Exposure of wild Caspian seals (Pusa caspica) to parasites, bacterial and viral pathogens, evaluated via molecular and serological assays

Disease surveillance of marine mammal populations is essential to understand the causes of strandings, identify potential threats to animal health, and to support development of conservation strategies. Here we report the first large multi-pathogen screening of prevalence for viruses, bacteria and parasites in a sample of 177 live, healthy, wild Caspian seals (Pusa caspica), captured and released during satellite telemetry studies 2007-2017. Employing molecular and serological assays we assess prevalence of pathogens known to be of significance for marine mammal health worldwide, and evaluate the results in relation to Caspian seal health and conservation. RT-PCR, and PCR assays find evidence for infection by Canine Distemper Virus (CDV), Phocine herpes virus, phocine adenovirus and Influenza A at prevalences of 5%, 6.4%, 21.7%, and 4% respectively. The genomes of CDV isolates collected in 2008 showed 99.59% identity with the 2000 Caspian seal CDV epizootic strain. A partial coding sequence for the Us2 gene from the Caspian seal herpes virus was identical to PhHV-1 isolate PB84, previously reported from a harbor seal (Phoca vitulina), while amplicon sequences for the adenovirus polymerase gene indicated a novel strain. ELISA assays detected exposure to Influenza A (55% of tested samples), adenovirus (25%), coronavirus (6%), CDV (8%), herpes virus (94%), Toxoplasma gondii (2.6%) and heartworm (1%). Hemagglutination inhibition (HI) tests detected exposure to Influenza B at a prevalence of 20%, and Leptospira microscopic agglutination tests detected suspected exposure to Leptospira serovars in 9% of tested samples. Overall, the risks, profile and prevalence of pathogens in Caspian seals appear comparable to other wild phocid seal populations. Our results suggest Caspian seals have exposure pathways to pathogens with epizootic potential or ability to cause significant morbidity, and that disease impacts could reduce the resilience of the population to other conservation threats. Caspian seals are listed as Endangered by the International Union for Conservation of Nature (IUCN), and we recommend that resources are invested to support further surveillance programs and to understand how anthropogenic pressures may influence future disease risks. A translated version of this is available in Russian and Kazakh in the Supplementary Material (Presentation 1 and Presentation 2)

Impacts of fungal disease on dyadic social interactions in a wild agamid lizard

Emerging infectious fungal diseases are responsible for the extinction of myriad species across a range of phyla. As recently shown by the COVID-19 pandemic, social transmission can be key to disease spread, and in this context, humans are not alone in trying to be alone. In group-living species, individuals have been shown to use social behaviour to avoid infection;diseased individuals can isolate from the group, or healthy animals can avoid diseased conspecifics. However, little is known about social behaviour as a mechanism to avoid fungal infection. In this study, we investigated the extent to which wild urban eastern water dragons, Intellagama lesueurii, a gregarious reptile, modify their social behaviour as a response to infection with a recently emerged infectious fungal disease, caused by the pathogen Nannizziopsis barbatae. Using individual data from a long-term study population inhabiting Roma Street Parkland in Brisbane's Central Business District (QLD, Australia) and focal sampling, we tested whether dragons exhibit self-isolation and social-distancing behaviours in the context of dyadic social approach events. Our results suggested that while the presence of the fungal disease had no effect on individuals' social behaviour, its severity did. Specifically, we found that (1) diseased individuals were no less social than their nondiseased conspecifics, (2) nondiseased individuals did not avoid or spend less time with diseased conspecifics, and (3) models considering the severity of skin lesions caused by N. barbatae, instead of their presence or absence, suggested that individuals avoided more severely diseased conspecifics regardless of their own disease status. © 2023 The Author(s)

Occurrence of Spike Antigen Specific SARS-CoV-2 Antibodies in Pre-Pandemic Samples of Domestic Cats Raises New Questions

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome of coronavirus SARS-CoV-2. Former studies showed the high similarity of SARS-CoV-2 to coronavirus (RaTG13) isolated from intermediate horseshoe bat and that the bats, ferrets, domestic cats were capable of transmitting the virus to contact conspecifics, which supports the virus circulation. We estimated the occurrence of antibodies to SARS-CoV-2 in domestic cats after the outbreak in Moscow and corresponded it with earlier data. Among the domestic cats of Moscow sampled in 2020 10% were positive for IgG against RBD antigen of SARS-CoV-2, however, five cats (of 172;2.9%) from Moscow 2018 were IgG-positive for RBD peptide of SARS CoV-2. There were no positive domestic cats sampled in the Russian Far East. The antibodies to SARS-CoV-2 were not detected in archive human samples from Moscow. These results forced us to suggest either the exposure of cats to SARS-CoV-2 in Moscow in 2018 which is highly unlikely, or the effect of other viral peptides on the false-positive results. All in all, these proteins were found only in cats in one region of Russia and were not related to the feline coronavirus.

SARS-CoV-2 exposure in wild white-tailed deer (Odocoileus virginianus).

Widespread human SARS-CoV-2 infections combined with human-wildlife interactions create the potential for reverse zoonosis from humans to wildlife. We targeted white-tailed deer (Odocoileus virginianus) for serosurveillance based on evidence these deer have angiotensin-converting enzyme 2 receptors with high affinity for SARS-CoV-2, are permissive to infection, exhibit sustained viral shedding, can transmit to conspecifics, exhibit social behavior, and can be abundant near urban centers. We evaluated 624 prepandemic and postpandemic serum samples from wild deer from four US states for SARS-CoV-2 exposure. Antibodies were detected in 152 samples (40%) from 2021 using a surrogate virus neutralization test. A subset of samples tested with a SARS-CoV-2 virus neutralization test showed high concordance between tests. These data suggest white-tailed deer in the populations assessed have been exposed to SARS-CoV-2.

Risk assessment of SARS-CoV-2 infection in free-ranging wild animals in Belgium.

The aim of this review paper is to evaluate the putative susceptibilities of different free-ranging wild animal species in Belgium to SARS-CoV-2 and provide a risk assessment of SARS-CoV-2 infection in those animals. Since the onset of the COVID-19 pandemic, natural SARS-CoV-2 infections have mainly been confirmed in domestic and production animals, and in wild animals kept in captivity, although the numbers remain limited when compared to human cases. Recently, the first SARS-CoV-2 infections in presumably escaped minks found in the wild have been detected, further addressing the much-feared scenario of transmission of the virus to animals living in the wild and its consequences. Considering the most likely origin of the virus being a wild animal and the putative susceptibilities of free-ranging wild animal species to SARS-CoV-2, the risk of infection with possible establishment of the virus in these populations has to be investigated closely. The authors conclude that most attention should be given to surveillance and awareness-raising activities for SARS-CoV-2 infection in wild mustelids, bats, wild canids and felids, particularly these collected in wildlife rescue centres. People involved in frequent and close contact with wild animals should take all necessary precautionary measures to protect wild animals against exposure to the virus. More than one year after the first detection of SARS-CoV-2 in humans, the time has come to increase investments in research and surveillance activities in animals, including in free-ranging wild animals, as part of a One Health control of this pandemic. This study focussing on Belgium could be helpful for other countries with similar animal densities and ecosystems.