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Since 1996, goose/Guangdong lineage H5 highly pathogenic influenza A viruses (HPIAV) have caused an unprecedented panzootic. In 2020, subclade 2.3.4.4b HPIAV H5N1 emerged and spread to multiple continents causing substantial [...]

Increasing reports of marine mammal deaths have been attributed to the parasite Sarcocystis neurona. Infected opossums, the only known definitive hosts, shed S. neurona sporocysts in their feces. Sporocysts can contaminate the marine environment via overland runoff, and subsequent ingestion by marine mammals can lead to fatal encephalitis. Our aim was to determine the prevalence of S. neurona in opossums from coastal areas of Washington State (USA) and to compare genetic markers between S. neurona in opossums and marine mammals. Thirty-two road-kill opossums and tissue samples from 30 stranded marine mammals meeting inclusion criteria were included in analyses. Three opossums (9.4%) and twelve marine mammals (40%) were confirmed positive for S. neurona via DNA amplification at the ITS1 locus. Genetic identity at microsatellites (sn3, sn7, sn9) and the snSAG3 gene of S. neurona was demonstrated among one harbor porpoise and two opossums. Watershed mapping further demonstrated plausible sporocyst transport pathways from one of these opossums to the location where an infected harbor porpoise carcass was recovered. Our results provide the first reported link between S. neurona genotypes on land and sea in the Pacific Northwest, and further demonstrate how terrestrial pathogen pollution can impact the health of marine wildlife.

Increasing reports of marine mammal deaths have been attributed to the parasite Sarcocystis neurona. Infected opossums, the only known definitive hosts, shed S. neurona sporocysts in their feces. Sporocysts can contaminate the marine environment via overland runoff, and subsequent ingestion by marine mammals can lead to fatal encephalitis. Our aim was to determine the prevalence of S. neurona in opossums from coastal areas of Washington State (USA) and to compare genetic markers between S. neurona in opossums and marine mammals. Thirty-two road-kill opossums and tissue samples from 30 stranded marine mammals meeting inclusion criteria were included in analyses. Three opossums (9.4%) and twelve marine mammals (40%) were confirmed positive for S. neurona via DNA amplification at the ITS1 locus. Genetic identity at microsatellites (sn3, sn7, sn9) and the snSAG3 gene of S. neurona was demonstrated among one harbor porpoise and two opossums. Watershed mapping further demonstrated plausible sporocyst transport pathways from one of these opossums to the location where an infected harbor porpoise carcass was recovered. Our results provide the first reported link between S. neurona genotypes on land and sea in the Pacific Northwest, and further demonstrate how terrestrial pathogen pollution can impact the health of marine wildlife.

Highly pathogenic avian influenza viruses (HPAIV) H5N1 clade 2.3.4.4b continue to have unprecedented global impacts on wild birds and mammals, with especially significant mortality observed in colonial surface-nesting seabirds and in some marine mammal species. In July of 2023 H5N1 HPAIV 2.3.4.4b was detected in Caspian terns nesting on Rat Island, Washington USA. An estimated 1,800–1,900 adult terns populated the breeding colony, based on aerial photographs taken at the start of the outbreak. On a near-weekly basis throughout July and August, we counted and removed carcasses, euthanized moribund birds, and collected swab and tissue samples for diagnostic testing and next-generation sequencing. We directly counted 1,101 dead Caspian tern adults and 520 dead chicks, indicating a minimum 56% loss of the adult colony population and potential impacts to reproductive success. Combining the observed mortality on Rat Island with HPAI-related Caspian tern deaths recorded elsewhere in Washington and Oregon, we estimate that 10–14% of the Pacific Flyway population was lost in the summer of 2023. Comparatively few adult Glaucous-winged gulls (hybrids) nesting on Rat Island died (~3% of the local population), although gull chick mortality was high. Sixteen harbor seals in the immediate or nearby area stranded during the outbreak, and H5N1 HPAIV was detected in brain and/or lung tissue of five seals. These cases are the first known detections of HPAIV in a marine mammal on the Pacific coast of North America. Phylogenetic analyses support the occurrence of at least three independent avian-mammalian virus spillover events (tern or gull to harbor seal). Whole genome sequencing indicated that H5N1 HPAIV may have been introduced to Washington from Caspian terns in Oregon. Ongoing monitoring and surveillance for H5N1 HPAIV in the marine environment is necessary to understand the epidemiology of this virus, assess conservation impacts to susceptible species, and provide support for data-driven management and response actions. [ABSTRACT FROM AUTHOR]

Sarcocystis neurona is an important cause of protozoal encephalitis among marine mammals in the northeastern Pacific Ocean. To characterise the genetic type of S. neurona in this region, samples from 227 stranded marine mammals, most with clinical or pathological evidence of protozoal disease, were tested for the presence of coccidian parasites using a nested PCR assay. The frequency of S. neurona infection was 60% (136/227) among pinnipeds and cetaceans, including seven marine mammal species not previously known to be susceptible to infection by this parasite. Eight S. neurona fetal infections identified this coccidian parasite as capable of being transmitted transplacentally. Thirty-seven S. neurona-positive samples were multilocus sequence genotyped using three genetic markers: SnSAG1-5-6, SnSAG3 and SnSAG4. A novel genotype, referred to as Type XIII within the S. neurona population genetic structure, has emerged recently in the northeastern Pacific Ocean and is significantly associated with an increased severity of protozoal encephalitis and mortality among multiple stranded marine mammal species.

Clinical metrics of baseline health in sentinel seabird species can offer insight into marine ecosystem dynamics, individual and population health, and assist in wildlife rehabilitation and conservation efforts. Protein electrophoresis is useful for detecting changes in acute phase proteins and immunoglobulin levels that may indicate subtle inflammatory responses and/or infectious disease. Serum biochemistry can highlight nutritional status, metabolic derangements, and organ injury and function. However, baseline values for such health parameters are largely unknown for many seabird species. Therefore, the objective of this study is to establish baseline clinical health reference intervals for serum protein electrophoresis, acute phase proteins including serum amyloid A and haptoglobin, and biochemistry parameters in the rhinoceros auklet (Cerorhinca monocerata), a key sentinel species in the North Pacific. From 2013 to 2019, 178 wild, apparently healthy breeding adult rhinoceros auklets were captured across four breeding colonies in British Columbia, Canada (Lucy Island, Pine Island, Triangle Islands, and SGang Gwaay) and from one colony in Washington, United States (Protection Island). Reference intervals were calculated for protein electrophoresis fractions and acute phase proteins (n = 163), and serum biochemistry (n = 35) following established guidelines by the American Society of Veterinary Clinical Pathology. Animals were also assessed for the presence of antibodies to the influenza A virus. Approximately 48% (70/147) of sampled birds were seropositive for influenza A virus, with a prevalence of 50% (6/12) in 2013, 75% (47/63) in 2014, and 24% (17/72) in 2019. This work provides clinical baseline health metrics of a key North Pacific sentinel species to help inform marine ecosystem monitoring, recovery, and rehabilitation efforts in the Pacific Northwest. [ABSTRACT FROM AUTHOR]

A newly described onygenalean fungus, Emydomyces testavorans, has been isolated from ulcerative shell and skin lesions of freshwater aquatic chelonians. To investigate the shell lesions associated with infection and determine if any lesional features were unique to E. testavorans, tissues from turtles housed in zoological institutions (n = 45) in the United States and free-living turtles (n = 5) submitted for diagnostic biopsy or necropsy were examined. Free-living turtles were from geographically distinct habitats in Florida (n = 1) and Washington (n = 4) at the time of sampling. Histologic shell sections were evaluated for the presence or absence of specific lesional features. Infection with E. testavorans was evaluated in all cases by screening GMS (Grocott-Gomori's methenamine silver)-stained histologic sections for the presence of morphologically consistent fungi and by quantitative PCR (polymerase chain reaction) on representative frozen tissue or formalin-fixed paraffin-embedded sections. Additionally, culture was performed for 15 cases with available fresh/frozen tissue. In total, there were 17 PCR-confirmed E. testavorans cases, 29 cases with morphologically consistent fungi on GMS-stained sections, and 21 cases of shell lesions without histologic or molecular evidence of E. testavorans infection. Epithelial inclusion cysts, defined as cystic structures within the dermis lined by keratinized stratified squamous epithelium and containing necrotic bone and keratin debris, were significantly (P <.01) associated with E. testavorans infection. Other significantly associated shell lesions included squamous metaplasia, hyperkeratosis, inflammation, and osteonecrosis (P <.05). This study identified characteristic shell lesions associated with E. testavorans infection. Further studies to prove causality are needed. [ABSTRACT FROM AUTHOR]

Free‐ranging feral cats (Felis catus) are increasingly found in colonies loosely managed by people. These colonies increase cat densities and, hence, pose threats to wildlife via disease and predation, particularly in insular ecosystems where native species have smaller populations and reduced pathogen exposure compared to continental systems. Given such concerns, our objectives were to: (a) identify feral cat colonies on the island of O'ahu in the vicinity of important native bird sites; and (b) test for Toxoplasma gondii, a parasite‐causing disease (Toxoplasmosis) of concern to native birds, at cat colony sites. We identified 32 important native bird locations and surveyed public lands near these sites to determine presence of cat colonies. Where cat colonies were present, we collected feces and used molecular tools to identify the presence of T. gondii. We identified 25 cat colonies near an important bird area and collected feces at four of these colonies, with three testing positive for T. gondii. The presence of cats near a majority of native bird areas suggests that cats may impose a serious threat to bird species. Our finding of T. gondii at three of the four colonies where cat feces were collected raises serious health concerns for humans, birds, and many other terrestrial and aquatic organisms. Native birds in Hawai'i, including highly endangered species, are susceptible to both predation and T. gondii, and finding its presence in locations relatively near to important native bird areas provides further evidence that reducing free‐ranging feral cat numbers is critical for reducing impacts on birds. [ABSTRACT FROM AUTHOR]

Brucella ceti and Brucella pinnipedialis have been documented as occurring in marine mammals, and B. ceti has been identified in 3 naturally acquired human cases. Seroconversion and infection patterns in Pacific Northwest harbor seals (Phoca vitulina richardii) and North Atlantic hooded seals (Cystophora cristata) indicate post-weaning exposure through prey consumption or lungworm infection, suggesting fish and possibly invertebrates play an epizootiologic role in marine Brucella transmission and possible foodborne risk to humans. We determined if real-time quantitative PCR (qPCR) assays can detect marine Brucella DNA in fish DNA. Insertion sequence (IS)711 gene and sequence type (ST)27 primer–probe sets were used to detect Brucella associated with marine mammals and human zoonotic infections, respectively. First, DNA extracts from paired-species fish (containing 2 species) samples were tested and determined to be Brucella DNA negative using both IS711 and ST27 primer–probe sets. A representative paired-species fish DNA sample was spiked with decreasing concentrations of B. pinnipedialis DNA to verify Brucella detection by the IS711 primer–probe within fish DNA. A standard curve, developed using isolated DNA from B. pinnipedialis, determined the limit of detection. Finally, the IS711 primer–probe was used to test Atlantic cod (Gadus morhua) DNA extracts experimentally infected with the B. pinnipedialis hooded seal strain. In culture-positive cod tissue, the IS711 limit of detection was ~1 genome copy of Brucella. Agreement between culture and PCR results for the 9 positive and 9 negative cod tissues was 100%. Although a larger sample set is required for validation, our study shows that qPCR can detect marine Brucella in fish. [ABSTRACT FROM AUTHOR]

The article provides an overview of pathogen surveillance in herpetofaunal populations, emphasizing study design, sampling strategies, and biosecurity measures. Topics discussed include methods for detecting pathogens using Polymerase Chain Reaction (PCR) and quantitative Polymerase Chain Reaction (qPCR), the importance of considering pathogen load and incidence in risk assessment, and the significance of implementing robust biosecurity protocols to mitigate pathogen spread.

Ecologists are increasingly interested in quantifying consumer diets based on food DNA in dietary samples and high-throughput sequencing of marker genes. It is tempting to assume that food DNA sequence proportions recovered from diet samples are representative of consumer's diet proportions, despite the fact that captive feeding studies do not support that assumption. Here, we examine the idea of sequencing control materials of known composition along with dietary samples in order to correct for technical biases introduced during amplicon sequencing and biological biases such as variable gene copy number. Using the Ion Torrent PGM©, we sequenced prey DNA amplified from scats of captive harbour seals ( Phoca vitulina) fed a constant diet including three fish species in known proportions. Alongside, we sequenced a prey tissue mix matching the seals' diet to generate tissue correction factors ( TCFs). TCFs improved the diet estimates (based on sequence proportions) for all species and reduced the average estimate error from 28 ± 15% (uncorrected) to 14 ± 9% ( TCF-corrected). The experimental design also allowed us to infer the magnitude of prey-specific digestion biases and calculate digestion correction factors ( DCFs). The DCFs were compared with possible proxies for differential digestion (e.g. fish protein%, fish lipid%) revealing a strong relationship between the DCFs and percent lipid of the fish prey, suggesting prey-specific corrections based on lipid content would produce accurate diet estimates in this study system. These findings demonstrate the value of parallel sequencing of food tissue mixtures in diet studies and offer new directions for future research in quantitative DNA diet analysis. [ABSTRACT FROM AUTHOR]

The article discusses an 11-year study that examined stranding data on the Great Shearwater (Puffinus Gravis), an abundant pelagic seabird that undertakes transequatorial migrations between the North and South Atlantic Ocean. It says that this was prompted by 12 separate mortality events where the cause of death was not attributed to infectious disease or heavy metals. It adds that the cause of death was an apparent increase in strandings, leading to large-scale mortality of emaciated birds.

Protozoal infections have been widely documented in marine mammals and may cause morbidity and mortality at levels that result in population level effects. The presence and potential impact on the recovery of endangered Hawaiian monk seals Neomonachus schauinslandi by protozoal pathogens was first identified in the carcass of a stranded adult male with disseminated toxoplasmosis and a captive monk seal with hepatitis. We report 7 additional cases and 2 suspect cases of protozoal-related mortality in Hawaiian monk seals between 2001 and 2015, including the first record of vertical transmission in this species. This study establishes case definitions for classification of protozoal infections in Hawaiian monk seals. Histopathology and immunohistochemistry were the primary diagnostic modalities used to define cases, given that these analyses establish a direct link between disease and pathogen presence. Findings were supported by serology and molecular data when available. Toxoplasma gondii was the predominant apicomplexan parasite identified and was associated with 100% of mortalities (n = 8) and 50% of suspect cases (n = 2). Incidental identification of sarcocysts in the skeletal muscle without tissue inflammation occurred in 4 seals, including one co-infected with T. gondii. In 2015, 2 cases of toxoplasmosis were identified ante-mortem and shared similar clinical findings, including hematological abnormalities and histopathology. Protozoal-related mortalities, specifically due to toxoplasmosis, are emerging as a threat to the recovery of this endangered pinniped and other native Hawaiian taxa. By establishing case definitions, this study provides a foundation for measuring the impact of these diseases on Hawaiian monk seals.