Detection of virus in water: sensitivity of the tentative standard method for drinking water

Our plain-English summary of Detection of virus in water: sensitivity of the tentative standard method for drinking water, by W.F. Hill, W. Jakubowski, E.W. Akin, et al (Applied and Environmental Microbiology, 1976).

The study

• Authors: W.F. Hill, W. Jakubowski, E.W. Akin, N.A. Clarke
• Journal: Applied and Environmental Microbiology
• Published: 1976;31(2):254-61
• Cited by: 26 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The sensitivity of several microporous virus-adsorbent media for reliably detecting low levels of poliovirus from 380 and 1,900 liters of drinking water by use of the tentative standard method was investigated. The virus-adsorbent media tested were (i) nitrocellulose membrane filters, (ii) epoxy-fiber glass-asbestos filters, (iii) yarn-wound fiber glass depth filters, and (iv) epoxy-fiber glass filter tubes. Virus was adsorbed to the filter media at pH 3.5 and eluted with glycine buffer, pH 11.5. The results from 44 samples demonstrated that poliovirus was detected with a 95% reliability at mean virus input levels of 3 to 7 plaque-forming units/380 liters when 1,900 liters of water was sampled. At mean virus input levels of less than 1 to 2 plaque-forming units/380 liters, the detection reliability was 66% in 76 samples when 1,900 liters of water was sampled. No significant difference in virus detection sensitivity was observed among the various virus adsorbent media tested. Overall virus recovery efficiency ranged from 28 to 42%, with a grand average of 35%. Members of the coxsackievirus groups A and B, echovirus, and adenovirus were also detected when 380 and 1,900 liters of water were sampled. These experimental observations attest to the sensitivity of the tentative standard method for detecting low levels of virus in large volumes of drinking water.

In plain English

This laboratory study tested a tentative standard method for detecting low levels of virus in drinking water. It did not study asbestos health effects; asbestos was only an ingredient of one filter type, the epoxy-fiber glass-asbestos AA Cox M-780. The authors added low amounts of poliovirus type 1 to Cincinnati tap water and passed it through filters, examining 120 samples. In 12 paired volume-comparison runs using membrane and Balston filters, virus was found in every 380- and 1,900-liter sample at 4 units per 380 liters; at 1 to 2 units, it was found in all 1,900-liter samples but only 25% of 380-liter samples. With 1,900 liters, detection reliability was 95% in 44 samples at 3 to 7 units per 380 liters, and 66% (95% confidence limits 55 to 77%) in 76 samples at less than 1 to 2 units. At that lowest level, differences among filter systems were not statistically significant. Average recovery was 35%, and other enteric viruses were also detected. The authors concluded the method could tentatively meet the need for examining suspect drinking water.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory evaluation of a virus-detection method using tap water deliberately seeded with known amounts of virus
• Who was studied: 120 experimental samples of Cincinnati tap water (380 or 1,900 liters each), seeded with virus; no people were studied
• Exposure: Water was seeded with poliovirus type 1 (LSc2ab strain), and some runs used other enteric viruses. The water was passed through four kinds of filters, one of which was an epoxy-fiber glass-asbestos filter (AA Cox M-780). No human or animal asbestos exposure was studied.
• Main results:
  • In the 12 paired volume-comparison runs (MF and Balston filter tubes), poliovirus was detected in all 380- and 1,900-liter samples at mean inputs of 4 PFU per 380 liters
  • In the same paired comparison, at mean inputs of 1 to 2 PFU per 380 liters, poliovirus was detected in all 1,900-liter samples but in only 25% of 380-liter samples
  • Asbestos-containing Cox filters: at 3 to 5 PFU per 380 liters, the 267-mm AA Cox M-780 alone detected virus in 9 of 10 runs (90%) and K-27 plus 127-mm AA Cox M-780 in 10 of 10 (100%). At less than 1 to 2 PFU per 380 liters, detection was 9 of 17 (53%, 95% confidence limits 29 to 77%) and 12 of 17 (71%, 49 to 93%) respectively. Average recovery was 29% and 35% respectively.
  • Balston epoxy-fiber glass filter tubes: detection was 100% (alone) and 90% (with K-27) at 3 to 7 PFU per 380 liters, and 53% and 71% at less than 1 to 2 PFU per 380 liters. The authors noted these detection rates were identical to those with the Cox filter systems.
  • With 1,900 liters sampled, poliovirus was detected with 95% reliability in 44 samples at mean inputs of 3 to 7 PFU per 380 liters
  • With 1,900 liters sampled, detection reliability at mean inputs of less than 1 to 2 PFU per 380 liters was 66% in 76 samples (95% confidence limits 55 to 77%) for all filter systems
  • Average virus recovery ranged from 28 to 42% across filter systems, with a grand average of 35%
  • The difference in detection reliability among filter systems at mean inputs of less than 1 to 2 PFU per 380 liters was not statistically significant
  • Members of coxsackievirus groups A and B, echovirus and adenovirus were also detected in 380- and 1,900-liter samples
• The authors' conclusion: The authors concluded that the method's detection sensitivity and reliability should tentatively satisfy the need for examining drinking water suspected in a viral disease outbreak. They saw little reason to designate any one of the filters tested on the basis of virus recovery efficiency.
• Limitations the authors state:
  • The sample size needed to detect 1 infectious unit per 380 liters with 100% reliability had not been established
  • Larger 1,900-liter samples occasionally caused filter clogging during reconcentration
  • Input levels of the other enteric viruses were higher than those of poliovirus
  • Virus recovery varied, which the authors attributed partly to unpredictable changes in water quality

Related studies

• Comparative study of four microporous filters for concentrating viruses from drinking water — W. Jakubowski, W.F. Hill, et al. (1975)
• Modified membrane-filter procedure for concentration of enteroviruses from tap water — P.A. Shields, S.A. Berenfeld, et al. (1985)
• Three potential sources of microfungi in a treated municipal water supply system in sub-tropical Australia — N.B. Sammon, K.M. Harrower, et al. (2011)
• A method of treating asbestos filter pads for virus filtration — N.S. Hyslop (1961)
• Drinking water and cancer — K.P. Cantor (1997)
• Drinking water and cancer — R.D. Morris (1995)

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