Chagas Disease - Trypanosoma Cruzi Mnemonic for USMLE

Trypanosoma cruzi is a flagellated protozoa, which is a unicellular eukaryotic organism.

Transmission occurs via the bite of a triatomine bug, also called the kissing bug, which deposits feces on the surface of the skin and then subsequently bites the area. Triatomine bugs are a subfamily of the Reduviidae bugs. The bite of a triatomine bug is classically painless. Following the bite, the human host scratches the area which facilitates penetration of the parasite.

Transmission occurs via the bite of a triatomine bug, also called the kissing bug, which deposits feces on the surface of the skin and then subsequently bites the area.

The bite of triatomine bugs is typically painless.

T. cruzi is most common in Central America and South America. It is estimated that as many as 11 million people in these regions have Chagas disease, although some may be asymptomatic.

Chagas disease is caused by the parasite T. cruzi. In the acute phase, individuals typically present with localized swelling at the site of entry. Symptoms of the acute phase usually resolve spontaneously but the infection can persist and enter a chronic phase which can cause damage to internal organs like the heart, esophagus, and colon.

The classic marker of acute Chagas disease is Romana's sign which is characterized by swelling of the eyelids near the bite or where bug feces was accidentally rubbed into the eye.

Dilated cardiomyopathy is a disease of the heart in which the heart becomes weakened and enlarged and is unable to pump blood efficiently throughout the body. This is the most common form of cardiomyopathy not due to ischemic causes.

Megacolon is characterized by an abnormal dilation of the colon, typically accompanied by paralysis of peristalsis. Chagas disease can cause megacolon due to damage of Auerbach's plexus in the walls of the intestinal tracts. Destruction of this autonomic nervous system innervation leads to loss of smooth muscle tone and subsequent gradual dilation.

Megaesophagus is characterized by abnormal dilation of the esophagus, typically accompanied by paralysis of peristalsis. Chagas disease can cause megaesophagus due to damage of Auerbach's plexus in the walls of the esophagus. Destruction of this autonomic nervous system innervation leads to loss of smooth muscle tone and subsequent gradual dilation.

Chagas disease can be diagnosed via blood smear with direct visualization of the parasite.

Nifurtimox is a drug commonly used to treat diseases caused by trypanosomes including Chagas disease. This drug is not effective for the symptoms caused by chronic infection. Side effects include skin disorder, brain toxicity, and GI discomfort.

Benznidazole is an antiparasitic medication used to treat Trypanosoma cruzi. It works by producing free radicals, which cannot be detoxified by this particular parasite. Side effects of this medication include rash and nausea.