Arctic | Mammals
Crassicauda spp . infection in Bowhead whales: Preliminary findings from urine sediment analysis Presenter: Raphaela Stimmelmayr , rafstimmel@gmail.com, North Slope Borough Larshe Hoffland , larshe.hoffland@north.slope.org, Public Health office and Veterinary clinic Forrest Neagak , forrest.neagak@north-slope.org, Public Health office and Veterinary clinic Kristin Hubbard , hubkri42@gmail.com, Public Health office and Veterinary clinic Kidney worm infection ( Crassicauda spp .) has emerged as a novel parasitic nematode infection in Western Arctic bowhead whales ( Balaena mysticetus ). Age distribution of infected bowhead whales is dominated by subadults (6-20 yrs) to mature (>20 yrs) animals. Infections in post-weaning bowheads (2- 5yrs) are rare (~3) and no cases have been detected in midterm to full term fetuses and yearlings (1-1.5 year old). This is in contrast to fin whales(Icelandic Jan Mayen stock), where adult worms (Crassicauda boopis) have been recovered from a calf. To further evaluate the mode of transmission in bowhead whales we completed urine sediment analysis on urine collected from 40 bowhead whales with confirmed kidney worm infection (2016-2022) during fall (September-October: 35), spring (April-May:3) and summer (August: 2). Parasite eggs including larvated and with embryonic mass were detected in 25/40 (62.5%) urine samples. Eggs oval and thick shelled ranged in size between 0.046 to 0.063 mm in length and 0.031 to 0.047 in width. Intensity (eggs/slide) varied with 56% of whales falling in category 1+ (1-10 eggs), 28% in class 2+ (11-50 eggs) and 16% in category 3+ (> 50 eggs). Hatching larvae, exiting through cranial and caudal poles of the eggs, and/or free larvae were also present in a few urine samples. Free larvae but no eggs were previously documented in fin whale urine during their northward feeding migration. Egg shedding was primarily observed during the southward migration of bowhead whales (23/25; 92%). Our findings suggest that kidney worm transmission among bowhead whales is a complex process with seasonal (fall biased) environmental shedding of eggs/larvae. Potential autoinfection (presence of larvae) may play a role in addition to direct/indirect transmission via unknown intermediate or paratenic hosts (vectors). Observed timing of egg shedding would result in effective direct transmission scenarios of eggs/larvae during the upcoming winter breeding season, the periodic large fall feeding aggregations of bowhead whales near Utqiagvik as well as ensure seeding of the marine environment along fall migration pathways.
Alaska Marine Science Symposium 2023 280
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