Trypanosoma cruzi (Chagas disease)

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Trypanosoma cruzi (Chagas disease)


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Trypanosoma cruzi (Chagas disease)

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A 30-year-old man comes to the physician for evaluation of fever, headache, and swelling in the right eye. The patient’s symptoms started a few days after he returned from a trip to South America. During the trip, he spent much time hiking outdoors and visiting rural towns. His temperature is 38.5°C (101.3°F), blood pressure is 120/75 mmHg, and pulse is 100/minute. Physical examination reveals swelling in the right orbital region and redness in the conjunctiva. A blood smear is obtained and shown below. If untreated, this patient is at risk of developing which of the following complications?
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External References

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Cardiomyopathy p. 317

Chagas disease p. 155

Chagas disease p. 155

achalasia in p. 385

cardiomyopathy in p. 317

labs/findings p. 720


Chagas disease p. 155


Chagas Disease, also called American trypanosomiasis, is a parasitic disease common in Central and South America, caused by a protozoan called Trypanosoma cruzi or T. cruzi for short.

T. cruzi is transmitted through the feces of the insect triatominae.

Triatominae is a type of reduviid bug also called the kissing bug because it typically bites people on the face as they sleep at night - one heck of a good night kiss, huh?

The disease gets its name from Carlos Chagas, the physician who first described it.

The life cycle of T. cruzi starts with the epimastigote T. cruzi which sits in the lumen of the Reduviid bug’s midgut.

–Mastigote refers to the whip-like structure called a flagellum which protrudes from the center of the T. cruzi and helps it move around.

While in the midgut, the epimastigote multiplies through binary fission.

Over time, the epimastigote transforms into a trypomastigote and at that point it loses its ability to divide, but the trade-off is that it gains the ability to invade human cells.

In fact “trypo” means to bore or punch into.

Reduviid bugs feed off the blood of humans, and they prefer biting a person’s face, which is why they’re also called kissing bugs.

But unlike a normal kiss, the reduviid bug then defecates at the bite site, and if the reduviid bug is infected with T. cruzi, the feces can contain trypomastigotes.

These trypomastigotes can then infect human skin cells at the bite location; or at mucous membranes, particularly the conjunctiva of the eyes.

That can happen if a person unknowingly transfers the trypomastigotes by rubbing the bite site on their face and then touching their eyes.

Once the trypomastigote invades a human cell, it transforms into an amastigote meaning that it loses its flagellum.

The amastigotes multiply intracellularly, again through binary fission, and then transform into blood trypomastigotes which can move through the blood and lymph to other tissues.

The blood trypomastigotes then invade more cells, and then again turn into amastigotes to multiply intracellularly again - and that’s how the cycle goes.

Now, a person infected by a T. cruzi infected reduviid bug, can then get bitten by a brand new reduviid bug.


Trypanosoma cruzi is a parasitic protozoan that causes Chagas disease, a serious illness common in Central and South America. The disease is transmitted to humans through the feces of infected triatomine bugs, commonly known as "kissing bugs," which are found in the walls and roofs of poorly constructed houses in rural and suburban areas.

Symptoms of Chagas disease may include fever, fatigue, body aches, and swelling at the site of infection, followed by more serious complications such as heart disease, digestive problems, and neurological damage as the infection progresses. The disease can be life-threatening if left untreated.

Treatment of Chagas disease typically involves antiparasitic medications, such as benznidazole or nifurtimox, which are most effective in the early stages of the disease. However, these medications may not be effective in treating the chronic form of the disease or in advanced cases.


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