Friday, February 25, 2011

OPV-related poliovirus (dedicated to Yu-Jin)

As we've talked about in class, poliovirus infections have been nearly eliminated due to the eradication efforts of various public health organizations, dedicated individuals, and massive funding. The four remaining regions: Nigeria, Afghanistan, Pakistan, and India, are especially difficult countries in which to eradicate polio due to issues of poverty, lack of infrastructure, and civil unrest.

Myanmar, which was declared polio-free in the year 2000, saw it's first non-imported polio case in years last December. A 7-month-girl who had not been vaccinated became an isolated case infected with a poliovirus believed to originate from the live-attenuated Oral Polio Vaccine (OPV). Because OPV strains replicate in the gut after vaccination, mutation of the strain may lead to shedding of infectious virus into the environment via human excrement. Conditions of poverty, such as poor hygiene and sanitation, facilitate the transmission of poliovirus from feces to human being. ProMed released a report today noting that Myanmar, which immunized over ten thousand children in response to this polio case, is continuing to vaccinate against poliovirus.

The report does not talk specifically about the type of vaccination given in Myanmar, but it would be interesting to see whether they chose to use OPV or the inactivated vaccine. It seems that since polio was eradicated and the infant girl was the only one affected, using inactivated vaccine would be ideal, especially since the young girl was infected by an OPV-mutant strain. Mass vaccination with OPV could potentially lead to more of these mutant-strain infections.  It is interesting to consider what the country has access to and whether mass vaccination with IPV would be feasible with regards to the resources and skills required to administer the inactivated vaccine.


No comments:

Post a Comment