Chagas’ disease

In 1907 the physician Carlos Chagas (1879-1934) was working in Lassance, a small poverty-stricken town on the Sao Francisco river in the state of Minas Gerais, Brazil. The town had been built along the railway from Rio de Janeiro to Belem. Chagas treated the workmen for injuries, syphilis, malaria etc. He noticed that cardiac arrhythmias occurred frequently. One day an engineer brought him an insect, of the type which was known to often suck the blood of humans at night. Chagas wondered if this creature could also transmit malaria, like the Anopheles mosquitoes. In the bug he discovered a unicellular parasite. In April 1908 he found the same parasite in a sick cat. Two weeks later, in the same house, the parasite was found in the blood of a 3-year-old child (Rita), who was ill with fever. Her face, liver, spleen and lymph nodes were swollen and the child died shortly afterwards. In the house there were countless bugs which tested positive for the parasite. He sent bugs to Rio, to Oswaldo Cruz, his former teacher (Brazilian physician 1872-1917). In the laboratory the parasite caused an infection in marmoset monkeys (Callithrix sp.), rodents and puppies. The disease caused by this parasite, American trypanosomiasis, was named after Chagas. The parasite was given the name Trypanosoma cruzi. The parasite did not always trigger disease, however. In 1908 Chagas also discovered the parasite in another person (Bernice). This woman died in 1989, still infected, but without signs of organ involvement.

The infection apparently already existed before contact with the West. In 1985, 22 mummies were found in the Andes mountains. These were 1500 years old. In approximately half of them the heart, colon and/or oesophagus were clearly enlarged (lesions typical for Chagas’ disease). Trypanosoma cruzi DNA was found in 1999 in a 4000 year-old mummy in Northern Chile. In one of his books Charles Darwin describes how in 1835 in South America he was bitten by the bugs. It is possible that he incurred infection and later developed a chronic form of the disease.

Category: Medicine Notes