Fig. 4.1
Carlos Chagas (Source: National Library of Medicine)
The disease is caused by the protozoan Trypanossoma cruzy (Fig. 4.2), a flagellated protozoan that is transmitted to humans by a blood-sucking insect (Fig. 4.3). Humans and a large number of species of domestic and wild animals constitute the reservoir, and the vector insect infests houses with thatched walls and roofs (Fig. 4.4). Non-vectorial mechanism of transmission such as blood transfusion, solid organ and bone marrow donation, ingestion of infected food and vertical transmission also play important role in CD’s spread nowadays. Insects of the subfamily Triatomidea act as vectors of protozoan, sheltering trypomastigotes in their digestive system. Humans contract trypanossomiasis when bitten by vector species. The protozoan present in the insect’s stools infiltrates man’s scratched skin or permissive mucosa, where a lymphoreticular response occurs. This local inflammatory response may be clinically apparent as an inoculation chagoma. Circulating forms (trypomastigotes) (Fig. 4.5) are taken to peripheral tissues, such as liver, spleen, lymphatic ganglia, skeletal and heart muscle, where they form pseudocysts of amastigotes (Fig. 4.6). Pseudocysts rupture triggers inflammatory reaction with muscle and neuron cell damage. The inflammatory reaction and cell destruction are maintained by the presence of Trypanossoma cruzy or its fragments and by the DNA of the parasite, with a late hypersensitivity reaction that results in esophageal aperistalsis and dilation [3].
Fig. 4.2
Trypanossoma cruzy. Chagas disease causative parasite (Courtesy: Dr. Clara Lúcia Barbiéri Mestriner. Chair, Department of Parasitology, Federal University of São Paulo, São Paulo, Brazil)
Fig. 4.3
Triatoma infestans. Chagas disease insect vector
Fig. 4.4
A typical thatched house that lodges the insect vector
Fig. 4.5
Circulating blood forms (trypomastigotes) of Trypanossoma cruzy. Chagas disease causative parasite (Courtesy: Dr. Clara Lúcia Barbiéri Mestriner. Chair, Department of Parasitology, Federal University of São Paulo, São Paulo, Brazil)
Fig. 4.6
Trypanossoma cruzy amastigotes (Courtesy: Dr. Clara Lúcia Barbiéri Mestriner. Chair, Department of Parasitology, Federal University of São Paulo, São Paulo, Brazil)
CD is characterized by an acute phase, which is assymptomatic in most cases. The majority (60–70 %) of infected individuals will never manifest the disease (indeterminate form). In about one-third of infected cases, a chronic form develops some 10–20-years later, causing irreversible damage to heart, esophagus and/or colon. Injury to these organs is characterized by:
1.
dilated cardiomiopathy and conduction system abnormalities, most frequently right bundle branch block or left anterior fascicular block (Fig. 4.7)
Fig. 4.7
Cardiomegaly due to Chagas’ disease with a pacemaker due to Chagas’ disease arrhythmia
2.
Achalasia-like esophagopathy with marked esophageal dilatation (Fig. 4.8)
Fig. 4.8
Megaesophagus due to Chagas’ disease
3.
megacolon, particularly of the sigmoid segment, usually complicated by fecal impaction or sigmoid volvulus (Fig. 4.9)
Fig. 4.9
Megacolon due to Chagas’ disease
The heart is the most commonly affected organ (60 %). The colon and the esophagus are affected in approximately 20 % of cases, with 60 % of the patients developing concomitant cardiopathy [4]. There is neither vaccine nor recommended drug available to prevent CD. Also specific treatment for chronic phase of the disease is non-existent. In Chagas Disease Esophagopathy (CDE) there is always some degree of destruction of the autonomic nervous system, which is presumed to precede the changes in esophageal motility. CDE leads to slow esophageal emptying due to nonrelaxing of the lower esophageal sphincter (LES) and absence of peristalsis of the esophageal body, similar to Idiopathic Achalasia (IA). Table 4.1 shows the characteristics of those with IA and CDE [5, 6].
Table 4.1
Putative differences between Idiopathic Achalasia (IA) and Chagas’ Disease Esophagopathy (CDE)
CDE | IA | |
|---|---|---|
Clinical presentation | Longer duration of complaints | Shorter duration of complaints |
Age at appearance of symptoms (years) | 30–50 | 40–60 |
Upper sphincter | ? | ? |
Esophageal body | Aperistalsis Chicago type III rare | Aperistalsis |
Lower sphincter | Variable | Hypertonic |
Esophageal dilation | Pronounced | Rare |
Diverticulum formation (%) | ? | 4–8 % |
Cancer prevalence (%) | 1–10 % | 0–7 % |
Clinical Presentation
CDE and IA have a similar clinical presentation. Dysphagia is the most frequent symptom in both situations (almost 100 % of cases). Other symptoms such as regurgitation, weight loss, heartburn, chest pain and cough are also very common for the two diseases. The duration of symptoms ranges from 8.5 to 18 years in CDE series versus 9 months to 8 years in IA series, probably as a result of the poor conditions of underdeveloped countries, where CD is endemic, with insufficient medical assistance and delay in diagnosis and treatment [5].
Esophageal Motility
Esophageal Body
Aperistalsis is the common manometrical abnormality found in CDE and IA (Fig. 4.10). According to the Chicago high resolution manometry classification for achalasia, Type III is a very rare finding in CDE. Moreover, when patients with positive serological tests for CD are studied, an undetermined form with multi-peaked peristaltic contractions, spontaneous and repetitive contraction waves can be also found that may represent a pre-disease [7, 8].
