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

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