Shigellosis Infections in Nantou County: 1995-1999
2001 Vol.17 NO.7
In 1995-1999, there had been in the six counties and cities in central Taiwan 279 cases of Shigellosis: 186 (67%) in Nantou County, and 53 (19%) in Taichung City. Most cases in Nantou County came from Jenai township and the neighboring Puli and Hsinyi townships, 121, 33 and 18 cases respectively. Of the strains isolated, 168 were Shigella flexneri (90% of all; 163 strains were of serotype 2a), 17 were S. sonnei; and one was S. boydii. No S. dysenteriae strains had been isolated. The only S. boydii strain isolated came from an imported case. In Jenai township in 1995, there were only four sporadic cases. In 1966 in mid-August after two typhoons, there was an outbreak with 35 confirmed cases. Some small-scale sporadic and family-clustering outbreaks continued to occur in villages. The number of cases increased to 38 in 1997 and decreased to 26 in 1998. In 1999 before the September 21 earthquake, there were four cases; there were small-scale outbreaks after the quake, and the number of cases increased to 18. In Puli township, the number of cases increased significantly in early 1997, possibly associated with the outbreaks of Jenai township in 1996. Epedemiologically, cases were sporadic and family-clustering in small-scale outbreaks. The directions of transmission were associated with the communication conditions between villages. Person-to-person contacts should be the major mode of transmission of Shigellosis in these areas. The many flies found in villages could have been an important medium in the transmission. The lifestyles of the villagers, the lack of safe and stable water supply, and the large number of carriers could have been the reasons for the continual outbreaks of Shigellosis in these areas. Intensive health education, more healthcare infrastructures, and strengthened reporting of cases by medical care institutions are some effective control measures.