国立感染症研究所

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The topic of This Month Vol.41 No.5(No. 483)

Enterohemorrhagic Escherichia coli (EHEC) infection as of March 2020 in Japan

(IASR Vol. 41 p65-66: May 2020)

    Enterohemorrhagic Escherichia coli (EHEC) is an important diarrheagenic E. coli that produces Verotoxin/Shiga toxin (VT/Stx) and/or possesses VT-encoding genes. The main signs/symptoms of EHEC infections are abdominal pain, watery diarrhea, and bloody diarrhea. Fever (≥38°C) and/or vomiting are occasionally observed. VT-producing EHEC can cause hemolytic uremic syndrome (HUS), which involves thrombocytopenia, hemolytic anemia, and acute renal failure; complications, such as encephalopathy, may develop, with potentially fatal outcomes.

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The topic of This Month Vol.41 No.6(No. 484)

Dengue fever and dengue hemorrhagic fever, 2015-2019

p>(IASR Vol. 41 p89-90: June 2020)

    Dengue fever (DF) is an infectious disease caused by the dengue virus (DENV). DENV belongs to the genus Flavivirus of the family Flaviviridae and consists of four serotypes, DENV-1, -2, -3, and -4. DENV is one of the mosquito-borne arboviruses, and the main vectors are Aedes aegypti and Ae. albopictus. DENV is mainly maintained in the human-to-mosquito-to-human transmission cycle. Currently, Ae. aegypti is not distributed in Japan, but Ae. albopictus inhabits a wide area excluding Hokkaido (see pp.91 & 92 of this issue). DENV infection in humans causes symptoms, such as fever, exanthema, and joint and muscle pain, after an incubation period of approximately 4 to 14 days (DF). In many cases, patients recover without sequelae. However, some DF patients develop severe symptoms, such as hemorrhage and/or neurological symptoms, including deterioration in consciousness, and may die due to multiple organ failure. Such a disease state is called severe dengue fever (SDF), and includes dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). There is no specific treatment for DF. A dengue vaccine is licensed and available in some countries (see p.99 of this issue). DF is mainly endemic in tropical and subtropical regions (see p.93 of this issue). Most DF patients in Japan were those, including returnees, infected with DENV in the endemic regions. Autochthonous outbreaks of DF were reported in 2019 for the first time in five years since 2014 (see p.94 of this issue).

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The topic of This Month Vol.41 No.4(No. 482)

Measles in Japan, as of February 2020

(IASR Vol. 41 p53-55: April 2020)

    Measles is an acute viral disease caused by the measles virus, characterized by fever, rash, and catarrh. The measles virus is transmitted by aerosol, droplets, or contact infection, and is highly contagious. The incubation period is 10-12 days, and the infectious period of the virus is from 1 day before onset to 3 days after the fever has subsided. There are few subclinical infections. Before the introduction of the measles vaccine (before 1965), most people were infected by the age of 15. However, due to the improvement of vaccination coverage, the number of measles cases has decreased and been ranging from tens to hundreds in recent years. In addition, many patients are over 20 years old.

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The topic of This Month Vol.41 No.3(No. 481)

Clostridioides difficile infection in Japan

(IASR Vol. 41 p35-36: March, 2020)

Clostridioides difficile infection (CDI)

    Clostridioides (Clostridium) difficile is an obligate anaerobic Gram-positive spore-forming bacillus. Toxins produced by the organism include toxin A, toxin B, and binary toxin.

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The topic of This Month Vol.41 No.2(No.480)

Acute Flaccid Paralysis in Japan as of December 2019

(IASR Vol. 41 p17-18: February, 2020)

 Acute flaccid paralysis (AFP) is medically a broad term for disorders presenting with acute flaccid motor paralysis of the extremities (see p. 19 of this issue). AFP develops when the anterior horn cells of the spinal cord, along with the peripheral nerves or muscles, are damaged. Typical diseases causing AFP include Guillain-Barré syndrome (GBS), acute poliomyelitis (polio), and acute flaccid myelitis (AFM).

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The topic of This Month Vol.41 No.1(No.479)

Syphilis, Japan

Syphilis is an infectious disease caused by the Treponema pallidum subspecies pallidum. T. pallidum is a spirochete bacterium sized 0.1-0.2 µm in diameter and 6-20 µm in length. It has active motility and can be observed microscopically by staining or dark field microscopy. The mechanism of pathogenicity is poorly understood because it cannot be cultivated in vitro. Treponema includes species and subspecies that do not cause sexually transmitted infections, but recently, the T. pallidum subspecies endemicum (bejel) was first reported in Japan as a sexually transmitted disease (see p. 4 of this issue).

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The topic of This Month Vol.40 No.12(No.478)

Rotavirus, from September 2004 to August 2019, Japan

Rotavirus is a double-stranded RNA virus of 11 segments categorized into the genus Rotavirus belonging to the family Reoviridae. Rotavirus has no envelope and is classified into nine species (group A to I). The rotaviruses that have been reported to infect humans are mainly groups A and C, and epidemics among humans are mostly caused by group A. Rotavirus is a major cause of acute viral gastroenteritis in infants, and the majority of people are believed to have experienced infection at least once by 5 years of age. The virus is transmitted via the fecal-oral route, and usually with an incubation period of 2-4 days, causes symptoms such as diarrhea, vomiting, and fever. There is no specific therapy, and symptomatic treatments, such as infusion and oral rehydration, are performed. Although patients usually recover within a week, dehydration is often more severe than in other types of viral gastroenteritis. Convulsion associated with gastroenteritis is one of the complications, which is characterized by a cluster of convulsions 1-6 days (average 2.3 days) after acute gastroenteritis onset (see p. 209 of this issue). Less frequent complications include renal or hepatic failure and encephalitis/encephalopathy. Many of the severe cases are reported in children at primary infection during the period from 6 months to 2 years old. Treatment is performed according to the level of complication.

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Clostridium difficile surveillance in England

(IASR Vol. 41 p39-41: March, 2020)

From 2002, the emergence of a previously uncommon but more virulent strain, known as Clostridium difficile North American pulsed field type 1 (NAP1) or ribotype 027, fundamentally changed the epidemiology of C. difficile infection (CDI). These marked changes in epidemiology occurred first in North America and then in Northern Europe.1,2 In 2007-08, more than 55 000 CDI cases were reported in England, of which almost a quarter were in younger people who had previously not been considered to be at high risk for this antibiotic associated infection. Furthermore, the number of death certificates including the term ‘C. difficile’ increased each year in England and Wales, from 2238 in 2004 to 8324 in 2007.3

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The topic of This Month Vol.40 No.11(No.477)

Influenza 2018/19 season, Japan

(IASR Vol. 40 p177-179: November, 2019)

The 2018/19 influenza season (from week 36 in September 2018 to week 35 in August 2019) was characterized by the predominance of the influenza A/H1pdm09 subtype in the beginning, followed by the AH3 subtype and B/Victoria lineage from week 10 in 2019.

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The topic of This Month Vol.40 No.10(No.476)

HIV/AIDS in Japan, 2018

(IASR Vol. 40 p163-164: October, 2019)

HIV/AIDS surveillance in Japan started in September 1984. It was conducted under the AIDS Prevention Law between February 1989 and March 1999, and has been operated under the Infectious Diseases Control Law since April 1999. Under the law, physicians must notify all diagnosed cases (see http://www.niid.go.jp/niid/images/iasr/34/403/de4031.pdf). The data in this article were derived from the annual report of the National AIDS Surveillance Committee for the year 2018 (published by the Tuberculosis and Infectious Diseases Control Division, the Ministry of Health, Labour and Welfare (MHLW), http://api-net.jfap.or.jp/status/index.html).

Copyright 1998 National Institute of Infectious Diseases, Japan

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