国立感染症研究所

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The topic of This Month Vol.39 No.1(No.455)

Invasive meningococcal infection, April 2013-October 2017, Japan

(IASR Vol. 39 p1-2: January, 2018)

Neisseria meningitidis is a gram-negative diplococcus.  It can be isolated from the nasopharynx of healthy persons, albeit infrequently, and is transmitted by droplet aerosol or secretions from colonized persons.  There are four classifications of invasive infection, namely, bacteremia without sepsis, sepsis unassociated with meningitis, meningitis and meningoencephalitis.  Development of sepsis has poor prognosis.  Waterhouse-Friderichsen syndrome is an acute fulminant form, manifesting as adrenal bleeding and/or systemic shock.  Noninvasive presentation includes various manifestations, such as pneumonia and urethritis.  Incubation period ranges from 2-10 days (average of 4 days) and the disease onset is sudden.

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The topic of This Month Vol.38 No.12(No.454)

Tuberculosis in Japan, 2016

(IASR Vol. 38 p231-232: December, 2017)

Tuberculosis (TB) is a category II infectious disease, which is to be notified immediately to a local public health center (PHC) by a physician who has made the diagnosis (see http://www.nih.go.jp/niid/images/iasr/38/454/de4541.pdf for notification criteria).  Mandatory notification of TB was introduced in 1951 under the revised Tuberculosis Prevention Law, which was integrated into the Infectious Diseases Control Law in 2007.  Based on notifications from physicians, PHCs located in prefectures, designated cities and special districts in Japan are responsible for registering the data of notified TB patients into the Japan TB Surveillance system (JTBS).  Here, we present an overview of the current epidemiological situation of TB in Japan based on data of case patients notified and registered to the JTBS between 1 January and 31 December 2016.

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The topic of This Month Vol.38 No.11(No.453)

Influenza 2016/17 season, Japan

(IASR Vol. 38 p209-211: November, 2017)

The 2016/17 influenza season (from week 36 in September 2016 to week 35 in August 2017) was characterized by the predominance of the A/H3 subtype, with a smaller contribution by both the Yamagata and Victoria lineages of influenza type B.

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The topic of This Month Vol.38 No.10(No.452)

Hand, foot, and mouth disease and herpangina, 2007 to September 2017 (week 38), Japan

(IASR Vol. 38 p191-193: October, 2017)

Hand, foot, and mouth disease (HFMD) and herpangina are pediatric enteroviral diseases that often occur in the summer.  Both are category V infectious diseases under the Infectious Diseases Control Law, notifiable based on clinical diagnosis from ~3,000 pediatric sentinel sites.  Reporting requires the following clinical manifestations: “2-5mm-sized blisters appearing on the palm, plantar, dorsum of foot or oral mucosa” that “heal without crust formation” for HFMD, and “sudden onset of high fever” and “vesicular rash, ulcers or reddening of the uvula” for herpangina.  Causative agents are mostly viruses belonging to Enterovirus A.

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The topic of This Month Vol.38 No.9(No.451)

HIV/AIDS in Japan, 2016

(IASR Vol. 38 p177-178: September, 2017)

HIV/AIDS surveillance in Japan started in 1984.  It was conducted under the AIDS Prevention Law from 1989 to March 1999 and since April 1999, has been operating under the Infectious Diseases Control Law.  Physicians are required to notify all the diagnosed cases (see http://www.niid.go.jp/niid/images/iasr/34/403/de4031.pdf for the reporting criteria).  The data in this article were derived from the annual report of the National AIDS Surveillance Committee for the year 2016 (reported by the Tuberculosis and Infectious Diseases Control Division, the Ministry of Health, Labour and Welfare (MHLW), http://api-net.jfap.or.jp/status/2016/16nenpo/16nenpo_menu.html).  HIV/AIDS cases are classified into two categories: as an “HIV case” if HIV infection was detected before clinical manifestation of AIDS, and as an “AIDS case” if the infection was detected after manifestation of AIDS symptoms*.

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The topic of This Month Vol.38 No.8(No.450)

Japanese encephalitis, Japan, 2007-2016

(IASR Vol. 38 p151-152: August, 2017)

Japanese encephalitis (JE) is caused by JE virus (JEV) transmitted by Culex tritaeniorhynchus.  Most infections are asymptomatic, but when symptomatic, after 1-2 weeks of incubation, case fatality can be 20-40% and half of the survivors will have sequelae.  JE is a category IV notifiable infectious disease under the Infectious Diseases Control Law and all diagnosed cases shall be notified immediately (see http://www.nih.go.jp/niid/images/iasr/38/450/de4501.pdf for notification criteria).  Prefectural public health institutes (PHIs) measure JEV antibody levels among humans and JEV infection levels among farmed pigs on a periodic basis, annually or once every few years, under the National Epidemiological Surveillance of Vaccine-Preventable Diseases (NESVPD) system.  The collected data are collated and summarized at the National Institute of Infectious Diseases.  This article describes the trends in JE from 2007-2016 (see IASR 30: 147-148, 2009 for data prior to 2008).

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The topic of This Month Vol.38 No.7(No.449)

Adenovirus infections, 2008 to June 2017, Japan

(IASR Vol. 38 p133-135: July, 2017)

Adenovirus (human mastadenovirus: Ad), is a physicochemically stable non-enveloped double-stranded DNA virus.  Over 80 types have been described, and are currently grouped into 7 species from A to G.  Ads have been reported as serotypes up to Ad51 (denoted as, for example, Ad1), but Ads discovered later (i.e. Ad52 or greater) have been reported based on the whole genome sequencing (see p. 136 of this issue).

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The topic of This Month Vol.38 No.2(No.444)

Pertussis in Japan, as of January 2017

(IASR Vol. 38 p23.-24: February, 2017)

Pertussis is defined as “acute respiratory tract infection caused by Bordetella pertussis” in the Infectious Diseases Control Law (see http://www.niid.go.jp/niid/images/iasr/38/444/de4441.pdf for the notification criteria).  The main symptom is a prolonged cough.  As severity may be greater among neonates and infants, vaccination is important.

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The topic of This Month Vol.38 No.1(No.443)

Norovirus trends in Japan, 2015/16 season

(IASR Vol.38: 1-3, January, 2017)

Norovirus (NoV) is a single stranded RNA virus.  It is classified into genogroups GI-GVII, and human infection is primarily associated with GI and GII.  Since the 2015/16 season, a new coding system based on the nucleotide sequence of the VP1 region has been used replacing the previous one, which was based on the nucleotide sequence of the capsid N/S region (see the comparison table; http://www.niid.go.jp/niid/images/iasr/rapid/graph/Vol.36/graph/pt4274a.gif).

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The Topic of This Month Vol.37 No.3(No.433)

Severe fever with thrombocytopenia syndrome (SFTS) in Japan, as of February 2016

(IASR 37: 39-40, March 2016)

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne systemic infection caused by SFTS virus (SFTSV), which belongs to Genus Phlebovirus, Family Bunyaviridae.  SFTS was first reported from China in 2011 as a novel bunyavirus infection. Since then, SFTS has also been reported from Japan and South Korea.  Incubation period is 5-14 days.  The signs/symptoms in the early phase of the disease are fever, gastrointestinal symptoms (anorexia, nausea, vomiting, etc.), headache and myalgia, followed by neurological symptoms (impaired consciousness) and bleeding (gingival oozing, bloody diarrhea, hematuria) in the later phase of the disease.  Other somatic signs such as lymph nodes enlargement and epigastric tenderness are commonly observed.  Laboratory findings include lymphopenia and thrombocytopenia in total blood cell counts (TBC), and increased level of AST, ALT and LDH in the serum chemistry.  Among survivors, TBC begins to improve 1 week after onset, and becomes normal within approximately 2 weeks after onset.  In severe cases, however, no recovery signs are observed in the later stage of the disease and signs/symptoms such as impaired consciousness and bleeding tendency appear.  The pathophysiology of fatal SFTS patients are a combination of the disseminated intravascular coagulation and multiple organ failure.  So far, the case fatality rate of notified SFTS patients in Japan has been approximately 30% at the time of notification.

Life cycle in nature and transmission route of SFTSV to humans:  In nature, SFTSV is maintained in ticks and mammals through the tick-tick cycle (vertical transmission from adult ticks to their offspring through transovarial transmission) and tick-mammal cycle (transmission from infected ticks to mammals and then from mammals to ticks).  SFTSV genome has been detected in several tick species in Japan, i.e., Takasago testudinarium (Amblyomma testudinarium), Haemaphysalis longicornis, Haemaphysalis flava, Haemaphysalis megaspinosa, and Haemaphysalis kitaokai.  High prevalence of SFTSV seropositivity has also been demon-strated among deer, wild boars, dogs, and raccoon dogs (see pp. 50 & 51 of this issue), and indicates that the tick-mammal infection cycle is already established in Japan.  While the main infection route of SFTSV to humans is via SFTSV-carrying tick-bite, transmission through direct contact with blood and/or body fluid of the SFTS patient to the patient’s family members or medical providers has been reported in China and South Korea (see p. 48 of this issue).

Molecular epidemiology: SFTSV isolates in Japan, China, and South Korea are classified into two major clades, i.e., a Chinese clade consisting of 5 genotypes, C1 to C5, and a Japanese clade consisting of 3 genotypes, J1 to J3. In Japan, majority of the Japanese SFTSV isolates detected belonged to genotype J1.  However, genotypes C3 to C5 have been detected from some Japanese SFTSV isolates on rare occasions, and conversely, genotype J3 has been detected from some Chinese and South Korean SFTSV isolates (see p. 44 of this issue).

SFTS patients in Japan: Since March 4, 2013, SFTS has been designated as a category IV infectious disease under the Infectious Diseases Control Law in Japan (see http://www.niid.go.jp/niid/images/iasr/35/408/de4081.pdf for notification criteria). Therefore, a physician, who diagnoses a patient as having SFTS, must notify the case within 24 hours to a local health center. SFTSV must be handled as a class III pathogen under the Infectious Diseases Control Law.

A total of 170 SFTS patients have been notified in Japan as of February 24, 2016 (Table).  Among them, 162 had onset in 2013 or afterwards (Fig. 1), while 8 had onset before 2013 (2, 1, and 5 cases in 2005, 2010, and 2012, respectively).  Majority of patients were reported during May to August (Fig. 1) and were from 20 prefectures located mostly in western Japan (Fig. 2).  Among 162 patients reported since 2013, 77 (45%) were male and 93 (55%) were female.  The majority were older than 60 years of age (range 5-95 years; median 74 years) (Fig. 3).  A pediatric case was reported in 2015 for the first time in Japan (see p. 42 of this issue).  Forty-six patients (27%) were fatal at the time of notification (Fig. 3).  Majority of patients had fever (168 cases, 99%) and gastrointestinal symptoms including abdominal pain, diarrhea, vomiting, and anorexia (150 cases, 88%). Thrombocytopenia and leukopenia were found in 162 (95%) and 150 (88%) patients, respectively (see p. 41 of this issue).

SFTS in other countries (China and South Korea) (see p. 47 of this issue): In China, approximately 3,500 SFTS patients have been reported through 2014, with the case fatality rate ranging from 7.8-12.2%.  In South Korea, since a fatal SFTS patient was confirmed in August 2012, 36 cases (17 fatal) and 55 cases (15 fatal) have been reported in 2013 and 2014, respectively.  The estimated case fatality rate in South Korea ranged from 27-47%.

Laboratory diagnosis in Japan: Virological tests for SFTS include detection/isolation of SFTSV from patients’ blood or other body fluids (throat swab, urine, etc.), and/or demonstration of a significant rise in IgG antibody titer against SFTSV in paired sera.  Prefectural and municipal public health institutes (PHIs) conduct the conventional one-step RT-PCR (see p. 43 of this issue), while the National Institute of Infectious Diseases (NIID) conducts the quantitative one-step RT-PCR upon request (see p. 45 of this issue).  Physicians who are concerned regarding laboratory tests should consult their local health center.

Challenges for the future: The first SFTS patient in Japan was reported in January 2013, and SFTS infections are expected to continue to occur.  Studies such as those conducted by NIID and PHIs and the Ministry of Health, Labour and Welfare-funded program, “Comprehensive studies for the control of SFTS”, have increased our knowledge and understanding of the SFTS patients’ geographical distribution, clinical picture, and pathology, and also regarding the lifecycle of SFTSV in nature, transmission route(s), and risk factors of SFTSV infection.

The most important preventive measure against SFTS is avoidance of tick-bite.  During spring to autumn when ticks are most active, exposed areas of the skin should be minimized when entering areas inhabited by ticks.  Repellents containing DEET are effective to some extent.  Other information regarding tick-bite prevention is available at http://www.niid.go.jp/niid/ja/sfts/2287-ent/3964-madanitaisaku.html

No vaccines or specific therapeutics against SFTS are currently available.  While there has been progress in developing therapeutics against SFTSV (see p. 49 of this issue), as the prognosis of SFTSV infection is quite poor, further research is imperative.

 

 

Copyright 1998 National Institute of Infectious Diseases, Japan

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