Strube Christina, Heuer Lea, Janecek Elisabeth
Institute for Parasitology, University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany.
Vet Parasitol. 2013 Apr 15;193(4):375-89. doi: 10.1016/j.vetpar.2012.12.033. Epub 2012 Dec 27.
The zoonotic roundworms Toxocara canis and T. cati are not only present worldwide in their definitive hosts; they also frequently occur in other animal species, including humans. In those so-called paratenic hosts, the larvae do not develop into the adult stage, but rather migrate throughout the somatic tissue and persist as infectious L3 stage for extensive periods. Those arrested larvae may lead to severe inflammatory reactions and consequently to a wide range of pathological and clinical manifestations. However, the infected paratenic hosts also constitute a potential source of infection for the definitive hosts or humans who may also function as paratenic hosts. In the present review, current knowledge of larval migration in a variety of possible paratenic hosts is summarized including variations of migration routes and susceptibilities. Furthermore, information about the clinical and pathological changes for the presented species and possible consequences of the somatic migration of larvae, i.e. the resulting tissue damage as well as adverse host reactions to arrested larvae are reviewed. There are still many questions unanswered regarding larval behaviour in hosts other than their definitive host. Therefore, it is of great importance to continue further elaboration on the biology of Toxocara spp. to prevent further spreading of larvae in both the paratenic and the definitive host.
人兽共患的蛔虫犬弓首线虫和猫弓首线虫不仅在全球范围内存在于其终末宿主中；它们还经常出现在包括人类在内的其他动物物种中。在这些所谓的转续宿主中，幼虫不会发育到成虫阶段，而是在体细胞组织中迁移，并在很长一段时间内以感染性L3期持续存在。那些停滞的幼虫可能会导致严重的炎症反应，并因此导致广泛的病理和临床表现。然而，受感染的转续宿主也构成了终末宿主或也可能作为转续宿主的人类的潜在感染源。在本综述中，总结了目前关于幼虫在各种可能的转续宿主中迁移的知识，包括迁移途径和易感性的变化。此外，还综述了有关所呈现物种的临床和病理变化以及幼虫体细胞迁移的可能后果，即由此产生的组织损伤以及宿主对停滞幼虫的不良反应的信息。关于幼虫在其终末宿主以外的宿主中的行为，仍有许多问题未得到解答。因此，继续深入研究弓首线虫属的生物学特性，以防止幼虫在转续宿主和终末宿主中进一步传播，具有重要意义。
