Chagas disease is caused by the parasite Trypanosoma cruzi, which is transmitted to humans when hematophagous insects known as triatomine bugs feed on their blood. Triatomine bugs hide in cracks in old walls or roofs of poor dwellings in rural areas and peripheral urban areas.
Following an acute phase subsequent to infection, the disease becomes chronic in over a third of infected individuals. Patients enter the chronic phase after 10 to 20 years of "silent" infection. Irreversible lesions may occur in the heart, esophagus, colon, and peripheral nervous system: 30% of infected individuals suffer from cardiac symptoms (chronic heart disease), potentially leading to sudden death. Approximately 10% of individuals suffer from chronic lesions of the digestive tract and 3% of infected individuals experience peripheral nervous system impairments (neurological disorders).
In 2020, the World Health Organization estimated that approximately 6-7 million people were infected with Trypanosoma cruzi in the endemic areas of 21 Latin American countries. The resulting chronic infection is incurable, sometimes debilitating, and claims over 10,000 lives every year.
People living in an area extending from the southern United States to southern Argentina are exposed to this parasite. A quarter of the population of Latin America is at risk of contracting Chagas disease. Brazil is the largest endemic country for this parasitic infection, accounting for 40% of disease prevalence. The risk of infection is strongly linked to socio-economic conditions. However, the parasite can also be transmitted by blood transfusions, during pregnancy, and by organ transplants. Consequently, for over a decade, the disease has also been diagnosed in individuals living in non-endemic areas such as the United States (over 300,000 cases among Latin American immigrants), Australia, Japan, and in almost all of Western Europe. Spain estimates some 50,000 cases in its territory, mainly among migrants from Ecuador, Argentina, Peru, and Bolivia. Although regional initiatives implemented since 1990 have made a significant contribution to controlling the vector-borne infection on the American continent, 50,000 new cases are still diagnosed annually.
A European Parliament directive of February 2006 concerning the donation, procurement, and testing of human tissues and cells provides for screening tests based on donors' medical history or travel to endemic areas and exposure to the risk of infection (2006/17/EC). Other European directives, including 2005/62/EC, lay down standards to be observed by blood transfusion establishments with regard to the quality of transfused blood and blood components imported from third countries. The French Blood Service (EFS) and the French Health Products Safety Agency (AFSSAPS), recently superseded by the French National Agency for the Safety of Medicines and Health Products (ANSM), have played an active role in validating and implementing appropriate serological screening techniques for Chagas disease, which are applied in the French West Indies and mainland France.
Prevention, treatment, and vaccines
Aside from vector control through insecticides, there are no means of controlling Chagas disease, no effective treatment for chronic forms, and no vaccine. The DNDi (Drugs for Neglected Diseases initiative) set up in 2003 to tackle neglected diseases such as Chagas disease includes the Institut Pasteur, the Indian Council of Medical Research (India), the Oswaldo Cruz Foundation (Brazil), the Kenya Medical Research Institute, Médecins Sans Frontières, and the Malaysian Ministry of Health.
These partners collaborate closely with the United Nations Development Program (UNDP), the World Bank, and the WHO Special Program for Research and Training in Tropical Diseases (WHO/TDR) on researching new drugs.
Global plans to tackle neglected diseases are included in the UN Millennium Development Goals. Chagas disease is responsible for productivity losses and estimated annual costs of 1.2 billion USD in Latin America. Several times this sum is spent on medical costs for treating individuals who develop severe heart or gastrointestinal disease. Every year, private and public funds are required for research on neglected parasitic diseases including Chagas disease.
Blood screening is essential to prevent infection by blood transfusions and organ transplants.