RESUMO
With humans, animals and the environment being as interconnected as they are, the science describing their interactions needs to cut across disciplinary boundaries. Systems research at the interface between the three goes by several names, such as 'Eco-Health' and 'Planetary Health', each with a varied focus, but the concept of 'One Health' (OH) has stood out as the most popular one. COVID-19 has reiterated the importance of OH in response to health challenges. This review aimed to assess the OH approach integration and implementation level in Kerala state, India, in the context of emerging zoonotic diseases. A systematic literature review was conducted by searching for relevant articles with specific keywords across six electronic databases. This involved screening the initial hits for titles and abstracts, then systematic sorting to identify the ones that met the criteria, followed by more thorough scrutiny to finally shortlist the six studies to be included in the review. We found that OH in Kerala has made good progress, as evident from a few recent examples, but has a long way to go with significant challenges. In line with the study's aim, identifying and analysing what is already done, what is missing and what needs to be done can have wider implications for future OH implementation. Relevant threats and opportunities were identified, with lessons for Kerala and India and broader applications.