Multilocus Sequence Typing of Mycoplasma ovipneumoniae Detected in Dall's Sheep (Ovis dalli dalli) and Caribou (Rangifer tarandus grantii) in Alaska, USA.

In 2018, Mycoplasma ovipneumoniae was detected in free-ranging caribou (Rangifer tarandus grantii) and Dall's sheep (Ovis dalli dalli) in Alaska, US. Evaluation of additional nasal swabs and archived tissues for M. ovipneumoniae suggested that this bacterium was widespread geographically and temporally in populations of both species. Multilocus sequence typing of four loci identified a single, novel, apparently stable strain type of M. ovipneumoniae in 11 Dall's sheep and 15 caribou in multiple populations across Alaska sampled over a period of 15 yr (2004-19). This strain type differs from those detected to date from wild or domestic sheep (Ovis aries) or goats (Capra aegagrus hircus) tested in Alaska or the lower 48 states. Although the population health implications of this strain are unknown, it has not been associated with population-wide mortality events. The presence of this strain does not decrease the potential risk from the introduction of a pathogenic M. ovipneumoniae strain associated with severe disease in other wildlife populations; therefore, continued monitoring for signs of disease and additional strains is important.

LABORATORY CONCORDANCE STUDY FOR THE MOLECULAR DETECTION OF MYCOPLASMA OVIPNEUMONIAE.

As part of a respiratory pathogen survey of Alaska wildlife, we conducted a concordance study to assess Mycoplasma ovipneumoniae detection among three different PCR assays using a total of 346 nasal swabs sampled from four species (Dall's sheep, Ovis dalli dalli; mountain goats, Oreamnos americanus; caribou, Rangifer tarandus granti; and moose, Alces alces gigas), and two taxonomic subfamilies (Bovidae subfamily Caprinae and Cervidae subfamily Capreolinae). A federal research laboratory performed two PCR assays (LM40 and intergenic spacer region [IGS]), and a state diagnostic laboratory performed the third (universal Mycoplasma [UM]). Overall concordance was good, ranging from 93% to 99%, which was probably a result of low detection rate of M. ovipneumoniae. Due to differences in positive agreement, the quality of concordance between LM40 and both IGS and UM was considered fair. However, the quality of concordance between IGS and UM was excellent. All three PCR methods detected M. ovipneumoniae in a non-Caprinae species (caribou), and the LM40-PCR assay also detected M. ovipneumoniae in additional Caprinae species. The LM40-PCR assay detected M. ovipneumoniae in a larger number of samples than did the other two assays (IGS, UM). Because of potential differences in detection rates, it is critical to consider test parameters when evaluating a host population for the presence of M. ovipneumoniae.

Streptococcus phocae isolated from a spotted seal (Phoca largha) with pyometra in Alaska.

A spotted seal harvested by subsistence hunters in Kotzebue Sound, Alaska (USA), showed a grossly enlarged uterus and associated lymph nodes. Streptococcus phocae was isolated from the purulent uterine discharge. Histopathologic examination revealed inflammation that was limited to the uterine mucosa. Lymph nodes draining the affected organ were reactive but no evidence of active infection was found in the lymph nodes. This report is the first Streptococcus phocae isolated from spotted seals as well as the first report of pyometra as the main pathologic finding associated with this pathogen. Isolation of this pathogen from Alaska expands the reported range to arctic pinnipeds. Zoonotic potential remains unknown.

Variation in bioaccumulation of persistent organic pollutants based on octanol-air partitioning: Influence of respiratory elimination in marine species.

Risk assessments of persistent organic pollutants (POPs) are often based on octanol-water (KOW) partitioning dynamics and may not adequately reflect bioaccumulation in air-breathing organisms. It has been suggested that compounds with low KOW and high octanol-air partitioning (KOA) coefficients have the potential to bioaccumulate in air-breathing organisms, including marine mammals. Here we evaluate differences in concentrations of POPs for two trophically matched Arctic species, spotted seal (Phoca largha) and sheefish (Stenodus leucichthys). We compared concentrations of 108 POPs in matched tissues (liver and muscle) across three ranges of KOW. We found a significant positive correlation between POP concentration and log KOA in spotted seal tissues for low log KOW compounds (log KOW <5.5, p<0.05). This provides further evidence for empirical models and observed bioaccumulation patterns in air-breathing organisms, and highlights the potential for bioaccumulation of these compounds in Arctic marine mammals.

Mercury concentrations in hair from neonatal and juvenile Steller Sea Lions (Eumetopias jubatus): implications based on age and region in this northern Pacific marine sentinel piscivore.

Mercury is a global contaminant of concern for the fetus and the neonate of piscivores. Methylmercury, produced within marine ecosystems, is of particular concern as a readily absorbed neurotoxicant transported across the blood brain barrier and transplacentally. In the North Pacific Ocean, Steller sea lions are broadly distributed apex predators and, as such, integrate complex food webs and the associated exposure and possible adverse effects of toxic and infectious agents. Hair, including lanugo, was examined using regional and age groupings to assess mercury concentrations in young Alaskan Steller sea lions. The highest concentrations of mercury occurred in the youngest animals, likely via in utero exposure. Based on the adverse developmental outcomes of methylmercury toxicity this specific cohort is of concern. Regionally, higher concentrations of mercury were observed in the endangered western population of Steller sea lions and mirrored patterns observed in human biomonitoring studies of Alaskan coastal communities. These data have broader implications with respect to human and ecosystem health as Steller sea lions rely on similar prey species and foraging areas as those targeted by commercial fisheries and subsistence users and are therefore valuable sentinels of marine ecosystem health.

Toxicokinetics of mercury in blood compartments and hair of fish-fed sled dogs.

BACKGROUND: Understanding mercury (Hg) distribution in blood and the importance of hair as an excretory pathway is critical for evaluating risk from long term dietary Hg exposure. The major objective of this study was to characterize changes in total Hg concentrations in specific blood compartments and hair over time due to long term piscivory. METHODS: Eight sled dogs (Canis lupus familiaris) were fed either a fish and kibble diet (n = 4), or a fish-free control diet (n = 4) for 12 weeks. Concentrations of Hg were monitored throughout the exposure period, and for 10 weeks post exposure, until Hg concentrations in all blood compartments of one of the exposed dogs dropped below detection limit. Additionally, foreleg hair was sampled during acclimation and weeks 0 and 12. RESULTS: Hg was detected primarily in whole blood and packed cells, although it was sporadically detected at low concentrations in plasma and serum in two of the fish fed dogs. Dogs ingested an estimated average of 13.4 ± 0.58 µg Hg per kg body weight per day. Hg was detectable in whole blood and packed cells within a week of exposure. Detected concentrations continued to rise until plateauing at approximately 3-6 weeks of exposure at a mean of 9.2 ± 1.97 ng/g (ppb) in whole blood. Hg concentration decreased post exposure following 1st order elimination. The mean half-life (t1/2) in whole blood for Hg was 7 weeks. Mean Hg in hair for the fish-fed dogs at week 12 was 540 ± 111 ppb and was significantly greater (about 7-fold) than the Hg hair concentration for the control dogs. The hair to blood ratio for Hg in fish-fed dogs was 59.0 ± 7.6:1. CONCLUSIONS: This study found the sled dog model to be an effective method for investigating and characterizing blood Hg distribution (whole blood, serum, plasma, packed cells) and toxicokinetics associated with a piscivorous diet, especially for Hg-exposed fur bearing mammals (such as polar bears). Although hair excretion and hair to blood Hg ratios were not similar to human concentrations and ratios, the sled dog toxicokinetics of Hg in blood, was more similar to that of humans than traditional laboratory animals (such as the rat).