[The 1991 dengue epidemic in Kaohsiung City]

In Kaohsiung City, dengue fever subsided for two years after the 1987-1988 epidemic. The main reason that it recurred was due to late diagnoses of the dengue fever in patients because of mild or atypical clinical presentations. The first patient contracted dengue fever from Thailand in mid-May, 1991. The disease then spread among his co-workers. Dengue fever was not suspected until the 9th patient contracted it in early July 1991. Through chain transmission, the epidemic spread in the community and even to other parts of Taiwan. There were 113 confirmed dengue cases in Kaohsiung City, and a total of 175 cases on the whole island during the 1991 epidemic. The clinical manifestations were mainly fever, body pain, dizziness, general weakness, and a skin rash. No instances of severe bleeding, shock or dengue hemorrhagic fever were found. Seven dengue 1 and three dengue 3 viruses were isolated from the sera of patients. We found that the clinical severity of the 1991 dengue epidemic was milder, and the viral isolation rate was lower, compared with the 1987-1988 epidemic, although these two outbreaks of dengue fever were both mostly due to dengue type 1. Genetic variation in the dengue virus may be the explanation. Clinically, about 35% of the patients were missed or not reported, although they were finally demonstrated to be dengue fever patients during a patient survey in the epidemic area. For early detection, viral surveys should be performed in new epidemic regions in addition to fixed-spot surveillance.(ABSTRACT TRUNCATED AT 250 WORDS)