A Disease That Could Render the Oral Polio Vaccine Ineffective. Source: The Wire, India, Jan 6 2016.
A tough-to detect and alarmingly common intestinal disease may have a lot to do with India’s stunted children and their susceptibility to polio and rotavirus infections.
In 2011, a team of scientists from the USA, the Netherlands and Bangladesh began a study to answer one mystery: More than 95% of children who contract paralytic polio in India have received more than 3 doses of the Oral Polio Vaccine. In Bangladesh, the oral rotavirus vaccine has shown to be effective only 43% of the time compared to 95% in Europe. What could be causing this vaccine inefficacy?
An infant receiving an oral polio vaccine.
One hypothesis claims that oral polio vaccines and rotavirus vaccines are less likely to work in children suffering from a type of intestinal damage called environmental enteropathy (EE), thought to be common in developing nations. The group built a strategy to test this.
Characterised by inflamed small intestines, resulting in faulty nutrient absorption, EE is believed to result out of repeated exposure to harmful pathogens. In low-income countries, where sanitation is often inadequate, EE is thought to be pretty common, but being a subclinical disease, it does not always show symptoms and hence has proved difficult to study.
The only foolproof way to identify EE patients would be via a biopsy, but since invasive techniques are not an option for large-scale studies on young subjects, the investigators made do with what they felt was the next best thing. The scientists of the Performance of Rotavirus and Oral Polio Vaccines in Developing Countries (PROVIDE) study diagnosed EE based on whether certain compounds were present in the subjects’ stool samples. These compounds, or biomarkers, have shown to be indicative of intestinal inflammation.
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