Persistence of wastewater enteroviruses in Yopougon Ivory Coast
Several environmental factors contribute to maintain infectivity of enteroviruses out of body in various hydrological media, sometimes for long periods. This in situ study aimed (i) to isolate these viruses from wastewater and a lagoon, in four cell lines, and (ii) to follow the distribution and persistence of these viruses under the influence of abiotic environmental factors. The wastewater samples were collected at nine sampling points along the channel, which flows into a tropical lagoon in Yopougon. Enteroviruses were concentrated by using Dextran T40 and polyethylen glycol 6000, according to WHO recommendations. Measurements of pH, temperature, conductivity and salinity were carried out on site. The determination of sulphates (SO42-) was performed by HACH method 8051. Among the samples of raw wastewater (n = 45) and lagoon water (n = 21), 68.9% and 52.4%, respectively, were positive for viral isolation. The presence of enteroviruses was confirmed by RT-PCR in 57.8% and 42.8% of samples of raw wastewater and lagoon water. We observed that for rainfall of 0.4 mm and 252.9 mm, the number of positive samples collected was respectively 44.4% and 60.9%. Moreover, infectious enteroviruses were detected in the lagoon environment for temperatures ranging from 26oC to 30oC, above the threshold of 22oC where survival would be affected in estuaries. This study seems to demonstrate that the maximum value of pH (pH Max = 9.57) and salinity (salinity Max = 10.7) coupled with other environmental factors do not allow the persistence of enteroviruses.