[An epidemiological study of clustering of sarcoidosis cases].

The clustering of sarcoidosis cases has been reported only in two places in the world; Vasterbotten Province, northern Sweden and Furano, central Hokkaido. In Furano basin, 45 sarcoidosis cases were histologically diagnosed during a 21 year period, 1972 through 1992. The incidence has recently re-increased, though it went down after the first notice of the clustering which promoted environmental improvement such as water supply and road pavement. 1) Of the 45 cases, 12 were males and 33 were females, with the preponderance of female cases over 40 years of age numbering 33. 2) Familial sarcoidosis was found in 4 families. 3) Furano cases tended to have persistent involvements of sarcoidosis with unfavourable prognosis. 4) Case-control studies did not elucidate any significant factors examined. 5) HLA examinations revealed a high rate in DR-9 and DRw53 and a low rate in DRw52.