More than half of all cases of TB every year could be prevented by ensuring that people get enough in terms of calories and proteins, says the study. Undernutrition is a frequently ignored factor in the fight against the disease.
Researchers from the Himalayan Institute of Medical Sciences, Jolly Grant, Uttarakhand, and McGill International TB Centre, McGill University, Montreal, used data on undernutrition in India from the National Family Health Survey 3 to assess the impact of undernutrition in Indian adolescents and adults on the incidence of TB.
Undernutrition is endemic in India, with 34 per cent men and 36 per cent women in the age group of 15-49 years being undernourished, according to the National Family Health Survey 3 estimates. These groups are up to four times more likely to develop TB than healthy people are, because undernutrition, the leading cause of immunodeficiency globally, weakens resistance to the TB bacillus.
The poorest one-fifth of the population are at greatest risk; women are more at risk than men.
India has the largest number of new cases of tuberculosis (2.3 million annually), and sees the most TB-related deaths in the world (estimated at 320,000 annually). The Revised National Tuberculosis Control Programme has not been able to make a significant impact on the number of new cases, the researchers note. The growing number of drug resistant cases threatens the success of treatment, while an effective vaccine is nowhere in sight.
In India, an estimated 400 million people, a number larger than the entire population of the USA, are infected with the TB bacillus, are asymptomatic but at risk of developing active TB. This infection can be contained if the immune system functions normally, Dr Anurag Bhargava, lead author of the study, told The Indian Express.
Undernutrition, which suppresses the immune system, is the major factor driving the progression of infection in these people to active tuberculosis in India rather than HIV, which accounts for only 7% of new cases, diabetes or smoking. In India endemic undernutrition in adolescents and adults plays a part in sustaining the TB epidemic, similar to that played by the endemic HIV infection in Africa. It is time that undernutrition in adults which is the highest in global terms is now addressed as part of the solution of TB in India, Bhargava said.
- ANURADHA MASCARENHAS