Distribution and Incidence

The earliest global survey of hookworm distribution was conducted in 1910, in preparation for a campaign against hookworm disease carried out by the Rockefeller Foundation. Responses from 54 countries led to a preliminary description of a "hookworm belt" girdling the Earth between 30° south latitude and 36° north. Another survey conducted at the same time estimated that 40 percent of the inhabitants of the southern United States suffered in varying degrees from hookworm infection. The larvae prefer shade, and light sand or loam soils. They thrive in the southeastern coastal plains of the United States, but not in the Piedmont clays. Although infection has not been eliminated in the United States, the public health menace of hookworm disease has disappeared, only in part because of the earlier treatment and control programs, but largely as an incidental consequence of the concentration of the population in cities and towns with sewer systems, and the general improvement in sanitary conditions and the standard of living for those remaining on the farms. Likewise in Europe and the United Kingdom, where the disease was sometimes found in mines, hookworm infection is no longer a problem. In Japan as well, rising living standards and antihookworm campaigns have eradicated the disease.

It is still, however, a chronic fact of life in most of the rest of the regions within the old "hookworm belt." In the Caribbean, Central and South America, Africa, China, India, Southeast Asia, and Oceania, endemic hookworm infection remains widespread and largely untreated. After a flurry of activity in the first three decades of the twentieth century, hookworm prevention and treatment programs have been sporadic and uncoordinated. This recent history of neglect has made it difficult even to estimate the incidence of hookworm disease in areas of the world where hookworm infection is known to be prevalent. A combination of factors helps to explain why hookworm lost the attention it once received from philanthropic organizations and public health agencies. The failure of earlier intensive efforts to make quick, dramatic reductions in the incidence of hookworm infection and hookworm disease led public health officials with limited budgets to conclude that a concentration of resources elsewhere would produce better results. Hookworm infection came to be regarded as a stubborn condition of rural poverty in developing nations. The campaigns of the 1910s and 1920s seemed to demonstrate the futility of treating the condition in a systematic way without major improvements in the general standard of living. Other diseases such as smallpox and malaria were both deadlier and less obviously the consequences of social and economic circumstances beyond the control of public health workers.

Other parasitic diseases for which there are no effective anthelmintics were given research priority and funding, thus distracting workers in developed countries and signaling public health officials in developing countries that hookworms and other soil-transmitted parasites were no longer as important as they once had seemed. Geopolitical factors — the economic depression of the 1930s, the Second World War, the dismantling of the European and American colonial empires, the Cold War, and political instability in many of the countries where hookworm infection is endemic - have also contributed to the reduction of support for elaborate countermeasures.

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