As many as four in five victims die from the gangrenous infection, while survivors are left with yawning holes in their faces -- unable to eat, speak, smile or breathe normally again.

"We are bringing this scourge -- unacceptable in the 21st century -- out from the shadows," Bertrand Piccard, president of the International NoNoma Federation, told an experts' meeting.

Noma is directly linked to malnutrition and poor hygienic conditions, but if caught early can be treated with disinfecting mouthwash and vitamins, as well as antibiotics.

The disease symbolises the gap between extravagant consumer societies and starving populations, according to Piccard, a Swiss psychiatrist best known as the first hot-air balloonist to circle the globe with Briton Brian Jones in 1999.

The devastating necrosis starts as a benign lesion in the mouth, often as gingivitis. Left untreated it quickly devours the soft and bone tissues of the face, disfiguring its victims who are almost always very young children.

Sub-Saharan Africa is the epicentre of the disease, which also affects parts of Asia and Latin America.

Luis Gomez Sambo, WHO's regional director for Africa, said that 22 countries on the continent had cases of Noma. The United Nations agency is able to support national prevention programmes in 12 of them, with a meagre budget of $2.5 million over five years, but needs more funds, he said.

"The world has no excuse to remain passive against this disease which disfigures victims beyond recognition. They go through psychiatric trauma for the rest of their lives," Sambo told the talks.

Razak Zampaligre and Soare Ouango, from Burkina Faso, are among the luckier Noma victims. Both men survived and underwent reconstructive surgery but still bear scars.

Zampaligre, who developed Noma as a two-year-old, recalls being "an object of mockery" as a child because of his deformed right eye. With the help of the foundation "Hymne aux Enfants", he was operated on in Switzerland as a teenager in 2000-01.

"It is a great joy for me to see that people are interested in this disease and are working to stop it," he said.