Mijele Domnic, Iwaki Takashi, Chiyo Patrick I, Otiende Moses, Obanda Vincent, Rossi Luca, Soriguer Ramon, Angelone-Alasaad Samer
Forensic and Genetics Laboratory, Kenya Wildlife Service, P.O Box 40241-00100, Nairobi, Kenya.
Meguro Parasitological Museum, 4-1-1 Shimomeguro, Meguro-ku, Tokyo, 153-0064, Japan.
Ecohealth. 2016 Dec;13(4):708-719. doi: 10.1007/s10393-016-1156-2. Epub 2016 Aug 23.
Very little is known about the influence of massive and long distance migration on parasite epidemiology. Migration can simultaneously minimize exposure to common parasites in their habitats and increase exposure to novel pathogens from new environments and habitats encountered during migration, while physiological stress during long distance movement can lead to immune suppression, which makes migrants vulnerable to parasites. In this paper, we investigated the diversity, prevalence, parasite load, co-infection patterns and predilection sites of adult gastrointestinal helminths in 130 migrating wildebeests and tested for their relation with animal age, sex and migration time (which also could indicate different migration routes), and compared them with the non-migratory wildebeest. Surprisingly, only four parasite species were found, Oesophagostomum columbianum, Haemonchus placei, Calicophoron raja and Moniezia expansa, which were lower than in non-migratory wildebeest reported in the literature. These parasites were generalists, infecting livestock, and suggests that wildebeest and livestock, because of their interaction during migration, have a cross-infection risk. There was a negative relation between parasites diversity, prevalence and intensity of infection, and host age, which suggests that wildebeests acquire protective immunity against these parasites as they get older. Prevalence and intensity of infection were higher among wildebeest crossing the Mara Bridge (early migrants) compared to those crossing the Serena (late migrants), which suggests that early migrants (or migrants originating from different areas) have varying infection intensities. The prevalence and intensity of infection were higher in males compared to females and may be due to ecological, behavioural, or physiological differences between males and females. Our findings compared to those of previous studies suggest that migration may provide a mechanism to minimize exposure of hosts to common parasites through migratory escape, but this result awaits examination of helminths epidemiology of non-migratory wildebeests from areas of migrant origins. The potential parasitic cross-infection between wildebeests and livestock is a real risk to be taken into account in the management of wildebeest migration corridors.
关于大规模长距离迁徙对寄生虫流行病学的影响，我们所知甚少。迁徙既能同时减少在其栖息地接触常见寄生虫的机会，又会增加在迁徙过程中遇到的新环境和栖息地中的新型病原体的接触风险，而长距离移动过程中的生理压力会导致免疫抑制，这使得迁徙动物易受寄生虫感染。在本文中，我们调查了130头迁徙中的角马体内成年胃肠蠕虫的多样性、流行率、寄生虫负荷、共感染模式和偏好部位，并测试了它们与动物年龄、性别和迁徙时间（这也可能表明不同的迁徙路线）的关系，还将它们与非迁徙角马进行了比较。令人惊讶的是，仅发现了四种寄生虫，即哥伦比亚结节虫、普氏血矛线虫、拉贾杯殖吸虫和扩展莫尼茨绦虫，这一数量低于文献中报道的非迁徙角马。这些寄生虫具有普遍性，会感染家畜，这表明角马和家畜由于在迁徙过程中的相互作用而存在交叉感染风险。寄生虫的多样性、流行率和感染强度与宿主年龄呈负相关，这表明角马随着年龄增长会获得针对这些寄生虫的保护性免疫力。与穿越塞雷纳桥的角马（晚期迁徙者）相比，穿越马拉桥的角马（早期迁徙者）的感染率和感染强度更高，这表明早期迁徙者（或来自不同地区的迁徙者）的感染强度有所不同。雄性角马的感染率和感染强度高于雌性，这可能是由于雄性和雌性在生态、行为或生理上的差异。与先前研究的结果相比，我们的发现表明迁徙可能提供了一种机制，通过迁徙逃避来尽量减少宿主接触常见寄生虫的机会，但这一结果有待对来自迁徙源头地区的非迁徙角马的蠕虫流行病学进行研究。角马和家畜之间潜在的寄生虫交叉感染是在管理角马迁徙走廊时需要考虑的一个实际风险。
