Clearance of a dermal Huffmanela sp. in a sandbar shark (Carcharhinus plumbeus) using levamisole

Abstract

A wild-caught captive sandbar shark Carcharhinus plumbeus developed a contiguous network of darkly pigmented linear tracks that progressed from the snout to the ventral cervical region. Microscopic examination of a skin scraping revealed nematode eggs of the genus Huffmanela, a group of histozoic nematodes that is known to parasitize requiem sharks and marine and freshwater teleosts. The fresh eggs were darkly pigmented with bipolar plugs, contained a larva, and measured 73.3 to 86.4 by 39.0 to 47.4 µm (n = 10). Formalin-fixed and paraffin-embedded eggs were significantly smaller (Wilcoxon rank sums test, p < 0.005), measuring 70.5 to 78.9 by 33.6 to 41.3 µm (n = 13). These measurements do not correlate with previously reported species of Huffmanela. Serial treatment with levamisole (10 mg kg Resale or republication not permitted without written consent of the publisherDis Aquat Org 73: [83][84][85][86][87][88] 2006 skin. These tracks wended their way from the right ventral snout to the left side of the mouth, reducing to a single track past the dorsal aspect of the left commissure, then once again formed a wide band that progressed caudomedially to terminate in the ventral cervical region, losing definition in the last 2 cm (Fig. 1).Blood was collected into sodium heparin from the caudal hemal arch using a 22 gauge 38 mm needle and a 6 ml syringe, then placed into a vial as part of the initial health evaluation. A differential blood count was performed manually, and plasma chemistry analyses were performed by automated bichromatic spectrophotometry (albumin, calcium, phosphorus, bicarbonate and glucose concentrations, and aspartate aminotransferase and lactate dehydrogenase activities) and ion-selective electrode (sodium, potassium and chloride concentrations) on a Roche/Hitachi 912 Clinical Chemistry System (Roche Molecular Systems) (Table 1) (Stoskopf 1993a(Stoskopf , 2000. When compared with previously reported values obtained from elasmobranchs (excluding compromised individuals), potassium concentrations in this specimen appeared to be lower and lactate dehydrogenase activity appeared to be higher; however, the clinical significance of these values is uncertain (Stoskopf 2000, Harms et al. 2002. A skin scrape of the pattern was collected approximately 2 cm caudal to the snout using a Number 10 scalpel blade and placed with a drop of exhibit water onto a glass slide with a coverslip sealed at the edges with ophthalmic ointment (to prevent desiccation) for examination. The shark was then moved into an offexhibit 26 000 l holding tank.Examination of the slide under a microscope revealed numerous darkly pigmented, trichuroid ova with bipolar plugs and thick, dark brown, apparently rugose shells that were embryonated with a motionless coiled larva (Fig. 2). The shell was covered with a thin transparent vitelline envelope and had a thickened chitinous layer at both ends that surrounded the slightly protruding polar plugs, forming a collar. Ten fresh eggs were measured in µm using a calibrated micro...

Huffmanela selachii n. sp. (Nematoda: Trichosomoididae: Huffmanelinae): A new species infecting the skin of the great hammerhead shark (Sphyrna mokarran) and the blacktip reef shark (Carcharhinus melanopterus) in the Arabian Gulf, off-shore Saudi Arabia

“…The current clinical and histopathological examination on the host-parasite relationships revealed that H. selachii in the great hammerhead shark and the blacktip reef shark deposited eggs in epidermal layer of the skin only. This observation was also noted by MacLean et al (2006) who found Huffmanela sp. infected skin only of the sandbar shark ( Carcharhinus plumbeus ).…”

“…eggs that share the same egg dimensions with the those herein were reported without a formal taxonomic assignment to species. The first one published by MacLean et al (2006) from sandbar shark, but those eggs have rugose outer eggshell surfaces. The remaining record of a recently reported Huffmanela sp.…”

Some trichinelloid nematodes from marine fishes off New Caledonia, including description of Pseudocapillaria novaecaledoniensis sp. nov. (Capillariidae)

“…In contrast, these tissue-dwelling nematodes are rarely reported from other parts of the world, although it can be expected that they are widely distributed among marine fishes, but they probably remain unnoticed during routine fish dissections. These parasites are hitherto little known mainly due to their remarkable mode of life, but the number of their records in different fish hosts and different geographical regions seems to increase during recent years (e.g., MacLean et al 2006, Carballo and Navone 2007, Justine 2007, Esteves et al 2009). …”

A Retrospective Study of Disease in Elasmobranchs

“…1, 2). 21 No other typical gross lesions of nematodiasis were recorded. Larvae generally appeared viable and were observed encysted with little host reaction, within microgranulomas, or free within blood vessels and capillaries.…”

“…This lesion was characterized by random foci of acute acinar necrosis and hemorrhage, sometimes delineated by small foci of granulocytic inflammation, edema, and thrombosis (Figs. 21,22). No infectious agents were seen in HE-stained sections or sections stained with B&B, WS, GMS, AF, Giemsa, or Gimenez techniques, and the cause was not determined.…”