Modifications to United States Environmental Protection Agency Methods 1622 and 1623 for Detection of Cryptosporidium Oocysts and Giardia Cysts in Water

Abstract

Collaborative and in-house laboratory trials were conducted to evaluate Cryptosporidium oocyst and Giardia cyst recoveries from source and finished-water samples by utilizing the Filta-Max system and U.S. Environmental Protection Agency (EPA) methods 1622 and 1623. Collaborative trials with the Filta-Max system were conducted in accordance with manufacturer protocols for sample collection and processing. The mean oocyst recovery from seeded, filtered tap water was 48.4% ؎ 11.8%, while the mean cyst recovery was 57.1% ؎ 10.9%. Recovery percentages from raw source water samples ranged from 19.5 to 54.5% for oocysts and from 46.7 to 70.0% for cysts. When modifications were made in the elution and concentration steps to streamline the Filta-Max procedure, the mean percentages of recovery from filtered tap water were 40.2% ؎ 16.3% for oocysts and 49.4% ؎ 12.3% for cysts by the modified procedures, while matrix spike oocyst recovery percentages ranged from 2.1 to 36.5% and cyst recovery percentages ranged from 22.7 to 68.3%. Blinded matrix spike samples were analyzed quarterly as part of voluntary participation in the U.S. EPA protozoan performance evaluation program. A total of 15 blind samples were analyzed by using the Filta-Max system. The mean oocyst recovery percentages was 50.2% ؎ 13.8%, while the mean cyst recovery percentages was 41.2% ؎ 9.9%. As part of the quality assurance objectives of methods 1622 and 1623, reagent water samples were seeded with a predetermined number of Cryptosporidium oocysts and Giardia cysts. Mean recovery percentages of 45.4% ؎ 11.1% and 61.3% ؎ 3.8% were obtained for Cryptosporidium oocysts and Giardia cysts, respectively. These studies demonstrated that the Filta-Max system meets the acceptance criteria described in U.S. EPA methods 1622 and 1623.

Presence of Cryptosporidium spp. and Giardia duodenalis in Drinking Water Samples in the North of Portugal

“…and cysts of G. duodenalis using Filta-Max system and IMS procedures from water samples were, according to the manufacturer, 50 ± 13% and 41 ± 79%, respectively [23].…”

Cryptosporidium e Giardia: desafios em águas de abastecimento público

“…Até o ano de 1998, o método recomendado pela USEPA, para análise de protozoários em água potável nos Estados Unidos, era o Método Tradicional, ou também denominado Método da Regra de Coleta de Informações (ICR). Sabe-se, porém, que há uma série de problemas com o método ICR devido à baixa eficiência de recuperação, altas taxas de falsa-positividade e falsa-negatividade, assim como baixa precisão e exatidão 18 . No Quadro 2, estão organizados os 15 trabalhos nos quais foram utilizados métodos alternativos para detecção e identificação de Cryptosporidium e Giardia, em água destinada ao abastecimento público.…”

Biological and Genetic Characterization of Cryptosporidium spp. and Giardia duodenalis Isolates from Five Hydrographical Basins in Northern Portugal

“…and cysts of Giardia spp. using the Filta-Max system and IMS procedures from water samples is, according to the manufacturer, 50 ± 13% and 41 ± 79%, respectively [21].…”