Prevalence Of Rotaviruses, Adenoviruses And Hepatitis A In Water Samples Collected From Domestic Water Sources In Windhoek

ABSTRACT

Background: A growing population contributes to increasing demand for water. Windhoek’s water supply is based on the use of surface and groundwater. However, all potable water resources within a radius of 500 km have been fully exploited. The rainfall is uncertain and long spells of severe droughts are frequently encountered. There are four main sources of water supply to the central area of Windhoek: surface water obtained from the Von Bach, Swakoppoort and Omatako dams; groundwater abstracted from 50 municipal production boreholes; reclaimed water recovered by suitable treatment from both the New Goreangab Water Reclamation Plant (NGWRP) and the Old Goreangab Water Reclamation Plant (OGWRP). Natural water sources which include rivers, lakes and ponds can be contaminated with microorganisms which inhabit the environment in the form of planktonic organisms and sessile biofilms. Microbial agents, associated with waterborne outbreaks, include bacterial organisms (Salmonella, Campylobacter, Escherichia coli and Vibrio cholera, amongst many others) as well as viruses (Hepatitis A virus, rotavirus and Norwalk virus), protozoa (Giardia and Cryptosporidium), helminths and fungi can contaminate water systems. Methodology: Ten litres of water was collected per site per week in sterile Nalgene bottles containing 0.8 g of sodium thiosulfate that was added for de-chlorination of the water at the sampling sites and transported to the laboratory on ice. The 0.8 g sodium thiosulfate de-chlorinates up to 5 mg/l of free chlorine from water samples. The range of free chlorine in Windhoek’s water is 0.1-5.0 mg/l. The water samples were collected from a house tap in Khomasdal (borehole and blended water), Central hospital line (blended water), Cimbebacia (borehole water), Von Bach dam (dam water) and Havana communal tap (surface water). The pH, temperature and specific gravity of each sample was measured using a portable pH meter (YSI pH 100 portable pH mV), pH strips, a mercury thermometer as well as dipstick for specific gravity. The water samples were then concentrated using the adsorption-elution method. The viral RNA and DNA were extracted using RNA/DNA extraction kits (Quick-DNA™Miniprep; Zymo Research, USA and Quick-RNA™ Miniprep; Zymo Research, Irvine, USA) which was followed by reverse-transcription. The amplification and the identification of rotavirus, adenovirus, hepatitis A, hepatitis E virus as well as Escherichia coli and Enterococcus organisms was done by using specific primers. The PCR products were photographed and visualized using a transiluminator. Results: All sites had physiological determinant results that were acceptable and conductivity that was below 150 ms/M at 25°C, this however was not identified as cause for concern with regards to the safety of drinking water. Havana and Von Bach had the majority of turbidity readings that were less