What is Chagas Disease?
Chagas disease, also known as American Trypanosomiasis, is a serious illness which could be life-threatening. It’s caused by the Trypanosoma cruzi parasite. Chagas disease is most common in Central and South America, Trinidad, and the southern parts of the United States. However, it’s less common outside of rural areas, typically occurring where particular insects are found mostly, in poorly built houses or shacks.
This disease is spread by insects known as triatomine bugs, often called “kissing bugs.” The bugs pick up the parasite when they feed on an infected person or animal. They then spread the disease to people by leaving feces or urine on the skin after biting them. Other ways that people can catch Chagas disease include getting a blood transfusion or organ transplant from someone who’s infected, or by consuming food or drinks that have been contaminated with the parasite.
Severe complications of this disease can include an enlarged heart (cardiomegaly), digestive disease, and in some cases damage to the nerves in the arms and legs (peripheral neuropathy).
What Causes Chagas Disease?
Chagas disease is a type of illness that is usually spread through contact with the waste of a certain type of insect known as the reduviid bug, kissing bug, or triatomine bug. This bug carries a harmful parasite named Trypanosoma cruzi, which is what actually causes the disease. At present, there are 11 different species of this bug. If you live in the southern part of the United States, the most common species are Triatoma sanguisuga and Triatoma gerstaeckeri. On the other hand, if you reside in Mexico, Central America, or South America, you will likely encounter Rhodnius prolixus and Triatoma dimidiata.
Both male and female reduviid bugs get their nutrition from blood, but mostly at night. However, only the female bugs need blood to lay their eggs. As they eat or afterwards, they pass their waste near mucus-coated surfaces, usually the mouth or eyes. The parasites that cause the disease are in the waste and they can enter a person’s body through thin tissues, like the eyes or mouth, or through a wound from an insect bite. The waste of infected reduviid bugs contain the most of the harmful form of the parasite, which can make people sick.
There are also other ways you can get Chagas disease. These include:
- From mother to baby during pregnancy, which leads to what is called congenital Chagas disease.
- Through organ transplants.
- By receiving infected blood and blood products during a transfusion.
Risk Factors and Frequency for Chagas Disease
Chaga’s disease is a common health issue in Latin America, ranging from the southern United States to northern parts of Argentina and Chile. However, as people are moving from these areas, the disease’s spread is changing. Domestic and wild animals often carry the parasite that causes the disease. The primary way the disease is transmitted is through bugs that can often be found in home cracks or in low-quality houses made from materials like mud, straw, or palm thatch. The disease can also be found in outdoor animal nests.
- The disease used to be transmitted via blood transfusions (prior to 2007),
- It can be passed from a mother to her child,
- It can be transmitted in labs, and
- It can be passed on through organ transplants from infected people.
Children are the ones most frequently affected by the disease, followed by women, and then men.
Signs and Symptoms of Chagas Disease
Chagas disease, caused by an infection, has three phases and its symptoms can vary greatly. Initial signs can include eye inflammation or a symptom called Romana’s sign. This involves swelling and redness in one eye, also known as “Chagoma”. This acute phase happens for about two months after getting infected.
- Fever
- Swelling
- Enlarged lymph nodes
- Anemia
- Enlarged liver and spleen
- Abnormalities in electrocardiogram (ECG)
- Problems in the central nervous system
In some severe cases, the disease could be fatal during this phase. After the acute phase, the disease goes into an indeterminate phase where there are no symptoms.
In the chronic phase, about 30% of patients may have heart problems and 10% may have issues with their gastrointestinal tract. At this point, they might have:
- Fever
- Enlarged heart
- Apical aneurysms (bulging of the top part of the heart)
- Abnormalities in electrocardiogram (ECG)
- Megaesophagus (enlarged esophagus)
- Megacolon (abnormally dilated and lengthened colon)
- Constipation
These occur because of damage to the nerve cells in the heart and gut.
Testing for Chagas Disease
When a person is in the early stages of a parasitic infection, doctors can often see the parasite under a microscope by examining a fresh sample of blood that has been treated so it doesn’t clot. But after about three months, the number of parasites in the blood can decrease to the point that they’re hard to detect with a microscope. As the disease moves from the beginning “acute” phase to the longer-lasting “chronic” phase, the test becomes less reliable.
An alternative test uses a technique called Polymerase Chain Reaction (PCR) which can identify the presence of the parasite in the blood. This is very useful in monitoring people who’ve recently had an organ transplant or could have been accidentally exposed to the parasite. PCR tests can show positive results before the parasite can be detected in a blood smear test.
In cases where the disease has become chronic, the body will start producing IgG antibodies against the parasite. Detecting these antibodies can help confirm that a chronic infection is present.
A chest x-ray can also be used to detect any involvement of the heart, revealing an enlarged heart if the disease has affected it.
Electrocardiogram (ECG) findings can show specific changes in the heart’s electrical activity. These may include blocks in the electrical pathways of the heart, especially the ones on the right side and/or the front part of the left side. They may also indicate diffuse disruptions in the ST-T segment of the ECG, an important part of the electrical signal that makes the heart pump blood.
Treatment Options for Chagas Disease
If someone has Chagas disease, the first line of treatment is usually nifurtimox and benznidazole. These two medicines work pretty well in more than 80% of people during the early stage of the disease. However, they may not be effective against a specific phase of the disease, known as the amastigote stage.
If the disease is already in a chronic phase and has started to affect specific organ systems, things work a little bit differently. In this case, the treatment will focus on helping to manage and alleviate the symptoms that are being caused by the damage in these specific organs. This is often referred to as supportive therapy because it supports the body in areas where it’s struggling, rather than trying to destroy the disease.
What else can Chagas Disease be?
There are various conditions that can present with similar symptoms that doctors must consider when making a diagnosis. These conditions include:
- Oesophageal motility disorders
- Oesophageal rupture
- Oesophagal spasm
- Esophagitis
- Gastroesophageal reflux disease
- Leishmaniasis
- Malaria
- Meningitis
- Myocardial infarction (heart attack)
- Myocardial rupture