Study location
A desktop review was conducted to identify the most appropriate study area on Java. Data of HPAI outbreaks between 2008 and 2014 and poultry population statistics were gathered from the Participatory Disease Surveillance and Response (PDSR) database in the Department of Animal Health of the Indonesian Ministry of Agriculture (Azhar et al., 2010b; Farnsworth et al., 2011). Based on HPAI disease reports, Purbalingga District (Figure 1) was eventually selected because the PDSR data showed evidence of historical outbreaks of HPAI H5N1; the presence of a range of poultry production systems and species spanning all four Sectors, based on livestock statistics data (Anon., 2019); a suitable level of commitment from the local animal health authorities, plus personnel in the livestock division who had received training in PDSR; and proximity to the Disease Investigation Centre (DIC) laboratory at which sample testing was performed. Purbalingga District is located in the Province of Central Java, with an area of approximately 700 square kilometres and elevation ranging between 25 and 2815 metres above sea level. It consists of 18 sub-districts and 239 villages. The human population in Purbalingga is 848,952 with varying density across the District. Based on these demographic characteristics, Purbalingga was considered to be representative of Java Island, both in terms of its demographics as well as the range of poultry enterprise types and trade patterns.