Polio vaccine

Question 1

Polio - virus

Answer 1

Enterovirus - RNA virus
3 serotpyes 1, 2 and 3

Question 2

Polio - transmission

Answer 2

Faecal-oral transmission [pharyngeal uncommon]

Question 3

Polio - pathogenesis

Answer 3

Virus to mucosa of GI tract - into lymphoid tissue - then CNS [flaccid paralysis]

Question 4

Polio - IP

Answer 4

7-14 days [3-35 days]

Question 5

Oral polio vaccine

Answer 5

Easy to administer, less expensive
Greater enteric immunit y= good IgA response, better at protecting against infection
Transmission of vaccine virus - so immunises more people that vaccinated

Paralysis in 1 per million doses [Vaccine attributable paralytic polio = VAPP]

Question 6

Polio eradication - geographic distribution

Answer 6

2003 - only 6 countries, <1,000 cases
210 countries polio-free
Largest ongoing burdern = Pakistan, Afghanistan

Question 7

Polio - clinical

Answer 7

25% mild febrile illness - sore throat, fever, headache [2-5 days]

Meningitis - 1-5%
Paralysis - 0.5%

Question 8

Challenges in eradication

Answer 8

Last wild type 2 case = 1999
2000 = circulating vaccine-derived virus [cVDPV] - mainly type 2