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THE DISEASES − CHAPTER 4
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4.2 Chagas disease
Introduction
Chagas disease, also known as American trypanosomiasis, is caused by infection with the
protozoan parasite Trypanosoma cruzi. The infection originally found in rural areas as of
the Americas, mostly in the 20th century, changed its epidemiological pattern with increased
prevalence, urbanization and spread to other continents (1).
Human transmission usually occurs through the faeces/urine of infected vector insects
(haematophagous triatomines). These bugs typically live in the cracks of poorly constructed
homes in rural or suburban areas. Normally they become active at night, feeding on mammal mmal
blood, including humans, biting exposed skin such as the face, and defecating close to the
bite. The parasites enter the body when the person instinctively smears the bugs’ faeces/urine
into the bite or any other skin break, or the eye or oral membranes. The ingestion of food
contaminated by faeces/urine of infected insects is another important route of transmission, sion,
especially in hot and humid climates.
Transmission can also occur through transfusion of infected blood, congenital transmission ssion
and, less frequently, organ transplantation or laboratory accidents. In areas with intradomiciliary
vectorial transmission, children aged under 5 years are more often found to be infected; in
areas without such transmission, the infection is detected in older children and is associated
with activities that provide greater exposure to peridomestic and sylvatic vectors.
Diagnosis during the initial acute phase or early chronic phase provides a critical but timelimited
opportunity to detect and successfully treat patients with antiparasitic medicines. Early
diagnosis can prevent the potentially catastrophic expenditures associated with underdiagnosis
or misdiagnosis leading to a high morbidity burden, consequent mortality and possible coinfections
and co-morbidities in the chronic phase (2,3).
Besides the biomedical approach, psychosocial approaches are crucial to change defective
perceptions of a silent and silenced disease as well as health-seeking behaviours (4–6).
Two medicines are available to treat T. cruzi infection: benznidazole, the first-line treatment
in most countries, and nifurtimox. During 2011–2012, WHO managed a global shortage of
benznidazole and consequent impairment of detection and treatment. In 2013–2014, both
medicines were made available, WHO updated its List of Essential Medicines for Children,
three paediatric presentations were offered for distribution globally and a WHO information
system on drug distribution was revised (7).