Poliovirus surveillance by examining sewage specimens. Quantitative recovery of virus after introduction into sewerage at remote upstream location

In order to assess the feasibility of environmental poliovirus surveillance , known amounts of poliovirus type 1, strain Sabin, were flushed into the s ewage network of Helsinki. Grab specimens collected at a remote downstream location and concentrated about a 100-fold revealed infectious poliovirus o n four successive days in all three separate experiments. As for concentrat ion, a simple two-phase separation method was found to be at least as usefu l as a several-fold more resource-demanding polyethylene glycol (PEG) preci pitation method. Recovery of the introduced virus was remarkably high (more than 10 %). Using the current system, it might be possible to detect polio virus circulation in a population of 700 000 people by examining a single 4 00 ml sewage specimen, if I out of 10000 inhabitants were excreting the vir us. It is concluded that environmental surveillance is a sensitive approach to monitor silent poliovirus circulation in populations served by a sewage network.