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THE SIGNIFICANCE OF ENTERIC VIRUSES AND WATERBORNE ILLNESS
Citation:
Ruecker, N. J., J. Lawrence, H. G. Peterson, G S. Fout, G. Appleyard, AND N. Christofi. THE SIGNIFICANCE OF ENTERIC VIRUSES AND WATERBORNE ILLNESS. Presented at 10th National Conference and 1st Policy Forum on Drinking Water, Halifax, Nova Scotia, April 27-30, 2002.
Impact/Purpose:
Overarching Objectives and Links to Multi-Year Planning
This task directly supports the 2003 Drinking Water Research Program Multi-Year Plan's long term goal 1 for "regulated contaminants" and long term goal 2 for "unregulated contaminants and innovative approaches" under GRPA Goal 2 (Clean and Safe Water). The overarching objective is to provide the Office of Water, Agency risk assessors and managers, academics, the scientific community, state regulators, water industry and industry spokes-groups the methods they need to measure occurrence of waterborne viral pathogens. The methods developed will improve the quality of risk-based assessments and tools used by the Agency to set regulations, policies and priorities for protecting human health and will allow the Agency to assure the public that the appropriate methods are being used to demonstrate that drinking water is safe from pathogenic agents.
Specific Subtask Objectives:
o Evaluate techniques for enhancement of growth of human enteric viruses in support of CCL #2 and #3 and for use in the UCMR (Subtask A; to be completed by 9/05 in support of LTG 2)
o Develop a multiplex RT-PCR method that incorporates internal controls for use in the UCMR (Subtask B; completed 9/03 in support of LTG 2)
o Develop and evaluate new molecular technologies for use in the UCMR. Included will be real-time RT-PCR methods for Norwalk virus and astroviruses, and integrated cell culture/molecular procedures for detection of infectious viruses (Subtask B; to be completed by 9/05 in support of LTG 2)
Description:
With growing concern over drinking water safety, considerable attention has been directed towards microbial pathogens in source waters, and the adequacy of current methods used to detect, monitor and treat for these pathogens. The focus has been on bacterial and protozoan pathogens such as E. coli and Cryptosporidium, when in fact, pathogenic viruses are estimated to account for more than half of all waterborne disease outbreaks. This is significant because, despite recent advances in this field, routine monitoring of human viruses in water supplies is essentially non-existent, for several reasons. Viruses are by far the most difficult group of pathogens to detect and confirm in source water. Use of available methods is limited by prohibititive cost and lack of facilities and trained personnel. Current molecular methods used to detect, identify and confirm viruses from clinical samples cannot be applied directly to most source waters. Due to the low infectious dose of many human enteric viruses, the application of these methods to source waters is limited by the need to concentrate virus from large sample volumes (up to 200L) of water. Organic and inorganic components which tend to inhibit molecular viral detection methodology are typically present in source water and co-concentrate along with virus. The presence of virus should be of particular concern in small communities with poor source waters and rudimentary or inadequate treatment. It is also thought that the risk increases in high density urban areas, since many wastewater treatment processes reduce, but do not completely inactivate viral pathogens. The result is that many illnesses are not traced to a drinking or recreational water source, and thus the true impact of viruses on human health is unknown. A crucial need exists to: i) develop feasible and effective detection and monitoring methods, ii) use these to estimate viral pathogen occurrence and frequency in water supplies in order to better understand outbreaks and iii) develop strategies for the control of these pathogens.