ThesisAnimal health surveillance plays a vital role in ensuring public health, animal welfare, and sustainable food production by monitoring disease trends, early detecting (new) hazards, facilitating disease control, and providing data for risk analysis. However, Tanzania's animal health surveillance system is currently not adequately equipped to address ever-increasing infectious diseases particularly emerging and re-emerging ones due to several inefficiencies, including fragmented data sources and their processing, delays in detection and underreporting. Lack of an efficient animal health surveillance system prevents the country from effective prevention and control of potential outbreaks and the spread of infectious livestock diseases resulting in high disease burden to the livestock keepers and the national economy. One of the solutions to such limitations could be to develop an integrated animal health surveillance system that is cost-effective by leveraging the existing technologies. The aim of the study was to develop integrative solutions for improving animal health system in Tanzania using a systems approach. The thesis integrates multiple research methods that give perspectives on various aspects of animal health surveillance systems. The study involved systematic review, extensive field investigation, and systems integration. The systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) 2015 checklist. Peer-reviewed articles obtained from five databases and eligible articles were assessed for quality using QualSyst Tool. The final list of articles was then synthesized thematically. Field investigations were organized into two phases: Phase I was conducted in Ngorongoro, Kibaha and Kongwa districts, focusing on the situational analysis of the existing animal health and related systems and process evaluation of the current national animal health surveillance system. Phase II involved Kilombero, Sikonge and Sumbawanga districts focusing on subnational level stakeholder mapping for the animal health surveillance system. Various data collection techniques were deployed during field data collection, including documentary reviews, cross-sectional surveys, key informants' interviews, non-participant observation, and stakeholders' workshops. The final part of the research was the development of a prototype of an interoperable animal health surveillance system in Tanzania. It was developed using Hypertext Processor (PHP) version 7.4 (Laravel framework), Python version 3.8.0 and MySQL database. Three animal health information systems: FAO EMPRES Global Animal Disease Information System (EMPRES-i), Sistema Informativo di Laboratorio (SILAB) and AfyaData were linked to the central data repository through Application Programming Interfaces (APIs). The findings of the study are presented in five scientific papers. The first three papers in this thesis focus on gaining an in-depth understanding of the appropriate integration mechanisms in health surveillance systems, animal health surveillance situation, and contextual factors that influence the performance of the systems. The last two papers focus on operationalizing the integrated animal health surveillance system in Tanzania by looking into stakeholders’ collaboration and prototype of the proposed integration. A systematic review (Paper 1) reveals that integration in health surveillance systems is a relatively new concept which picked pace in the 2010s. There were very few integrated systems in animal health surveillance compared to human health. The common integration mechanisms were interoperability and semantic consistency. The results in paper 2 shows a lot of commonalities in the data sources in terms of relevant surveillance variables and area coverage but diverse in quality. However, despite the richness of the data sources for animal health surveillance, very few of them were being used actively and are fragmented. Paper 3 confirms that the performance of animal health surveillance is attributed to several interconnected factors which need to be analyzed and addressed holistically. More specifically, it reveals deviations in the implementation of surveillance from core principles and guidelines. Most identified challenges were systemic hence need systemic solutions and very little financial commitment to surveillance activities and its effect spilt over every component. Paper 4 demonstrates the importance of animal health stakeholder mapping, especially at the sub-national level, and how stakeholders’ collaboration can be leveraged to improve the efficiency of the system in early disease detection and response. The study established that community-level stakeholders had the strongest relationship with government animal health practitioners compared to other stakeholder categories. Meanwhile, the private sector had more resource-based influential stakeholders, while political leaders had more non-resource-based influence. Paper 5 presents a generic prototype of an interoperable animal health surveillance system in Tanzania, the Wanyama heAlth suRveillaNce (WARN). The prototype has demonstrated the possibility of having an integrated multi- data source animal health surveillance system through the interoperability of existing animal health information systems. This research confirms the complexities of the animal health surveillance systems and that their analyses require systems lens and integrative solutions. The final output of this thesis is the prototype. Its generic and flexible architectural features make it adaptable hence can be used beyond Tanzania with provision for data integration from other surveillance systems. Therefore this should be considered in the future to experiment on how we can move from single- to multi-sectoral health surveillance systems in the direction of One Health approach.Government of United Republic of Tanzania and the World Bank for financing my study [WB-ACE II Grant PAD1436) through SACIDS Africa Centre of Excellence for Infectious Diseases of Humans and Animals in East and Southern Africa. I also thank Royal Veterinary College, University of London, UK for hosting during my two-month visiting studentship and supported me with all the necessary facilities including office space, library, ICT resources, accommodation and serene study environment.