Chagas Disease (American Trypanosomiasis)


Article Author:
Tina Nguyen


Article Editor:
Muhammad Waseem


Editors In Chief:
Silvio de Melo Jr.
Vittorio Giuliano
Truptesh Kothari


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
3/13/2019 4:26:03 PM

Introduction

American Trypanosomiasis, also known as Chagas disease, is a potentially life-threatening zoonotic illness caused by the parasite Trypanosoma cruzi. The disease is most commonly seen in Central and South America, Trinidad, and the southern United States. However, it is less common outside of rural areas where vectors are commonly found in rustic housing. The vector-borne disease is transmitted through vertical transmission between mother and fetus or via contact with contaminated feces/urine of the reduviid bug (triatomine bug, kissing bug) and hence serves as the intermediate host for the parasite. Other modes of transmission include transfusion of blood products, transplant of the infected organ, or by consumption of infected food or drinks. Major complications of this disease includes cardiomegaly, gastrointestinal disease, and in some case peripheral neuropathy.[1]

Etiology

Chagas disease is a vector-borne disease commonly transmitted through contact with contaminated feces/urine of the reduviid bug, also known as the kissing bug or triatomine bug. It is this insect which in turn carries the causative agent, the parasite Trypanosoma cruzi. Currently, there are 11 different species of the triatomine bug. The most common species in the southern United States are Triatoma sanguisuga and Triatoma gerstaeckeri. The main vectors for Mexico, Central, and South America are Rhodnius prolixus and Triatoma dimidiata. Both sexes of reduviid bug take its blood meal at night, but female bugs must take blood meals to lay their eggs. As it takes the meal or even after the meal, they defecate and expels parasites in the feces/urine near mucous membranes, commonly the mouth or eyes. The parasite then enters through the mucous membrane, or through an open bite wound. Feces of infected reduviid bugs carry the largest number of the infectious trypomastigote form.[2]

Other mode transmissions include:

  • Vertical transmission from mother to fetus leading to congenital Chaga's disease
  • Organ transplantation
  • Transfusion of blood and blood products

Epidemiology

Chaga's is endemic in Latin America, from the southern United States to northern Argentina and Chile[3]. However, the distribution of the disease is changing due to the relocation of individuals from the endemic countries. Domestic and wild mammals are a common host for this parasite. The major route of transmission occurs through infected reduviid bugs, which can be found in cracks indoors or the roofs of substandard housing made from mud, straw or palm thatch. Outdoor locations include animal nests. Other modes of transmission include blood transfusion (before 2007), vertical transmission from mother to child, laboratory transmission, and organ transplant from infected patients. Children are most commonly affected, followed by women, then men.

Pathophysiology

After the parasite enters through an open wound or mucous membrane, the infectious trypomastigote is found in the bloodstream plasma. The amastigote stage of the parasites is found inside pseudocysts located in muscle or nerve cells. There is a predilection for the myocardium or myenteric plexus of the gastrointestinal tract, where it replicates by binary fission. There are three phases of the disease: acute, indeterminate and chronic. In acute infection, symptoms can occur immediately following infection and can last approximately 2 months. Chronic infections can last for years.

Histopathology

T. cruzi, in its leishmanial form, enters macrophages through phagocytosis and initially lack flagella. Then it multiplies in the cytoplasm. As it transverses the gastrointestinal tract, it becomes flagellated in the midgut. Finally, it becomes the infective form in the hindgut. Leishmanial forms can be seen on fixed macrophages with aspiration from spleen, lymph node, bone marrow, or liver. Leishmanial forms can also be seen in rows or cyst-like dilation within the myocardial fiber.

Acute phase: can last from 8 to 12 weeks due to the circulation of the trypomastigotes. Histologically the primary lesion has numerous histiocytes, inflammatory cells, and areas of fat necrosis. Multiplication occurs in nearby macrophages and will cause invasion of smooth and cardiac muscles, glial cells, neurons, and fat cells.

Chronic phase: usually start with an indeterminate form for the first 10 to 30 years of the phase, where the patient will have positive serology but will be asymptomatic. Eventually, progresses to determinant form which may involve the heart and gastrointestinal tract. 

Heart disease: generalized hypertrophy and dilation, mural thrombus commonly seen in the right auricle and apex of the left ventricle. Microscopically will show chronic fibrosis, focal area of necrosis and granular degeneration, and interfibrillar edema.

Gastrointestinal (GI) disease: megacolon and megaesophagus due to fibrosis and degeneration of autonomic ganglia in the myenteric plexus.

History and Physical

Intense local inflammation and/or 2 months of uniocular conjunctivitis, known as Chagoma/Romana's sign.

Acute phase lasts for approximately 2 months following infection. May present with fever, edema, lymphadenopathy, anemia, hepatosplenomegaly, ECG abnormalities, central nervous system (CNS) involvement, and death.

Indeterminate phase: Asymptomatic

Chronic phase: Thirty percent of patients may have cardiac involvement and may present with fever, cardiomegaly, apical aneurysms and/or ECG abnormalities. Ten percent of patients may have gastrointestinal tract involvement and may present with fever, megaesophagus, megacolon due to the destruction of myenteric plexus, and constipation.[4]

Evaluation

Diagnosis during the acute phase is made by detecting the parasite microscopically, from a fresh preparation of anticoagulated blood or buffy coat, due to the high level of parasitemia. However, levels may decrease within 90 days of infection and may be undetectable by microscopy, as the sensitivity of the test decreases and as the disease progresses from acute to chronic. Polymerase chain reaction (PCR) is another diagnostic tool that may be used during the acute phase, monitoring for acute infection in organ transplant recipients or following accidental exposures. PCR assays can demonstrate positive results days to weeks before a peripheral blood smear detects circulating trypomastigotes. Detection of IgG antibodies to T. cruzi can be used to demonstrate chronic infections.[5]

A chest x-ray may show heart involvement with cardiomegaly.

ECG findings may include intraventricular blocks, particularly a right bundle branch block and/or on the left the anterior fascicular block and diffuse ST-T changes.

Treatment / Management

Treatments for the Chagas disease include nifurtimox and benznidazole, with more than 80% success during acute phase; but, with no effect on the amastigote stage. Supportive therapy for the chronic phase is dependent on which organ system is involved.

Pearls and Other Issues

There is currently no vaccine for this disease. The main methods for prevention of transmission include education, improved housing, vector control using bed netting, and screening of donated blood and children in endemic areas.

Enhancing Healthcare Team Outcomes

The diagnosis and management of chagas disease is complex and best done with a multidisciplinary team that consists of an infectious disease expert, cardiologist, emergency department physician, gastroenterologist, nurse practitioner and an internist. The disorder is very rare in North America and may be encountered in people visiting the US from South America. The disorder can be treated but most patients have severe residual sequelae. There is currently no vaccine for this disease. [6][7]The main methods for prevention of transmission include education, improved housing, vector control using bed netting, and screening of donated blood and children in endemic areas.[8]


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    Contributed by U.S. CDC
Attributed To: Contributed by U.S. CDC

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Chagas Disease (American Trypanosomiasis) - Questions

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A patient who has just come from a trip to Brazil has been complaining of a low-grade fever, muscle aches, and malaise. A blood smear reveals banana-shaped organisms in the red blood cells. What condition may he have acquired?



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A South American patient is seen at a clinic. He says he has not been feeling well for more than a year. Initially, he had difficulty with swallowing which was relieved with a dose of botulinum toxin. A workup reveals a cardiomyopathy. Which type of cardiomyopathy is associated with his disease?



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What is the most common cause of death in patients with Chagas disease?



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Besides the heart and esophagus, what organ is commonly affected by Chagas disease?



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Which part of the gastrointestinal system is most commonly affected by T cruzi?



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Which of the following is the most appropriate drug for the treatment of Chagas disease?



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A patient recently traveled to South America and now has several skin ulcers. Examination of a smear reveals organisms that have a corkscrew-like appearance. Which of the following is the likely diagnosis?



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A 35-year-old female from Brazil presents to the emergency room with congestive heart failure. She has no significant past medical history. Exam shows heart failure and poor perfusion. ECG shows right bundle branch block and first-degree atrioventricular block. An echocardiogram reveals thinned and dilated ventricles, apical aneurysm, and ventricular thrombus. Cardiac catheterization shows no coronary artery disease. Select the correct statement.



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Which organism causes Chagas disease?



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What is not a characteristic of Trypanosoma cruzi infection?



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The organ most commonly involved in chronic Chagas disease is the:



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The heart in chagas disease is characterized by:



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A 53-year-old male who recently immigrated from Honduras presents to the clinic to establish primary care. He has no complaints at this time and denies any medication use, surgical history or allergies. He states when he was in his early 30’s, he was diagnosed with Chagas disease but never underwent any treatment. Which of the following tests should be considered to screen for the most likely complication of the disease?



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An immigrant from Central America presents to the emergency department with complaints that he has not been feeling well for the past two weeks. He states that he was bitten by an insect while visiting family in Mexico. He has had flu-like symptoms, fever, malaise, anorexia, chills, and a headache for at least 14 days. Physical exam reveals a heart rate of 120 bpm, blood pressure 110/70 mmHg, and temperature 101 F. There is diffuse edema around the upper face. There is a tender reddish nodule on the side of the neck. His WBC is elevated with a relative lymphocytosis. The blood smear is shown below. What study should be ordered next?

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Attributed To: Image courtesy S Bhimji MD



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Chagas Disease (American Trypanosomiasis) - References

References

Padilla N A,Moncayo AL,Keil CB,Grijalva MJ,Villacís AG, Life Cycle, Feeding, and Defecation Patterns of Triatoma carrioni (Hemiptera: Reduviidae), Under Laboratory Conditions. Journal of medical entomology. 2019 Feb 15;     [PubMed]
Martins-Melo FR,Carneiro M,Ribeiro ALP,Bezerra JMT,Werneck GL, Burden of Chagas disease in Brazil, 1990-2016: findings from the Global Burden of Disease Study 2016. International journal for parasitology. 2019 Feb 7;     [PubMed]
Echeverria LE,Morillo CA, American Trypanosomiasis (Chagas Disease). Infectious disease clinics of North America. 2019 Mar;     [PubMed]
Vieira JL,Távora FRF,Sobral MGV,Vasconcelos GG,Almeida GPL,Fernandes JR,da Escóssia Marinho LL,de Mendonça Trompieri DF,De Souza Neto JD,Mejia JAC, Chagas Cardiomyopathy in Latin America Review. Current cardiology reports. 2019 Feb 12;     [PubMed]
Mayta H,Romero YK,Pando A,Verastegui M,Tinajeros F,Bozo R,Henderson-Frost J,Colanzi R,Flores J,Lerner R,Bern C,Gilman RH, Improved DNA extraction technique from clot for the diagnosis of Chagas disease. PLoS neglected tropical diseases. 2019 Jan;     [PubMed]
Romay-Barja M,Boquete T,Martinez O,González M,Álvarez-Del Arco D,Benito A,Blasco-Hernández T, Chagas screening and treatment among Bolivians living in Madrid, Spain: The need for an official protocol. PloS one. 2019;     [PubMed]
Barros F,Soares JCA,Barros FP,Sangenis LHC,Silva GMSD,Fonseca ABM,Hasslocher-Moreno AM,Sousa AS,Saraiva RM,Mediano MFF, Agreement between upper endoscopy and esophagography in the diagnosis of megaesophagus in Chagas disease. Revista da Sociedade Brasileira de Medicina Tropical. 2019 Mar 7;     [PubMed]
Daflon-Teixeira NF,Coutinho C,Gomes TF,Toma HK,Duarte R,Bóia MN,Carvalho-Costa FA,Almeida CE,Lima MM, Multiple Approaches to Address Potential Risk Factors of Chagas Disease Transmission in Northeastern Brazil. The American journal of tropical medicine and hygiene. 2019 Feb;     [PubMed]

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