The Burden of Chagas Disease: Estimates and Challenges

Abstract

Chagas disease, caused by infection with the protozoa Trypanosoma cruzi is transmitted most often by Triatominae insect vectors, but also through blood transfusion, organ transplant, and congenital transmission. Between 5 and 18 million people are currently infected and the infection is estimated to cause more than 10,000 deaths annually. The disease has 3 phases: acute, indeterminate, and chronic. The acute phase immediately follows infection. It is typically asymptomatic but produces fever and malaise in up to 5% of people. The indeterminate phase is asymptomatic. More than one-half of those infected will remain in this phase for life and never experience long-term sequelae. After a decade or more, 20% to 30% of people will experience chronic cardiovascular Chagas disease with sequelae including heart failure, arrhythmias, and thromboembolism. Another 15% to 20% will experience chronic digestive sequela including megaesophagus and megacolon. A complete accounting of the burden of Chagas disease requires estimating the prevalence of the infection, the prevalence of each of its sequelae among those with the infection, and the number of deaths attributable to the infection. Attempts to estimate Chagas disease prevalence are complicated by several challenges imposed by the disease's extreme spatial heterogeneity, quickly evolving temporal trends, the decades-long lag between infection and symptomatic disease, biased prevalence data, incomplete recognition of Chagas-attributable deaths, limited data on sequela, and a near total absence of data outside of endemic countries. Even though researchers have found methodological approaches to dealing with these challenges, there is a need for better data.

Chagas Disease Diagnostic Applications

“…With 8 to 10 million people already infected and up to 120 million individuals at risk of infection, Chagas disease constitutes the most important parasitic disease in Latin America and one of the most common globally (Stanaway and Roth, 2015). Its exact burden is however difficult to assess due to several factors including the widespread geographic distribution of T. cruzi vector-borne transmission, the decades-long lag between infection and appearance of symptoms, certain pitfalls of current diagnostic methods, biased prevalence data, and incomplete recognition of Chagas disease-attributable symptoms (Stanaway and Roth, 2015). The most recent estimates indicate that Chagas disease is responsible for ~550,000 disability adjusted life years (DALY), a measure that captures both premature mortality (~12,000 deaths per year) and non-fatal health losses (Stanaway and Roth, 2015).…”

“…Its exact burden is however difficult to assess due to several factors including the widespread geographic distribution of T. cruzi vector-borne transmission, the decades-long lag between infection and appearance of symptoms, certain pitfalls of current diagnostic methods, biased prevalence data, and incomplete recognition of Chagas disease-attributable symptoms (Stanaway and Roth, 2015). The most recent estimates indicate that Chagas disease is responsible for ~550,000 disability adjusted life years (DALY), a measure that captures both premature mortality (~12,000 deaths per year) and non-fatal health losses (Stanaway and Roth, 2015). Despite this enormous toll, only two trypanocydal drugs, benznidazole and nifurtimox are currently available for chemotherapy.…”

The contemporary distribution of Trypanosoma cruzi infection in humans, alternative hosts and vectors

“…It is endemic across most of Latin America causing high levels of morbidity and mortality. An estimated 10 million people are affected worldwide 1,2 , with approximately 8,000 deaths in 2015 (ref. 3).…”

“…3). High levels of geographic variation in the burden of disease have been observed 2,4 with people in poor, rural areas most at risk 5 . Further spatial variation results from heterogeneity in T. cruzi vectors 6,7 , mediated by vector control programmes that are themselves spatially heterogeneous 8,9 .…”

Development of a PCR Assay to Detect Low Level Trypanosoma cruzi in Blood Specimens Collected with PAXgene Blood DNA Tubes for Clinical Trials Treating Chagas Disease

“…About 6 to 7 million people, primarily in Mexico and Central and South America, are estimated to be infected [1]. Left untreated, up to 30 to 40% of chronically infected patients will progress to have symptomatic disease, manifested as serious heart and digestive problems [2], with an estimate of more than 10,000 deaths annually [3]. Current anti-parasitic medications such as benzindazole (BNZ), although highly effective in treating acute phase infection, have limited efficacy in eliminating T .…”