The highest rates of under-five mortality due to diarrhoea were in sub-Saharan Africa and South Asia, with India and Nigeria combined registering 42 per cent of the 499,000 global under-five deaths due to diarrhoea in 2015, according to medical journal 'Lancet'.
"Diarrheal diseases disproportionately affect young children," said lead author Dr Ali Mokdad, of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.
Globally, diarrhoea is the fourth biggest killer of children under the age of five, while India is its third biggest victim.
According to the analysis by US researchers, about half of the all under-five deaths occur in only five countries - India, Nigeria, Pakistan, Democratic Republic of the Congo and China.
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Over 100,000 deaths of under-fiver-year-old children have been reported due to diarrhoea in 2015.
While overall diarrhoea deaths in children under the age of five dropped by 34.3 per cent globally between 2005 and 2015, in India the rate of reduction was at 43.2 per cent.
The number of under-five deaths in India declined from 3.33 million in 1990 to 1.34 million in 2013.
The number of under-five deaths worldwide has declined from 12.7 million in 1990 to 6.3 million in 2013, the study based on data from the 'Global Burden of Disease Study 2015' found.
However, diarrhoea is still the fourth-biggest killer of children globally, with almost 500,000 a year dying before their fifth birthday.
The 'Lancet' study said that better access to clean water and sanitation is the key, with fewer weak and malnourished children becoming infected.
Diarrhoea is also indirectly responsible for large numbers of deaths by exacerbating the effects of other diseases, such as pneumonia and measles.