It is estimated that between 576 and 740 million individuals are infected with hookworm. Of these infected individuals, about 80 million are severely affected. The major cause of hookworm infection is "N. americanus" which is found in the Americas, sub-Saharan Africa, and Asia. "A. duodenale" is found in more scattered focal environments, namely Europe and the Mediterranean. Most infected individuals are concentrated in sub-Saharan Africa and East Asia/the Pacific Islands with each region having estimates of 198 million and 149 million infected individuals, respectively. Other affected regions include: South Asia (50 million), Latin America and the Caribbean (50 million), South Asia (59 million), Middle East/North Africa (10 million). A majority of these infected individuals live in poverty-stricken areas with poor sanitation. Hookworm infection is most concentrated among the world's poorest who live on less than $2 a day.