Investigation on Cryptosporidium and Giardia in Guangxi waters
Objective To understand the contamination status of Cryptosporidium and Giardia in source water,factory water and sewage in some cities and towns in Guangxi,and provide a theoretical basis for the medical and health and water conservancy departments to formulate scientific and reasonable prevention and control measures.Methods From December 2015 to March 2023,9 rivers in the Pearl River Basin,Red River Basin,and coastal rivers in southern Guangxi,as well as 18 towns in three counties in the central part of Guangxi were used as sampling points.Use the Filta-Max xpress steps in the Methods for the inspection of standards of potable drinking water(GB/T 5750.12-2023)to collect source water and factory water and perform Cryptosporidium and Giardia detection.At the same time,a basic investigation was conducted on the water plant to test the water quality related indicators of 39 factory water samples,including chromaticity,turbidity,pH value,total colony count,total coliform group,thermotolerant coliform group,chloride,sulfate,total dissolved solids,total hardness,oxygen consumption and ammonia nitrogen.Results A total of 193 water samples were collected,the detection rate of Cryptosporidium was 17.6％,and the detection rate of Giardia was 14.5％.Other water quality test indicators of 39 samples of factory water exceeded the standard,including chromaticity of 5.1％,turbidity of 2.6％,pH value of 5.1％,total colony count of 10.3％,total coliform bacteria and thermotolerant coliforrn bacteria of 15.4％,oxygen consumption of 5.1％,ammonia nitrogen of 10.3％,chloride,sulfate,total dissolved solids,and total hardness were not exceeding the standard.Cryptosporidium was negatively correlated with raw water chloride(r=-0.35,P＜0.05),raw water sulfate(r=-0.34,P＜0.05),raw water total dissolved solids(r=-0.45,P＜0.05),and raw water total hardness(r=-0.38,P＜0.05),and was positively correlated with the total colony count in factory water(r=0.38,P＜0.05)and raw water turbidity(r=0.34,P＜0.05).Giardia was negatively correlated with total dissolved solids in raw water(r=-0.32,P＜0.05),total hardness of raw water(r=-0.39,P＜0.05),total hardness of factory water(r=-0.35,P＜0.05),and pH of factory water(r=-0.35,P＜0.05),and was positively correlated with the total colony count in factory water(r=0.34,P＜0.05).Conclusions Some raw water and factory water in the survey area were contaminated by Cryptosporidium and Giardia;Mountain spring water,reservoir water,river water and groundwater were all at risk of being contaminated.A complete water plant treatment process could effectively remove Cryptosporidium and Giardia.
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