Cohort profile: the Bambui (Brazil) Cohort Study of Ageing.

Ageing of the population is the most important demographic change facing many countries around the world. The speed of demographic ageing in Latin American and the Caribbean, however, will be unprecedented in comparison with Western European and North American countries. This demographic change will generate populations with large numbers of elderly who at some time in their lives have been exposed to infectious diseases. Infections may affect ageing in different ways. Most important postulated mechanisms include enhanced inflammation, pathogen-dependent tissue destruction or accelerated cellular ageing through increased turnover. Most epidemiological studies of ageing have, understandably, focused on non-communicable diseases and related conditions. To our knowledge, no previous population-based cohort study had examined the consequences of the double burden of non-communicable diseases and a parasitic chronic infection in old age. Chagas disease, which is caused by the protozoan Trypanosoma cruzi, is endemic in Latin American countries, with about 8 million people infected. As a consequence of immigration from endemic countries, Chagas disease is an emerging issue in North America and Europe, and an example in the era of globalization of how infectious diseases extend beyond endemic areas. Chagas disease is related to poor socio-economic circumstances in early life. In endemic areas, the main source of infection is a bloodsucking triatomine insect that colonizes poor households. Most individuals in these areas acquire the infection at <20 years of age, and 30% develop chronic chagasic cardiomyopathy. The ageing of the population, together with a cohort effect observed in endemic areas where the household insect transmission has been interrupted, will lead to increases in the number of older adults who are already infected by T. cruzi. The main objective of the Bambui Cohort Study of Ageing is to examine the separate and joint effects of chronic T. cruzi infection and non-communicable diseases on health outcomes in old age.