Chagas' disease

Chagas' disease is an American variant of the African sleeping sickness and is a serious environmental health risk. It is one of the most serious tropical diseases found in Latin America, both in terms of occurrence and impact on human health and productivity. One-third of those infected are at risk of developing chronic Chagas disease, which can trigger cardiac and intestinal complications years or decades after the initial infection. It can kill after 10 years or more of debilitating illness. There is no satisfactory cure for the chronic phase of Chagas' disease, which is rarely diagnosed during the early, acute phase.

The disease is caused by the pathogenic hemoflagellate Trypanosoma cruzi, and is transmitted to man by blood-sucking insects called triatomines (triatomid bugs, nicknamed “kissing bugs” because they typically bite around the lips or eyes). The bugs live in the forest and fields. Domestic animals, such as cats, dogs and guinea pigs, and humans in rural areas and in slums become infected by contamination of the bite wound with the insect's' faeces, which harbour the invasive trypanosomes. While Chagas is not transmissible via person-to-person contact, it can be transmistted via blood transfusion, organ transplantation and/or eating food in which the insect has defecated. An infected mother can also transmit Chagas to her unborn child

The acute form of Chagas disease occurs predominantly in young children and is characterized by fever, adenopathy, spleen and liver enlargements, and in some forms facial oedema. The brain is often affected and convulsions may result in permanent mental damage or even in death. The chronic form may be mild, but cardiopathy due to parasite development in the heart muscles may be extremely serious, provoking in some cases sudden death from heart failure.

The economic harm caused by the disease is considerable. In the first place, the incapacitating symptoms of the chronic forms of the disease generally develop in the second half of life when the individual is making his greatest contribution to society. Secondly, the disease is found principally in rural areas where those affected are often rendered incapable of the heavy physical work demanded of them. Equally costly is the hospitalization and subsequent rehabilitation of patients with Chagas disease.

South American trypanosomiasis occurs in 21 countries there, the highest prevalence being in Bolivia, Argentina, Brazil, Chile, and Venezuela. An estimated 12 million people are infected. Another 90 million live under conditions favouring transmission and are at risk of acquiring the disease.

As reported by the CDC in 2018, an estimated 300,000 people in the USA have Chagas, including 40,000 pregnant women, and prevalence is on the rise. The disease was initially reported in Texas in 2010, but has since been identified in 28 states. Chagas disease has also been identified in Spain, Italy, France, Switzerland, Australia, Japan and the U.K. Globally, Chagas disease is thought to be responsible for 10,000 deaths each year.

The risk is greatest for the rural poor. The insect vectors of Chagas' disease are endemic to nearby fields and forests and naturally infest dwellings constructed of conventional mud wattle, substandard cement, and thatched roofs, living in the cracks between the construction materials. Futhermore, traditional construction methods foster a lack of natural interior light and poor ventilation, factors that maintain the dark and humid conditions that are favourable to these insects. One solution would have houses periodically sprayed with insecticides. This is an expensive intervention, using imported chemicals that are costly and themselves a health risk, and usually cannot be sustained or replicated in developing countries. The endemic nature of the insects ensures that reinfestation will occur as soon as the pesticide has lost its effectiveness (usually over the course of one year).