Indian Journal of Medical Microbiology Home 

Year : 2002  |  Volume : 20  |  Issue : 1  |  Page : 56-

In reply

G Sridharan, P Abraham 
 Department of Clinical Virology, Christian Medical College Hospital, Vellore - 632 004, India

Correspondence Address:
G Sridharan
Department of Clinical Virology, Christian Medical College Hospital, Vellore - 632 004

How to cite this article:
Sridharan G, Abraham P. In reply.Indian J Med Microbiol 2002;20:56-56

How to cite this URL:
Sridharan G, Abraham P. In reply. Indian J Med Microbiol [serial online] 2002 [cited 2020 Jul 5 ];20:56-56
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Full Text

Dear Editor,

Thank you very much for referring Dr. Yash Paul's letter regarding polio viruses effect on wild polio virus circulation. We give below our response to his queries.

It is now known that multiple entroviruses including poliovirus vaccine or wild strains can multiply in the gut simultaneously. This is evident from the trivalent OPV eliciting a seroresponse. If a given wild poliovirus serotype is infecting a child there may be interference with the corresponding vaccine (OPV) virus serotype. OPV strain may not alter the replication dynamics of wild poliovirus, which has already entered the host. Dr. Paul has alluded to the possibilities of administering OPV to a child who has developed paralytic poliomyelitits as may be practiced in pulse polio immunization campaigns. The administration of OPV to such a child who has established paralytic disease possibly caused by one of the poliovirus serotypes should not make any difference to the established disease. In fact, it may immunize to heterologous types to which a child is non-immune.

It is primarily a question of which of the virus got access to the host first. If the child is first exposed to the vaccine strains then the vaccine strains would cause gut immunity to develop. This gut immunity and systemic immunity against poliovirus, causing large proportion of the previously susceptible population to be thus immune, will break the natural cycle of transmission of wild poliovirus at a community level. In a given individual the vaccine virus, if given after the exposure to the wild virus will not replace the former. So pre-emptive intervention with vaccine regularly in the community reducing the build up of susceptible individual (children) will eventually abolish the wild virus circulation as it appears that humans are the only natural reservoir of polio viruses.


1Melnick JL. Attenuated poliovirus vaccines in: Vaccines Ed. Plotkin SA and EA Mortimer. Chapter 7. W.B. Saunders Co. Philadelphia. P 155.