A Ten-year Survey of Giardia Cysts in Drinking Water Supplies of Seoul, the Republic of Korea

To understand the distribution of Giardia cysts in drinking water supplies in Seoul, Korea, we collected water samples quarterly at 6 intakes in the Han River, its largest stream and 6 conventional water treatment plants (WTPs) serving drinking water, from 2000 to 2009. Giardia cysts in each of 10 L water were confirmed in 35.0% of intake water samples and the arithmetic mean was 1.65 cysts/10 L (range 0-35 cysts/10 L). The lowest cyst density was observed at Paldang and Kangbuk intakes, and the pollution level was higher at 4 intakes downstream. It seemed that these 4 intakes were under influence of Wangsuk stream at the end of which cysts were found in all samples with the mean of 140 cysts/10 L. The annual mean number of cysts was 0.21-4.21 cysts/10 L, and the cyst level at the second half of the 10 years was about 1/5 of that at first half on average. The cysts were more frequently found in winter, and their mean density was 3.74 cysts/10 L in winter and 0.80-1.08 cysts/10 L in other seasons. All finished water samples collected at 6 WTPs were negative for Giardia in each of 100 L sample for 10 years and cyst removal by physical process was average 2.9-log. It was concluded that conventional water treatment at 6 WTPs of Seoul appears to remove the cysts effectively under the present level of their source water. Domestic wastewater from the urban region could be an important source of Giardia pollution in the river.

Parásitos en aguas del arroyo Napostá, aguas de recreación y de consumo en la ciudad de Bahia Blanca (Provincia de Buenos Aires, Argentina) / Parasites in water used for consumption and for recreational purposes as well as in the water from arroyo Naposta in city of Bahia Blanca, Province of Buenos Aires, Argentina

The aim of the present study was to detect the presence of sanitarily important parasit es in the water from Arroyo Napostá as well as in the water used for recreational purposes (public swimming-pools) and for consumption in the city of Bahía Blanca, province of Buenos Aires, Argentina. To this end, 24,000 liters of water from different sectors of Arroyo Napostá; 2,000 liters of water from each of the three public swimming-pools of Bahía Blanca; and 8,000 liters of water for consumption were collected using polypropylene spun cartridge filters with a 1 mm porosity (Cuno Micro Wind II). Further processing was conducted following Madore´s technique (1987) modified by Pezzani (2000). Detection of Cryptosporidium sp. Giardia sp. was carried out via direct immunofluorescence. Our study confirmed the presence of the following parasites in the areas of study: Hymenolepis diminuta eggs, Giardia sp cysts, Toxocara sp eggs, Entamoeba sp cysts, Endolimax sp cysts, Nematode larvae, Trichostrongylus sp eggs, Ascaris sp eggs, and Cryptosporidium sp cysts in the water from Arroyo Napostá; Hymenolepis diminuta eggs, Giardia sp cysts, Toxocara sp eggs, Entamoeba sp cysts, Endolimax sp cysts, Nematode larvae, Trichostrongylus sp eggs, Ascaris sp in the water from swimming-pools; and Cryptosporidium sp in the water for consumption. The results from the present study urge sanitary authorities from the city of Bahía Blanca to take measures in order to prevent not only humans but also animals from getting in contact with these waters which are contaminated and dangerous to health.

El objetivo del presente trabajo fue detectar la presencia de parásitos de importancia sanitaria para el hombre, en el arroyo Napostá, en aguas recreacionales (piscinas públicas) y de consumo en Bahía Blanca (Provincia de Buenos Aires) Argentina. Se recolectaron 24.000 litros de agua de diferentes sectores del arroyo Napostá, 2.000 litros de cada una de las tres piscinas públicas y 8.000 litros de agua de consumo, mediante filtros de poro de una micra de diámetro (Cuno Micro Wind). El procesamiento posterior se efectuó siguiendo la técnica de Madore (1) modificada por Pezzani (2). La detección de Cryptosporidium sp. Giardia sp. se realizó mediante inmunofluo-rescencia directa. Las formas parasitarias observadas, fueron: huevos de Hymenolepis diminuta, quistes de Giardia sp, huevos de Toxocara sp, quistes de Entamoeba sp. Quistes de Endolimax sp, larvas de Nematodos, huevos de Trichostrongylus sp, huevos de Ascaris sp y quistes de Cryptosporidium sp. en las aguas del Arroyo Napostá; huevos de Hymenolepis diminuta, quistes de Giardia sp, huevos de Toxocara sp, quistes de Entamoeba sp. quistes de Endolimax sp, larvas de Nematodos, huevos de Trichostrongylus sp, huevos de Ascaris sp. en agua de piscina; y quistes de Cryptosporidium sp. en agua de consumo.En conclusión es necesario que las autoridades sanitarias adopten medidas tendientes a evitar que el hombre y los animales tomen contacto con estas aguas contaminadas y peligrosas para la salud.

A comparison of various methods for the determination of viability of parasitic flagellates.

To find out a simple, rapid, accurate, and reliable viability assay for in vitro anti-protozoa drug testing, a comparison among the various methods for the determination of flagellate viability was made. Micro-colony forming efficiency up to 90% for three different flagellates was obtained by the agar plate method. Macro-colony forming efficiency obtained by the culture tube method was generally lower (20-45%). Viability determined by trypan blue exclusion correlated closely with viability determined by micro-colony count (r = 0.94). The growth of the remaining parasites survived from serum treatment was not inhibited while that from metronidazole pretreatment was inhibited. The standard regrowth assay based on the 48-hr cultivation could be applied only for those survival not inhibited. The inhibitory effect of metronidazole on parasites was further testified by the longer generation time for metronidazole-pretreated flagellates in comparison with that for control (p less than 0.001). If the inhibitory effect of a drug is involved in the mechanisms against parasites, only the trypan blue exclusion and the micro-colony count can give an accurate and reliable viability determination. Moreover, the simple and rapid diagnosis provided by trypan blue exclusion is especially useful for the in vitro anti-protozoa drug susceptibility test.