Parasites can cause chronic stress in some animal species, and this type of stress response has been associated with adverse consequences for the host. In order to know whether parasitism elicited a stress response associated with decreased host fitness, hookworm (Uncinaria sp.) infection was studied in a colony of South American fur seals (Arctocephalus australis) in which hookworms infect nearly all pups born in a reproductive season. A parasite-free group was generated by treating a subset of pups with an antiparasitic drug before they developed patent hookworm infection. Stress and metabolic hormones, energy balance, and humoral and cellular immune parameters were measured in this group and hookworm-infected pups. Hookworms elicited a marked increase in plasma cortisol levels in fur seal pups. These hookworm-infected pups were able to maintain constant glucose levels, despite losing body mass over the course of infection potentially because of increased protein catabolism. Infected pups were able to mount an effective immune response against the parasite and eliminated hookworms from the intestine, recovering partial body mass lost as a result of hookworm infection at the end of the study period. As shown in previous studies, adequate glucose levels are critical for proper T lymphocyte reactivity, and it is possible that, through activation of a stress response, energy can be readily available for immune response against the parasite contributing to early recovery from infection. Although there are potential fitness costs to mounting a sustained stress response, these could also be adaptive and promote survival during critical life-history stages.

中文翻译：

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寄生引起了一种应激反应，该反应为南美海狗（Arctocephalus australis）的免疫功能分配了资源。

寄生虫可引起某些动物的慢性应激，这种应激反应与宿主的不良后果有关。为了了解寄生虫是否引起与寄主适应性降低相关的应激反应，在南美海狗（Arctocephalus australis）的一个殖民地中研究了钩虫（Uncinaria sp。）感染，其中钩虫感染了几乎所有繁殖季节出生的幼崽。在寄生幼虫发展成钩形虫感染之前，先用抗寄生虫药治疗幼崽，从而形成无寄生虫组。在该组和钩虫感染的幼犬中测量了压力和代谢激素，能量平衡以及体液和细胞免疫参数。钩虫在海狗幼崽中引起血浆皮质醇水平显着增加。这些钩虫感染的幼犬尽管在感染过程中失去了体重，但可能由于蛋白质分解代谢增加而使葡萄糖水平保持恒定。受感染的幼犬能够对寄生虫产生有效的免疫反应，并从肠道内消除钩虫，从而在研究期末恢复了因钩虫感染而损失的部分体重。如先前的研究所示，足够的葡萄糖水平对于适当的T淋巴细胞反应性至关重要，并且有可能通过激活应激反应，很容易获得能量用于抵抗寄生虫的免疫反应，从而有助于早期从感染中恢复。尽管增加持续的压力反应可能会产生健身成本，