Peak occurrences of ciguatera fish poisoning precede cholera outbreaks in Hong Kong.

Occurrences of ciguatera fish poisoning (CFP) and Vibrio cholerae infected patients in Hong Kong were reviewed for the 13-year period 1989-2001. Peak activity of CFP preceded peak activity of cholera in nine of the years except in 4 years (1990, 1991, 1992, 1996) where it was observed that the total number of cholera cases were all less than or equal to five per year (P < 0.05). Average time interval was 2.4 months between peaks of CFP and Vibrio cholerae outbreaks. Findings suggested that the factors that affect cholera and ciguatera occurrences may not be operating in some years but when they are operating, they will affect both cholera and CFP. CFP peaks have consistently occurred before Vibrio cholerae peaks in our locality so much so that the occurrence of the latter can now be almost accurately predicted since 1998. CFP peaks served as an early warning for public measures to be in place before occurrence of cholera outbreaks.