The MAHERY study was set up in 2004 to understand the human health impacts of environmental change (e.g., deforestation, unsustainable hunting, biodiversity loss, climate change, etc.) in Madagascar. The current study, set in north-eastern Madagascar, is divided into two communities (A and B) and two cohorts (1 and 2). Cohort 1 was formed in 2008 and conducted within Community A (near Makira Natural Park), consisting of 28 households. It focused primarily on pre-adolescent children (12 years of age and younger) and excluded girls who had reached menarche. Cohort 2 was formed in 2013 and included Community A, where Cohort 1 was conducted, but also expanded to Community B (approximately 10 km west of Community A, more embedded within the rainforest). The initial 28 households enrolled in Cohort 1 were expanded to 95 households in Community A, and an additional 57 households were enrolled in Community B.