A new study found that a man in the United Kingdom, immunized with polio vaccine as a child, has been shedding live virus in his stool for 28 years. Though he received vaccination at the right intervals, his health condition subdued his immune system, and was incapable of destroying the virus.
More than 100 stool samples taken from the unnamed man over a period of 20 years, confirmed the virus’ presence. His immune disorder affected the ability of the immune system to kill the weakened live virus, and stayed briefly in his digestive tract. The virus in his stool was potent as the mice that were injected with the samples were paralyzed. The study has been published in the Thursday’s edition of the journal PLoS Pathogens.
“The virus is no different than any other polio virus,” said Dr. Javier Martin, biologist at the National Institute for Biological Standards and Control in the U.K and author of the study.
However, researchers found that the virus was neutralized in lab tests of human blood. Martin added that if people are properly immunized, there is no reason for infection, and it is not known how many people are excreting polio virus after immunization.
There has been only 73 such cases between 1962 and 2014, and only seven had the infections lasting about five years. But, researchers have found strains of the virus from sewage systems in Isreal, Slovakia, Finland and Estonia, indicating that there might be more people with a similar condition.
Though the British man posed no harm to others with proper immunization, others with his same condition will be affected. The Global Polio Eradication Initiative aims to eradicate polio by 2018, but global conflict and mutation through the vaccine has made this difficult. There are also three dangerous strains of polio in the world, and the World Health Organization is set to test a new vaccine, starting April 2016.[ Source ]