The WHO website states:

‘Neglected tropical diseases (NTDs) are a diverse group of communicable diseases that prevail in tropical and subtropical conditions in 149 countries and affect more than one billion people, costing developing economies billions of dollars every year…’

and the CDC website confirms:

‘Neglected Tropical Diseases (NTDs) are a group of parasitic and bacterial diseases that cause substantial illness for more than one billion people globally…. More than 1 billion people—one-sixth of the world’s population—suffer from one or more Neglected Tropical Diseases (NTDs).’

I find this figure surprisingly high, don’t you? I looked in vain for evidence to back it up.

I wrote to WHO who kindly pointed me to two publications on NTDs: