Makindo Medical Notes

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Chagas disease was first described in 1909 in Brazil by physician Carlos Chagas. It is an infectious disease caused by the parasite Trypanosoma cruzi, which is found in the faeces of the triatomine (reduviid) bug.

Bug’s kiss Brazil hut
Puffed wink, stuck food, fluid glut
Right bundle branch block
Chagas Disease
Triatomine ‘Kissing’ Bug
@DrCindyCooper

About

• Chagas disease is endemic in South America, causing over 50,000 deaths annually.
• It is caused by infection with the protozoan Trypanosoma cruzi.

Aetiology

• The vector for this infection is the reduviid bug, also known as the "kissing bug".
• Infection occurs when the bug bites an infected animal or person, becoming a carrier of T. cruzi.
• The parasite is passed through the bug’s faeces, entering the human host through mucous membranes or breaks in the skin.
• Reduviid bugs thrive in the walls of houses in impoverished areas, transmitting the parasite through bites.
• Chagas disease can also be spread by blood transfusions and vertical transmission from mother to baby.

Clinical Features

• Acute phase: Non-specific symptoms like aches, fever, headache, rash, vomiting, and diarrhoea. Patients may present with hepatosplenomegaly, lymphadenopathy, oedema, myalgia, and myocarditis. A chagoma (local swelling) may develop at the parasite’s entry site. Romana's sign involves swelling of the eyelids near the site of infection.
• Chronic phase: Often silent for decades, but some patients may develop complications such as dilated cardiomyopathy, heart failure, arrhythmias, and cardiac arrest. Gastrointestinal involvement may lead to mega-oesophagus and megacolon, causing difficulty swallowing and defecating.

Investigations

• FBC, U&E, ESR, CXR, and ECG are used to assess organ involvement.
• Echocardiography may show evidence of cardiomyopathy.
• Barium meal or Endoscopy can reveal achalasia in gastrointestinal cases.
• Blood smear: Detects parasites during the acute phase when they circulate in the blood.
• Serology: Useful for chronic disease with detectable IgG antibodies but not during acute infection.

Management

• Benznidazole or nifurtimox is recommended for acute and early chronic phase infections, or during reactivation in immunosuppressed patients. Treatment is long and can cause side effects.
• For established pathology like cardiomyopathy or megacolon, antiparasitic treatment will not reverse damage, and management focuses on symptomatic relief.
• In cases of cardiomyopathy, rhythm control and anticoagulation are required.
• Mega-oesophagus may be managed with dietary changes and balloon dilation.
• Megacolon: High-fibre diet, fluids, and enemas.

Prevention

• Living in well-constructed homes reduces exposure to triatomine bugs, which are most active at night and infest poorly built dwellings.
• Prevention includes insect repellent, bed nets treated with insecticides, and protective clothing. Travellers should avoid blood transfusions and contaminated food in endemic regions.
• Control measures should focus on preventing transmission through blood transfusion, organ transplantation, and congenital transmission.

Screening for Blood Donors

• People should not donate blood if they were born in South or Central America (including southern Mexico), or if they lived in rural areas for extended periods.
• Blood donation is permissible after at least 6 months of no exposure, provided they test negative for T. cruzi antibodies.

Pregnancy

• Offer serological testing for Chagas disease to at-risk pregnant women and refer positive cases to specialist centres.
• Follow up infants born to seropositive mothers to detect and treat congenital transmission.