禽流感导致许多鸟类和某些动物死亡，但对人类的影响却微乎其微；科学家研究不同物种致死率的差异。 Bird flu kills many birds and certain animals, yet has minimal impact on humans; scientists study differences in lethality among species.

禽流感已经导致全球数百万只野生和家养鸟类、海豹、海狮、水貂和其他动物死亡，但并未对人类造成重大影响。 Bird flu has killed millions of wild and domestic birds, seals, sea lions, mink, and other animals worldwide, but has not affected humans significantly. 科学家们正在研究为何禽流感对某些物种来说是致命的，而对其他物种来说却只会引起轻微症状，并且致死率的潜在变化让他们夜不能寐。 Scientists are studying why bird flu is lethal to some species and causes mild illness in others, with potential changes in lethality keeping them awake at night. 可能的解释包括感染方式的差异，或流感病毒复制和引起疾病所需的特定物种的微观对接点的差异。 Possible explanations include differences in infection methods or species-specific microscopic docking points that the flu virus needs to replicate and cause illness.