Initially, harmful algal blooms (HABs) or red tides in Malaysia occur only in the western coastal waters of Sabah, which was first reported in 1976. Since then, blooms occur frequently almost every year in the west coast and recently, for the first time at the beginning of the year 2000, PSP was detected from fishes and shellfish sampled from the east coast. The causative organism is the marine dinoflagellate, Pyrodinium bahamense var. compressum. The dinoflagellate produces paralytic shellfish poisoning (PSP) in shellfish, causing illness and deaths to human and economic losses to fisheries industry. Monitoring of PSP is carried out by the Fisheries Department of Sabah and is based on toxin analyses of shellfish samples using the mouse-bioassay technique and cells count of water samples taken from monitoring stations located in the infested areas.

Sequence of red tide and PSP events in Sabah are show in the table below:

Year	Events
1976	Red tide	7 children died, 201 persons hospitalized
1977	Red tide	No PSP cases
1978	Red tide	No PSP cases
1979	Red tide	One person died, 3 persons hospitalized
1980	Red tide	2 persons died, 30 persons hospitalized
1981	Red tide	No PSP cases
1982	Red tide	No PSP cases
1983	Red tide	4 persons died, 9 persons hospitalized
1984	Red tide	No PSP cases
1985	Red tide	8 persons died, 21 persons hospitalized
1986	Red tide	2 persons hospitalized
1987	Red tide	8 persons hospitalized
1988	Red tide	9 persons died, 51 persons hospitalized
1989	Red tide	No PSP cases
1990	Red tide	No PSP cases
1991	Red tide	No PSP cases
1992	Red tide	No PSP cases
1993	Red tide	No PSP cases
1994	Red tide	No PSP cases
1995	Red tide	No PSP cases
1996	Red tide	No PSP cases
1997	Red tide	No PSP cases
1998	Red tide	No PSP cases
1999	Red tide	No PSP cases
2000	Red tide	No PSP cases