The Contamination Of Cryptosporidium And Giardia In Raw And Tap Water In Shanghai, China

In order to investigate the occurrence, source and human-infective potential of Cryptosporidium and Giardia in raw and tap water in Shanghai, China, a total of 80 water samples, including 50 raw water samples and 30 tap water samples, were collected from Shanghai, China. All the water samples were analyzed by the Environmental Protection Agency (EPA) Method 1623. Sixteen and nine out of 50 raw water samples were positive for Cryptosporidium (32%) and Giardia (18%) using method 1623, with the concentration of 1.8 to 22/10L and 2 to 8/10L for Cryptosporidium and Giardia, respectively. In order to find a cost-effective method to replace standard method, the raw water samples were also concentrated using a calcium carbonate flocculation (CCF) method, and lower occurrence of 11 and 5 out of 50 raw water samples were positive for Cryptosporidium (22%) and Giardia (10%) using CCF method., with the concentration of 2 to 16/10L and 1 to 4.5/10L for Cryptosporidium and Giardia, respectively. When CCF combined with PCR method, the occurrence of Cryptosporidium (28%) was similar to that detected by standard method. Highest occurrence of Cryptosporidium was found in winter, followed by autumn and summer while the occurrence of Giardia was higher in winter and summer than in autumn. Genotyping for raw water pretreated with either filtration or CCF identified Cryptosporidium spp. in 17 water samples (34%), with C. andersoni the dominant species (detected in 14 samples) followed by C. suis (detected in 6 samples). Therefore, cattle and pigs are the contamination source in raw water in Shanghai. The other species including C. baileyi, C. hominis and C. melegridis were only detected in one to two samples. Although human-pathogenic species were detected in raw water, they might not pose a significant risk to human health due to the low frequency detected. However, potential hazards to the public health should be paid attention because two out of 30 tap water samples were detected Cryptosporidium-positive by the standard method.