Prevalence, quantification and typing of adenoviruses detected in river and treated drinking water in South Africa

Abstract

Aims: Human adenoviruses (HAds), of which there are 51 serotypes, are associated with gastrointestinal, respiratory, urinary tract and eye infections. The importance of water in the transmission of HAds and the potential health risks constituted by HAds in these environments are widely recognized. Adenoviruses have not previously been quantified in river and treated drinking water samples. In this study, HAds in river water and treated drinking water sources in South Africa were detected, quantified and typed. Methods and Results: Adenoviruses were recovered from the water samples using a glass wool adsorptionelution method followed by polyethylene glycol/NaCl precipitation for secondary concentration. The sensitivity and specificity of two nested PCR methods were compared for detection of HAds in the water samples. Over a 1-year period (June 2002 to July 2003), HAds were detected in 5AE32% (10/188) of the treated drinking water and 22AE22% (10/45) of river water samples using the conventional nested PCR method. The HAds detected in the water samples were quantified using a real-time PCR method. The original treated drinking water and river water samples had an estimate of less than one copy per litre of HAd DNA present. The hexon-PCR products used for typing HAds were directly sequenced or cloned into plasmids before sequencing. In treated drinking water samples, species D HAds predominated. In addition, adenovirus serotypes 2, 40 and 41 were each detected in three different treated drinking water samples. Most (70%) of the HAds detected in river water samples analysed were enteric HAds (serotypes 40 and 41). One HAd serotype 2 and two species D HAds were detected in the river water. Conclusions: Adenoviruses detected in river and treated drinking water samples were successfully quantified and typed. The detection of HAds in drinking water supplies treated and disinfected by internationally recommended methods, and which conform to quality limits for indicator bacteria, warrants an investigation of the risk of infection constituted by these viruses. The risk of infection may have implications for the management of drinking water quality. Significance and Impact of the Study: This study is unique as it is the first report on the quantification and typing of HAds in treated drinking water and river water. This baseline data is necessary for the meaningful assessment of the potential risk of infection constituted by these viruses.

Concentration of Enteroviruses, Adenoviruses, and Noroviruses from Drinking Water by Use of Glass Wool Filters

“…Large volumes and high filtration rates did not pose any problems; the 2-to 4-liters min Ϫ1 filtration rate used in the present study exceeded the previously reported maximum filtration rates of 1.7 liters min Ϫ1 (44, 45) and 0.27 liters min Ϫ1 (7). Another advantage was that passing water samples through glass wool appeared to diminish PCR inhibition, an observation also noted by van Heerden et al (41).…”

“…The fibers are inexpensive and require no water conditioning outside of pH adjustment in some circumstances (30,48). Glass wool has been used in virus monitoring studies involving wastewater (10), drinking water (14,41,46), groundwater (6,30,31,43), river water (18,41), and reservoirs (6,43). However, only a handful of studies have attempted to quantify how effective glass wool is for concentrating viruses (7,44,45), and these examined only enteroviruses and rotavirus.…”

“…However, only a handful of studies have attempted to quantify how effective glass wool is for concentrating viruses (7,44,45), and these examined only enteroviruses and rotavirus. Investigators using glass wool for quantitative virus monitoring have implicitly assumed 100% recovery (18,31,41) or an average of 40% (42). Such assumptions contribute additional uncertainty when virus data derived from glass wool concentration are used in exposure and risk assessment analyses (40,42).…”

Diverse norovirus genotypes identified in sewage-polluted river water in South Africa

“…After a 14-day incubation period, which included a blind passage at day 7 post-infection, the infected cells were harvested for molecular analysis for human adenoviruses [21] and enteroviruses [20], as well as for blind passage onto monolayers of Vero African Green Monkey cell line (ECACC 84113001) in cell culture tubes with flying coverslips. After a further incubation of 7 days at 37 xC, the infected cell cultures were examined for cytopathic effects, stained with haematoxylin and eosin and examined for virusspecific inclusion bodies [22].…”

Detection and quantification of human bocavirus in river water

“…2). Accordingly, even though it might not cause gastroenteritis, we cannot exclude the role of contaminated water in transmission, as proposed for respiratory adenoviruses (van Heerden et al, 2005).…”