Detection and characterization of hepatitis A virus in water samples in Thailand

Abstract

Aims: Outbreaks of hepatitis A in Thailand have been reported continuely and associated with water supply. However, the genetic analysis of hepatitis A virus (HAV) in water is limited. This study described the application of virus concentration method and reverse transcriptase‐nested polymerase chain reaction (RT‐nested PCR) to detect HAV RNA and analyse the genetic sequence of the virus in environmental water samples. Methods and Results: The HAV from water samples was concentrated by using a developed virus concentration method (adsorption‐elution and subsequent speedVac reconcentration) and the viral RNA was detected by RT‐nested PCR followed by sequencing of the amplified DNA products. Detection limit of HAV determined by the RT‐nested PCR was 1·29 radioimmunofocus assay (RIFA) units ml−1. The DNA band appeared at 183 basepairs. No cross‐reactivity was observed in the presence of other enteric viruses (poliovirus and rotavirus). A total of 180 water samples were collected, concentrated, and detected for HAV. The HAV was found in 6/40 (15%) of water samples collected from a swamp and 3/30 (10%) collected from a canal. Ten river samples and 100 tap water samples stored in containers for drinking and domestic uses were negative for HAV. In sequence analysis of the DNA products and alignment with the HAV sequence deposited in the GenBank, six water samples showed the nucleotide sequence associated with HAV. The 120 nucleotides in the N‐terminal VP1 region obtained from two swamp samples showed 95 and 96·7% identity to HAV genotype IA. In nearly all water samples where HAV was present bacterial indicators (faecal coliforms and Escherichia coli) were found for faecal contamination. Conclusions: A coupled virus concentration method and RT‐nested PCR was successfully applied to examine HAV in water samples collected from various sources. DNA sequencing of nested PCR products showed the genotype IA associated with HAV that is predominate in Thailand. Significance and Impact of the Study: This research is the first study of genetic sequence of HAV in water samples in Thailand. The presence of naturally occurring HAV might pose a potential health risk for people.

Detection and Characterization of Enteric Viruses in Flood Water from the 2011 Thai Flood

“…Sewage from households may have been present in the tested water samples. However, the detection rates of viral genes in our study were lower than those in reports examining other environmental water sources in Thailand (19)(20)(21). The differences in these detection rates may also be explained by differences in the targeting samples (flood water versus normal environmental water).…”

“…Data from other studies conducted in Thailand showed that some enteric viruses (or their genes and/or antigens) were present in non-flood environmental water from canals, swamps, or sewage (19)(20)(21). However, to the best of our knowledge, there are no previous reports of NV or HEV in any type of environmental water in Thailand.…”

“…In another study, the RV gene was detected in 20z (river), 26z (canal), and 25z (sewage) of samples (20). The HAV gene was detected in 15z (sewage, swamp) and 10z (canal) of samples, and the genotypes of these HAVs were GIA (19,21). Kittigul et al performed a surveillance of EV in environmental water but did not detect EV (19).…”

“…Kittigul et al performed a surveillance of EV in environmental water but did not detect EV (19). Their report suggested that enteric viral contamination is impacted by sewage from households (21). Enteric viruses are transmitted by the fecal-oral route; the spread of these viruses has been attributed to the consumption of food and drinking water contami- Fig.…”

Real-time PCR quantitative assessment of hepatitis A virus, rotaviruses and enteroviruses in the Tyume River located in the Eastern Cape Province, South Africa

“…Also, the use of pools found in the river for recreational activities like swimming is common practice among rural children, which raises both the chances of surface water contamination with enteric viruses and also the risk of swimmers getting infected. Waterborne RVs have been detected elsewhere (Kittigul et al, 2005b) and the first large waterborne epidemic in an adult population was caused by Group B rotaviruses in China (Logan et al, 2006). Faecally-polluted natural surface water used for recreational activity could therefore pose a potential health risk to the public (Venter et al, 2007).…”