川崎病の原因は風で運ばれる細菌

［40数年前に我家でも経験した「川崎病」の原因に繋がる研究の紹介，中国東北部，ジェット気流，カンジタ菌］

乳幼児に血管の炎症を引き起こす「川崎病」が日本で起こるのは，中国北東部から風に乗って運ばれてくる物質が関与している可能性があるとの研究がカリフォルニア大学医学部やスペインの研究機関，自治医大などの日米欧国際チームによって，5月19日付のアメリカ科学アカデミー紀要」電子版に発表された．

川崎病は，主に４歳以下の乳幼児がかかる病気で，小児科医の川崎富作氏が，1967年世界で初めて報告した．主な症状は５日以上続く熱や両目の充血，発疹などで，国内では年間約１万人が発症し，近年増加傾向を示している．2012年には1万3917人と，この30年で最も多くなっている．発見されて40年近くなるが，また原因は分かっていない．

研究チームは，川崎病の発症日と気流の関係を調査した．日本で川崎病が大流行したのは１９７９，８２，８６年であり，発症者が多かった日の気流を解析したところ，中国北東部の穀倉地帯付近から流れてきたと推測され，８７～２０１０年でも同様の結果であった．

川崎病は原因不明の病気とされているが，特定の時期に患者数が増えることは知られていた．今回の研究では，季節によって異なる患者の発生数に着目し，発症の多い3月に日本上空２千～３千メートルの大気を集めて微生物を調べたところ，「カンジダ」と呼ばれる真菌（追記）が54％を占めていた．これまでの研究では，カンジダから抽出した物質をマウスに投与すると，川崎病と同様の症状を発症することが分かっている．気流と川崎病の関連を証明するにはさらなる検証が必要と思われるが，新しいパラダイムの提案であることは否定できない．

この記事を読んでまったく別のことが心配になった．

もし福島原発並みの事故が，大陸の日本海沿岸で起こったら，日本を逃げ出すしかないということである．

追記 細菌と記述していたら，友人の緒方靖哉先生から「Candida菌は細菌でなく、真菌（酵母類）」との指摘があった．

原報

Tropospheric winds from northeastern China carry the etiologic agent of Kawasaki disease from its source to Japan

Xavier Rodóa,b,1,Roger Curcollb,Marguerite Robinsonb,Joan Ballesterb,c,Jane C. Burnsd,Daniel R. Cayane,f,W. Ian Lipking,Brent L. Williamsg,

Mara Couto-Rodriguezg,Yosikazu Nakamurah,Ritei Ueharah,Hiroshi Tanimotoi, and Josep-Anton Morguíb

Author Affiliations

a Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Catalonia, Spain;

b Unitat de Dinàmica i Impacte Climàtic (UDIC), Institut Català de Ciències del Clima, 08005 Barcelona, Catalonia, Spain;

c Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125;

d Department of Pediatrics, Rady Children’s Hospital-San Diego and University of California, San Diego, La Jolla, CA 92093;

e Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92037;

f US Geological Survey, La Jolla, CA 92037;

g Center for Infection and Immunity, Mailman School of Public Health of Columbia University, New York, NY 10032;

h Department of Public Health, Jichi Medical Hospital, Togichi 108-8639, Japan; and

i Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba 305-8506, Japan

1. Edited* by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved April 4, 2014 (received for review January 9, 2014)

Abstract Full Text Authors & Info Figures SI Metrics Related Content PDF PDF + SI

Significance

Kawasaki disease (KD), the leading cause of acquired heart disease in children worldwide, has remained a mystery for more than 40 y. No etiological agent has yet been identified. By using simulations with the flexible particle dispersion model from different Japanese cities from each single high (low) KD incidence day, the source region KD is retrieved in cereal croplands in northeastern China. We infer the incubation time for KD ranges from 6 h to 2 d, thus favoring an antigenic or toxic exposure as the trigger. Candida sp. is reported as the dominant fungal species collected aloft (54% of all fungal DNA clones) demonstrating the potential for human disease in aerosols transported by wind currents traveling long distances.

Abstract

Evidence indicates that the densely cultivated region of northeastern China acts as a source for the wind-borne agent of Kawasaki disease (KD). KD is an acute, coronary artery vasculitis of young children, and still a medical mystery after more than 40 y. We used residence times from simulations with the flexible particle dispersion model to pinpoint the source region for KD. Simulations were generated from locations spanning Japan from days with either high or low KD incidence. The postepidemic interval (1987–2010) and the extreme epidemics (1979, 1982, and 1986) pointed to the same source region. Results suggest a very short incubation period (<24 h) from exposure, thus making an infectious agent unlikely. Sampling campaigns over Japan during the KD season detected major differences in the microbiota of the tropospheric aerosols compared with ground aerosols, with the unexpected finding of the Candida species as the dominant fungus from aloft samples (54% of all fungal strains). These results, consistent with the Candida animal model for KD, provide support for the concept and feasibility of a windborne pathogen. A fungal toxin could be pursued as a possible etiologic agent of KD, consistent with an agricultural source, a short incubation time and synchronized outbreaks. Our study suggests that the causative agent of KD is a preformed toxin or environmental agent rather than an organism requiring replication. We propose a new paradigm whereby an idiosyncratic immune response, influenced by host genetics triggered by an environmental exposure carried on winds, results in the clinical syndrome known as acute KD.

northeastern China source | agriculture | heart disease | FLEXPART | cereal croplands

Footnotes

• 1To whom correspondence should be addressed. E-mail: xavier.rodo@ic3.cat.

• Author contributions: X.R., J.C.B., D.R.C., W.I.L., Y.N., H.T., and J.-A.M. designed research; X.R., R.C., M.R., J.B., W.I.L., B.L.W., M.C.-R., Y.N., R.U., H.T., and J.-A.M. performed research; X.R., R.C., B.L.W., M.C.-R., R.U., H.T., and J.-A.M. contributed new reagents/analytic tools; X.R., M.R., J.B., W.I.L., B.L.W., Y.N., and R.U. analyzed data; and X.R., J.C.B., D.R.C., W.I.L., B.L.W., and J.-A.M. wrote the paper.

• The authors declare no conflict of interest.

• *This Direct Submission article had a prearranged editor.

• This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1400380111/-/DCSupplemental.

資料

論文URL http://www.pnas.org/content/111/22/7952

図は論文から引用しました．

(2014.7.8)