IASR

ISSN 0915-5813

Vol. 41 No. 8 (No. 486) August 2020
Infectious Agents Surveillance Reporthttps://www.niid.go.jp/niid/en/iasr-e.html

Incidence of Japanese spotted fever and distribution of ticks inShizuoka Prefecture............................................................................ 136
Comparison of clinical features of Japanese spotted fever and severe
fever with thrombocytopenia syndrome in Miyazaki Prefecture..... 137
Distribution of ticks transmitting Rickettsia japonica in Japan......... 138
Investigation of spotted fever group rickettsiosis in ticks in Yamagata
Prefecture............................................................................................ 139
Summary of the diagnostic manual for rickettsia infections (June 2019edition)................................................................................................. 141
Genomic characteristics of Rickettsia japonica and Rickettsia
heilongjiangensis................................................................................. 142

National Institute of Infectious Diseases andTuberculosis and Infectious Diseases
Control Division,
Ministry of Health, Labour and WelfareFirst case of COVID-19 in Japan indicating an outbreak ofcommunity- acquired infection in Wuhan, China............................... 143
Usefulness of a health management app in responding to a COVID-19
outbreak on a cruise ship.................................................................... 144
COVID-19 epidemic in Tokyo (January – May 2020)........................... 146
Outbreak of COVID-19 in Ishikawa Prefecture................................... 148
Descriptive epidemiology of the first wave of COVID-19 in Ibaraki
Prefecture............................................................................................ 149
Characteristics of carbapenem-resistant Enterobacteriaceae infection
in small and medium-sized medical institutions.............................. 151<THE TOPIC OF THIS MONTH>
Japanese spotted fever 1999-2019
Japanese spotted fever is a tick-borne rickettsiosis that has been recently increasing; it was first reported in 1984 in Tokushima
prefecture, Japan, based on the difference in the Weil-Felix reaction for scrub typhus (tsutsugamushi disease), which is endemic in
Japan. It is caused by Rickettsia japonica, an obligate intracellular bacterium classified as a member of the spotted fever grouprickettsia, causing fever and rash as major symptoms. Tick-bite sites and eschars are found in many patients. The rash extends fromthe extremities to the trunk, and is also noted on the palms and soles. The bite site is often smaller than that of scrub typhus, which
is clinically similar. The primary risk of infection is outdoor activity and the incubation period from tick bite to disease onset is 2-8days, which is shorter than that of scrub typhus (5-14 days). Japanese spotted fever is a Category IV Infectious Disease that requires
reporting of all cases under the Act on the Prevention of Infectious Diseases and Medical Care for Patients of Infection (Infectious
Diseases Control law; notification criteria are available at https://www.niid.go.jp/niid/images/iasr/38/448/de4482.pdf). Clinicaldifferentiation from scrub typhus is difficult and laboratory diagnosis is required for notification.
National Surveillance: According to a survey by the Working Group for Tsutsugamushi Disease Surveillance, the Associationof Public Health Laboratories for Microbiological Technology, which was the only national surveillance system before enactment of theInfectious Diseases Control Law, about 10 to 20 cases of Japanese spotted fever were confirmed annually from 1984 to 1998 in 10
prefectures west of the Kanto area (Tokushima, Kochi, Hyogo, Shimane, Kagoshima, Miyazaki, Wakayama, Mie, Kanagawa, andChiba), with a cumulative total of 213 cases (see IASR 20: 211-212, 1999).
After Japanese spotted fever was designated as a Category IV Infectious Disease under the Infectious Diseases Control Law in1999, the annual number of cases was 30-60 until 2006, but it increased to 337 in 2017, the highest number reported. Since then, morethan 300 cases have been reported every year (Fig. 1, Table 1 and Table 2 on p.135) (see IASR 27: 27-29, 2006, 31: 120-122, 2010 & 38:109-112, 2017), and as of July 2020, the number of reported cases has been at the same rate as in 2017, when the number of cases was
the highest in the year. After the system for monitoring infectious disease occurrence was changed to the current central databasesystem in 2006, 2,726 cases were reported between 2007 and 2019, and all cases were presumed to have been infected in Japan. Mie
Prefecture had the highest number of reports (annual average 37.2 cases), followed by Hiroshima, Wakayama, Kagoshima, Shimane,and Kumamoto. In recent years, however, new cases suspected to have been infected in Fukushima, Niigata, Tochigi, Ibaraki, Ishikawa,Shiga, Nara, and other prefectures have been reported, and the suspected places of infection are thought to be expanding (Fig. 2 on p.134
and Table 2 on p.135).
Even within the same municipality, number of cases is increasing in some remote areas (see p. 136 of this issue). There are also
reports of multiple cases occurring at around the same time in limited areas (see IASR 38: 171-172, 2017 & 41: 13-14, 2020). In
addition to outdoor activities, neonatal cases caused by ticks, presumably brought indoors by family members, have been reported(IASR 33: 304-305, 2012).
Sex and age distribution: Among the cases notified during 2007-2019, 1,262 (46%) males and 1,464 (54%) females werereported, with the majority of patients being in their 60s or older (median 71 years, 69 years for males and 73 years for females).
Signs and symptoms: According to the written notification forms during 2007-2019 (n=2,726), frequently reported signs/
symptoms were fever (99%), rash (94%), liver dysfunction (73%), eschar (67%), headache (30%), and disseminated intravascular
coagulation syndrome (DIC, 21%). The occurrence of eschar was lower than that in scrub typhus. Complications of acute infectious
3503002502001501005001990
1991
199219931994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
20072008
20092010
2011
2012
2013
20142015
2016
2017
2018
2019

No. of notified cases

Figure 1. Yearly number of notified Japanese spotted fever cases, 1990-2019*, Japan

Year of diagnosis*Based on the Association of Public Health Laboratories for Microbiological Technologyʼs“Working Group for Tsutsugamushi Disease Surveillance in Japan” (prior to April 1, 1999) and“National Epidemiological Surveillance of Infectious Diseases” (from April 1, 1999); as of 10 June 2020

1′（133′）

Table 1. Number of notified Japanese spotted fever cases
and fatal cases, April 1999-December 2019, Japan
Year ofNo. ofYear ofNo. ofdiagnosis notified cases
diagnosis notified cases
392010
132 (3)
1999
2000
38
2011
190 (2)
2001
40 (1)
2012
171
2013
175 (1)
2002
36 (1)
2003
52
2014
241
2015
215 (5)2004
66 (1)
2005
62 (1)
2016
277 (3)2006
49 (1)
2017
337 (6)98
2018
305 (4)2007
2008
135 (1)2019
318 (13)132 (1)
Total
3,108 (44)2009
No. in parenthesis denote the no. of notified fatal cases(National Epidemiological Surveillance of Infectious Diseases: as of 10 June 2020)（Continued on page 134′）

IASR Vol. 41 No. 8（Aug. 2020） 2′（134′）（THE TOPIC OF THIS MONTH-Continued）
Figure 2. Number of notified Japanese spotted fever cases by prefecture, 1999-2019, Japan
1999-2005
No. of notified cases
01-9
10-49
50-99
100-199
200-

1999-2010
No. of notified cases
01-910-49
50-99
100-199200-(n=333)

1999-2015
No. of notified cases
01-910-49
50-99
100-199200-(n=879)

1999-2019
No. of notified cases
01-910-4950-99
100-199200-(n=1,871)(n=3,108)(National Epidemiological Surveillance of Infectious Diseases: as of 10 June 2020)

purpura fulminans (AIPF) were also reported (IASR 31: 135-136, 2010), and fatal cases were observed after DIC and multiple organfailure.
At the time of notification, 31 deaths (case fatality rate 1.1%, 31/2,790) were reported between April 1999 and the end of 2018,
whereas 13 deaths (case fatality rate 4.1%, 13/318) were reported in 2019 alone (Table 1 on p.133).
Blood test findings in the acute phase include increases in liver enzymes and C-reactive protein (CRP), and decreased platelets(white blood cell count within a near-normal range), and information for clinical differentiation from severe febrile thrombocytopenia
syndrome (SFTS), which has a similar epidemiological background, such as tick bites and geographic distribution, but with a different
treatment regimen, is accumulating (p.137 of this issue).
Vectors: The number of reports of Japanese spotted fever cases by month increases from May to October, peaking from Augustto October, which coincides with the tick activity period. The causative R. japonica has been isolated or detected in eight tick species
from three genera (unconfirmed in nine species from four genera, including Amblyomma testudinarium), but it is thought to be mainly
caused by Haemaphisalis spp. ticks such as H. hystricis (p.138 of this issue). However, although some of these tick species arewidespread throughout Japan, previously unidentified ticks from warmer regions have been found in the northeastern part of thecountry (p.139 of this issue), suggesting that the more widespread tick distribution is responsible for the expanded area of occurrenceof Japanese spotted fever cases.
Laboratory diagnosis: A specific laboratory diagnosis of Japanese spotted fever is made by antibody detection using theindirect ﬂuorescent antibody method or indirect immune-peroxidase method, and gene detection methods such as PCR. However, it
is not covered by health insurance and the number of facilities where testing is possible is limited. If a patient is clinically suspectedof Japanese spotted fever, testing is available at the National Institute of Infectious Diseases or Public Health Institutes through local
health centers. As specific laboratory diagnoses are difficult except for municipalities where many patients have been reported, theManual for Diagnosis of Rickettsial Infections was revised in 2019 (p.141 of this issue) to facilitate implementation at more institutions.
Treatment: Tetracyclines are most effective for rickettsioses, including Japanese spotted fever. Therefore, if rickettsiosis issuspected, immediate administration of antibiotics is recommended without waiting for the laboratory diagnosis. This is theinternational consensus for rickettsiosis, which can be fatal if untreated.
Diversity of spotted fever group Rickettsiosis in Japan and imported cases: Spotted fever group rickettsiosis suspected
to be infected in Japan is not limited to Japanese spotted fever, and is also caused by R. heilongjiangensis, R. tamurae, and R. helvetica.
A case reported as Japanese spotted fever in Miyagi Prefecture was later found to be Far-Eastern spotted fever caused by R.
heilongjiangensis, which was found to be similar to R. japonica by subsequent detailed inspection (IASR 31: 136-137, 2010); and, onecase in Aomori Prefecture was also likely to be Far-Eastern spotted fever (Table 2 on p.135). Many cases of spotted fever grouprickettsiosis have also been reported as imported (IASR 20: 218-219, 1999, 27: 41-42, 2006, 31: 120-122, 2010, 31: 137-138, 2010 & 38:
123-124, 2017). Each species of spotted fever group rickettsia is genetically similar, and differences among strains of the same species,
by year of isolation or by region, are very small (p.142 of this issue). The intensity of antigen cross-reactivity, inﬂuenced by genetic
similarity, makes serological differentiation of spotted fever group rickettsiosis difficult, and the definition of the notification may need
to be reconsidered, as in the United States.
Additional remarks: The number of cases of Japanese spotted fever is increasing and the geographical area is expanding.
Although effective antibiotics are available, fatal cases are still being reported. In addition to Japanese spotted fever and otherrickettsioses, various tick-borne infectious diseases have emerged, making it increasingly important to differentiate them based onclinical symptoms and geographical areas of occurrence. It is necessary to understand the disease information, patient information,and outbreak situation accurately, and, to enable more effective medical and public health responses, to strengthen and sustain
surveillance systems, laboratory diagnostics systems, and information dissemination activities.
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 Act on the Prevention of Infectious Diseases and Medical Care for Patientswith Infectious Diseases, and 2) other data covering various aspects of infectious diseases. The prefectural and municipal health centers andpublic health institutes (PHIs), the Department of Environmental Health and Food Safety, the Ministry of Health, Labour and Welfare, andquarantine stations, have provided the above 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

Hokkaido
Aomori
Iwate
Miyagi
Akita
Yamagata
Fukushima
IbarakiTochigi
Gunma
Saitama
Chiba
Tokyo
Kanagawa
NiigataToyamaIshikawa
Fukui
Yamanashi
NaganoGifu
Shizuoka
Aichi
MieShiga
Kyoto
Osaka
Hyogo
Nara
Wakayama
Tottori
Shimane
OkayamaHiroshima
Yamaguchi
Tokushima
KagawaEhime
Kochi
Fukuoka
Saga
Nagasaki
Kumamoto
Oita
MiyazakiKagoshima
Okinawa

Total

北海道
青森県
岩手県
宮城県
秋田県
山形県
福島県
茨城県
栃木県
群馬県
埼玉県
千葉県
東京都
神奈川県
新潟県
富山県
石川県
福井県
山梨県
長野県
岐阜県
静岡県
愛知県
三重県
滋賀県
京都府
大阪府
兵庫県
奈良県
和歌山県
鳥取県
島根県
岡山県
広島県
山口県
徳島県
香川県
愛媛県
高知県
福岡県
佐賀県
長崎県
熊本県
大分県
宮崎県
鹿児島県
沖縄県

総39

1292
115
1
17-

1999

38

9164
103
5-

2000

2002

2003

40（1） 36（1） 52

14（1） 332281113242
14714
143286（1） 14-

2001（1） 62（1） 49（1） 98
66

2005
2006
2007
1141126（1） 20
11（1） 141271631112310122
155121048463
113（1） 10
122211151431713
16
11-

2004
6136（1）
51132
173
1062
16595
126(2)
1120
316（1）
1517738611
1
131337（1）
1121
311
3
20（1）
10
113152
1920
4912011438
1241825
1742162291712012135（1） 132（1） 132（3） 190（2） 17117134141621342562188（1）11-

診断年 Year of diagnosis
200820092010
1611134151113426430
21371272514182714-

2014

175（1） 241

4151
1518242271215131220（1）
1014-

2013

1999年以降の（ ）内は死亡例（死亡例は発生動向調査の届出時での情報であることから, 自治体情報とは異なる場合があります）, *2019年は暫定値, †人口は2015年国勢調査を基にした年平均報告数
Nos. in parenthesis denote the no. of reported fatal cases since 1999.（The number of fatal cases are as of the time of NESID notification and therefore may differ from information reported by subnational levels.）*Provisional data from 2019 †Per 1,000,000 person-year（2015 population Census of Japan）

数Prefecture

都道府県

表 2. 年別都道府県別日本紅斑熱患者届出数、1999〜2019年
Table 2. Yearly number of notified Japanese spotted fever cases, by prefecture, 1999-2019

10
12（1）
148（1）
51317
10
15
536
4
6
7
13
13688
19
26（1）
22-

2016
9111
16（1）
42（1）
36（1）
751（1）
6107692
108（1）
14611
3
2014（1）281812017
11113151
38（1）932
216（1）541
34
11
913（1）
410（1）
1971922-

2018
12（1）
1
15
11042（1）2（1）
4819（2）13016（1）367（3）
412
610（2）
106（1）
8156（1）
2818-

2019*

（感染症発生動向調査：2020年 6 月10日現在届出数）（National Epidemiological Surveillance of Infectious Diseases: as of 10 June 2020）

2.14

0.08
0.04
0.10
0.07
0.10
0.05
0.01
1.22
0.03
0.03
0.04
0.17
0.25
0.10
0.65
0.08
26.65
0.14
0.54
0.41
1.61
0.15
31.85
6.81
18.01
1.77
14.14
1.35
10.05
5.12
9.60
12.77
0.71
4.80
8.35
10.64
0.94
9.33
11.65
0.28

人口100万対†Per 1,000,000†

1
122（1）
2
1291
4
312
3
325（2）
6492（8）2（1）1438（2）
117（4）
2327（1）40
194（2）
34407（6）
19
99（1）
50（3）
153（2）
172（2）
37（1）
41（1）
118
193（4）
12128（2）266（1）
4

合計
Total

215
（5） 277（3） 337（6） 305（4） 318（13） 3,108（44）

5
1225
2
19171010345（1）
26（1）
9（2）
144
31311（1）3911-2015

病原微生物検出情報 Vol. 41 No. 8（2020. 8） 3 （135）（特集つづき）（THE TOPIC OF THIS MONTH-Continued）