Wild bird infections and the ecology of avian influenza viruses

Disentangling the role of Africa in the global spread of H5 highly pathogenic avian influenza

“…Although the three epi-based datasets were built to be fairly balanced in terms of sampling location, collection date and host (Supplementary Methods), the number of sequences from wild birds turned out to be very heterogeneous per region. To overcame this host skewed data for certain geographic areas, such as West and East-Central Africa, South Asia and the Middle East, for which the available sequences from wild birds ranged from 5% (West Africa) to 24% (the Middle East), we repeated the analyses by allowing only host species transitions from wild to domestic birds, as to consider the abundant evidence that during and after 2005, Gs/GD lineage introduction in poultry in multiple regions was associated with wild bird migration 12,13,15,[25][26][27][28][29][30][31][32][33][34][35][36] . Using such enforcement, our estimates reveal a significantly higher rate of viral spread in wild birds compared to domestic ones (Fig.…”

“…Detections of HPAI H5 viruses in clinically healthy migratory birds 27,34,[52][53][54] and experimental infection data 52,[55][56][57][58] indicated that several waterfowl species can spread HPAI H5 during the period of asymptomatic infection, making migratory birds potential candidates for the intercontinental spread of the virus. The key role of long-distance migrants in the dispersal of HPAI H5 viruses has been suggested by several authors based on phylogenetic analyses, epidemiological investigations and on the timing and direction of the intercontinental spreads, which coincided with fall bird migrations 25,[28][29][30][31][32][33][34][35][36] . Moreover, HPAI H5-infected wild species have been reported in a variety of countries before or simultaneously with poultry outbreaks, and direct or indirect contacts with wild birds have been frequently identified as the most probable cause of virus introduction into poultry 12,13,15,26,27,29,35 .…”

Low‐pathogenicity influenza viruses replicate differently in laughing gulls and mallards

“…Low‐pathogenicity avian influenza viruses (LPAIVs) have been identified in many bird species, but primarily from the orders Anseriformes (ducks, geese, and swans) and Charadriiformes (gulls, terns, and shorebirds). 1 Mallards ( Anas platyrhynchos ) and other dabbling duck species are important LPAIV hosts, and transmission between ducks occurs through the fecal‐oral route involving contaminated water. 1 , 2 However, gulls also are susceptible and can contribute to geographic spread, reassortment, and the evolution of AIVs.…”

“…All HA subtypes have but detected in ducks and gulls, but the H3 and H4 subtypes predominate in ducks, and H13 and H16 in gulls. 1,[3][4][5] In this study, our goals were to understand AIV infectivity and pathogenesis in gulls, through clinical assessment, viral shedding patterns, and seroconversion, to related findings to potential mechanisms of transmission and ecological maintenance. Such experimental studies with gulls have been previously conducted on H13 and H16 viruses but not on less prevalent LPAIV subtypes.…”

Fighting Avian Flu

“…As AIV is shed in high concentrations in feces of infected birds (França et al, 2012), infected waterfowl in the vicinity of outdoor ranges can contaminate the farm environment. Depending on environmental conditions, the virus may persist in the environment for many months (Brown et al, 2007;Stallknecht and Brown, 2017). Chickens can become infected directly via coprophagic behavior (Hyun and Sakaguchi, 1989;von Waldburg-Zeil et al, 2019), or indirectly via contact with an environmental virus reservoir (Brown et al, 2007;Rohani et al, 2009).…”