Chagas disease is a transmissible protozoal infection, the causative agent of which is pathogenic Trypanosoma cruzi, and the carrier is triatom bugs. The acute form is manifested by fever, headache and muscle pain, edema, rash, lymphadenitis, hepatosplenomegaly, cardiomegaly and myocarditis, meningoencephalitis; chronic – heart failure, megaesophagus, megacolon. The diagnosis is based on the data of anamnesis, clinical picture, microscopic, cultural and serological studies. In the treatment of Chagas disease, antiparasitic drugs, symptomatic agents are used, with complications – surgical intervention.
ICD 10
B57 Chagas disease
General information
Chagas disease (American trypanosomiasis) is a protozoism caused by an intracellular protozoan parasite of the genus Trypanosoma (T. cruzi), leading to inflammatory and degenerative changes in the heart, nervous system, gastrointestinal tract. Chagas disease refers to natural focal diseases, is widespread in almost all countries of the American continent: trypanosomiasis endemic areas are Central and South America. In rural areas, the majority of the population becomes infected with trypanosomiasis in childhood, often the invasion is asymptomatic. Among those infected with Chagas disease, males predominate.
Causes
The causative agent of Chagas disease is the flagellated protozoan Trypanosoma cruzi, whose complex development cycle includes a change of hosts – vertebrates and humans, and the specific carrier is blood-sucking bugs of the subfamily Triatominae (Triatomaceae). T. cruzi has a spindle-shaped shape, flagellum and undulating membrane. The parasite goes through several phases of the life cycle: an amastigote living in human tissue cells; an epimastigote growing in the intestines of carriers; and a trypomastigote found in the blood of animals and humans. The main host is T. cruzi serves humans, additional ones are armadillos, anteaters, monkeys and pets (dogs, cats, pigs). The invasive stage for vectors and hosts are trypomastigous forms.
Infection of bedbugs occurs in the process of feeding human or animal blood containing trypomastigotes. The causative agent of Chagas disease is introduced into the human body together with infected feces of bedbugs when combing wounds after their bites on the skin and mucous membranes of the lips, nose, conjunctiva. A characteristic feature of T. cruzi is the ability to intracellular parasitism in the macrophages of the skin and mucous membranes, in the cells of the myocardium, endothelium of lymph nodes, spleen, liver, lungs, and neuroglia. After the rupture of the affected cells, overflowing with multiplied amastigotes, infection of new cells occurs. Parasitization of trypanosomes leads to inflammatory-dystrophic and degenerative damage to internal organs. The most common method of infection with Chagas disease is transmissible, transmission by alimentary, sexual, transplacental, hemotransfusion and organ transplantation is possible. T. cruzi is characterized by persistence in the host body throughout life.
Chagas disease symptoms
The incubation period of the disease lasts 1-3 weeks. Then, at the site of trypanosome penetration, a local inflammatory reaction (shagoma) may develop in the form of an erythematous node with swelling and redness, or unilateral purplish edema of the eyelid (Romigny’s symptom) with conjunctivitis, accompanied by an increase in regional lymph nodes. Chagas disease occurs in 2 stages: acute (the first 2 months) with the circulation of a large number of parasites in the blood and chronic – with the concentration of trypanosomes in the internal organs.
In the acute stage of Shigas disease, in most cases, there are no symptoms, some patients manifest themselves in a mild form. Children under 5 years of age develop the most severe form with systemic manifestations and mortality up to 10-14%. Among the common symptoms of Chagas’ disease, malaise, persistent or remitting fever (up to 39-40 ° C), headache and muscle pain, swelling on the legs, puffiness of the face, small macular rash may be noted. Cervical, inguinal and axillary lymphadenitis, hepatosplenomegaly are characteristic. Secondary pedomas may occur – dense nodes in the subcutaneous tissue. There is a predominant lesion of the heart, central nervous system and peripheral ganglia, organs of the reticuloendothelial system. Acute inflammation and expansion of all chambers of the heart (cardiomegaly), diffuse myocarditis, cardiac dysfunction develops. In some patients (especially in young children), acute specific meningoencephalitis, hemorrhage into the meninges may occur. Congenital Chagas disease can lead to spontaneous abortion or premature birth; in newborns, it is accompanied by severe anemia, hepatosplenomegaly, jaundice, convulsions, and often fatal.
In the chronic form of Chagas disease, symptoms may be absent for a long time until irreversible damage to internal organs occurs. Most often, cardiomyopathy develops, expressed by heart failure, arrhythmia, thromboembolism. The gastrointestinal tract is characterized by pathological enlargement of the esophagus (megaesophagus), manifested by dysphagia, pain when swallowing, and enlargement of the colon (megacolon), accompanied by intestinal obstruction, accumulation of fecal stones. Vegetative disorders and peripheral neuropathy occur. Over time, Chagas disease can lead to sudden death due to the progressive destruction of the heart muscle.
Diagnostics
Diagnosis of Chagas disease includes a thorough collection of anamnesis (taking into account the patient’s place of birth, trips to endemic areas of the disease), analysis of clinical picture data and laboratory studies (microscopic and cultural methods, serological analyses and PCR).
Blood, cerebrospinal fluid, punctates from primary lesion sites, lymph nodes, spleen, bone marrow are used as the test material. In the acute stage of Chagas disease (the first 6-12 weeks), parasites can be detected by microscopy of a thick drop of blood or fixed colored preparations. Bacteriological seeding of the patient’s blood helps to identify a pure culture of T. cruzi. In Chagas’ disease, xenodiagnostics is used, including examination of the intestinal contents of an uninvolved triatom bug after saturation with the patient’s blood. It is possible to conduct a biological test with the introduction of the patient’s blood to guinea pigs or white mice and subsequent examination of tissue samples.
In chronic Chagas disease, serodiagnostics are more effective: complement binding reaction, indirect fluorescence reaction, indirect hemagglutination reaction, ELISA. The presence of specific IgM indicates an acute stage of Chagas disease, with chronic there are only IgG. Some infections, for example, malaria, syphilis, leishmaniasis can give false positive results for trypanosomiasis, therefore it is recommended to use at least two independent serodiagnostic methods. Differential diagnosis of pathogenic trypanosomes from non-pathogenic species that can be found in the human body without causing the development of the disease is necessary.
Chagas disease treatment
To date, the treatment of Chagas disease is ineffective; therapy can reduce mortality among patients, but does not give confidence in the complete eradication of intracellular forms of T. cruzi. In the treatment of Chagas disease, two antiparasitic drugs are used: nifurtimox and benznidazole, the reception of which is more effective in the acute stage of the disease. In the chronic stage of infection, treatment is aimed at alleviating the symptoms of the developed complications of Chagas disease. In case of heart failure and arrhythmia, ACE inhibitors, cardiac glycosides, antiarrhythmic agents, anticoagulants are prescribed for the prevention of thromboembolic conditions, in severe cases, coronary artery bypass grafting, pacemaker implantation, heart transplantation are indicated. Treatment of meningoencephalitis is symptomatic; when the gastrointestinal tract is affected, corticosteroids can be used; with megacolon, surgical intervention is possible: colostomy, colon resection.
The prognosis of Chagas disease depends on the stage of the disease, the severity of development and reversibility of inflammatory and degenerative lesions of internal organs, the age of the patient. Patients with late-stage Chagas disease often die from acute heart failure, heart attack, stroke, young children – from rapidly developing acute meningoencephalitis. Prevention of Chagas disease includes insecticidal treatment of human housing, poultry houses, pigsties – the main habitats of bedbugs carrying parasites, home improvement; selection and examination for trypanosomiasis of potential blood and organ donors, public health education.
