Trypanosomiasis, American / Chagas Disease
Chagas disease is an inflammatory, infectious condition caused by a parasite and which is transmitted to humans through the feces of the infected reduvid bug.
Chagas disease is common in South America, Central America and Mexico, the primary home of the reduvid bug. Chagas disease has also spread to the southern United States in recent years.
Chagas disease, also called American trypanosomiasis, has two phases. During the acute phase, signs and symptoms are often mild. Left untreated, Chagas disease may become chronic, possibly resulting in serious heart and digestive problems.
Treatment focuses on killing the parasite and managing signs and symptoms. You can take steps to prevent the infection.
The cause of Chagas disease is the parasite Trypanosoma cruzi.
T. cruzi is transmitted to humans by various species of bloodsucking insects called "kissing bugs," such as the reduvid bug. These insects become infected by T. cruzi when they ingest blood from an animal already infected with the parasite.
Reduvid bugs live primarily in mud, thatch or adobe huts in South America and Central America. They hide in cracks or crevices in the walls or roof during the day, then come out at night — often feeding on sleeping humans.
When infected reduvid bugs bite humans, they defecate — passing the T. cruzi parasites in their feces. The parasites can then enter your body through your eyes, mouth, a cut or scratch, or the wound from the reduvid bug's bite. The parasites can be helped into these openings if you scratch or rub at the bite site.
You may also become infected from :
- Eating uncooked food contaminated with feces from infected reduvid bugs
- Being born to a woman infected with T. cruzi
- A blood transfusion containing infected blood
- An organ transplant containing infected blood
- Accidental transmission in a laboratory
Risk Factor :
The following factors may increase your risk of getting Chagas disease :
- Living in impoverished rural areas of Central America, South America and Mexico — rarely, cases of Chagas disease are acquired in the southern United States
- Living in a residence that contains reduvid bugs
- Receiving a blood transfusion or organ transplant from a person who carries the infection
It's rare that travelers to the areas at risk in South America, Central America and Mexico contract Chagas disease. However, if you're traveling to these areas for a significant period of time, take precautions to avoid infection with T. cruzi.
When to seek medical advice :
See your doctor if you live in or have traveled to an area at risk of Chagas disease and you're exhibiting the signs and symptoms of the condition, such as swelling at the infection site, fever, fatigue, body aches, rash and nausea.
Chagas disease occurs in two phases: the acute phase and the chronic phase. Symptoms in either phase can range from mild to severe. Many people don't experience symptoms until the chronic stage.
The acute phase of Chagas disease may be symptom-free. When signs and symptoms do occur, they are usually mild and may include :
- Redness and swelling at the site of infection, especially around your eye and eyelid
- Body aches
- Loss of appetite
- Nausea, diarrhea or vomiting
- Swollen glands
- Enlargement of your liver or spleen
The chronic phase of Chagas disease may occur 10 to 30 years after initial infection. In severe cases, Chagas disease symptoms may include :
- Irregular heartbeat
- Inflamed, enlarged heart (cardiomyopathy)
- Congestive heart failure
- Difficulty swallowing due to enlarged esophagus
- Abdominal pain or constipation due to enlarged colon
Your doctor will conduct a physical exam, asking about your symptoms and any factors that put you at risk of Chagas disease.
If you have the signs and symptoms of Chagas disease, blood tests can confirm the presence of the T. cruzi parasite or the proteins that your immune system creates (antibodies) to fight the parasite in your blood.
If you're diagnosed with Chagas disease, you'll likely undergo additional tests to determine whether the disease has entered the chronic phase and caused heart or digestive complications. These tests may include :
- Electrocardiogram, a procedure that records the electrical activity of your heart
- Abdominal X-ray, a procedure that uses radiation to capture images of your stomach, intestines and colon
- Upper endoscopy, a procedure in which you swallow a thin, lighted tube (endoscope) that transmits images of your esophagus onto a screen
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 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, distension and severe constipation.
Treatment for Chagas disease focuses on killing the parasite and managing signs and symptoms.
During the acute phase of Chagas disease, the prescription medications benznidazole and nifurtimox may be of benefit. Both drugs are available in the regions most affected by Chagas disease. In the United States, however, benznidazole is not available and nifurtimox is currently undergoing clinical trials. Nifurtimox is available from the Centers for Disease Control and Prevention when necessary.
Once Chagas disease is in the chronic phase, medications aren't effective for curing the disease. Instead, treatment depends on the specific signs and Symptoms:
- Heart-related complications. Treatment may include medications, a pacemaker or other devices to regulate your heart rhythm, surgery, or even heart transplant.
- Digestive-related complications. Treatment may include diet modification, medications, corticosteroids or, in severe cases, surgery.
If you live in an area that increases your risk of Chagas disease, these steps can help you prevent infection :
- Avoid sleeping in a mud, thatch or adobe house, if possible. These types of residences are more likely to harbor reduvid bugs.
- Use netting over your bed when sleeping in thatch, mud or adobe houses.
- Use insecticides to remove insects from your residence.
If you need a blood transfusion, make sure the blood you get is tested for Chagas disease. In Central America and South America, blood donors are routinely screened for exposure to T. cruzi. In the United States, this is less common. However, due to the recent introduction of Chagas disease to the United States, the Food and Drug Administration has approved a test to screen blood donors for T. cruzi.