ISSN 0915-5813

IASR

Vol. 36 No. 3 March 2015
Infectious Agents Surveillance Report
http://www.nih.go.jp/niid/en/iasr-e.html

First confirmed autochthonous case of dengue fever in Japan innearly 70 years, 2014 ........................................................................... 35
Outbreak of dengue fever in Tokyo’s Yoyogi Park and its vicinity,
2014....................................................................................................... 37
Clinical description of autochthonous cases of dengue fever patientsin Japan, 2014 ...................................................................................... 38
Cases of dengue fever exported from Japan, 2014 ................................ 39
Laboratory diagnosis of dengue fever and important considerations ... 40
Timing of specimen sampling for laboratory diagnosis of dengue
fever ...................................................................................................... 41

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

Vector control: routine activities and measures during outbreaks ...... 42
Developing dengue vaccines: current state and challenges .................. 44
Current global trends in dengue fever ................................................... 46
Chikungunya fever cases reported under NESID, 2011-2014 .............. 47
Current global trends in chikungunya fever ......................................... 48
Law Concerning the Prevention of Infectious Diseases andMedical Care for Patients of Infectious Diseases: summary ofamendments, April 2016 ...................................................................... 49<THE TOPIC OF THIS MONTH>
Dengue fever and dengue hemorrhagic fever, 2011-2014
Dengue virus is a member of the flavivirus family with four known serotypes, type 1-4. It is transmitted to humans bymosquitoes Aedes aegypti and Aedes albopictus, via the human to mosquito to human cycle. Ae. aegypti are often found in urban
areas while Ae. albopictus is found in both urban and rural areas, including in much of Japan. Persons bitten by infected mosquitoes
develop clinical signs or symptoms, such as fever, exanthema and pain (mainly arthralgia), 3-7 days later (see pp. 35, 38 & 41 of thisissue, IASR 35: 241-242, 2014). Dengue fever is endemic in many tropical/sub-tropical areas of the world (see p. 46 of this issue).
No commercialized vaccine or specific therapies are available (see p. 44 of this issue), and patients are treated symptomatically withrehydration and/or antipyretic analgesics. Hemorrhage or shock syndrome, though rare, may occur; fatality can be reduced byappropriate treatments.
1. National Epidemiological Surveillance of Infectious Diseases (NESID)
Dengue fever is a Category IV infectious disease under the Infectious Diseases Control Law. Physicians who have made adiagnosis of dengue fever must notify the cases immediately (see http://www.nih.go.jp/niid/images/iasr/36/421/de4211.pdf for
notification criteria).
During 2007-2009, 89-105 dengue cases were reported annually. From 2010 to 2013, during each year, 244, 113, 221, and 249
cases were reported, respectively (Fig. 1 and Table 1). In 2014, a total of 341 cases were notified, which included 179 imported cases
and 162 autochthonous cases; it had been nearly 70 years since the last confirmed autochthonous dengue case was reported inJapan (see pp. 35, 37 & 38 of this issue). In recent years, the majority of dengue virus serotypes detected among imported cases weretype 1 (Table 2). Among autochthonous cases detected in 2014, only serotype 1 was detected (see pp. 35, 37, 38 & 40 of this issue).
Seasonality: Historically, the number of reported dengue cases has been highest during August-September, including in 20112014 (IASR 32: 159-160, 2011) (Fig. 1). The trend is likely attributable to seasonality of travelers going abroad and the dengue
activity level at their destinations (see p. 46 of this issue). Among autochthonous cases in 2014, the majority (133 of 162 cases) were
Figure 1. Monthly number of reported dengue fever and dengue hemorrhagic fevercases, January 2011-December 2014, Japan
180
160

No. of cases

140
120

Autochthonous

100

Imported

80
60
40
20
0
1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 Month

2011

2012

2013
Month of diagnosis

2014

Year

(National Epidemiological Surveillance of Infectious Diseases: as of February 13, 2015)

Table 1. Number of reported dengue cases by year of
diagnosis, 2011-2014
DengueNo. ofhemorrhagic
cases
fever
2011
109
4
113
2012
208
13
221
2013
237
11
249 *
2014
332
9
341
Total
886
37
924
2014 cases (imported vs. autochthonous)
Imported
171
8
179
Autochthonous
161
1
162
*Includes an asymptomatic case(National Epidemiological Surveillance of Infectious
Diseases: as of February 13, 2015)
Year ofdiagnosis

Denguefever

Table 2. Dengue virus serotypes detected among dengue fever and dengue
hemorrhagic fever cases, 2011-2014
Year ofdiagnosis
2011
2012
2013
2014
Total

Dengue virus serotype
No. reported
casesType 1 Type 2 Type 3 Type 4 Unknown
21
15
7
1
70
113 *
48
25
14
4
131
221 *
54
22
24
5
144
249
111
21
14
7
188
341
234
83
59
17
533
924

䚷2014 cases (imported vs. autochthonous)
䚷䚷Imported
34
21
14
7
103
179
䚷䚷Autochthonous
77
85
162
* There was a single case coinfected with serotype 1 and 3 in 2011 and 2012
(National Epidemiological Surveillance of Infectious Diseases: as ofFebruary 13, 2015)

1′（ 33′）（Continued on page 34′）

IASR Vol. 36 No. 3（Mar. 2015） 2′（ 34′）（THE TOPIC OF THIS MONTH-Continued）

No. of cases

No. of cases

Figure 2. Age distribution of dengue fever and dengue hemorrhagic
also diagnosed in September (Fig. 1).
fever cases, 2011-2014, Japan
Suspected place of infection: During 2011-2014, sus80
Imported (2011-2014)
pected place of infection included at least 37 countries/areas70
Male(Table 3 in p. 35). During 2011-2013, 554 of 583 cases (95%)
Female60
had visited Southeast and other Asian countries, such as
50
Indonesia, the Philippines, Thailand, India, Cambodia, and40
Malaysia. There were also cases who had traveled to Central
30
and South America, Oceania or Africa. Similarly, in 2014, 165
of 179 imported cases (92%) were suspected to have been
20
infected in the Asian region. Among 162 autochthonous cases,
10
159 were suspected to be infected in Tokyo (see pp. 35 & 37 of
0
05- 10- 15- 20- 25- 30- 35- 40- 45- 50- 55- 60- 65- 70this issue).
Age group (year)
Gender and age: Among 762 imported cases reported in
30
Autochthonous(2014)
Male
2011-2014, 471 were male (62%) and 291 female (38%). There
20
Femalewere 218 cases in their 20s (29%), 201 cases in their 30s (26%)
10
and 126 cases in their 40s (17%) (Fig. 2). Among 162
0
autochthonous cases in 2014, similarly, 95 (59%) were male.
05- 10- 15- 20- 25- 30- 35- 40- 45- 50- 55- 60- 65- 70While the median age among autochthonous cases was 27 years,
Age group (year)(National Epidemiological Surveillance of Infectious Diseases: as of February 13, 2015)
age distribution varied widely, from 4 to 77 years (Fig. 2).
Dengue hemorrhagic fever: About 5% of all imported
dengue cases in recent years were dengue hemorrhagic fever (DHF) cases [4/133 (4%) in 2011, 13/221 (6%) in 2012, 11/249 (4%) in
2013, and 8/179 (4%) in 2014] (Table 1 in p. 33′). The median age among DHF cases was 32 years (range: 3-64 years). There wasno gender difference in the proportion of dengue cases that were DHF, with 23 DHF among 471 dengue cases (5%) in males and 13
DHF among 291 dengue cases (4%) in females. Among 162 autochthonous cases in 2014, there was only one DHF case (1%). No
fatal cases were reported during 2011-2014.

2. Laboratory diagnosis
Prefectural and municipal public health institutes (PHIs) and the National Institute of Infectious Diseases (NIID) conduct
laboratory diagnosis of dengue fever including virus isolation, viral genome detection by RT-PCR, and serological tests (e.g. IgM
antibody detection and neutralization test) (see p. 40 of this issue). Amendment of the Quarantine Law in November 2003 included
dengue fever in the list of quarantine-authorized infectious diseases; enabling quarantine stations to offer medical examinations
and laboratory testing to travelers coming from dengue fever endemic areas (IASR 35: 112-114, 2014). The detection of the nonstructural protein NS1 antigen was added to the notification criteria of dengue fever in April 2013, and during the domestic dengue
fever epidemic in 2014, the rapid diagnostic kits based on NS1 antigen detection were distributed to the PHIs (see pp. 40 & 41 of
this issue). Since 2013, majority of laboratory diagnoses for dengue were RT-PCR for viral genome detection, IgM antibody detection
and NS1 antigen detection (Table 4).
3. Countermeasures in Japan
As Ae. albopictus, a dengue fever vector, inhabits Japan (see p. 42 of this issue), and as the number of imported cases comingfrom dengue endemic countries continue to increase, there is an ongoing concern for potential dengue outbreaks in Japan. In 2014,
dengue cases infected in Japan were also reported from abroad (see p. 39 of this issue). Prevention and countermeasures against
dengue fever are important not only domestically but also internationally, given the ever increasing globalization of human travel.
For preventing the spread of mosquito-borne infectious diseases, such as dengue fever and chikungunya fever (see pp. 47 & 48 of
this issue), the Ministry of Health, Labour and Welfare is planning to release the guidelines specific for mosquito-borne infectious
diseases in April 2015. The guidelines recommend, as necessary measures, (i) routine, ongoing implementation of control measuresagainst mosquitoes that transmit infectious diseases, (ii) rapid detection of human cases of mosquito-borne infectious diseases, (iii)
implementation of prompt and appropriate measures against mosquitoes in case of outbreaks, and (iv) provision of appropriate
medical care to patients. For combatting dengue fever, not only government and medical personnel but each and every citizen must
actively participate.
Table 4. Method of laboratory diagnosis among dengue fever and dengue hemorrhagic fever cases*, 2011-2014
Year ofdiagnosis
2011
2012
2013
2014
Total

Virus detection
Isolation
PCR
NS1
3
57
15
125
14
129
78
12
188
210
44
499
288

IgM
57
115
106
127
405

Serology
HI test
2
2
1
5

NT
1
2
-1
4

No. reported
cases*
113
221
249
341
924

2014 cases (imported vs. autochthonous)
Imported
10
92
89
64
1
1
179
Autochthonous
2
96
121
63
162
*Includes testing by more than one method
NS1: non-structural protein antigen detection, HI test: hemagglutination inhibition test, NT: neutralization test
(National Epidemiological Surveillance of Infectious Diseases: as of February 13, 2015)

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. 3（2015. 3） 3 （ 35 ）た。8 月22日（第 3 病日）には嘔吐と下痢が出現し, そ＜特集関連情報＞
約70年ぶりに確認された国内感染デング熱の第 1 例の後も39℃を超える高熱が持続した。8 月25日（第 6病日）の頭頚胸腹骨盤部 CT では特記所見なく, 同日に関する報告の血液検査では白血球・血小板の減少を認め, CRPは
デング熱は蚊が媒介するデングウイルスの急性感染

1.59 mg/dl と軽度の増加を示した（次ページ図）。症症で, アジア, 中南米等の熱帯・亜熱帯地域で広く流状や検査値の経過から重症熱性血小板減少症候群

1）

行している 。近年, 日本国内では, 海外の流行地で（SFTS）の可能性も考えたが, 発症前 1 カ月以内には感染した輸入症例が年間 200 例前後報告されてきたが,国内・国外とも旅行歴がなく, マダニの刺伵を思わせ

国内での感染は, 1940 年代前半に東南アジア地域の戦る経過や皮膚病変も確認されなかった。一方, 発症直地から持ち帰られたデングウイルスが西日本で大規模前には都内の代々木公園で頻繁に蚊に刺されていたエな流行を起こして以来, 報告がなかった2）。

ピソードがあり, 海外渡航歴はなかったものの, デング

2014 年 8 月26日, 東京都内で感染したと考えられる
3）

熱の可能性を疑った。当院では以前よりデング熱輸入

デング熱症例が確認され , その後 2 カ月余りで160 名症例を経験していたことからデング熱迅速検査キットに及ぶ国内感染例が報告される端緒となった4）。本稿

DENGUE NS1 Ag STRIP（Bio-Rad 社）とDengue Duo

は, 約 70 年ぶりに確認された国内感染デング熱の第 1

Cassette（Panbio 社）を用意（保険適用外）しており,

例に関する報告である。

8 月25日（第 6 病日）に検査を行ったところ, 前者で症例は都内の学校に通う18 歳女性。既往歴に特記事

NS1抗原（＋）, 後者でIgM（＋）・IgG（−）の結果が得項なし。2014 年 8 月20日（第 1 病日）夕刻に突然の高られた。デング熱の可能性が高まり, 患者・家族に説熱と全身の痛みで体動困難となり, 救急車でさいたま明したところ, 入院前に代々木公園で活動をともにし市立病院の救急外来を受診した。来院時, 意識 JCS
I -1, 体温 39.9℃, 血圧115/68 mmHg, 脈拍数 100/分,ていた級友 2 名が同時期から同様の症状を呈している

呼吸数 18/分。身体所見では顔面紅潮, 両下肢に多数

ま市保健所へデング熱発生届を提出するとともに,ことも明らかとなった。このような経過から, さいたの虫刺され痕, 四肢大関節に強い圧痛を認めた他には

代々木公園を感染地とするデング熱の症例が複数発生

特記事項なし。血液検査では明らかな異常を認めずしている可能性が懸念される旨, 報告を行った。8 月（次ページ図）。入院後, まずは伝染性単核球症, 伝染

26日（第 7 病日）には国立感染症研究所（感染研）で確性紅斑等のウイルス感染症, SLE 等の自己免疫疾患を認検査が行われ, 第 1 , 第 4 , 第 7 病日の血清からリ疑って検査を進めたが, EBV VCA-IgM（−）, CMV-

アルタイム PCR（TaqMan 法）でデングウイルス 1 型

IgM（−）, HIV（−）, ヒ ト パ ル ボ ウ イ ル ス B19-IgM

遺伝子が検出された。また, 臨床経過において, ヘマ（−）, 抗核抗体（−）との結果で診断には至らなかっ

トクリット値の増加が認められないことからデング熱（特集つづき）表3. デング熱・デング出血熱症例の推定感染地, 2011〜2014年
Table 3.䚷Suspected place of infection of imported dengue and dengue hemorrhagic fever cases, 2011-2014
推定感染地
報告数
報告数
推定感染地
No. of cases
No. of cases
Suspected place
Suspected place
中南米・カリブブラジル
国内
5
Autochthonous
162
Brazilジャマイカ
国外（輸入例） Imported
762
Central and3
Jamaica
アジア
インドネシアIndonesia
180
South America/ ハイチ
Haiti
2
パラグアイ
フィリピン
The Philippines
157
Carribean
Asia
Paraguay1
ベリーズ
タイ
Thailand107
Belize
1
インド
ペルー
India
66
Peru
1
マレーシア
メキシコ
Malaysia
43
1
Mexicoカンボジア
Cambodia33
中東・アフリカ
タンザニア
スリランカ
Sri Lanka
19
Tanzania3
ミャンマー
サウジアラビア
Myanmar
14
Middle East/
Saudi Arabia
2
ベトナム
パキスタン
12
AfricaPakistan
Vietnam2
バングラデシュウガンダ
Bangladesh
10
Uganda1
シンガポールケニア
Singapore
9
1
Kenya
ラオス
ジブチ
Laos
7
Djibouti
1
モルディブ
マダガスカル
Maldives
6
Madagascar
1
東ティモール
ルワンダ
East Timor
2
Rwanda
1
中国
China
1
59
その他（2カ国以上訪問）Others (2 or more locations visited)オセアニア フィジー
Fiji
4
Total
924
総 数
グアム
OceaniaGuam
2（感染症発生動向調査：2015年2月13日現在）
オーストラリア
Australia
1(National Epidemiological Surveillance of Infectious Diseases:
タヒチ
Tahiti1
as of February 13, 2015)
ツバル
Tuvalu1
ニューカレドニア New Caledonia
1マーシャル諸島
Marshall Islands1