Gut infection can cause vaccine failure

Looking at why providing food is not always enough to treat malnutrition in developing countries, researchers have discovered that damage to the gut from infection can cause malnutrition and vaccine failure.

It has been estimated that if every nutritional measure known to be helpful were applied to every child in the world, global malnutrition would be decreased by only a third, the study said.

"We found that the longer that the child suffered from inflammation, the worse was their nutrition, suggesting that the body's immune response may be the root cause of the problem of malnutrition and a target for prevention," said Bill Petri from University of Virginia School of Medicine in the US.

For the study, the researchers for the last four years have enrolled children at birth and their parents from an urban slum in Dhaka, Bangladesh. The children are visited in their homes twice a week, receive free medical care and are observed for the development of malnutrition. Malnutrition is measured by children becoming stunted or abnormally short for their age.

Despite vaccination, free medical care and nutritional counseling and care, stunting increased from 9.5 per cent at enrollment to 27.6 per cent at one year of age. This demonstrated what has long been known, that malnutrition is extraordinarily difficult to prevent or treat.

"The fact that the infants became malnourished despite our best efforts showed me what a difficult problem this is to solve," Caitlin Naylor from University of Virginia said. The group suspected that food was not being properly digested by the children who were becoming stunted.

"We decided to test to see if damage to their gut from infection was causing malnutrition," Petri said. The researchers found that nearly every child had abnormal results, indicating their guts were damaged.

"Children living in poverty have problems not only with nutrition but with vaccination," Rashidul Haque, director of the field study in Bangladesh, said.

One of the obstacles to the global campaign to eradicate polio has been the relative ineffectiveness of the oral vaccine in developing countries, sometimes necessitating upwards of 10 doses to be effective.

The potentially life-saving rotavirus vaccines also are substantially less effective in these children that need the vaccines the most.

"Since these two vaccines immunise the intestine, we tested if children with the worst gut damage also suffered from vaccine failure," Petri said.

This was found to be the case, demonstrating that a damaged gut caused both malnutrition and oral vaccine failure. (The findings appeared in the journal EbioMedicine.)