OCCURRENCE OF GIARDIA CYSTS AND CRYPTOSPORIDIUM OOCYSTS IN RAW AND TREATED WATER FROM 2 WATER-TREATMENT PLANTS IN SELANGOR, MALAYSIA

The occurrence of Giardia cysts and Cryptosporidium oocysts was determ ined both in the raw water and the treated waters from two water treat ment plants in Selangor, Malaysia between July 1994 and January 1995. At each treatment plant, raw and treated water samples were collected fortnightly on 10 separate occasions. Physical parameters, including d issolved oxygen, pH, temperature, conductivity, turbidity and free and total chlorine were measured, and samples were also taken for faecal coliform analyses. The isolation and enumeration of cysts and oocysts was according to UK standard methods. Whilst Giardia cysts were detect ed in 90% of the raw water samples (range 0-60 cysts per litre) no Cry ptosporidium oocysts were detected. Higher concentrations of cysts wer e detected in the raw water of the first treatment plant. All raw wate r samples were faecally contaminated, as faecal coliform counts ranged from 4.6 x 10(4) to 1.3 x 10(5) colony forming units per 100 mi. No c orrelation between the concentration of Giardia cysts and the concentr ation of faecal coliforms could be demonstrated statistically, nor was there any correlation between the concentration of Giardia cysts and the physical parameters tested for any of the raw waters. No cysts, oo cysts or faecal coliforms were detected in samples of treated water. ( C) 1997 Elsevier Science Ltd.