PakistanIndiaSulfonesPurinesPiperazinesPhosphodiesterase InhibitorsPhosphodiesterase 5 Inhibitors3',5'-Cyclic-GMP PhosphodiesterasesErectile DysfunctionCyclic Nucleotide Phosphodiesterases, Type 5Homosexuality, MalePenile ErectionAfghanistanMethamphetamineVasodilator AgentsCyclic GMPGeorgiaUnsafe SexRisk-TakingSexual BehaviorPoliomyelitisDeveloping CountriesPrevalenceGeographic MappingPoliovirus Vaccine, OralCross-Sectional StudiesRural PopulationAsia, WesternTertiary HealthcarePoliovirus Vaccines