Abstract
BackgroundAccess to clean and safe drinking water that is free from pathogenic protozoan parasites, especially Cryptosporidium parvum and Giardia lamblia that cause gastrointestinal illness in humans, is still an issue in Southeast Asia (SEA). This study is the first attempt to detect the aforementioned protozoan parasites in water samples from countries in SEA, using real-time polymerase chain reaction (qPCR) assays.MethodsA total of 221 water samples of 10 l each were collected between April and October 2013 from Malaysia (53), Thailand (120), the Philippines (33), and Vietnam (15). A physicochemical analysis was conducted. The water samples were processed in accordance with the US Environmental Protection Agency’s methods 1622/1623.1, microscopically observed and subsequently screened using qPCR assays.ResultsCryptosporidium oocysts were detected in treated water samples from the Philippines (1/10), with a concentration of 0.06 ± 0.19 oocyst/L, and untreated water samples from Thailand (25/93), Malaysia (17/44), and the Philippines (11/23), with concentrations ranging from 0.13 ± 0.18 to 0.57 ± 1.41 oocyst/L. Giardia cysts were found in treated water samples from the Philippines (1/10), with a concentration of 0.02 ± 0.06 cyst/L, and in untreated water samples from Thailand (20/93), Vietnam (5/10), Malaysia (22/44), and the Philippines (16/23), with concentrations ranging from 0.12 ± 0.3 to 8.90 ± 19.65 cyst/L. The pathogens C. parvum and G. lamblia were detected using using qPCR assays by targeting the 138-bp fragment and the small subunit gene, respectively. C. parvum was detected in untreated water samples from the Philippines (1/23) and Malaysia (2/44), whilst, G. lamblia detected was detected in treated water samples from the Philippines (1/10) and in untreated water samples from Thailand (21/93), Malaysia (12/44), and the Philippines (17/23). Nitrate concentration was found to have a high positive correlation with (oo)cyst (0.993).ConclusionThe presence of (oo)cysts in the water samples means that there is potential risk for zoonotic disease transmission in the studied countries. Detection using qPCR is feasible for quantifying both pathogenic C. parvum and G. lamblia in large water samples.
Highlights
Access to clean and safe drinking water that is free from pathogenic protozoan parasites, especially Cryptosporidium parvum and Giardia lamblia that cause gastrointestinal illness in humans, is still an issue in Southeast Asia (SEA)
Cryptosporidiosis and giardiasis can be primarily transmitted via direct contact with contaminated water, [5] via contact with water that has been deficiently treated [6], and via accidental ingestion of water containingcysts [7]; infection with either can lead to potentially fatal diseases in humans
Because the data on water contamination with protozoan parasites is limited, this study aims to examine the current distribution of waterborne protozoan parasites in various types of water samples from four countries in SEA, namely Malaysia, Thailand, the Philippines, and Vietnam
Summary
Access to clean and safe drinking water that is free from pathogenic protozoan parasites, especially Cryptosporidium parvum and Giardia lamblia that cause gastrointestinal illness in humans, is still an issue in Southeast Asia (SEA). Cryptosporidium parvum (C. parvum) and Giardia lamblia (G. lamblia) are protozoan parasites that can cause gastrointestinal illness in humans [1]. Both parasites can be transmitted through water in environments where there are poor sanitation systems, lack of hygiene, an inadequate water management system, and wastewater reuse practices. The existence of protozoans in open water reservoirs and treated water supply is mainly due to the contamination of the environmentally resistant of Cryptosporidium oocyst and Giardia cyst stages. Cryptosporidiosis and giardiasis can be primarily transmitted via direct contact with contaminated water (diving, swimming, bathing, etc.), [5] via contact with water that has been deficiently treated [6], and via accidental ingestion of water containing (oo)cysts [7]; infection with either can lead to potentially fatal diseases in humans
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