New estimates from PAHO to find out “where and how many we are” affected by Chagas disease

The Pan American Health Organization (PAHO) recently presented an update on the epidemiological situation of Chagas disease in the 21 endemic countries of the Americas. This report, based on data collected up to 2018, offers an analysis of the overall magnitude of this parasitic disease, as well as the ongoing risk of transmission and its implications for public health. The study cautions that some of the information, especially regarding mother-to-child transmission, should be interpreted with care due to a lack of robust and reliable data.

• The exposed population has increased from over 70 million to over 100 million people.
• There are concerning figures regarding infection in women of childbearing age (1.8 million) and cases with heart disease, perhaps due to increased diagnosis.
• Screening programs in blood banks are functioning well.
• Bolivia has the highest prevalence of cases; Brazil has almost 4 million people affected.
• It remains a significant public health problem.

The report details that the total population in endemic areas was approximately 599 million people in 2018, of whom more than 104 million were exposed to the transmitting vector, representing 17.5% of the total. This is an increase from the previous estimate of around 70 million people. Furthermore, 7.4 million people (1.25% of the population) had contracted the T. cruzi infection, according to the report.

Five countries —Brazil, Bolivia, Argentina, Mexico, and Colombia— account for the vast majority of infection cases, totaling nearly 85%. The highest prevalence was observed in Bolivia (6.85%), while in most of the other countries it was less than 1%. The estimates for Brazil, which suggest almost 4 million people may have the infection, are particularly noteworthy.

One worrying aspect is the high proportion of women of childbearing age (15 to 44 years) with Chagas disease, estimated at almost 1.8 million, representing 23.6% of all people with the infection. This population group poses a significant risk of mother-to-child transmission. Specifically, in 2018, an estimated 9,129 new cases were transmitted via this route, showing an incidence of 9.25 cases per 10,000 live births.

Regarding vector-borne transmission, approximately 7,216 new cases were recorded, reflecting an incidence of 6.9 cases per 100,000 exposed inhabitants. The report highlights the significant reduction in vector-borne cases compared to previous years, suggesting that efforts in national vector control programs have had a positive impact. However, the report notes “a growing incidence of cases of oral transmission, which are still being characterized.” This also suggests that the increase in diagnosed cases through different transmission routes is due to a persistent problem of vector-borne transmission.

Chagas cardiomyopathy, the most severe clinical manifestation associated with the disease, affected more than 1.5 million infected individuals, approximately 20.6% of the total. This cardiac damage continues to represent a significant public health challenge due to the high morbidity and mortality it causes.

Chagas disease, caused by the parasite Trypanosoma cruzi, often develops without symptoms. The report acknowledges important limitations, such as the underestimation of cases due to deficiencies in surveillance systems, variability in data quality, and the lack of integration of national registries.

The precarious socio-environmental conditions in many rural and peri-urban communities favor the persistence of the vector (known as the kissing bug, triatomine bug, or other names depending on the area of ​​the endemic regions) and the transmission of the infection. It largely affects populations lacking access to robust healthcare systems. These are some of the reasons why obtaining reliable epidemiological data to better activate Chagas disease prevention, control, and care mechanisms is so difficult. Until now, research has relied more on estimates than on data. The previous available estimates dated back to 2010. These challenges underscore the urgent need to strengthen epidemiological information systems.

Despite the lack of solid data, a successful mechanism for detecting positive cases has been established through blood banks. The prevalence of infection in blood donors shows a significant decrease, reaching a regional average of 0.66%, which highlights the importance of maintaining robust universal screening programs.

The study concludes by highlighting that, although significant progress has been made in reducing vector-borne transmission and implementing preventive measures, Chagas disease remains a major public health problem. Therefore, sustained and coordinated efforts are needed to improve both prevention and control strategies, as well as surveillance and clinical care systems, especially among the most vulnerable populations in Latin America.