Chagas disease is common in places where the triatomine bug transmits the parasite Trypanosoma cruzi. These places include South America, Central America and Mexico.The disease can be mild, causing swelling and fever, or it can be long lasting. Left untreated, it can cause congestive heart failure. Treatment for Chagas disease focuses on taking medication that kills the parasite and on managing symptoms.Treatment. To kill the parasite, Chagas disease can be treated with benznidazole and also nifurtimox. Both medicines are nearly 100% effective in curing the disease if given soon after infection at the onset of the acute phase including the cases of congenital transmission.