Iwami Shingo, Takeuchi Yasuhiro, Liu Xianning
Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561, Japan.
J Theor Biol. 2009 Mar 7;257(1):181-90. doi: 10.1016/j.jtbi.2008.11.011. Epub 2008 Nov 27.
Outbreaks of highly pathogenic H5N1 avian influenza in Southeast Asia, Europe and Africa have led to devastating consequences for poultry, and have resulted in numerous infections in humans. Although these infections from the animal reservoir continue to accumulate, the virus does not seem to spread extensively among humans. However, for example, a process of genetic reassortment could occur in a human who is co-infected with avian influenza A virus and a human strain of influenza A virus. The resulting new virus might then be able to easily infect humans and spread from human to human. Therefore, many experts expect the occurrence of a pandemic due to a mutant virus which can be easily transmitted among humans. Thus, currently, a major public health concern is the next influenza pandemic; yet it remains unclear how to control such a crisis. In this paper, we investigate relations between the evolution of virulence and an effectiveness of pandemic control measures after the emergence of mutant avian influenza; one is an elimination policy of infected birds with avian influenza and the other is a quarantine policy of infected humans with mutant avian influenza. We found that each of these prevention policies can be ineffective (i.e., increase human morbidity or mortality). Further, interestingly, the same intervention might, under the same conditions, increase human morbidity and decrease human mortality, or vice versa. Our practical findings are that the quarantine policy can effectively reduce both human morbidity and mortality but the elimination policy increases either human morbidity or mortality in a worst case situation.
东南亚、欧洲和非洲高致病性H5N1禽流感的爆发给家禽业带来了毁灭性后果，并导致众多人类感染。尽管来自动物宿主的这些感染病例持续增加，但该病毒似乎并未在人类中广泛传播。然而，例如，当一个人同时感染甲型禽流感病毒和一种人类甲型流感病毒毒株时，可能会发生基因重配过程。由此产生的新病毒可能随后能够轻易感染人类并在人际间传播。因此，许多专家预计会出现由一种能够轻易在人际间传播的变异病毒引发的大流行。所以，目前一个主要的公共卫生问题是下一次流感大流行；然而，如何控制这样一场危机仍不明朗。在本文中，我们研究了变异禽流感出现后毒力演变与大流行控制措施有效性之间的关系；一种是对感染禽流感的禽类实施扑杀政策，另一种是对感染变异禽流感的人类实施隔离政策。我们发现，这些预防政策中的每一种都可能无效（即增加人类发病率或死亡率）。此外，有趣的是，在相同条件下，相同的干预措施可能会增加人类发病率并降低人类死亡率，反之亦然。我们的实际研究结果是，隔离政策可以有效降低人类发病率和死亡率，但在最坏的情况下，扑杀政策会增加人类发病率或死亡率。
