American Trypanosomiasis

What is it?

It is an infectious disease caused by a parasite protozoan called Trypanosoma cruzi, named after the Brazilian scientist Carlos Chagas, who discovered it, in honor to another scientist, Oswaldo Cruz, also Brazilian.

How is it acquired?

When the Trypanosoma enters the blood of humans through the bite wound of the triatomine, the popular blood-sucking bugs. These triatomines feed on blood and infect themselves with the parasite when they suck the blood of infected mammals that are the natural reservoir hosts (cattle, for example), or even other infected. Once in the digestive tube of the bug, the parasite is eliminated with the feces at the insect bite, when they suck the blood of humans, who are thereby infected. Other forms of contact occur during intrauterine life with infected pregnant women, blood transfusions or accidents with puncturing instruments by health professionals in laboratories, the latter two alternatives being far rarer.

What does one feel?

The disease has an acute phase and another chronic one. At the bite site by the vector (agent that transmits the disease, in this case, the bug), the area becomes red and hardened, constituting/making what is called a chagoma, name given to the lesion caused by the Trypanosoma. When this lesion occurs near the eyes, it takes the name of Romaña’s sign. The chagoma is usually followed by swollen glands near the affected area.

After a variable incubation period ( without any symptoms), but not less than one week, fever occurs, swollen glands all over the body, enlarged liver and spleen, and skin redness similar to an allergy that lasts a short time. During this phase, in more severe cases, an inflammation of the heart may develop, with alterations of the electrocardiogram and the number of heartbeats per minute increased. Still, in more severe cases, symptoms of inflammation of the protecting layers of the brain (meningitis) can occur and inflammation of the brain (encephalitis). Fatal cases are rare, but when they do occur it is at this phase as a consequence of heart or brain inflammation. Even without treatment, the disease becomes milder and the symptoms disappear after some weeks or months. The infected individual may be without symptoms for many years or even for life, with infection being detectable only by means of laboratory tests. Unlike the acute phase, the detection of the parasite in the blood now becomes quite difficult, although the presence of antibodies against the parasite is still high, denoting active infection.

During the chronic phase of the disease, the manifestations are related to disease of the heart muscle, that is, irregular heartbeats (arrhythmia), loss of the heart's pumping capacity, progressively, until it eventually causes fainting and may still develop into fatal cardiac arrhythmia. The heart can get very enlarged and have its function impaired. Other manifestations of this phase can be an enlarged esophagus and colon, causing difficulties in swallowing, chocking and pneumonia by aspiration, as well as chronic constipation and abdominal pain.

More recently, the association of the Chagas disease with AIDS or other states of immunosuppression has shown forms of severe exacerbation unknown until now, such as the development of the neurological conditions related to the inflammation of the layers that coat the brain (meningitis).

How do we make the diagnosis?

Suspicion should always be raised when an individual who has been to an endemic area and presents compatible symptoms. Tests for detection of antibodies to Trypanosoma in the blood, more commonly, as well as the detection of the parasite itself in the blood, at the more acute phases, make the diagnosis.

How do we treat it?

The medication used in Brazil the benznidazole, which has proven to be very toxic, especially due to length of the treatment that can take from three to four months. Its use has proven beneficial during the acute phase. During the chronic phase, the treatment is directed to the manifestations. The decreased capacity of the heart function is treated as in the failure of this organ due to other causes, and may, in some cases, even require the need of a transplant.

How to prevent it?

Basically, by the elimination of the vector bug through measures that make less favorable their survival near humans, for example the construction of better dwellings.