Oro-facial gangrene (Noma/cancrum oris): Pathogenetic mechanisms

Cancrum oris (Noma) is a devastating infectious disease which destroys the soft and hard tissues of the oral and para-oral structures. The dehumanizin g ore-facial gangrenous lesion affects predominantly children ages 2 to 16 years, particularly in sub-Saharan Africa, where the estimated frequency in some communities varies from 1 to 7 cases per 1000 population. The risk fa ctors are poverty, malnutrition, poor oral hygiene, residential proximity t o livestock in unsanitary environments, and infectious diseases, particular ly measles and those due to the herpesviridae. Infections and malnutrition impair the immune system, and this is the common denominator for the occurr ence of noma. Acute necrotizing gingivitis (ANG) and oral herpetic ulcers a re considered the antecedent lesions, and ongoing studies suggest that the rapid progression of these precursor lesions to noma requires infection by a consortium of micro-organisms, with Fusobacterium necrophorum (Fn) and Pr evotella intermedia (Pi) as the suspected key players. Additional to produc tion of a growth-stimulating factor for Pi, Fn displays a classic endotoxin , a dermonecrotic toxin, a cytoplasmic toxin, and a hemolysin. Without appr opriate treatment, the mortality rate from noma is 70-90%. Survivors suffer the two-fold afflictions of ore-facial mutilation and functional impairmen t, which require a time-consuming, financially prohibitive surgical reconst ruction.