Marine Research, AZTI- Basque Research and Technology Alliance (BRTA), Txatxarramendi s/n, 48395, Sukarrieta, Bizkaia, Spain.
CBET Research Group, Department of Zoology and Animal Cell Biology, Faculty of Science and Technology, Research Centre for Experimental Marine Biology and Biotechnology PIE-UPV/EHU, University of the Basque Country UPV/EHU, Areatza z/g, 48620, Plentzia, Bizkaia, Spain.
Acta Parasitol. 2022 Jun;67(2):835-841. doi: 10.1007/s11686-022-00525-5. Epub 2022 Feb 9.
It has been suggested that the removal of infected viscera on board is responsible for the high prevalence of anisakid larvae present in wild fish species. The aim of this work is to assess the re-infection capacity of anisakid larvae in European seabasses, a natural host species for the parasite by feeding with pieces of parasitised hake liver under controlled experimental conditions.
To prove this potential link between manipulation and re-infestation, 50 farmed seabasses free of anisakid nematodes were fed with fresh hake liver pieces naturally infested with anisakid larvae.
After digestion periods from 4 to 21 days, the seabasses showed a prevalence of Anisakis of 6%, and a low retention rate of 0.11 larvae/seabass after four days' digestion, and 0.0021 after 21 day digestion. Two nematodes were found in the intestine and in the visceral cavity, and 13 Anisakis were found partially digested in the stomach of one same individual after 4 day digestion. Results showed that only a small number of Anisakis ingested with the viscera were able to reinfect the seabasses, as most of the larvae seemed to be quickly digested or defecated.
it seems that the availability of larvae that could re-enter the life cycle and re-infect a fish after the removal and discarding the infected viscera on board could be much less important than commonly believed.
有人认为，船上清除受感染的内脏是导致野生鱼类中存在大量异尖线虫幼虫的原因。本研究的目的是通过在受控实验条件下用受寄生虫感染的鳕鱼肝脏进行喂养，来评估鲈鱼（寄生虫的天然宿主）体内异尖线虫幼虫的再感染能力。
为了证明这种操作与再感染之间的潜在联系，50 条无异尖线虫感染的养殖鲈鱼被喂食了新鲜的鳕鱼肝脏，这些肝脏自然感染了异尖线虫幼虫。
在 4 至 21 天的消化期后，鲈鱼的异尖线虫感染率为 6%，4 天后的幼虫保留率为 0.11 条/鲈鱼，21 天后的幼虫保留率为 0.0021 条/鲈鱼。在肠道和内脏腔中发现了 2 条线虫，在同一条鱼的胃中发现了 13 条部分消化的异尖线虫。结果表明，只有少量与内脏一起摄入的异尖线虫能够重新感染鲈鱼，因为大多数幼虫似乎很快被消化或排出体外。
看来，与普遍认为的相反，在船上清除和丢弃受感染的内脏后，能够重新进入生命周期并重新感染鱼类的幼虫的数量可能远没有那么重要。
