Current practice and future directions in syndromic surveillance for animal health: A scoping review and analysis

Syndromic surveillance, the monitoring of non-specific indicators or symptoms, is a powerful tool for monitoring health or well-being. We conducted a scoping review to provide an up-to-date, global overview of syndromic surveillance for animal health, focusing on variation between animal sectors (livestock, companion, and wildlife), geography, indicators, data providers, and One Health approaches. We searched the Scopus and PubMed databases for articles describing or using data from syndromic surveillance systems or testing the potential of a data set or method for syndromic surveillance and supplemented this information with gray literature to determine further development of systems. We identified 126 syndromic surveillance systems from 165 articles. Most systems (n = 84, 67 %) were in the proof-of-concept phase, while only 25 (20 %) were established operational systems. These were mostly run by governments (n = 15, 58 %), as well as nonprofits (n = 4, 15 %), and academic institutions (n = 3, 12 %). The majority of systems monitored livestock (n = 89, 71 %); just over half were located in Europe (n = 64, 51 %) and a further 28 % (n = 35) in North America. Only eight systems (6 %) monitored multiple animal sectors. Twelve systems (10 %) used a One Health approach, linking data or surveillance concerning the same threat in humans and any animal sector. The most common data collectors were private veterinarians (n = 35, 28 %) and animals' owners (n = 29, 23 %); the most commonly used indicators were mortality (n = 52, 41 %), general illness (n = 36, 29 %), and reproductive symptoms (n = 31, 25 %). While syndromic surveillance for animals continues to develop, there is still a gap between research and implementation. However, even established systems are vulnerable to lack of continued funding and support. By compiling and analyzing this data, we highlight developments in syndromic surveillance for animals as well as differences in practices between sectors and regions of the world.