Detection of polioviruses and non-polio enteroviruses by acute flaccid paralysis and environmental surveillances in Sistan and Balouchestan Province

In some countries, though wild poliovirus isolation from clinical specimens has not been done, evidences of silent circulation of wild virus in sewage system have been reported. On the other hand, based on WHO recommendations, if there is any probability of wild virus entrance from endemic countries, environmental surveillance is advised as a completion to Acute Flaccid Paralysis (AFP) surveillance.

AFP and environmental surveillance were performed simultaneously in Sistan and Balouchestan province to confirm wild poliovirus eradication. To perform AFP surveillance, 21 stool specimens of AFP suspected cases were collected in a one year period and evaluated using L20B, RD and Hep-2 cell lines. To perform environmental surveillance, 86 samples from urban and hospital sewage disposal systems were collected. Using direct, Pellet and Two-phase methods for virus concentration, Enterovirus existence was investigated in above-mentioned cell lines.

Non-polio enteroviruses and polioviruses were isolated from 53.49% and 20.93% of sewage specimens, respectively. Sabin-Like polioviruses were isolated from 9.52% of AFP cases, and non-polio enteroviruses from 14.28% of them. Poliovirus type 2 was not isolated form stool specimens and there was no Poliovirus type 1 isolation from sewage specimens, either.

The environmental surveillance as a completion to AFP in Sistan and Balouchestan Province in Iran confirms poliovirus eradication.