Polio

poliovirus

• family Picornaviridae, genus Enterovirus
  • Human enterovirus A, B, C, D
    • PV belongs to HEV-C
    • EV71 belongs to HEV-A
    • EV68 (EV-D68) belongs to HEV-D
• non-enveloped single stranded positive sense RNA virus
  • 4 capsid proteins
• 3 serotypes
  • wPV2 already eradicated in 2015
  • wPV3 was declared to be eradicated in 17 October 2019 by WHO
  • wPV1 is still circulating in Pakistan and Afghanistan
• African region was certified as wild polio-free in 2020 by WHO

VDPV

• cVDPV1 and cVDPV2 are endemic in Africa and Southeast Asia as well as in Pakistan and Afghanistan
  • in recent 12 months no local transmission in Southeast Asia
• cVDPV3 is not identified so far

• VDPV is relatively physically stable in environment but cannot keep infectivity not for long time, thus continuous detection of VDPV in enviromnent means continuous transmission and/or excretion of VDPV from people living in the community
• distribution of breech (disinfectant) and/or irradication ultraviolet light may be effective against PV/VDPV
• threshold of immunization coverage to maintain PV/VDPV free is 85-90%

==Global Polio Eradication

• strategies
  • extensive immunization with OPV or IPV
  • surveillance of acute flaccid paralysis
  • lab diagnosis

• AFP cases and true poliovirus infection overlap very little
  • ⇔Variola cases and true smallpox infection overlapped almost identically

• novel OPV2
  • using genetically modified stain
  • more stabilized genomically

clinical

• mostly asymptomatic
• many mild manifestation
• polio paralytic cases 79% by wPV1, 8% by wPV2, 13% by wPV3 in 2010