Outbreak of cryptosporidiosis after contamination of the public water supply in Saitama Prefecture, Japan, in 1996.

An outbreak of cryptosporidiosis occurred in Ogose Town, Saitama Prefecture. Japan, in June 1996. Of 12,345 respondents to a questionnaire sent to households in the town (population; 13,809), 8,812 (71.4%) reported an acute gastrointestinal illness some time between May and July. In addition, 274 traceable visitors at local inns, golf courses, and the like during this period and 54 employees from out of town were infected. Cases of cryptosporidiosis were estimated to 9,140. Of these, 2,856 subjects were treated at outpatient clinics and 24 subjects were hospitalized (some subjects counted twice). No deaths were attributed to the outbreak. Among the visitors to Ogose who were traced, 7 persons who stayed only one day during the outbreak and drank half a glass to 2 glasses (100 to 360 ml) of tap water had cryptosporidiosis confirmed by laboratory tests. The median incubation period for the 14 persons for whom this calculation was possible was 6.4 days (range, 5 to 8 days). Of 469 pupils reporting details of their fever and diarrhea, abdominal cramps, or these combined signs and symptoms, the median maximum body temperature was 37.8 degrees C (range, 36.7 to 40.3 degrees C). The duration of illness, reported by 608 of the pupils, was 5.2 days (range, 1 to 15 days), and that reported by 187 employees was 4.8 days (range, 1 to 18 days). The longest known time for discharge of oocysts after onset was 44 days. Blood was not found in the 609 stool specimens examined. The outbreak was caused by contamination of the town's potable water by Cryptosporidium parvum oocysts. The town's water treatment plant treated river water by coagulation, sedimentation, sand filtration, and chlorination. Contamination arose because of various natural and artificial factors: one was that the monthly precipitation in May was much lower than average, causing the river water level to drop. Another factor was heavy rainfall one night in May that increased water turbidity. The amounts of the coagulant added seemed to be insufficient. There are two inns, three public lavatories, and two small-scale wastewater treatment plants upstream 400 m and 1,200 m of the intake point of the town's water treatment plant. However, there are no farms with livestock in the area. We suggest that the location of the water treatment facilities was inappropriate, and that oocysts had circulated from the potable water to humans to sewage to the river and back to the potable water.

[Temporal and geographical variation in epidemics determined from the results of an infectious disease surveillance system in Japan description of epidemic patterns by data-based criteria for epidemic periods].

OBJECTIVE: After developing criteria for epidemic periods for 16 infectious diseases, we investigated temporal (annual and monthly) and geographical (regional) variation in epidemics. METHODS: Data from an infectious disease surveillance system for the years 1993 to 1997 were used for the analysis. The weekly number of patients per monitoring station was calculated from the data and used in developing criteria for an epidemic period. Based on these latter, we calculated the average number of epidemics occurring at each public health center in a year, an average length of the epidemic period, and the average number of patients per monitoring station reported during an epidemic period. These figures were used to explore temporal (annual, monthly) and geographical (regional) variation. RESULTS: With most diseases, the average number of epidemics occurring at a public health center was 0.3-0.5 per year and the average length of an epidemic period was 6-12 weeks. The average number of patients per monitoring station reported during an epidemic period differed according to the diseases. These indices showed that there were few annual differences, but great monthly differences, in most diseases. The average number of epidemics occurring in a public health center showed regional differences with some diseases. CONCLUSION: Temporal and geographical variation in epidemics for 16 infectious diseases was established by developing criteria for an epidemic period.

Iodine-induced hypothyroidism as a result of excessive intake of confectionery made with tangle weed, Kombu, used as a low calorie food during a bulimic period in a patient with anorexia nervosa.

A 20-year-old Japanese female anorectic patient developed primary hypothyroidism associated with generalized edema because of excessive daily intake (40 to 50 g) of confectionery made with tangle weed, Kombu, which she substituted to food during bulimic periods; TSH 60.35 mcU/ml, free T3 1.19 pg/ml, and free T4 0.48 ng/dl, and her weight increased by 12 kg to 45 kg over 4 months. After withdrawal of Kombu her thyroid function returned to normal, and her weight decreased by 7 kg to 38 kg along with disappearance of edema. In conclusion, the physician noticed that susceptible anorectic patients may sometime develop hypothyroidism or hyperthyroidism because of excessive iodine intake of sea-weed confectionery as a substitute of high calorie cakes during bulimic period.