Chagas suspected that the parasite could cause human disease, due to the prevalence of the insect vector in human households and its habit of biting people, so he took blood samples and, on April 23, 1909, discovered for the first time the same "Trypanosoma" parasite in the blood of a 3-year-old girl. He also observed parasitic inclusions in the brain and myocardium that would explain some of the clinical manifestations in diseased people and closed the proposed lifecycle of the parasite by suggesting that the armadillo could be its natural reservoir. To complete his work on the pathology of the new disease, Chagas described 27 cases of the acute form of the disease and performed more than 100 autopsies on patients who exhibited the chronic form.