Protozoan parasites are very resistant to environmental conditions and to disinfection methods used in conventional water treatment; therefore, these organisms may be present in drinking water and water used for recreational purposes. Cryptosporidium and Giardia are enteric protozoan parasites of particular concern when present in drinking water due to their resistance to commonly used disinfectants, such as chlorine. The presence of even a small number of Cryptosporidium oocysts or Giardia cysts poses a definite risk to human health as the infectious dose is very low.
These parasites have been linked to numerous waterborne disease outbreaks. In 1993, Cryptosporidium was responsible for the largest documented waterborne outbreak in the U.S. when over 400,000 people became ill in Milwaukee, WI due to inadequately treated drinking water. Ingestion of these parasites can cause acute gastrointestinal illness, and Cryptosporidium in particular has shown increased health effects in sensitive populations (e.g., infants, AIDS patients, the elderly), including death.
Parasites have a low infectious dose and presence of low concebntrations (1 parasite/10 liters) may be indicative of contamination. Thus, the method requiers sampling of 10 liters for source water and 100 liters for treated drinking water. Client may either submit bulk water sample or collected filter sample. Bulk water is submitted in 10 liter (2.5 gallon) or larger container. BCS supplies 10 liter sterile cubitainer bladder that is used for the sample collection upon request. Alternatelly, to conserve on shipping costs or for larger volume, water is passed through specially provided filter capsule (Envirochek HV) on site and the the filter is shipped to the lab for analysis. BCS supplies (see below) the sampling kit with all necessary supplies needed to collect the sample from a water source.
BCS Laboratories conducts Cryptosporidium and Giardia as per method EPA1623.1 analysis to ensure compliance with local and federal safe water standards and Long Term Enhanced Surface Water Treatment Rule (LT2). Additionally, we provide Cryptosporidium Infectivity and Viability Testing.
Viability is assessed via cell culture assay and the number of infectious oocysts can be estimated using methods outlined in published literature (Slifko et al., 1999). Concentrated samples from Method 1623.1 are inoculated onto HCT-8 cell monolayers in 8-well chamber glass cell culture slides and are incubated in a 5% CO2 atmosphere at 37° C for 48 hours. Viable Cryptosporidium oocysts are enumerated by the Foci Detection-Most Probable Number Method described by Slifko et al. (1999). Results are reported as viable oocysts per 100 liters.
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