Takumi K, Van der Giessen J
Microbiological Laboratory for Health Protection, National Institute for Public Health and Environment, Antonie van Leeuwenhoeklaan 9, PO Box 1, 3720 BA Bilthoven, The Netherlands.
Parasitology. 2005 Jul;131(Pt 1):133-40. doi: 10.1017/s0031182005007456.
On the basis of high prevalences of Echinococcus multilocularis in the growing fox populations in Central Europe, its total biomass may have increased significantly in the past 20 years. E. multilocularis is now also found in areas outside the known endemic area in Central Europe. Therefore, E. multilocularis, the causative agent of a serious parasitic zoonosis, might be of major concern for public health and a challenge to control. Some experimental field trials to control E. multilocularis using an anti-worm drug reduced parasite burden in a contaminated region during the control campaign, but failed to eradicate the parasite completely. It was our aim to develop a mathematical model describing the biomass of egg, larval, and adult worm stages of the E. multilocularis life-cycle, and simulate a hypothetical control campaign. Additionally, we derived the reproduction number of this parasite and explored conditions for the persistence of the parasite's life-cycle. Our model shows that while control campaigns rapidly reduce the worm burden in the definitive host, and consequently eggs in the environment, the pool of larvae in the intermediate host remains large. The parasite's life-cycle persists in a region where prevalence in the intermediate host is low (approximately 1%). Therefore, we conclude that the parasite is likely to re-emerge if control is discontinued on the basis of reduced worm population. Continued treatment of the definitive host is required to eradicate the larval stage of the parasite from the intermediate host population.
基于中欧不断增长的狐狸种群中多房棘球绦虫的高流行率，在过去20年中其总生物量可能已显著增加。现在在中欧已知流行区以外的地区也发现了多房棘球绦虫。因此，作为一种严重的寄生性人畜共患病的病原体，多房棘球绦虫可能是公共卫生的主要关注点以及控制方面的一项挑战。一些使用驱虫药控制多房棘球绦虫的实地试验在控制行动期间降低了受污染地区的寄生虫负担，但未能完全根除该寄生虫。我们的目标是建立一个数学模型来描述多房棘球绦虫生命周期中虫卵、幼虫和成虫阶段的生物量，并模拟一次假设的控制行动。此外，我们推导出了这种寄生虫的繁殖数，并探索了寄生虫生命周期持续存在的条件。我们的模型表明，虽然控制行动迅速减少了终末宿主中的蠕虫负担，从而减少了环境中的虫卵，但中间宿主中的幼虫库仍然很大。在中间宿主患病率较低（约1%）的地区，寄生虫的生命周期持续存在。因此，我们得出结论，如果基于蠕虫数量减少而停止控制，寄生虫很可能会再次出现。需要持续治疗终末宿主，以便从中间宿主种群中根除寄生虫的幼虫阶段。
