The cause of Chagas disease is the parasite Trypanosoma cruzi, which is spread from an insect known as the triatomine bug, or "kissing bug." These insects can become infected by this parasite when they swallow blood from an animal that is infected with the parasite.
Triatomine bugs live primarily in mud, thatch or adobe huts in Mexico, South America and Central America. They hide in crevices in the walls or roof during the day and come out at night — often feeding on sleeping humans.
Infected bugs defecate after feeding, leaving behind parasites on the skin. The parasites can then enter your body through your eyes, mouth, a cut or scratch, or the wound from the bug's bite.
Scratching or rubbing the bite site helps the parasites enter your body. Once in your body, the parasites multiply and spread.
You may also become infected by:
- Eating uncooked food contaminated with feces from bugs infected with the parasite
- Being born to a person who is infected with the parasite
- Getting a blood transfusion or an organ transplant from someone who was infected with the parasite
- Being accidentally exposed to the parasite while working in a lab
- Spending time in a forest that contains infected wild animals, such as raccoons and opossums