Huang zhong bing, the “yellow puffy disease” caused by parasitic hookworms living in the human small intestine, was common throughout pre-liberation China. Hookworms contributed significantly to the nation's reputation as the sick man of Asia. However, even today China has the world's greatest number of cases of human hookworm infection. From estimates based on diagnostic surveys obtained during the early 1990s on over one million patients, there are approximately 194 million Chinese infected with hookworm. Most of these infections occur among the rural poor in the south and south-west. Even more recent data obtained in 1997 and 1998 indicate that hookworm remains a major public health problem in Hainan, Sichuan and Yunnan provinces. Populations of the elderly and middle-aged women are emerging as the groups now at greatest risk for acquiring hookworm. New evidence indicates that in addition to threatening health, hookworms also contribute significantly to economic under-development. Hookworms are a living reminder of China's often-forgotten rural southern poverty and a rapidly growing urban–rural inequality; they are an impediment to China's future economic growth.