Prevention of Vertical Transmission: A Challenge in Primary Care
About two thirds of the individuals affected by Chagas disease currently live in urban areas, and only 10% of them are aware of their condition. In addition, most of the new cases are due to vertical transmission. Therefore, for those of us who work in such scenarios day after day, the preventive approach in primary care is a challenge that mobilizes us to action.
In particular, the Metropolitan Area of Buenos Aires is one of the regions that has most attracted internal and international migration in the last decades. A large proportion of the population living in poor neighbourhoods are from, or are descendants of people from, endemic areas.
Thus, the institution I coordinate, located in Chacarita neighbourhood, within a shanty town in the centre of the city of Buenos Aires, became a key site to tackle Urban Chagas.
General and National context
In 2010, the World Health Organization (WHO) indicated the need to explore diagnostic systems that allow for the rapid detection of T. cruzi infection in the primary care centres that do not have laboratory equipment. Since then, some studies have evaluated the performance of the Rapid Diagnostic Tests (RDTs). The Pan American Health Organization (PAHO) recommends RDTs for field screening assays.
In Argentina, diagnosis and treatment of Chagas disease in the general population usually take place late or do not take place at all. According to National Law 26281/2007 testing for Chagas disease is mandatory for all pregnant women. During pregnancy, drugs are contraindicated, which implies a risk of vertical transmission and the need for screening and follow-up of the new-borns during the first 10 months of life. Likewise, evidence shows that treating women of childbearing age (WCA) before pregnancy significantly reduces vertical transmission; therefore, treatment is recommended in this population.
The availability of low-complexity tools that allow us to detect infection in WCA at the primary care level might be a highly valuable strategy that allows for early treatment.
Despite the recommendations by WHO/PAHO, successful experiences in the use of RDTs for other infections (like HIV and syphilis), and their approval by ANMAT (National Medicines, Food and Medical Technology Authority), the Ministry of Health of Argentina has still not incorporated them to the national regulations due to the scarcity of data about their performance in the field.
A new challenge
While the approval of the law has allowed us to improve the approach to future new cases, we face challenges to complete follow-up of babies born to infected mothers. Expressions like: “the mother did not return with her baby”, “we can’t find her”, “the phone number is no longer valid” or “it seems that she has moved away” are frequent in our practice. This evidence stresses the importance of making interventions before pregnancy.
Therefore, bringing the issue to the fore in the City of Buenos Aires, facilitating diagnosis and ensuring treatment of WCA before pregnancy has become our challenge.
In a joint work with the National Institute of Parasitology, in 2003, we conducted research with the aim to evaluate the use of Rapid Diagnostic Tests as a strategy for screening for T. cruzi at the primary care level, in an attempt to generate evidence for their possible inclusion in the national regulations.
Our working hypothesis was that “good performance of RDTs to detect infection with T. cruzi would allow us to improve access to early diagnosis of Chagas in WCA in low-complexity primary care facilities”. Likewise, knowing the epidemiological situation of WCA from an urban population at risk, through the field implementation of tools that facilitate diagnosis, would be a strategy towards a better and highly cost-effective health care in the comprehensive approach to Chagas disease.
Some thoughts
Despite limitations in the sensitivity observed in our study, RDTs were found to be useful and practical tools that were accepted by the population. This result makes them a viable option to extend the diagnosis and treatment coverage of WCA with the aim to prevent vertical transmission in future pregnancies. Likewise, the implementation of the research project was the starting point to raise awareness among health care providers and the population of the neighbourhood about the topic.
Our next challenge is to train primary care professionals in the management of infection by T. cruzi in WCA, while strengthening the coordination with secondary care specialists. This comprehensive approach is key to improving prevention and treatment of Chagas disease in urban settings.