Virological control of groundwater quality using biomolecular tests

Abstract

Deep groundwater, even if generally protected, could be contaminated by surface or rain water infiltration through soil fractures, septic tanks, cesspits, land irrigation, disposal of wastewater and disposal of muds from depuration systems. The sanitary importance of such possible contamination is related to the different uses of the water and it is at the maximum level when it is intended for human use. Routine microbiological analyses do not consider viruses, only bacterial parameters, as contamination indicators. However, it is known that enteric viruses can survive a long time in deep aquifers and that they may not always be associated with bacterial indicators. The virological analysis of waters intended for drinking use is provided only as an occasional control exercised at the discretion of the sanitary authority. Technological difficulties with obtaining data about groundwater viral contamination led to a study to devise rapid and efficient methods for their detection and the application of these methods to samples from different sources. Four acid nucleic extraction techniques have been tested (classic proteinase K- phenol/chloroform, QIAamp Viral RNA Kit (Qiagen), SV Total RNA Isolation System (Promega) and NucleoSpin Virus L (Macherey-Nagel). Sensitivity and specificity of RT-PCR protocols for entero- (EV), hepatitis A (HAV) and small round structured (SRSV) viruses have been verified. Deep groundwater samples (100 L) were concentrated (2-step tangential flow ultrafiltration) and the concentrate contaminated with serial 10-fold dilutions of a known titre of poliovirus type 3. Extracted RNA was concentrated (microcon-100) and analysed by RT-PCR using specific EV primers and visualising amplification products by agarose gel electrophoresis. In addition, two different methods of RT-PCR for non-cultivable viruses have been tested: (a) RT-PCR and nested RT-PCR for HAV and (b) RT-PCR with generic primers and RT-PCR with specific primers for SRSV. Different specificity tests have been carried out in the presence of some of the commoner microorganisms. The most efficient, sensitive and specific protocols were used to test 35 x 100L deep groundwater samples. Sample concentrates were split with one part treated with chloroform and analysed by cell culture (BGM and Frp/3, derived from FrHK/4, cells) and the other tested by RT-PCR for HAV, EV and SRSV. Results demonstrated the high efficiency of the classic and QIAamp methods. Microcon-100 did not increase the sensitivity of the technique used. The highest sensitivity was observed for RT-PCR with specific primers for SRSV and for nested RT-PCR for HAV. One sample showed a cytopathic effect, not confirmed at the third subculture, while the RT-PCR allowed the detection of echovirus 7. Cell culture did not allow detection of the majority of the enteric viruses while PCR gave sensitive, specific and rapid detection of a range of agents in the same samples. Even if it was impossible to fix a virological quality standard, it would be necessary to find a viral indicator ...

Confined aquifers as viral reservoirs

“…However, the identity of these viral groups remains relatively unknown. Previous works in classifying viral groups present in deep aquifers have predominantly focused on viruses that are known to infect humans (Carducci et al, 2003;Borchardt et al, 2007), but a non-targeted approach allowing for a complete picture of the viral communities present in deep aquifers is currently lacking.…”

Occurrence of norovirus and other enteric viruses in untreated groundwaters of Korea

“…Following reports of enterovirus prevalence in groundwater (Marzouk et al 1979), potentially pathogenic enteric viruses, such as human enteroviruses (EV) and NoV, have been subjected to systemic surveys in many countries as a common cause of epidemic waterborne viral gastroenteritis (Abbaszadegan et al 1999;Dahling, 2002;Carducci et al 2003;Fout et al 2003;Powell et al 2003;Borchardt et al 2004;van Zyl et al 2004). While drinking contaminated well water appeared responsible for 80% of the waterborne outbreaks associated with a viral agent in the United States for 1997 and 1998 (Barwick et al 2000), approximately onethird of waterborne illnesses, including gastroenterifis, occurred in populations served by community or noncommunity groundwater systems from 1971 to 2002 (Reynolds et al 2008).…”

Effect of Temperature on the Survival of F-Specific RNA Coliphage, Feline Calicivirus, and Escherichia coli in Chlorinated Water

“…However, enteric viruses are resistant to water treatment and may therefore be present in treated waters [6,7]. Since noroviruses (NoVs) are a leading cause of food and waterborne illnesses throughout the world [8,9], experts have called for routine water monitoring for viruses as a safeguard against waterborne viral diseases [1,[9][10][11][12]. However, routine monitoring for pathogenic viruses in water is currently not feasible because of the lack of simple and inexpensive methods for detecting low levels of viruses in large volumes of water [11].…”