ABSTRACT: Crassicauda spp. (Nematoda) infest the cranial sinuses of several odontocetes, causing diagnostic trabecular osteolytic lesions. We examined skulls of 77 Indian Ocean humpback dolphins Sousa plumbea and 69 Indo-Pacific bottlenose dolphins Tursiops aduncus, caught in bather-protection nets off KwaZulu-Natal (KZN) from 1970-2017, and skulls of 6 S. plumbea stranded along the southern Cape coast in South Africa from 1963-2002. Prevalence of cranial crassicaudiasis was evaluated according to sex and cranial maturity. Overall, prevalence in S. plumbea and T. aduncus taken off KZN was 13 and 31.9%, respectively. Parasitosis variably affected 1 or more cranial bones (frontal, pterygoid, maxillary and sphenoid). No significant difference was found by gender for either species, allowing sexes to be pooled. However, there was a significant difference in lesion prevalence by age, with immature T. aduncus 4.6 times more likely affected than adults, while for S. plumbea, the difference was 6.5-fold. As severe osteolytic lesions are unlikely to heal without trace, we propose that infection is more likely to have a fatal outcome for immature dolphins, possibly because of incomplete bone development, lower immune competence in clearing parasites or an over-exuberant inflammatory response in concert with parasitic enzymatic erosion. Cranial osteolysis was not observed in mature males (18 S. plumbea, 21 T. aduncus), suggesting potential cohort-linked immune-mediated resistance to infestation. Crassicauda spp. may play a role in the natural mortality of S. plumbea and T. aduncus, but the pathogenesis and population level impact remain unknown.

中文翻译：

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来自南非的两个沿海海豚物种中的颅骨颅耳聋主要是一种未成熟个体的疾病。

摘要：Crassicauda spp。（Nematoda）感染了数种齿形突科的颅窦，导致诊断性小梁溶骨性病变。我们检查了1970-2017年在夸祖鲁-纳塔尔省（KZN）附近的沐浴者保护网中捕获的77头印度洋座头海豚Sousa plumbea和69支印度太平洋宽吻海豚Tursiops aduncus的头骨，以及沿着南部搁浅的6 S. plumbea的头骨。1963年至2002年在南非的开普敦海岸。根据性别和颅骨成熟度评估颅骨颅耳聋的患病率。总体而言，铅中毒链球菌和阳ad线虫的患病率起飞的KZN分别为13和31.9％。寄生虫病会影响1个或多个颅骨（额骨，翼状，肉，上颌骨和蝶骨）。两种物种的性别均未发现显着差异，因此可以将性别合并。但是，随着年龄的增长，病变的患病率存在​​显着差异，未成年人的T. aduncus患病率是成年人的4.6倍，而S. plumbea，相差6.5倍。由于严重的溶骨性病变不太可能无法治愈，因此我们建议感染未成年的海豚更可能产生致命的后果，这可能是由于骨骼发育不完全，清除寄生虫的免疫能力降低或炎症反应过度旺盛所致。寄生酶侵蚀。在成熟的男性（18 S. plumbea， 21 T. aduncus）中未观察到颅骨溶解，提示潜在的队列相关免疫介导的抗病性。Crassicauda属。可能在自然死亡率的作用S. plumbea和T. aduncus，但发病机制和群体水平的影响仍然未知。