Coyner Donald F, Spalding Marilyn G, Forrester Donald J
Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, USA.
J Parasitol. 2003 Apr;89(2):290-8. doi: 10.1645/0022-3395(2003)089[0290:EOEIIF]2.0.CO;2.
Under laboratory conditions, 2 modes of transmission of Eustrongylides ignotus (Nematoda: Dioctophymatoidea) to fish were identified. Eastern mosquitofish (Gambusia holbrooki) became infected after ingestion of either eggs of E. ignotus containing first-stage larvae or aquatic oligochaetes (Limnodrilus hoffmeisteri) containing third-stage larvae of E. ignotus. After removal from the uterus of gravid E. ignotus females and incubation for 17-28 days, depending on temperature, it was found that parasite eggs contained first-stage larvae that were infective to fish and oligochaetes. Larvae developed to the third stage in oligochaetes and were infective to fish 35-77 days postinfection (PI) and when fed to fish, developed to the fourth stage between 127 and 184 days PI. Eggs containing first-stage larvae fed directly to fish developed to the fourth stage between 84 and 105 days PI. The amount of time for development from the undifferentiated egg to the fourth-stage larva was 78-156 days shorter when fish ingested eggs containing first-stage larvae than when fish ingested oligochaetes containing third-stage larvae. Three species of large piscivorous fish, including black crappie (Pomoxis nigromaculatus), largemouth bass (Micropterus salmoides), and warmouth (Lepomis gulosus), were fed mosquitofish containing fourth-stage larvae. At necropsy, live E. ignotus larvae were recovered from all 3 species. Several fish had multiple infections after ingesting > 1 larva, indicating that bioaccumulation of the parasite in the food chain may occur.
在实验室条件下，确定了艾氏真圆线虫（线虫纲：膨结线虫科）向鱼类传播的两种模式。东部食蚊鱼（盖氏食蚊鱼）在摄入含有第一期幼虫的艾氏真圆线虫卵或含有艾氏真圆线虫第三期幼虫的水生寡毛类动物（霍氏水丝蚓）后会被感染。从怀孕的艾氏真圆线虫雌性子宫中取出虫卵并根据温度孵化17 - 28天后，发现寄生虫卵中含有对鱼类和寡毛类动物具有感染性的第一期幼虫。幼虫在寡毛类动物体内发育到第三期，在感染后35 - 77天对鱼类具有感染性，当喂食给鱼类时，在感染后127 - 184天发育到第四期。直接喂食给鱼类的含有第一期幼虫的虫卵在感染后84 - 105天发育到第四期。当鱼类摄入含有第一期幼虫的虫卵时，从未分化的虫卵发育到第四期幼虫的时间比鱼类摄入含有第三期幼虫的寡毛类动物时短78 - 156天。三种大型食鱼性鱼类，包括黑鲈（黑斑叉尾鲈）、大口黑鲈（大口美州鲈）和暖口鲈（贪食美洲鲈），被喂食了含有第四期幼虫的食蚊鱼。尸检时，从所有这三种鱼类中都发现了活的艾氏真圆线虫幼虫。几条鱼在摄入> 1只幼虫后出现了多重感染，这表明寄生虫可能在食物链中发生生物累积。
