Research - Category III: Water Quality

Development of a Rapid, Sensitive, and Quantitative Method to Detect Infective Hepatitis A Virus in Water
(Funded 2000-2001)

Principal Investigators:
Marylynn V. Yates
Department of Environmental Sciences
UC Riverside
(909) 787-5116
marylynn.yates@ucr.edu

Wilfred Chen
Department of Chemical & Environmental Engr.
UC Riverside
(909) 787-2473
wilfred.chen@ucr.edu

Executive Summary:
Critical state water research problem to be addressed: Microorganisms are responsible for more than 90% of the reported waterborne disease outbreaks in the United States; enteric viruses, such as hepatitis A virus, are identified as causing almost 10% of these. However, in 50% of the outbreaks, no causative agent is identified due to limitations in our ability to isolate and detect viruses in water samples. Historically, consumption of contaminated ground water has been the source of one-half of the reported outbreaks; in recent years, that fraction has risen to more than two-thirds. The most frequently reported source of contamination in these outbreaks is domestic sewage from septic tanks, leaking sewer lines, cesspools, etc.

As a result of the continuing waterborne disease outbreaks, and the growing fraction of them associated with consumption of ground water, the USEPA is finalizing a regulation, the Ground Water Rule, to minimize the risk of acquiring a microbial illness from ground water. This regulation will require all public water systems that use ground water as a source to assess the potential for fecal contamination of the water. One potential source of fecal contamination is the reuse of recycled water. Even tertiary treated wastewater may contain contaminants, including disease-causing microorganisms such as viruses, bacteria and parasites. Information about the numbers and types of some of these microorganisms, especially viruses, present in tertiary treated wastewater is scarce due to the limitations in the methods that are needed to detect these microorganisms in water. Current methods to detect viruses in water samples, for example, require highly specialized analytical facilities and at least two to four weeks to obtain results. In addition, the standard methods only detect one group of viruses, the enteroviruses (which includes polioviruses). From records on waterborne disease outbreaks in the U.S., it is known that the enteroviruses are not the major cause of reported viral waterborne disease; other viruses such as hepatitis A virus and caliciviruses are the public health concern. The lack of information about the presence of hepatitis A virus in water and its log survival times in water caused the USEPA to add it to the list of contaminants to be considered for regulation in drinking water.

When recycled water is used to artificially recharge groundwater, there is the potential for some microorganisms, especially viruses due to their small size, to contaminate the underlying groundwater. Although most of the microorganisms may be removed during recharge, if even a few are transported to the ground water, that is of concern, as the USEPA has determined that one virus in 10,000 liters of drinking water constitutes a public health concern.

In response to the increasing demand for water as California's population increases, the use of recycled water increases, care must be taken to ensure that this practice does not have negative impacts on the environment or on public health. As stated above, the USEPA is in the process of developing the Ground Water Rule, which will require all public water systems to assess the potential for fecal contamination of their source waters. Thus, in areas where recharge of recycled water occurs, the water supplier will have to demonstrate that fecal contamination (e.g., viruses) is not reaching the ground water. If this cannot be demonstrated, the water will have to be treated prior to distribution. At this time, 45% of the community and 80% of the non-community public ground water systems do not disinfect their ground water prior to distribution.

Approach: We proposed to develop a method that will allow the detection and quantitation of as few as one infectious virus particle from thousands of liters of water in 24-48 hours. As hepatitis A virus has the longest reported survival time in ground water, and has been included on the USEPA's list of candidate drinking water contaminants, this virus will be the focus of the study. The research approach will include the: 1) optimization of a molecular method (using monoclonal antibodies) to detect only infective hepatitis A viruses (current molecular methods detect both infective and non-infective viruses); 2) development of extremely sensitive molecular probes that can specifically detect as few as one hepatitis A virus particle; 3) analysis of water that has been spiked with hepatitis A viruses using the newly-developed method, and 4) testing of protocols on spiked environmental water sample concentrates to enable an assessment of the sensitivity of the method to inhibitors present in environmental waters.

Expected Results: The lack of standardized methods that can be routinely performed in a short time period to detect and quantify infective hepatitis A viruses has limited the amount of information available on the occurrence of these viruses in drinking water and other environmental samples. Thus, an assessment of the risk of hepatitis A virus infection as a result of exposure to ground water that is impacted by artificial recharge with recycled water is not possible at this time. The methods developed in this study should improve our ability to provide quick and efficient results for the detection and quantitation of infective hepatitis A virus in samples from environmental waters. In light of the impending Ground-Water Rule, this method will provide a tool that can be used to quickly assess the potential impacts of artificial recharge. The methods can be adapted to facilitate the detection of other microorganisms in water, improving our ability to calculate risks from those organisms as well.