Distribution of waterborne parasites in raw and treated water from the selected water sources in Kuching Division

Waterborne parasites are associated with numerous gastrointestinal disease outbreaks worldwide. Despite being treated at water treatment plants, waterborne parasites are resistant to conventional water treatments and persistent in the treated water for public uses. The safety of water supply in Sarawak towards waterborne parasites, including for the public or small community, has not been determined thus far. This study was conducted to determine the distribution of waterborne parasites in raw and treated water of Batu Kitang, Bau and Siniawan drinking water treatment plants, Tringgus catchment area and a rural village (Bong Village) in Bau. A total of 69 raw and treated water samples were collected from Batu Kitang, Bau and Siniawan Water Treatment Plants, Tringgus catchment area, Bong Village rural settlement. Water samples were also collected at each sampling site and analysed for faecal coliform analysis. Moreover, physicochemical parameters (pH, temperature, turbidity, dissolved oxygen, conductivity and total dissolved solids) were also recorded on-site and 24-hour antecedent rainfall intensity was recorded. The 10-L water samples were processed with aluminium sulphate flocculation and sucrose floatation method. Cryptosporidium and Giardia were detected using Aqua-GloTM G/C Direct, FL kit and diamidino-2-phenylindole dihydrochloride staining, while other parasites were detected using Lugol’s iodine staining. Overall, six species of waterborne parasites were found in the raw water from all water treatment plants which were Cryptosporidium (11.11%; 2/18 samples), Giardia (11.11%; 2/18), hookworm (11.11%; 2/18), Ascaris (11.11%; 2/18), Schistosoma (5.56%; 1/18) and nematode larvae (16.67%; 3/18), whilst three species of parasites were found in the treated water which were Cryptosporidium (16.67%; 3/18), Enterobius (5.56%; 1/18) and nematode larvae (11.11%; 2/18). Whereas, two species of parasites were found in samples from Tringgus catchment which were Cryptosporidium (50%; 6/12) and Giardia (8.33%; 1/12). At Bong Village, three species were detected which were Cryptosporidium (9.52%; 2/21) Giardia (4.76%; 1/21) and Clonorchis (9.52%; 2/21). Based on the correlation analysis, no correlations were found between parasite occurrence with the parameters (i.e. physicochemical parameters, faecal coliform concentration and rainfall intensity), except Cryptosporidium was found positively correlated with dissolved oxygen of the water (Tb = 0.206; P<0.05) and negatively correlated with rainfall intensity (Tb = - 0.185; P<0.01), Giardia was found positively correlated with pH (Tb = -0.166; P<0.01), while nematode larvae was found positively correlated with turbidity (Tb = 0.185; P<0.01) and faecal coliform concentration of the water (Tb = 0.181; P