Forgotten People, Forgotten Diseases. Peter J. Hotez

Forgotten People, Forgotten Diseases

Forgotten People, Forgotten Diseases - Peter J. Hotez

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infections, perceived ill health and access to health care among poorer and less poor schoolchildren of rural Côte d’Ivoire. Trop Med Int Health 10:42–57.

      chapter 3

      Schistosomiasis (Snail Fever)

      Welcome the sunrise, come under the stars, work from dusk to daybreak

       Our strength is boundless, our enthusiasm is redder than fire . . .

       Be the river like a sea, drained clean it shall be . . .

       Empty the rivers to wipe out the snails, resolutely to fight the big-belly disease.

      WEI WEN-PO,1958

      Schistosomiasis is a waterborne parasitic worm infection affecting up to 400 to 600 million people in developing countries.1 More than 90% of the cases occur in Africa, and today schistosomiasis is one of the most common parasitic infections in Africa. An additional 1 to 2 million cases each also occur in the Americas (primarily in Brazil) as well as in the Middle East (primarily in Yemen), and there are approximately 1 million cases of Asian schistosomiasis in China, the Philippines, and Southeast Asia (Fig. 3.1).1 Unlike the soil-transmitted helminths, which are nematodes, the schistosomes are a type of flatworm, also known as a trematode or fluke. As adult worms, schistosomes live in the bloodstream (and are known also as blood flukes), where they release eggs armed with a spine that produce serious disease either in the urinary tract or in the intestine and liver, depending on the particular species of parasite. Humans acquire schistosomiasis by direct contact with the larval stages (known as cercariae) that swim in freshwater. Prior to becoming cercariae, the immature developing and reproducing forms of these parasites spend a part of their life history living in various species of aquatic snails.

      Few other infectious diseases have influenced history more than schistosomiasis has. Joshua’s curse and the abandonment of Jericho have been attributed to the disease.2 Schistosomiasis was well known to the ancient Egyptians, and it was a major scourge of Napoleon’s army during its disastrous military campaign in Egypt between 1798 and 1801.2 However, some of the most dramatic examples of the schistosome’s historical impact draw from postrevolutionary China during the second half of the 20th century. Shortly after the Chinese revolution in 1949, Mao Zedong (Mao Tse-tung) began planning a massive amphibious assault to bring Taiwan (then known as Formosa) under Communist control. While undergoing rigorous water training around the eastern tributaries of the Yangtze River, tens of thousands of People’s Liberation Army (PLA) troops were exposed to the infectious cercariae of Schistosoma japonicum, the parasitic larvae that live in the water and are shed by snails living in the wet mud along the riverbanks. Within weeks, tens of thousands of soldiers experienced the early acute phase of schistosomiasis, a condition known as Katayama syndrome, which can last for weeks and is characterized by fever, extreme fatigue, muscle pains, and coughing.3 As a result, the launch of the amphibious attack was delayed just long enough for the U.S. Seventh Fleet to enter the Strait of Formosa and abort a Communist takeover. These events are described in a 1959 Harper’s Magazine article titled “The Blood Fluke That Saved Formosa.”4

      Figure 3.1 Distribution of schistosomiasis, worldwide, 2009. (See http://gamapserver.who.int/mapLibrary/Files/Maps/Global_schistosomiasis_2009.png [© 2010 WHO].)

      Undoubtedly, the derailment of the PLA by a blood fluke transmitted by a snail made a deep impression on the Chinese Communist Party leadership. Beginning in 1955 on the order of Chairman Mao, a special nine-man committee on schistosomiasis was established and a seven-year plan for the eradication of the disease was launched.5 In 1958, beginning with the Great Leap Forward, millions of peasants were mobilized to the Yangtze River valley, where they drained the marshes and buried the “devil snails” under dirt or, in some cases, removed the snails individually with sticks.6 The quotation in the opening of this chapter is from a 1958 paper written by Wei Wen-po (the second-in-command of the nine-man committee) that appeared in the Chinese Medical Journal under the title “The People’s Boundless Energy during the Current Leap Forward.”7 Later, chemical agents to kill the snails were applied. Such low-technology interventions directed at snail control had an important impact and helped to reduce the overall prevalence of schistosomiasis from 12 million or more cases before the revolution to approximately 1.6 million cases by the mid-1980s.6 Mao himself wrote a poem about these successes entitled “Farewell to the God of Plague.” Today, there is a new concern that the completion of

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