History and Geography

Chagas' disease is unusual in that its etiological agent, vector, and the major features of its epidemiology were described before the first human case was ever reported. All this was done by Carlos Chagas, a Brazilian physician, in a series of publications beginning in 1909, with the result that the disease appropriately bears his name.

The illness, however, is not new. Studies undertaken of mummies from the Tarapaca Valley in northern Chile have revealed megacardia, megacolon, and megaesophagus in a number of individuals who lived more than 2,000 years ago, and although the etiological agent was not discovered, the valley today is an endemic area of Chagas' disease (see Figure VIII.25.1).

According to L. J. da Silva (1985), nineteenth-century visitors to Brazil reported instances of megaesophagus and the presence of the cone-nosed bug vectors of Chagas' disease. Most interesting is the case of Charles Darwin, who wrote that he was bitten by a huge Triatoma carrier of the infection while in South America. Frank Burnet (1962) reported that Darwin's mysterious chronic illness, from which he always suffered, dated from this time, and cited a distinguished protozoologist who believed that Darwin was infected with Chagas' disease.

The disease, although similar to the African form

Figure VIII.25.1. Megaesophagus from a case of possible Chagas' disease from the Tarapaca Valley in northern Chile (c. third century A.D.). (From author's original slide.)

of trypanosome disease (sleeping sickness), most likely had an independent evolutionary journey. Its cradle is believed to be the Bahia-Minas-Gerais area of Brazil, although as noted previously it has subsequently spread throughout the Americas and has a notable presence in Argentina. In fact, it was in that country that a systematic study carried out by S. Mazza and colleagues (1941) established that the disease was much more widespread than previously believed and stimulated other such studies, all of which led to the recognition that Chagas' disease was a serious health threat to South America. It would seem to be a growing threat as well. Since the 1950s, the illness has become increasingly common in the Arequipa area of southern Peru, although the vector (called "chirimacha") is known throughout all of Peru.

Marvin J. Allison

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