Treatment for a group of "neglected" tropical diseases is required for at least 1.4 billion people and almost two-thirds are going without adequate medical care, said eradication campaigners on Wednesday.
Ailments including intestinal worms, elephantiasis and river blindness -- lumped together as "neglected tropical diseases" (NTDs) -- mostly affect poor people living in remote rural areas, slums or conflict zones.
A new report from the World Health Organisation, released in Paris on Wednesday and supported by billionaire philanthropist Bill Gates, found that 700 million people received some form of treatment for NTDs in 2012.
But many did not complete a full course of drugs, while hundreds of millions received nothing at all.
"We still need diagnostics and we still need drugs," Gates said at the launch of the WHO progress report dubbed "Uniting to Combat NTDs".
The list of NTDs also includes Guinea worm, blinding trachoma, bilharzia, leprosy, Chagas disease and visceral leishmaniasis (black fever).
The diseases are carried by parasites and bacteria that tend to spread in dirty, cramped living conditions with polluted water and poor sanitation.
They "shackle more than a billion people of the world and most of them are women and children," said WHO chief Margaret Chan.
Many of the diseases are treatable and avoidable, yet they kill, impair and disable millions every year.
More than 800 million children live in areas where worms are "intensively transmitted" and are assumed to be infected. That has an impact on their nutrition, education and general health.
"Funding shortfalls and constrained human capacity in many endemic countries continue to limit the scale-up of drug delivery," the report said.
The report said progress was gradually being made, with the pharmaceutical industry donating nearly 1.35 billion doses of treatments last year.
The World Bank Group will commit $120 million (87 million euros) for NTD treatment in low-income African countries, it said in a statement, while a group of donors announced on Wednesday they would give a similar amount to combat intestinal worms in poor communities.