This study reports the occurrence of Blastocystis in water from two rivers, Sungai Congkak and Sungai Batu, located in recreational areas in Malaysia. This protozoan was detected in samples from both rivers with an average of 33.3% and 22.1%, respectively. It was detected highest at the downstream (73.8% and 33.8%) followed by midstream (17.5% and 25.0%) and upstream (8.8% and 7.5%) stations, with additionally higher detection during holidays (with average 47.5% and 30.8%) than week days (with average 19.2% and 13.3%), in both rivers, respectively. There was a strong association with the daily activities of locals and visitors, who came for water recreational activities, mainly located between midstream and downstream and was observed to be higher at Sungai Congkak. The detection of Blastocystis in these rivers' water implies that this protozoan could potentially be transmitted to humans by the waterborne route. Pearson correlation analysis showed that their occurrence was significantly correlated with faecal coliforms count; inconsistent correlation with dissolved oxygen, temperature and turbidity and no correlation with pH, conductivity and rainfall for both rivers. The correlation of coliforms and Blastocystis suggests the source of the Blastocystis in the water body is likely to be faecal. 1. Introduction Blastocystis has been associated with human gastrointestinal disease in both immunocompromised and immunocompetent hosts [1, 2]. Clinical features due to infection by this protozoan include acute or chronic diarrhea, sometimes self-limited, and could be accompanied by abdominal pain, tenesmus, pruritus, anorexia, nausea, vomiting, fever, and eosinophilia [3, 4]. The symptom is generally more severe in immunosuppressed patients than in immunocompetent hosts [5, 6]. Blastocystis is globally distributed and infections are common in tropical, subtropical, and developing countries [7]. Other than food, contaminated water was reported to be an important risk factor for Blastocystis transmission via the faecal-oral route [8, 9]. In Malaysia, although Blastocystis infection has attracted the attention of many researchers, studies on its contamination of surface waters are still lacking. To date, there is no published information on its occurrence in recreational water sites even though this has important implications to the public health. Therefore, this study was carried out to determine the occurrence of Blastocystis in two rivers which are widely used for recreational activities amongst people from the capital city of Kuala Lumpur, Malaysia.
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