Neurologic Hazards of Diving

The results of a trachoma survey of 58,480 primary and junior high school students in Naha, Okinawa were compared to findings from two earlier, smaller surveys carried out in five rural villages elsewhere in the Ryukyu Islands. The overall prevalence of trachoma in Naha school children was 4.1% with girls predominating in the pre-school age groups and hoys among older children. Trachoma prevalence in Tonaki, the only village of the five without a piped water supply, was significantly greater than that for Naha or the other villages. A similar picture emerged when Naha was compared to the city of Ishikawa, which, like Tonaki, lacks a piped, treated water supply. It appears that a piped water supply decreases trachoma prevalence. The reasons for this are probably more closely related to the different patterns of water utilization in water-scarce and water-rich areas than to purity of water per se.