Chagas Disease - Causes, Symptoms, Diagnosis

Chagas disease is a dangerous disease that is transmitted by blood-sucking bugs. The name of the disease comes from the name of the Brazilian doctor who discovered the disease.

The content of the article:

• 1 Chagas disease
• 2 Key facts
• 3 Causes of Chagas disease
• 4 Transmission of infection
• 5 Who is the carrier of Chagas disease
• 6 Distribution
• 7 Localization of the disease
• 8 Symptoms of Chagas disease
• 9 Chagas disease and esophageal motility disorders
• 10 Chagas disease in ICD-10
• 11 Diagnosing Chagas disease
• 12 Chagas disease: treatment and medications
• 13 FDA approval of benznidazole, the first drug to treat Chagas disease
• 14 Complications of Chagas disease
• 15 Prevention of Chagas disease
• 16 WHO activities

Chagas disease

Chagas disease (American trypanosomiasis) is a protozoan disease caused by an intracellular protozoan parasite of the Trypanosome genus (T. cruzi), leading to inflammatory and degenerative changes in the heart, nervous system, and gastrointestinal tract.

Chagas disease refers to natural focal diseases, widespread in almost all countries of the American continent: Central and South America are endemic areas for trypanosomiasis. 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.

Key facts

• An estimated 7 to 8 million people worldwide are infected with Trypanosoma cruzi (the parasite that causes Chagas disease), mainly in Latin America.
• Vector-borne transmission occurs in the Americas. The triatomaceous bug is a carrier of the parasite Trypanosoma cruzi, which causes disease.
• At one time, Chagas disease was only common in the Americas, mainly in Latin America, but now it has spread to other continents.
• Chagas disease can be cured if treatment is started soon after infection.
• 30% of chronically infected people develop cardiac changes and 10% develop alterations in the digestive system, nervous system, or mixed changes that may require special treatment.
• The best way to prevent Chagas disease in Latin America is vector control.
• Blood tests are vital to prevent infection from blood transfusions or organ transplants.
• Diagnosing the infection in pregnant women, their newborn babies and siblings is important.

Causes of Chagas disease

The causative agent of Chagas disease is the flagellate protozoan Trypanosoma cruzi, the complex development cycle of which includes a change of hosts - vertebrates and humans, and blood-sucking bugs of the Triatominae subfamily (triatoms) serve as a specific carrier. T. cruzi has a fusiform shape, a flagellum, and an undulating membrane. The parasite goes through several phases of its life cycle: amastigote, which lives in human tissue cells; epimastigote growing in the intestines of the carriers; and trypomastigote found in the blood of animals and humans.

The main host of T. cruzi is humans, the additional hosts are armadillos, anteaters, monkeys, and domestic animals (dogs, cats, pigs). The invasive stage for vectors and hosts are trypomastigous forms.

Infection of bedbugs occurs in the process of feeding on human or animal blood containing trypomastigotes. The causative agent of Chagas disease is introduced into the human body along with infected feces of bedbugs when combing wounds after their bites on the skin and mucous lips, nose, conjunctiva.

A characteristic feature of T. cruzi is the ability to intracellular parasitism in macrophages of the skin and mucous membranes, in the cells of the myocardium, endothelium of the lymph nodes, spleen, liver, lungs, neuroglia.

After the rupture of the affected cells, overflowing with multiplying amastigotes, new cells are infected. Parasitizing trypanosomes leads to inflammatory-dystrophic and degenerative damage to internal organs. The most common method of infection with Chagas disease is transmissible; transmission is possible by alimentary, sexual, transplacental, blood transfusion and organ transplantation. T. cruzi persists throughout its life in its host.

Transmission of infection

In Latin America, T. cruzi parasites are transmitted primarily through infected feces of blood-sucking triatomine bugs. Typically, these parasite-carrying bugs live in the cracks of poorly built homes in rural or suburban areas. In the daytime they hide, and at night they become active and feed on human blood. They usually bite into exposed areas of the skin, such as the face. Near the bite, the bug defecates. Parasites enter the human body when he instinctively rubs bug feces into the bite site, eyes, mouth, or any crack in the skin.

T. cruzi can also be transmitted:

• through food contaminated with T. cruzi, for example through contact with faeces from a triatomine bug;
• with blood transfusion from infected donors;
• from an infected mother to her newborn baby during pregnancy or childbirth;
• when transplanting organs taken from infected donors;
• during laboratory incidents.

Who is the carrier of Chagas disease

Despite the fact that the causative agent of the disease is one, there may be more carriers. The most common killer beetle is found in the countryside and on the outskirts of cities, where there are clay structures.

He becomes infected from a person and after 2 weeks spreads the disease further. One insect will transmit infection for its entire life. In the villages of America, children have been infected since childhood.

Statistics show that American trypanosomiasis affects more men. Also carriers of chagas disease are armadillo, possum, forest rat and monkey.

The transmissible mode of transmission reinforces sexual, alimentary and transplacental transmission.

These causes of Chagas disease are less common but cannot be ruled out. If a pregnant woman becomes infected, the fetus will also become infected. The mother's milk will also be the carrier.

Organ transplantation and blood transfusion are capable of spreading chagas disease.

In American clinics, about 40% of donated blood was found, in which the pathogen T. Cruzi is located.

Spread

Chagas disease is common mainly in Latin America. However, over the past decades, it has been increasingly found in the United States of America, Canada, many European countries and some countries in the Western Pacific. This is mainly due to the movement of people between Latin America and the rest of the world.

Infection is also possible through blood transfusions, hereditary transmission (from an infected mother to her child) and organ donation, although these cases are more rare.

Localization of the disease

The carrier bites the skin near the mucous membrane. A sleepy person may not feel this. The pathogen infects healthy tissue cells and lays eggs in them.

When there are many parasites in the cell, it bursts and T. cruzi infect new areas. Huge tumors appear on the face. The triatomite bug often stings the eyelids and lips.

Chagas disease symptoms

The incubation period for American trypanosomiasis is 1-3 weeks. When the pathogen enters the skin, the following chagas symptoms may appear :

• 

  erythematous nodes;
• swelling;
• redness;
• conjunctivitis.

Chagas disease goes through 2 stages. The first acute stage lasts about 2 months. At this moment, parasites circulate in huge quantities through the blood.

The next stage is chronic. Here trypanos attack the internal organs. During the first stage, symptoms may not appear in any way. In young children, the severe form manifests itself in periods. Under the age of 5, the mortality rate reaches 15%.

American trypanosomiasis has the following common symptoms:

• malaise;
• fever;
• headache;
• muscle pain;
• swelling of the limbs;
• swelling of the face;
• small rash.

Often, the disease of chagas causes lymphadenitis. It has some biological features. The heart is quickly affected, its chambers become inflamed, and activity is disrupted. The central ganglion is also instantly affected.

In young children, the causative agent of protozoa can cause hemorrhage in the meninges.

If a woman has a congenital chagas disease, then it provokes a miscarriage and premature birth. Newborns suffer from severe anemia, jaundice and seizures. It is not uncommon for an infected mother to give birth to a stillborn baby.

The chronic stage of the chagas disease may not appear for a long time. It is found when internal organs are affected. A person has cardiomyopathy and arrhythmia.

The esophagus also expands, swallowing becomes painful and fecal stones accumulate. Sometimes chagas disease causes sudden death.

Chagas disease and esophageal motility disorders

Chagas disease is characterized by esophageal motility disorders similar to those of cardia achalasia. It can lead to the loss of intramural ganglia, aperistalsis and incomplete relaxation of the lower esophageal sphincter (Bordin D. S., Valitova E. R.). The disease occurs in two phases. The first is acute and is associated with the circulation of parasites in the blood. The second phase is manifested in the penetration of Trypanosoma cruzi into the heart and the muscular layer of the esophagus, where they accumulate.

The process is accompanied mainly by damage to the intermuscular plexuses of the esophagus, which leads to subsequent degenerative changes in them and impaired motor function of the esophagus. In this phase, a violation of the relaxation of the lower esophageal sphincter occurs and atony of the esophagus develops, which are manifested by dysphagia, esophageal vomiting and pain along the esophagus when food is swallowed (Yevsyutina Yu. V. et al.).

Chagas disease in ICD-10

Chagas diseases in the International Classification of Diseases ICD-10 in "Class I. Some infectious and parasitic diseases (A00-B99)", in the block "B50-B64 Protozoal diseases" there is a three-character heading "B57 Chagas disease" with the following content:

• 

  In ICD-10, optional additional codes are highlighted that relate to the manifestation of the disease in a separate organ or area of the body, which is an independent clinical problem (marked with an asterisk)
• B57.1 Acute Chagas disease without cardiac involvement
• B57.2 Chagas disease (chronic) with cardiac involvement
• B57.3 Chagas disease (chronic) with digestive system involvement
• B57.4 Chagas disease (chronic) with nervous system involvement
• B57.5 Chagas disease (chronic) with involvement of other organs

In addition, the ICD-10 highlighted optional additional codes related to the manifestation of the disease in a separate organ or area of the body, which is an independent clinical problem (marked with an asterisk):

• in the block "K20-K31 Diseases of the esophagus, stomach and duodenum" code K23.1 * Dilation of the esophagus in Chagas disease (B57.3 †)
• in the block "K90-K93 Other diseases of the digestive system" code K93.1 * Megacolon in Chagas disease (B57.3 †)

Diagnosing Chagas disease

It is worth noting that the diagnosis of American trypanosomiasis is rather difficult. In addition to examining the patient, a vector is analyzed.

The patient needs to donate blood, cerebrospinal fluid, puncture from the first affected areas, lymph nodes, spleen and bone marrow.

In the chronic stage, serodiagnosis is necessary. Certain serious illnesses can affect the results. Therefore, experts insist on several types of diagnostics.

Chagas disease: treatment and drugs

Unfortunately, treatment for American trypanosomiasis is ineffective. It will not completely rid the body of the parasite. The drugs only reduce mortality. For treatment, nifurtimox and benznidazole are used.

With these medicines, the treatment of chagas disease is effective in the acute stage. Otherwise, the medicine only relieves the symptoms. In case of heart damage, the doctor prescribes heart medications. In the worst cases, an organ transplant is required. Treatment of children is very difficult, sometimes medications do not even cope with symptoms.

FDA approved benznidazole, the first drug to treat Chagas disease

For the treatment of Chagas disease, benznidazole (a nitroimidazole derivative) or nifurtimox (a nitrofuran derivative) are used. Both drugs belong to the ATX section "P01C Drugs for the treatment of leishmaniasis and trypanosomiasis" and have the codes "P01CA02 Benznidazole" and "P01CC01 Nifurtimox". In Russia, both of these drugs are not approved for use. Benznidazole produced by the Brazilian company Lafepe Medicamentos is approved for use in Brazil and some other Latin American countries.

On August 29, 2017, the FDA fast-tracked benznidazole for use in children 2 to 12 years old, the first drug in the United States to treat Chagas disease. The safety and efficacy of benznidazole has been established in two placebo-controlled clinical trials in children aged 6 to 12 years.

The most common adverse reactions in those taking benznidazole were abdominal pain, rash, weight loss, headache, nausea, vomiting, abnormal white blood cell count, urticaria, pruritus, and decreased appetite. Bendnidazole has been associated with serious risks including severe skin reactions, nervous system effects, and depression. Animal studies have shown that benznidazole can be harmful to the fetus when taken by a pregnant woman.

Complications of Chagas disease

American trypanosomiasis is very severe in the heart. Complications are associated with this particular organ. The patient is rapidly developing heart failure, heart attack and stroke occur.

In most cases, they lead to immediate death. In young children, complications manifest themselves in the form of acute meningoencephalitis.

Prevention of Chagas disease

Preventive measures in American trypanosomiasis are primarily aimed at eliminating the vectors. It is necessary to treat the walls and roof of the room with sufficiently effective insecticides.

Be sure to spray not only the living quarters, but also chicken coops and sheds.

When transfusing blood, a thorough examination of the donor should be carried out.

These are the main precautions, because there is no vaccine for Chagas, and the above drugs only work on the parasite.

In Russia, American trypanosomiasis is a rare case brought by a person from America.

In our latitudes, carrier bugs do not live, although the chagas disease is common in other countries. It has already hit at least 16 million people.

WHO activities

Since the 1990s. significant advances have been made in the control of parasites and disease vectors in Latin America, namely in the Southern Cone, Central America, the Andean Pact countries and the Amazonian Intergovernmental Initiatives with the participation of the Secretariat of the Pan American Health Organization - the Technical Secretary of PAHO. These multinational initiatives have led to a significant reduction in domestic vector transmission.

In addition, the risk of transmission through blood transfusions has been significantly reduced throughout Latin America. These achievements were made possible by the strong commitment of endemic Member States and their trusted organizations for research and vector control, with the support of many international partners.

At the same time, it is necessary to solve a number of additional problems, such as:

• maintaining and strengthening the progress made in combating the disease;
• the emergence of Chagas disease in areas previously considered free of the disease, such as the Amazon;
• re-emergence of the disease in areas with vector control, such as the Chaco area of Bolivia;
• the spread of the disease mainly as a result of increased population mobility between Latin America and the rest of the world;
• expanding access to diagnosis and treatment for millions of infected people.

To achieve the goal of eliminating the transmission of Chagas disease and providing care for infected / sick patients in both endemic and non-endemic countries, WHO seeks to expand global networking and strengthen regional and national capacities, focusing on measures such as:

• strengthening surveillance and information systems around the world;
• preventing transmission of infection through blood transfusion and organ transplants in endemic and non-endemic countries;
• promoting the development of diagnostic tests for screening and diagnosing infection;
• expanding secondary prevention of congenital infection transmission and management of congenital and non-congenital infections;
• promoting consensus on appropriate case management.

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