Received this via David Rands, Dist Rotary Foundation Chair
The Polio outbreak in PNG is due to Vaccine Derived Polio (VPP)
Even if the wild polio virus has been eliminated and a country is declared Polio Free (no cases for 3 years), the action of immunising children can introduce Vaccine Derived Polio.
It occurs where immunisation levels are low and is especially of concern in under developed areas with poor sanitation and water supply.
Children receive the vaccine, it can live in the gut for up to 2 weeks and is excreted and the virus ends up in the water system and in turn healthy but non-vaccinated people are infected with Polio.
The 'herd mentality' is the term used in that if there are high levels of immunisation then the chances of VPP are lower, but if communities become complacent and immunisation is low, then VPP can occur simply as a result of an immunisation campaign.
This can be seen in PNG where communities down stream take water that has been contaminated up stream and the hardy polio virus is in the water drunk by an unvaccinated person further down the water supply system.
The attached file outlines the tremendous response that has occurred in PNG with significant Rotary involvement.
The same concern about levels of immunisation or more so non immunisation in Australia for a range of diseases, concerns health authorities in that any preventable communicable disease could take hold in communities where vaccination levels are low.