Poliovirus environmental surveillance in Sistan-Balouchestan Province, isolation and identification of viruses by cell culture and microneutralization, and intratypic differentiation by ELISA and probe hybridization

In some countries, wild polioviruses have been isolated from environment despite the absence of viruses being recovered from clinical cases, therefore to confirm of final Polio eradication, WHO has recommended environmental surveillance using sewage specimens and surface water. During the present study, in order to assure the polio eradication in Iran, Sistan-Balouchestan province was chosen as the target area. During a 12-month period, 86 specimens from 2 sewage disposal systems and 5 hospitals, as well as surface water from several rural areas were collected by Grab Sampling and tested for polioviruses using direct and concentrated specimens with 2 concentration Pellet and Two-phase. Then the isolated viruses were serotyped by microneutralization method and differentiated intratypically by ELISA and probe hybridization techniques. Of all studied specimens, 18 (20.9%) were identified as poliovirus, none of which were wild virus fortunately. Among these, 2 (2.3%), 8 (9.3%) and 13 (15.1%) were isolated from direct specimens, Pellet and Two-phase concentrated specimens, respectively. The most frequent viruses were Polio 2 (72.2%) and Polio 3 (27.8%). Results have revealed the efficacy of immunization coverage in Iran. Meanwhile, sufficient surveillance programs have been observed during the recent years.