Prevalence of Avian Influenza H9N2 in human and other mammals in Iran: A Systematic Review and Meta-analysis

Avian Influenza is a contagious zoonotic disease that can be transmitted from birds to mammals. In this study, we conducted a systematic review and meta-analysis to investigate and summarize the occurrence of avian influenza H9N2 in humans and other mammals in Iran. Data were collected systematically until July 1 2023 from four English and two Persian databases. According to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) and inclusion criteria, 14 eligible studies were obtained. Occurrences of AI H9N2 are reported in humans, dogs, and water buffaloes (Bubalus bubalis) in Iran. The pooled prevalence of AI H9N2 using a random model among humans was 0.15 (95% CI, 0.12-0.18). Pooled prevalence using the HI test was 0.16 (95% CI, 0.13-0.20). The pooled prevalence by different cut-offs for the HI test was equal to 0.34, 0.11, 0.02, and 0.01, respectively for cut-offs 1:20 to 1:160. Pooled prevalence using the HI test, among persons with possible exposure, hospitalized persons and hospital staff (0.20, 0.31, and 0.30) was higher than the prevalence in apparently healthy individuals (0.01). The group of individuals with possible exposure revealed the highest pooled prevalence of 0.25 (95% CI, 0.17-0.33) using the HI test. This was observed predominantly in slaughterhouse workers.  The pooled prevalence using the ELISA test was 0.27 (95% CI, 0.23-0.31). These results can help policymakers to create prevention and control programs for possible epidemics in the future and can help researchers to tailor the design and objectives of future studies in this area.