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April 29, 1974


Author Affiliations

Okayama University Medical School, Okayama, Japan

JAMA. 1974;228(5):566-567. doi:10.1001/jama.1974.03230300014009

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To the Editor.—  Oakley (225:395, 1973) has referred to Kono's article (Jap J Med Sci Biol 24:195, 1971) containing results obtained by 18 neurologists' investigation of the neurotoxicity of halogenated hydroxyquinoline (iodochlorhydroxyquin). Kono reported that the incidence of subacute myelo-optic neuropathy (SMON) between January 1970 and January 1971 decreased corresponding to the suspension of use of the compound by the Japanese government during the period. However, it should be emphasized that SMON disappeared spontaneously long before 1970 in the majority of areas where epidemic outbreaks of SMON were seen in Japan. Although SMON prevailed in 1964 in Toda City of the Saitama Prefecture, its incidence decreased sharply in the following year. Outbreaks of SMON during 1964 and 1965 at Kushiro District of Hokkaido terminated in 1968. SMON has not recurred since January 1970 in the Yuzawa District of the Akita Prefecture where many residents developed the syndrome in 1967 and