The cause of Chagas disease is the parasite Trypanosoma cruzi, which is transmitted to humans from a bite from an insect known as the triatomine bug. These insects can become infected by T. cruzi when they ingest blood from an animal already 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, then come out at night — often feeding on sleeping humans.

Infected bugs defecate after feeding, leaving behind T. cruzi 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 T. cruzi-infected bugs
  • Being born to a woman infected with T. cruzi
  • Having a blood transfusion containing infected blood
  • Getting an organ transplant containing viable T. cruzi
  • Working in a laboratory where there's an accidental exposure to the parasite
  • Spending time in a forest that contains infected wild animals, such as raccoons and opossums
  • Being around an infected pet
Jun. 07, 2014

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