“Keiko Yamaguchi’s troubles began with diarrhea. After a few weeks, her toes went numb. The numbness and weakness crept up her legs, to her hips, and her vision began to fail. That was in early 1967. By the end of 1968, Yamaguchi, just 22 years old, was blind and paralyzed from the waist down.
She was one of more than 11,000 people in Japan, (with reported cases also occurring in Great Britain, Sweden, Mexico, India, Australia, and several other nations) who were struck by a mysterious epidemic between 1955 and 1970. The outbreak was concentrated in Japan where an estimated 900 died of the disease, which doctors eventually named SMON, for subacute myelo-optic neuropathy—“myelo” from the Greek word referring to the spinal cord; “optic” referring to vision; and neuropathy indicating a disease of the nerves.
The illness usually started with bouts of diarrhea and vomiting. Some patients, like Yamaguchi, became paralyzed and blind. (My efforts to track her down have been unsuccessful.) An uncertain number developed “green hairy tongue”: Their tongues sprouted what looked like tiny green hairs. Some of the afflicted developed green urine. Family members, too, came down with the disease, as did doctors and nurses who treated it. Approximately 5 to 10 percent of SMON patients died.
What was causing the outbreak? During the 1960s, Japan—where SMON was concentrated—launched vigorous research efforts to find out. Doctors thought an answer was at hand when a researcher studying SMON patients announced that he’d isolated the echovirus, which is known to cause intestinal problems. But soon other viruses were found in patients, including Coxsackie and a herpes virus. The herpes finding was compelling, since those viruses are known to affect the nervous system. But one by one, each claim was disproved when independent researchers were unable to replicate earlier laboratory findings.
Other possible causes were considered and shot down. No drinking water pathogen was detected. Pesticides? That hypothesis was discarded when a study found that farmers, who would have the greatest exposure, had lower rates of SMON than non-farmers. There was some excitement when researchers found that many victims had taken two types of antibiotics, but it seemed unlikely that two different antibiotics would both suddenly cause the same highly unusual disease. Besides, experts noted, some patients took the antibiotics only after developing symptoms of SMON.
Then, in late 1970, three years after the drug theory was dismissed, a pharmacologist made a forehead-slapping discovery. The two presumably different antibiotics, it turned out, were simply different brand names for clioquinol, a drug used to treat amoebic dysentery. The green hairy tongue and green urine, it turned out, had been caused by the breakdown of clioquinol in the patients’ systems. One month after the discovery, Japan banned clioquinol, and the SMON epidemic—one of the largest drug disasters in history—came to an abrupt end.
It appeared that the epidemic was concentrated in Japan in part because the drug was routinely used not just for dysentery, but to prevent traveler’s diarrhea and various forms of abdominal upset; and in part because Japanese doctors prescribed the drug at far higher doses and for longer periods than was customary in other countries.
The illusion that SMON was an infectious disease was compelling: When patients with abdominal upset or diarrhea were treated with clioquinol and developed SMON, family members, doctors and nurses often took the drug thinking it would protect them—inadvertently creating the very disease they feared. The resulting cluster outbreaks made SMON look like an infectious disease. In short, what people thought was a cure for SMON was in fact its cause.
Few doctors know the story of SMON, and perhaps even fewer use the catchphrase “cure as cause.” Yet the phenomenon is more relevant today than ever. A study published last year suggests that medical interventions, including problems with prescribed drugs and implanted medical devices—from cardiac stents to artificial hips and birth control devices—are now the third leading cause of death in the U.S.”
- Jeanne Lenzer, Undark Magazine, “When a Medical “Cure” Makes Things Much, Much Worse.” Smithsonian.com, January 2, 2018.
