Search

BACKGROUND Avian influenza (AI) outbreaks occurred frequently in 2022 and continue to pose a health, economic, and food security risk. A comprehensive review of current global AI surveillance information is key to assessing the pandemic risk of AI viruses. OBJECTIVE We provide an analysis of global AI surveillance information from the last decade and identify risk factors of interest and surveillance gaps. METHODS We compared AI reports submitted to animal and public health authorities from January 2013 – June 2022 to January 2005 – December 2012. A multivariable regression analysis was used to evaluate associations between risk factors of interest and reported animal AI outbreaks. RESULTS From 2013–2022, 52% (95/182) of World Organization for Animal Health (WOAH) member-states identified 34 AI virus subtypes during 21,249 outbreaks. The most frequently reported subtypes were high pathogenic AI H5N1 (10,079, 47.4%) and H5N8 (6,722, 31.6%). Ten high pathogenic AI and six low pathogenic AI virus subtypes were reported to WOAH for the first time during 2013–2022. One in four member-states (26/95) did not report an outbreak prior to 2013. AI outbreaks in animals occurred in 26 more countries than reported in the previous eight years. Decreasing World Bank income classification was significantly associated with decreases in reported AI outbreaks. Seventeen (8.8%, 17/194) World Health Organization (WHO) member-states reported 2,000 human AI virus infections of 10 virus subtypes. H7N9 (1,568, 78.4%) and H5N1 (254, 12.7%) viruses accounted for the most human infections. Eight member-states did not report a human case prior to 2013. Of 1,953 human cases with available information, 75% (1,461/1,953) had a known animal exposure. The median time from illness onset to the notification posted on the WHO event information site was 15 days (IQR=21, Average= 23). Seasonality patterns of bird outbreaks and human infections with AI viruses were very similar, occurred year-round, and peaked during November through May. CONCLUSIONS Our analysis suggests that AI outbreaks are more frequent and geographically widespread than in the past. Global surveillance gaps include reporting delays and inconsistent reporting from all regions. Continued monitoring for AI outbreaks in animals and human infections with AI viruses is crucial for pandemic preparedness.

Due to their documented epidemiological relevance as hosts for influenza A viruses (IAV), humans, poultry and pigs in backyard production systems (BPS) within wetlands could be key to the emergence of novel IAV variants able to transmit between humans or animals. To better understand the circulation of IAV at the human-animal interface of BPS within wetlands, we studied IAV in backyard duck flocks and pig herds in the Pacific Coast of Guatemala. From April 2013 to October 2014, we estimated the monthly IAV per cent seropositive and viral positive flocks and herds in two resource-limited communities. We detected antibodies in sera against the IAV nucleoprotein through ELISA. We also detected IAV viral RNA in respiratory (ducks and pigs) and cloacal (ducks) swabs through rRT-PCR directed at the matrix gene. We attempted viral isolation in eggs or MDCK cells followed by sequencing from swabs positive for IAV. During our study period, IAV seropositivity in duck flocks was 38%, and viral positivity was 23% (n = 86 BPS sampled). IAV seropositivity in pig herds was 42%, and viral positivity was 20% (n = 90 BPS sampled). Both flocks and herds had detectable antibodies against IAV mostly year-round, and IAV was detected in several months. We isolated an H3N2 virus from one pig sampled at the end of 2013. Standard nucleotide BLAST searches indicate that the isolated virus was similar to seasonal viruses circulating in humans, suggesting human-to-pig transmission. Our data show concurrent circulation of IAV in multiple species of poultry and pigs that were commingled in rudimentary conditions in proximity to humans, but no significant risk factors could be identified.