Key facts
- It is estimated that approximately 6 to 7 million people worldwide, most of them in Latin America, are infected with Trypanosoma cruzi, the parasite that causes Chagas disease.
- The infection can be transmitted by an insect called the triatomine bug (vector-borne infection), orally (food-borne infection), during pregnancy or childbirth (congenital infection), through blood/blood product transfusions, through organ transplants, and laboratory accidents.
- Chagas disease can be treated if treatment with antiparasitics is started early during the acute phase of the disease. In the case of chronic infection, treatment and follow-up can prevent or limit the progression of the disease and prevent transmission of infection, for example during pregnancy and childbirth.
- Up to a third of people with chronic infection have heart changes and 1 in 10 people have gastrointestinal, nervous or mixed changes that may require specific treatment.
- The main strategies for preventing Chagas disease include vector control (in Latin America) and blood screening before transfusion and organ transplantation; Testing the detection and treatment of the disease in girls, women of reproductive age, newborns, and their siblings from infected mothers; and provide information, education and communication to local communities and health professionals.
Overview
Chagas disease is an infectious disease caused by the protozoan parasite (Trypanosoma cruzi). But this condition is caused by a complex health problem that is typically one of the neglected tropical diseases and socially determined diseases. This infection can turn into a life-threatening condition if the opportunity to diagnose it is missed or delayed and is coupled with the lack or inadequacy of treatment and follow-up.
It is estimated that approximately 6 to 7 million people in the world are infected with the parasite Trypanosoma cruzi, which kills approximately 12,000 people annually. Although Chagas disease is increasingly present in the world, its presence is mainly concentrated in endemic areas in 21 continental Latin American countries (1) where transmission is largely linked to the presence of its vectors. Today, approximately 75 million people are at risk of infection.
This disease was named after Carlos Chagas, the Brazilian physician and researcher who discovered it on April 14, 1909, after diagnosing it for the first time in an individual. Today, April 14, is World Chagas Disease Day.
Geographical distribution of the disease
Chagas disease was initially quite confined to the continental rural areas of the Americas. However, due to increased population movement, most people infected now live in urban areas, and the disease has been detected in 44 countries (including Canada, the United States of America, several European countries and some countries in the Western Pacific, Africa and the Eastern Mediterranean).
Disease transmission
In Latin America, T. cruzi parasites are transmitted primarily by contact with the feces/urine of blood-sucking, infected triatomine bugs. These bugs typically live in cracks in the walls or ceilings of homes and adjacent structures, such as chicken coops, barns, and warehouses, in rural or suburban areas. Under normal circumstances, these bugs hide during the day and are active at night to feed by sucking animal and human blood. Bedbugs often bite exposed areas of the skin, such as the face, and excrete their waste or urinate near the site of the bite. Parasites leak into the body when a person spontaneously delivers bug feces or urine to the site of a bite or to any other crack in the skin, eyes, or mouth. T. cruzi can also infect animals, and common opossums are considered one of the most important wild reservoirs of T. cruzi infection.
Trypanosoma cruzi infection can also be transmitted by:
- Eating foods or beverages contaminated with Trypanosoma cruzi through, for example, contact with feces or urine excreted by triatomine bugs or infected common opossums; Note that this type of transmission usually causes outbreaks;
- During pregnancy or childbirth;
- transfusion of blood or blood products;
- Some organ transplants (such as heart or kidney);
- And accidents in laboratories.
Signs and symptoms
Chagas disease presents in two stages. The initial acute phase lasts for about two months after infection. Although a large number of parasites are able to spread in the blood, its symptoms do not appear or are mild and non-specific in most cases (fever, headache, swollen lymph nodes, paleness, muscle pain, difficulty breathing, the appearance of tumors, and abdominal or chest pain). Less frequently, the first noticeable signs of the disease appear in people bitten by triatomine bugs and can take the form of skin ulcers or a purple swelling on the eyelid.
During the chronic phase of the disease, the parasites are mainly hidden in the muscles of the heart and digestive system. One or three decades after infection, up to a third of patients develop cardiac disorders and up to one in ten people experience gastrointestinal changes (usually enlargement of the pharynx or colon), nervous system, or Mixed. These patients may suffer in later years from damage to the nervous system and heart muscle and the resulting irregular heartbeat or progressive heart failure and sudden death.
treatment
Chagas disease can be treated with benznidazole or nifurtimox, which both eliminate the parasites and are highly effective if taken early in the acute phase of the disease, including congenital transmissions. However, the effectiveness of the two drugs decreases the longer the infection lasts. Adverse reactions are also more frequent with age. The treatment is also indicated for patients in whom the infection is reactivating (e.g. due to immunosuppression), and for patients at the beginning of the chronic phase, including girls and women of reproductive age (before or after pregnancy) to prevent congenital transmission.
Treatment should be provided to infected adults, especially those who are asymptomatic, because antiparasitic medications can also prevent or limit the progression of the disease. In other cases, the potential benefits of preventing or delaying the progression of Chagas disease should be weighed based on the duration of treatment (up to 2 months) and the potential adverse reactions to treatment (seen in up to 40% of adults). Benznidazole and nifurtimox should not be given to pregnant women or to those suffering from kidney or liver failure. It is also prohibited to give Nifurtimox to those suffering from neurological or psychological disorders. In addition, it is necessary to provide specific, lifelong treatment and follow-up for those suffering from symptoms of heart, digestive or neurological disorders.
Disease control and prevention
The presence of a large reservoir of T. cruzi parasites in wild animals throughout the Americas indicates that the infection cannot be eradicated. Instead, the specific public health goals are elimination of the disease to prevent transmission to humans, early access to health care services, and lifelong monitoring of the status of those infected.
There is no vaccine to prevent Chagas disease. Trypanosoma cruzi parasites can infect several species of triatomine bugs, the majority of which are found in the Americas. Vector control remains the most effective means of preventing this disease in Latin America. Blood testing is also essential to prevent infection through blood transfusion, organ transplantation, and congenital transmission, and to increase the detection of infection cases and provide care to infected people throughout the world.
WHO recommends the following approaches to infection prevention and control by geographic area:
- Develop information, educational materials and communication activities in this area that are appropriate to the context of different scenarios and actors based on the One Health approach;
- Spraying residual insecticides in homes and surrounding areas.
- maintaining and cleaning homes to prevent the spread of infection vectors;
- Take personal protective measures such as using mosquito nets and adhering to good hygiene practices in preparing, transporting, storing and eating food;
- Screening blood donors;
- Organ, tissue or cell donors and their recipients undergo screening tests for the disease;
- Providing early diagnosis, treatment and follow-up methods;
- and examination of newborns and other children of infected mothers.
It has been shown that the cost of medical care for patients suffering from chronic diseases of the heart, digestive system, nervous system, or mixed forms of diseases is 80% higher than the cost of spraying residual insecticides for vector control and infection prevention.
Health professionals working at the first level of care (primary health care) play a major role in enhancing efforts to detect and treat the disease, follow up on the condition of those infected, and notify of its cases.
It is critical to evaluate available diagnostic methods (including serological or rapid chemiluminescence tests and molecular biology tests) and the most cost-effective algorithms to enhance early detection of disease cases.
Enhancing biomedical, psychosocial and environmental studies focusing on the determinants and risk factors of Chagas disease is essential to propose new approaches to its prevention and control.
National information systems for monitoring the number of acute and chronic disease cases and active transmission routes are also indispensable, although these systems have only been implemented in 6 out of 44 countries that have so far reported cases of the disease.