Combes C
Centre de Biologie Tropicale, Unité Mixte de Recherches Université-CNRS 5555, Perpignan, France.
Int J Parasitol. 1997 Jan;27(1):1-10. doi: 10.1016/s0020-7519(96)00168-3.
Parasites improve their fitness as a result of the selection of traits which determine their relationships with their hosts. Some of these relationships are examined briefly. There is a cost of virulence for parasites, paralleling the cost of resistance for hosts, which implies that the good health of the host can be a component of parasite fitness; conversely, some transmission modes imply that the host be markedly weakened by the parasite. Pathogenicity can be influenced by characters such as a transmission of the parasite from parents to offspring, or the demographic characteristics of the host populations. Important components of parasite fitness are: the complexity of the life-cycle; the degree of specialization for a more or less open host range; the conspicuousness or discretion of the infective and parasitic stages. However, the best possible adaptation to a particular host is not always selected: when a parasite exploits several host species, the gene flows between parasites which have developed in different hosts may be responsible for "maladaptation". This may be important for an understanding of the pathogenicity of certain human parasitic diseases.
寄生虫通过选择决定其与宿主关系的性状来提高自身适应性。本文简要探讨了其中一些关系。寄生虫存在毒力成本，这与宿主的抵抗力成本类似，这意味着宿主的健康状况可能是寄生虫适应性的一个组成部分；相反，一些传播方式意味着宿主会因寄生虫而明显衰弱。致病性可能受到诸如寄生虫从亲代传递给子代，或宿主种群的人口统计学特征等因素的影响。寄生虫适应性的重要组成部分包括：生命周期的复杂性；对或多或少开放的宿主范围的特化程度；感染阶段和寄生阶段的显著程度或隐蔽性。然而，对特定宿主的最佳适应性并不总是被选择：当一种寄生虫利用多种宿主物种时，在不同宿主中发育的寄生虫之间的基因流动可能导致“适应不良”。这对于理解某些人类寄生虫病的致病性可能很重要。
