The World Health Organization (WHO) is shifting its focus towards active screening of girls and women of childbearing age to detect the presence of Trypanosoma cruzi, the causative parasite of Chagas disease. Recent evidence demonstrates that diagnosing and treating women of this age group before pregnancy can effectively prevent congenital transmission.

The Triatoma or “kissing” bug. Image/CDC
The Triatoma or “kissing” bug.

Identifying pregnant women already infected with the parasite, as well as newborns and siblings, has been a major challenge in both endemic and non-endemic countries” said Dr Pedro Albajar Viñas, Medical Officer, WHO Department of Control of Neglected Tropical Diseases. “With the progressive control of transmission by vectors and through blood transfusion, updating, reinforcing and expanding standardized screening measures for congenital transmission make absolute sense.”

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Up to now, control and prevention strategies for Chagas disease largely relied on the early detection and treatment of infected newborns and siblings of pregnant women. But a recent shift in approaches to prevent transmission globally – including in non-endemic countries – is through active, systematic screening of girls and women at risk of infection and provides excellent opportunities for prevention of posterior transmission throughout pregnancy and birth.

The global strategy to eliminate Chagas disease is supported by the donation to WHO of the two available and alternative antiparasitic medicines for treatment of Trypanosoma cruzi infection, which leads to Chagas disease.

Nifurtimox, donated by Bayer, has been distributed free of charge for patients of all ages since 2008. Benznidazole, donated by Insud Pharma, will be distributed freely to treat patients aged under 19 years.

“Implementing universal screening programmes requires appropriate laboratory protocols that, according to availability, should include old and new diagnostic tests, such as standardized and validated chemiluminescence,” said Dr Amadeo Sáez-Alquezar , National Programme of Quality Control, Brazilian Society of Clinical Analysis. “This also implies building capacity and assessing the costs of implementation of screening and diagnosis as well as the necessary follow-up of patients.

Chagas disease is found mainly in endemic areas of 21 Latin American countries where infection is transmitted mostly by vectors to humans by contact with feces or urine of triatomine bugs (known as “kissing bugs”, among many other popular names).

About 6 to 7 million people worldwide are estimated to be infected with Trypanosoma cruzi, the parasite that causes Chagas disease. There is no vaccine against Chagas disease. Domiciliary vectorial control and transfusional control, together with congenital transmission, remain the most effective methods of preventing transmission in Latin America.