RESUMEN
We sought to identify factors associated with being a reservoir district for wild poliovirus in Pakistan. Differences between reservoir and non-reservoir districts were identified using acute flaccid paralysis surveillance data, population census statistics and data from a survey of district health officials [DHOs]. Of the 11 poliovirus reservoir districts identified, population density was significantly higher [median 550 persons/km2] than the non-reservoirs [median 175 persons/km2]. DHOs from reservoir districts more often reported that planning was affected by refugees and they had more frequent DHO transfers compared with non-reservoir districts. Multivariate analysis confirmed that reservoirs more often had high population density and frequent DHO transfers. Assessment of district-level and management characteristics can supplement surveillance methods to further improve health programmes