Poliovirus Flashcards
True or false: poliovirus is nationally notifiable?
Yes - urgent.
Which organism causes poliovirus?
Poliovirus (an enterovirus)
Types 1, 2, 3
How is poliovirus transmitted?
Person-person:
* Droplet
* Faecal-oral
What are the clinical features of poliovirus?
95% asymptomatic.
* Abortive: URTI/GI/ILI
* Non-paralytic: as above + meningeal irritation
* Paralytic: < 1% of cases; acute flaccid paralysis (1 muscle group to quadriplegia)
Abortive = mild. CFR 5-10%.
True or false: vaccine-associated paralytic poliovirus (VAPP) is common?
False.
Very rare complication of OPV.
What is vaccine-associated paralytic poliovirus?
Circulating vaccine-derived poliovirus infection (cVDPV) occurs when weakened OPV strain circulates in under-immunised populations, or replicates in an immunodeficient individual, and reverts to a form that causes illness and paralysis.
Which groups are high-risk for poliovirus?
- Unvaccinated
- Children < 5yo
- Refugees living in camps
- HCWs / lab workers
- Travellers to endemic areas
What are the case definitions for poliovirus?
Paralytic infection
Confirmed: clinical + lab definitive
Probable: clinical only
Non-paralytic infection
Confirmed: lab definitive only without typical clinical features
Case definitions for paralytic for wild, VAPP, cVDPV
How is poliovirus diagnosed?
- Viral culture (faeces/blood/CNS/throat)
- PCR
- Acute and convalescent sera
National Enterovirus Refence Lab (VIDRL) differentiates wild type, VAPP, VDP
What is the incubation period for poliovirus?
Usually 7-14 days
Range 3-35 days
What is the infectious period for poliovirus?
As long as virus excreted:
* 1 week from pharynx
* 6 weeks in faeces (inc OPV)
Highest 7-10 days before and after Sx onset
How is surveillance for poliovirus conducted?
Stool samples from all children with AFP regardless of provisional diagnosis.
AFP = acute flaccid paralysis
What is the outbreak definition of poliovirus?
Single case (either wild / VDPV) considered a public health emergency.
How are outbreaks of poliovirus managed?
Usual OB management principles: case, contact, environmental management
See Australia’s poliovirus infection outbreak response plan.
How is poliovirus prevented?
- Vaccination - NIPS 2, 4, 6mo and 4 years
- Sanitation and hygiene.
Oovercrowing, poor hygiene and sanitation correlated with infection risk
What is the main difference between the OPV and IPV?
OPV is live-attenuated.
IPV is inactivated.
Why do high-income countries use IPV over OPV?
No risk of VAPP/cVDPV
Why is the oral poliovirus vaccine (OPV) used in developing countries over the inactivated poliovirus vaccine (IPV)
Greater intestinal immunity, low cost, east of administration.
OPV needs to cease for eradication - replaced with IPV.
Apart from children (NIP) who is the poliovirus vaccine recommended for?
Unvaccinated people
HCW who have contact with polio
Travellers to endemic countries
Booster every 10 years for HCW and travellers.
What resources are available for public health management of poliovirus?
DH protocol.
Australian poliovirus infection outbreak response plan.
No SoNG.
How are cases of poliovirus managed?
- Interview - DRSVECT
- Treatment - supportive only; droplet/contact precautions
- Isolation/exlusion - home/hospital until 2 x negative stool samples 7 days apart; no work/school/institution at least 14 days from onset and fully recovered
- Education
DRSVECTA = demo, rfs, sx, vax, exposure, contacts, travel hx, animal contact.
Who are considered contacts of poliovirus cases?
- HH
- Shared toilet (workplace, school, CC)
- HCW who cared for case
- Lab worker
- Ate food prepared by case
How are contacts of poliovirus managed?
- Treatment - check immunisation status; IPV booster (or full course) for all contacts
-
Isolation/exclusion
HH contacts quarantine at home until 2x negative stool samples 24-48hrs apart.
Consider excluding contacts from high-risk occupations (food handler, HCW, CC) until known not infectious - Monitor -
- Education - Sx, transmission, resp/hand hygiene
What environmental management is required for poliovirus?
Effective disinfectants are those which contain free chlorine, such as sodium
hypochlorite or bleach, glutaraldehyde solutions, formaldehyde solutions and
iodophores.
How many WHO regions (including Australia) are polio free?
5 out of 6
When was the Global Polio Eradication Initiative (GPEI) launched?
1988
Which countries have wild type polio circulating?
Afghanistan and Pakistan
How many global cases of polio were there in 2023?
536
True or False: poliovirus is considered a PHEIC?
True
