Global prevalence of chicken ectoparasites: a systematic review and meta-analysis

Parasitism is the second most significant disease affecting chickens after infectious diseases. Among various parasites, ectoparasites continue to spread worldwide, exerting a detrimental impact on both chicken health and national economies. This study aims to assess the prevalence of ectoparasites in chickens in different production systems globally. Two databases were systematically reviewed to identify eligible studies for the final meta-analysis, following the PRISMA statement. The meta-analysis encompasses 44 research papers spanning a 44-year period (1980–2024). The ‘meta’ package in the R software was used for the meta-analysis, with the random effects model chosen for data pooling. The overall prevalence of ectoparasites in chickens was found to be 70.2%, ranging from 0 to 100% across studies. In a subgroup analysis, the African continent had the highest number of studies (n = 21), showing an infestation rate of 73.2%. At the country level, prevalence varied widely, ranging from 9.6% to 100%. Backyard free-range production systems exhibited higher infestation rates compared to intensive systems. Additionally, indigenous chicken breeds showed the highest infestation rates. Notably, more than 33 species belonging to three groups, Phthiraptera, Siphonaptera, and Acari, were identified in chickens worldwide. Among species of medical interest were the chewing lice group, Echidnophaga gallinacea, Dermanyssus gallinae, Ornithonyssus spp. Megninia spp. Knemidokoptes mutans, Laminosioptes cysticola, and Argas persicus. This analysis offers crucial insights into the current status of ectoparasite infestations in chickens and their distribution, providing valuable data for surveillance and prevention strategies.