Bourouiba L, Teslya A, Wu J
Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA.
Department of Mathematics, Ryerson University, 350 Victoria St., Toronto, Canada ON M5B 2K3.
J Theor Biol. 2011 Feb 21;271(1):181-201. doi: 10.1016/j.jtbi.2010.11.013. Epub 2010 Dec 10.
The spread of highly pathogenic avian influenza (HPAI) H5N1 remains a threat for both wild and domestic bird populations, while low pathogenic avian influenza (LPAI) strains have been reported to induce partial immunity to HPAI in poultry and some wild birds inoculated with both HPAI and LPAI strains. Here, based on the reported data and experiments, we develop a two-strain avian influenza model to examine the extent to which this partial immunity observed at the individual level can affect the outcome of the outbreaks among migratory birds in the wild at the population level during different seasons. We find a distinct mitigating effect of LPAI on the death toll induced by HPAI strain, and this effect is particularly important for populations previously exposed to and recovered from LPAI. We further investigate the effect of the dominant mode of transmission of an HPAI strain on the outcome of the epidemic. Four combinations of contact based direct transmission and indirect fecal-to-oral (or environmental) routes are examined. For a given infection peak of HPAI, indirect fecal-to-oral transmission of HPAI can lead to a higher death toll than that associated with direct transmission. The mitigating effect of LPAI can, in turn, be dependent on the route of infection of HPAI.
高致病性禽流感（HPAI）H5N1的传播仍然对野生和家养鸟类种群构成威胁，而据报道，低致病性禽流感（LPAI）毒株能使接种了HPAI和LPAI毒株的家禽及一些野生鸟类产生对HPAI的部分免疫力。在此，基于已报道的数据和实验，我们构建了一个双毒株禽流感模型，以研究在个体水平观察到的这种部分免疫力在不同季节能在多大程度上影响野生候鸟种群层面疫情爆发的结果。我们发现LPAI对HPAI毒株所致死亡数有明显的缓解作用，且这种作用对于先前接触过LPAI并从中恢复的种群尤为重要。我们进一步研究了HPAI毒株的主要传播模式对疫情结果的影响。研究了基于接触的直接传播和间接粪口（或环境）传播的四种组合。对于给定的HPAI感染峰值，HPAI的间接粪口传播比直接传播导致的死亡数更高。反过来，LPAI的缓解作用可能取决于HPAI的感染途径。
