 18 22 26 30 34 38 42 46 50 2

2014

25
2015
1018202224262830
323436
3840302224262830
32
34
36
3840
42443030

6 10 14 18 22 26 30 34 382015

No. of cases/sentinel site

40
AH1pdm09

22242628303234363840424446

No. of isolated viruses(Infectious Agents Surveillance Report: as of October 27, 2015)
850
800
750
700
650
600
550
500
450
400
350
300
250
200
150
100
500

50WeekYearThe 2014/15 influenza season (week 36 in September 2014 to week 35 in August 2015), which peaked in January 2015, wascharacterized by the predominance of AH3, after observing relatively low AH3 activity during the previous season. From week 12of 2015, influenza virus B was the dominant type for the remainder of the season.
Epidemiology of the 2014/15 Influenza season: Under the National Epidemiological Surveillance of Infectious Diseases(NESID), approximately 5,000 influenza sentinel sites (approximately 3,000 paediatric and 2,000 internal medicine healthcare
facility sites) report patients diagnosed as influenza on a weekly basis (http://www.nih.go.jp/niid/images/iasr/34/405/de4051.pdf).
In the 2014/15 season, the number of reported patients per sentinel in Japan exceeded 1.0 (indicator of the nationwide start ofinfluenza season) in week 48 of 2014 and weekly influenza activity remained at or above this level until week 18 of 2015; the peak
was the week 4 of 2015 (39.4 patients/sentinel) (Fig. 1) (http://www.nih.go.jp/niid/en/10/2096-weeklygraph/2572-trend-week-e.html).
Iwate prefecture was the first prefecture to attain the alert level of 10.0 patients/sentinel/week in week 48 of 2014. In week 2 of2015, all 47 prefectures exceeded the alert level. For the 2014/15 season, cumulatively there was a total of 289.8 patients/sentinel(301.0 patients/sentinel in the 2013/14 season).
Soon after the start of the 2014/15 season, outbreaks in healthcare facilities were reported from several prefectures, such as
Hiroshima prefecture (see p. 207 of this issue). Okinawa prefecture had reported influenza activity during the summer months
every year since 2005; however, during the 2012/13 and 2013/14 seasons, such summer influenza activity was no longer observed.
However, in the 2014/15 season, Okinawa again reported influenza activity during the summer, and was the only prefecture thatcontinuously reported at least 1.0 influenza patient/sentinel/week from week 47 of 2014 to week 42 of 2015. In addition, Okinawa
reported an influenza outbreak in a healthcare facility in July 2015 (see p. 209 of this issue).
Based on sentinel surveillance, the estimated number of medically attended influenza patients nationwide was approximately
15,030,000 from week 36 of 2014 to week 20 of 2015 (September 1, 2014-May 17, 2015). Hospitalized influenza surveillance, whichcollects data for hospitalized influenza patients from 500 designated sentinel hospitals with ≥300 beds (initiated in September2011), reported a total of 12,705 hospitalized influenza patients in the 2014/15 season, which was higher than the previous season
by 28% (9,905 in 2013/14) (see p. 210 of this issue). From the surveillance system for acute encephalitis, a category V notifiable1′（199′）（Continued on page 200′）IASR Vol. 36 No.11（Nov. 2015） 2′（200′）（232） 病原微生物検出情報 Vol. 36 No.11（2015. 11）（THE TOPIC OF THIS MONTH-Continued）

Figure 3. Distribution of influenza cases by age and influenza type in the 2014/15 influenza
season, Japan(Infectious Agents Surveillance Report: as of October 14, 2015)

01020304050607080

100 %

90

No. of cases*
234-

5678912Age group (year)

111360693970≤151930 50-

103039-B/Victoria

5059-

2029

AH3B/Yamagata

4049

13-

1-

0-

AH1pdm09

3,683

55647

14

* excludes cases with unknown age

infectious disease, 101 influenza acute encephalitis cases (tentative statistic that is not officially final) were notified during the2014/15 season, relative to 96 cases in the previous season (see p. 212 of this issue). In addition, during the 2014/15 season, the total
number of deaths exceeded the excess mortality threshold in January 2015, with an estimated excess of 5,000 deaths (see p. 213 ofthis issue).
Isolation/detection of influenza virus: In the 2014/15 season, prefectural and municipal public health institutes (PHIs)
reported a total of 6,170 samples with isolation/detection of influenza viruses (4,456 isolations and 1,714 detections without
isolation) (Table 1 in p. 201 of this issue). Among them, 5,100 were reported from influenza sentinels, and 1,070 from the otherfacilities (Table 2 in p.201 of this issue).
Distribution of influenza viruses isolated/detected in the 2014/15 season was 85% AH3, 14% type B (Yamagata lineage toVictoria lineage ratio 9:1) and 1% AH1pdm09 (Table 2 in p.201 of this issue). AH3 began increasing in week 46 of 2014 and peakedin week 2 of 2015. Influenza B began increasing in week 2 of 2015 and peaked in week 12, surpassing influenza A thereafter (Figs.
1 and 2 in p. 201 of this issue). Among AH3 isolates, 26% were isolated from patients 5-9 years old and 24% from those 10-14 yearsold (Fig. 3 and http://www.nih.go.jp/niid/images/iasr/rapid/inf2/2015_35w/innen5e_150924.gif). Among type B isolates, 32% wereisolated from patients 5-9 years old.
Antigenic characteristics of 2014/15 isolates (see p. 202 of this issue): The National Institute of Infectious Diseases (NIID)
conducts antigenic analysis of isolates submitted from Japan and other Asian countries. All the 99 AH1pdm09 isolates, except two
isolated in Taiwan, were antigenically similar to the 2014/15 vaccine strain A/California/7/2009. Most of the 366 AH3 isolates belonged
to the genetic lineage clade 3C.2a; clades 3C.3a and 3C.3b were few. Antigenicity determined by neutralization test (the isolates’
hemagglutination activity was too low for the HI test) revealed that more than 70% of the AH3 isolates were antigenically different
from the 2014/15 vaccine strain A/New York/39/2012 (clade 3C.3). The 205 B/Yamagata-lineage isolates had antigenicity similar tothat of the 2014/15 vaccine strain B/Massachusetts/02/2012, and all the 39 B/Victoria-lineage isolates were antigenically similar tothat of the 2011/12 vaccine strain B/Brisbane/60/2008.
Antiviral resistance of 2014/15 isolates (see p. 202 of this issue): Except for one AH3 isolate that was resistant to oseltamivir
and peramivir and with low sensitivity to zanamivir, 42 AH1pdm09 and 353 AH3 isolates from Japan were all sensitive to oseltamivir,
zanamivir, peramivir and laninamivir. All Influenza B isolates from Japan and abroad were sensitive to all four antiviral drugs.
Immunological status of the Japanese population: Sero-surveillance for influenza has been conducted under the Preventive
Vaccination Law (revised on April 1, 2013) (see p. 214 of this issue). According to approximately 7,000 serum samples collected
before the 2014/15 season (from July to September in 2014), the age-group specific HI antibody positive prevalence (titer higher
than 1:40) to A/California/7/2009 [A(H1N1)pdm09] was ≥75% among 10-24 year olds and <40% among 0-4 year olds and those older
than 60 years. For A/New York/39/2012 [A(H3N2)], age-group specific HI antibody positive prevalence was ≥80% among 10-14 yearolds, <30% among 0-4 year olds, and 40-60% among those older than 30 years; for B/Brisbane/60/2008 (B/Victoria-lineage), theseroprevalence was 50% for 40-44 year olds and <30% for those aged 0-4, 25-29 and ≥60 years.
Influenza vaccine: Approximately 33,460,000 vials (calculated as 1mL/vial) of trivalent vaccines were produced in the
2014/15 season, of which an estimated 26,490,000 vials were used for vaccination.
The 2015/16 season tetravalent vaccine consists of two strains of type A and one strain each for B/Yamagata and B/Victoria(see p. 217 of this issue). The AH1 strain was A/California/7/2009pdm09 (X-179A), same as for 2010/11-2014/15 seasons. The AH3
and influenza B/Yamagata strains were changed, respectively, to A/Switzerland/9715293/2013 (NIB-88) [previously A/New York/39/2012 (X-233A)] and B/Phuket/3073/2013 [previously B/Massachusetts/2/2012 (BX-51B)]. The newly added B/Victoria lineage
strain was B/Texas/2/2013.
Conclusion: Trends in influenza activity should be monitored continuously by sentinel surveillance, school closure surveillance,
hospitalized influenza surveillance and other systems. Virus isolation should be conducted throughout the year and antigenic andgenetic changes should be monitored to select vaccine candidate strains. Monitoring of antiviral resistance and influenza
seroprevalence in the Japanese population should also be continued. These measures are all important for future risk management
measures. The epidemiology of the 2014/15 influenza season is described in http://www.nih.go.jp/niid/ja/flu-m/flutoppage/2066-ids/
related/5647-fludoko-2914.html, in Japanese, and isolation and detection of influenza viruses in the 2015/16 season in see pp. 223,
224 & 225 of this issue; http://www.nih.go.jp/niid/en/iasr-inf-e.html.
The statistics in this report are based on 1) the data concerning patients and laboratory findings obtained by the National Epidemiological
Surveillance of Infectious Diseases undertaken in compliance with the Law Concerning the Prevention of Infectious Diseases and Medical Care forPatients of Infections, and 2) other data covering various aspects of infectious diseases. The prefectural and municipal health centers and publichealth institutes (PHIs), the Department of Food Safety, the Ministry of Health, Labour and Welfare, and quarantine stations, have provided theabove data.

Infectious Disease Surveillance Center, National Institute of Infectious Diseases
Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, JAPAN Tel (+81-3)5285-1111

病原微生物検出情報 Vol. 36 No.11（2015. 11） 3 （201）（特集つづき）（THE TOPIC OF THIS MONTH-Continued）
表1. インフルエンザウイルス分離・検出報告数, 2011/12〜2014/15シーズン
Table 1. Isolation/detection of influenza viruses during the 2011/12-2014/15
influenza seasons*ᆺ*䝅䞊䝈䞁 䚷Season
2011/122012/132013/142014/15
A H1pdm09
11 (4)109 (54)40 (22)
2,847 ( 649)----A H1
3,667 ( 1,379)
1,204 ( 535)
3,699 ( 1,529)
A H3
3,709 ( 1,434)
A NT14)15)
4)12)- (- (- (- (357 (28)
B/Victoria
1,088 (14)627 ( 116)
55 (8)
B/Yamagata
547 (8)805 (31)
1,656 ( 278)649 ( 104)
B NT
82 ( 304)
49 ( 195)
20 ( 272)
11 (39)- (C
25 (36)2)
21 (9)
2
ྜィ Total
5,462 ( 1,814)
6,375 ( 1,863)
4,456 ( 1,714)
4,987 ( 1,704)
A NT: Aளᆺᮍྠᐃ, B NT: B⣔⤫ᮍྠᐃA NT: A not subtyped, B NT: B lineage not determined*ྛ䝅䞊䝈䞁(ᙜᖺ9᭶䡚⩣ᖺ8᭶)䛻᥇ྲྀ䛥䜜䛯᳨య䛛䜙ྛᆅ᪉⾨⏕◊✲ᡤ䛷ศ㞳䛥䜜䛯䜴䜲䝹䝇ሗ࿌ᩘ, -ሗ࿌䛺䛧, ( )ෆ䛿䜴䜲䝹䝇䛿ศ㞳䛥䜜䛶䛔䛺䛔䛜, 㑇ఏᏊ᳨ฟ䜎䛯䛿ᢠཎ᳨ฟ䛻䜘䜛ሗ࿌ᩘ䜢ูᥖ䠄⑓ཎᚤ⏕≀᳨ฟ᝟ሗ 㻦 2015ᖺ10᭶14᪥⌧ᅾሗ࿌ᩘ䠅*Sampling season during September through August in the following year.
( ): Nos. in parentheses denote gene or antigen detection without isolation, not includedin the total.
[Infectious Agents Surveillance Report: as of October 14, 2015 from prefectural andmunicipal public health institutes (PHIs)]

Type

表2. インフルエンザウイルス分離・検出報告数,
2014/15シーズン
Table 2. Isolation/detection of influenza viruses
during the 2014/15 influenza season
ᆺ TypeTotal (A+B)(A)(B)
A H1pdm09
6249
13
A H1A H3
5,228
4,297931
A NT
1239B/Victoria
6355
8B/Yamagata753653
100
B NT50428C
211ྜィ Total
6,170
5,100
1,070
(A) 䜲䞁䝣䝹䜶䞁䝄ᐃⅬ䠄ᑠඣ⛉+ෆ⛉䠅㻌Reports frominfluenza sentinels (pediatric & internal medicine sites)(B) 䜲䞁䝣䝹䜶䞁䝄ᐃⅬ௨እ䠄ᇶᖿᐃⅬ+䛭䛾௚䠅㻌
Reports from sites other than influenza sentinels
A NT: Aளᆺᮍྠᐃ, B NT: B⣔⤫ᮍྠᐃA NT: A not subtyped, B NT: B lineage not determined2014ᖺ9᭶䡚2015ᖺ8᭶䛻᥇ྲྀ䛥䜜䛯᳨య䜘䜚ྛᆅ᪉⾨⏕◊✲ᡤ䛷ศ㞳䞉᳨ฟ䛥䜜䛯䜴䜲䝹䝇ሗ࿌ᩘ䚸- : ሗ࿌䛺䛧䠄⑓ཎᚤ⏕≀᳨ฟ᝟ሗ䠖2015ᖺ10᭶14᪥⌧ᅾሗ࿌ᩘ䠅
Based on samples collected from September 2014-August2015.
(Infectious Agents Surveillance Report: as of October14, 2015 from PHIs)

図2. 都道府県別インフルエンザウイルス分離報告状況, 2014/15シーズン（病原微生物検出情報 : 2015年10月14日現在報告数）
Figure 2. Isolation of influenza viruses by prefecture during the 2014/15 influenza season(Infectious Agents Surveillance Report: As of October 14, 2015 from PHIs)
Weeks 43-47
Weeks 43-47Weeks 48-52(Oct.20-Nov.23)(v.24)(Nov.24-Dec.28)

AH1pdm09
No. isolation reports

01
2-5
6-10
11-AH3No. isolation reports

01
2-5
6-10
11-B/Victoria
No. isolation reports

01
2-5
6-10
11-B/Yamagata
No. isolation reports

012-5
6-10
11-Weeks 1-5(Dec.29-Feb.1)

Weeks 6-10(Feb.2-Mar.8)

Weeks 11-15(Mar.9-Apr.12)

Weeks 16-20(Apr.13-May 17)