The use of H-index to assess research priorities in poultry diseases

Identifying which diseases represent a priority is crucial to optimize resources for diagnostics, control, and prevention. Here, the impact of 111 poultry pathogens belonging to Viruses (n = 31), Bacteria (n = 33), and Other (n = 47) was assessed using the H-index. The overall mean H-indexes suggested that poultry Viruses have statistically greater impact than Bacteria, which in turn are statistically more relevant than Others. Among the 20 highest H-indexes, 45% were zoonotic, and almost a third was Office International des Epizooties-listed. Avian influenza virus (H-index 127), Salmonella enteritidis and Salmonella typhimurium (H-index 72), and Eimeria spp (H-index 70) ranked the highest in Virus, Bacteria, and Other, respectively. Pathogens that produce overt clinical diseases and economic damage, cause immunosuppression, and/or are zoonotic had the highest H-index scores. The evolution of citations of particular pathogens reflected severe poultry outbreaks and/or zoonotic outbreaks in relatively wide geographic areas. Also, the evolution of citations based on taxonomic groups mirrored major changes in poultry production practices and management throughout history. Thus, Others were the most cited pathogens until the 1970s and, following 3 decades of unpopularity because of widespread use of intensive production practices, regained importance in the 2000s thanks to welfare regulation changes. Citations for Bacteria increased especially from the 1990s onward, probably because of the ban of growth promoters in western countries and the need to find new control methods for bacterial and protozoal infections. In general, countries with the greatest poultry production and research budgets had higher research production, that is the United States of America (USA) and China. Interestingly, the United Kingdom was among the top research producers despite falling behind other countries in poultry production and research budget. Moreover, the USA exhibited the strongest poultry research production based on number and diversity of publications (Dcos-index). In conclusion, the H-index could be a valid, simple tool to prioritize funding or interest in poultry diseases, especially when used as a preliminary selection approach in combination with other metrics.