Causative agent poliovirus is the member of the family picornaviridae which is one of the largest and most important families of human pathogens .these are smallest RNA viruses .Despite a member of enterovirus poliovirus as well as other enterovirus don’t produce enteric disease they are named because the alimentary canal is their predominant site of replication
Vaccine against poliomyelitis
There are two kinds of vaccines for immunization against virus
1- a vaccine mad of noninfectious virus particles ( killed or inactivated virus vaccine administered by injection referred to as killed poliovaccine KPV or inactivated poliovaccine IPV )
2- made of infectious virus particles attenuated in neurovirulence (live attenuated virus vaccine LPV administered orally referred to as live poliovaccine or oral poliovaccine OPV )
Oral polio virus vaccine
the trivalent oral poliovirus vaccine TOPV is mixture of three types (monovalent ) of attenuated polioviruses which are propagated separately in appropriate cell cultures and then mixed .A stabilizer magnesium chloride is added to this blended mixture .Each dose contains less than 25?g of each of the antibiotics ,streptomycin and neomycin .phenol added as indicator of the PH, before being released by the manufacturer the vaccine in final containers is kept continuously in the frozen temperature below -20 C .under this condition of storage ,the expiry date of vaccine is fixed which is not more than two years. after thawing OPV may be refrigerated at temperature of 2-8 C for a period not exceeding 30 days .
inactivated poliovirus vaccine
this vaccine contains 40,8 and 32 D unit respectively of type 1,2 and 3 in each dose of the vaccine which gives adequate immunity after two doses given parenterally
Advantages with IPV
1- confers humoral immunity in a satisfactory proportion of vaccines if a sufficient number of doses are given .
2- incorporated into regular pediatric immunization with other DPT
3- Absence of living virus precludes potential mutation and reversion to virulence
Absence of living virus perm