Ausencia de circulación de poliovirus en departamentos colombianos con coberturas vacunales inferiores a 80%

Abstract

This study aims to explore a possible silent circulation of wild and vaccine-derived polioviruses in departments of Colombia with polio vaccination coverage of below 80%. The study collected 52 samples of wastewater concentrated as a result of precipitation with polyethylene glycol and sodium chloride. The viral detection was carried out through isolation and the identification through neutralization of the cytopathic effect, as well as through a conventional polymerase chain reaction following reverse transcription. The isolated polioviruses were characterized by the VP1 gene sequence. In two of the 52 samples, there was a presence of the Sabin type 2 poliovirus with more than 99% sequence similarity with the Sabin type 2 strain polio. Circulation of the nonpolio enterovirus was detected in 17.3% of the samples. The serotypes identified corresponded to coxsackievirus B1, echovirus 30, and echovirus 11. No evidence of the spread of either vaccine-derived poliovirus or wild poliovirus was detected in the departments of Colombia with polio coverage lower than 80%.

Environmental Surveillance of Polioviruses in Armenia, Colombia before Trivalent Oral Polio Vaccine Cessation

“…Remarkably, Sabin strains were isolated in approximately 50% of the grab samples, proving this method to be an effective supplemental support to AFP surveillance to sensitively monitor poliovirus (wild, VDPV, and Sabin) within a population [7]. Our results appear to be consistent with those of a previous study conducted by our laboratory, which led to the demonstration of an absence of VDPV and wild poliovirus in Colombian departments with vaccination coverage below 80% [20]. This implies the effectiveness of polio immunization and a high level of protection against polio in the region.…”

“…Additionally, non-polio enterovirus isolation in the present study can be considered a proxy indicator to validate that the environmental samples were processed and analyzed appropriately to preserve infectiveness [5]. This, in turn, confirms previous results showing that non-polio enterovirus circulates broadly in the region [20,21,22,23,24,25,26].…”

“…This observation is consistent with the lower rate of type 2 poliovirus isolation in stools randomly sampled from the population of the area where wastewater was collected, indicating the lower excretion of this serotype in relation to types 1 and 3 [6,21]. Furthermore, it has been demonstrated that Sabin 2 is considerably more immunogenic than types 1 or 3 [20]. It is likely that a higher immunological response to the type 2 component of the OPV limits the excretion of this serotype in stool and, consequently, there was lack of Sabin type 2 strains in wastewater.…”