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

duration of activity in environment/sewage - seeding period of years means duration of activity of each virus or continuous producing of VDPV due to OPV
how to keep activity in environment/sewage - can the virus propagate in some cells in sewage
any intervention directly to sewage where VDPV has been found, like disinfectant
where the sabin virus obtains mutation to VDPV
threshold of immunization coverage to maintain VDPV free

==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