Detection of Enteric Viruses from Wastewater and River Water in Botswana

Waterborne diseases remain a public health concern in developing countries where many lack access to safe water. Water testing mainly uses bacterial indicators to assess water quality, which may not fully indicate the threat from other non-bacterial pathogens like enteric viruses. This study was done to ascertain and establish the viral load, the temporal and spatial distribution of rotavirus A and norovirus (GI and GII) in sewage and river water samples. A total of 45 samples of raw and treated sewage, and surface water, were collected from a sludge activated wastewater treatment plant in Gaborone, and after treatment from the Notwane River, Botswana, over a period of 9 months (February 2016 to October 2016). Viruses were concentrated using polyethylene glycol/NaCl precipitation. Virus detection was performed using real-time polymerase chain reaction (RT-PCR). Rotavirus A was the most prevalent (84.4% positive samples), followed by Norovirus GI (48.9% positive samples), and Norovirus GII 46.7% positive samples). Detected viral loads went up to 10⁴ genome copies per liter (copies/L) for all the viruses. The enteric viruses were detected in all the study sites with highest detection from site S1 (inlet). There was no significant association between physicochemical parameters and viral loads, except for pH which showed significant relationship with rotavirus and norovirus GII (p ≤ 0.05). This is the first study in Botswana to highlight the occurrence and quantification of the enteric viruses in treated and untreated wastewater, as well as surface water.