Noma is a devastating gangrenous disease that leads to severe tissue destructions in the face. It is seen almost exclusively in children living in less developed countries. The exact prevalence of the disease is unknown and the cause remains unknown too. Risk factors are: malnutrition, a compromised immune system, poor oral hygiene and a lesion of the gingival mucosal barrier, as well as an unidentified bacterial factor. Herpes viruses might also contribute. Studies of the buccal flora in acute phases of noma and comparison with control children do not exist. Our study takes place in Niger. For each child (cases and controls) we take samples of gingival fluid, saliva, blood and mouth mucosal swabs. The samples are analysed in Geneva in different laboratories. We control the serologies for Herpes viruses and measles. We also perform a nutritional assessment and the mucosal swabs are cultivated for the presence of viruses. The gingival flora is investigated by microarrays. These microarrays are instrumental to test for the presence of thousands of different bacteria in each clinical sample. This method allows a qualitative and quantitative description of the oral flora in noma-children and control cases. This is the first large scale study on the etiology of noma which uses new technical approaches for humanitarian purposes.