Chagas disease can cause a sudden, brief illness (acute), or it may be a long-lasting (chronic) condition. Symptoms range from mild to severe, although many people don't experience symptoms until the chronic stage.

Acute phase

The acute phase of Chagas disease, which lasts for weeks or months, is often symptom-free. When signs and symptoms do occur, they are usually mild and may include:

• Swelling at the infection site
• Fever
• Fatigue
• Rash
• Body aches
• Eyelid swelling
• Headache
• Loss of appetite
• Nausea, diarrhea or vomiting
• Swollen glands
• Enlargement of your liver or spleen

Signs and symptoms that develop during the acute phase usually go away on their own. If left untreated, the infection persists and, in some cases, advances to the chronic phase.

Chronic phase

Signs and symptoms of the chronic phase of Chagas disease may occur 10 to 20 years after initial infection, or they may never occur. In severe cases, however, Chagas disease signs and symptoms may include:

• Irregular heartbeat
• Congestive heart failure
• Sudden cardiac arrest
• Difficulty swallowing due to enlarged esophagus
• Abdominal pain or constipation due to enlarged colon

The cause of Chagas disease is the parasite Trypanosoma cruzi, which is transmitted 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

The following factors may increase your risk of getting Chagas disease:

• Living in impoverished rural areas of Central America, South America and Mexico
• Living in a residence that contains triatomine bugs
• Receiving a blood transfusion or organ transplant from a person who carries the infection

It's rare for travelers to the at-risk areas in South America, Central America and Mexico to contract Chagas disease because travelers tend to stay in well-constructed buildings, such as hotels. Triatomine bugs are usually found in structures built with mud or adobe or thatch.

If Chagas disease progresses to the chronic phase, serious heart or digestive complications may occur. These may include:

• Heart failure. Heart failure occurs when your heart becomes so weak or stiff that it can't pump enough blood to meet your body's needs.
• Enlargement of the esophagus (megaesophagus). This rare condition is caused by the abnormal widening (dilation) of your esophagus, which can result in difficulty with swallowing and digestion.
• Enlargement of the colon (megacolon). Megacolon occurs when your colon becomes abnormally dilated, causing abdominal pain, distention and severe constipation.