Publications by authors named "Rideout B"

The driving forces behind the evolution of early metazoans are not well understood, but key insights into their ecology and evolution can be gained through ecological analyses of the in situ, sessile communities of the Avalon assemblage in the Ediacaran (~565 million years ago). Community structure in the Avalon is thought to be underpinned by epifaunal tiering and ecological succession, which we investigate in this study in 18 Avalon communities. Here we found that Avalon communities form four distinctive Community Types irrespective of succession processes, which are instead based on the dominance of morphologically distinct taxa, and that tiering is prevalent in three of these Community Types.

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Article Synopsis
  • Infections, particularly from specific parasites, are prevalent in both wild and captive passerine birds, with some species co-evolving with certain parasites.* -
  • The severity of disease can range from mild to fatal, which raises concerns for institutions managing endangered bird species, especially in mixed-species settings.* -
  • Research aimed at understanding the host-specificity of these parasites has shown that genetic sequences mainly align with specific bird species, indicating a need for further investigation on interspecies transmission and disease risk factors.*
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  • Climate change is affecting wildlife disease dynamics, particularly in polar bears, but long-term studies on this issue have been limited.
  • A study examined serum samples from polar bears in Canada over three different time periods, revealing an increase in exposure to certain zoonotic and bacterial pathogens between 1986 and 2017.
  • The research indicates that changing climate factors, like temperature and precipitation, influence pathogen prevalence in polar bears, highlighting the connection between climate change and wildlife health.
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The goal of this study was to evaluate longitudinal patterns of avian mycobacteriosis spread through a social network. Specifically, we wanted to determine whether the patterns of connectivity over time can predict future infections, and whether this pattern can distinguish between different sources of infection. The study population included 13,409 individuals nested in a larger population of birds that were closely monitored in zoological facilities for over 22 years (1992-2014).

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is a promiscuous bacterium that infects a variety of species but has not been reported in free-ranging polar bears . Sera from 385 polar bears from the western Hudson Bay region, 1986 to 2017, were tested for reactivity to with enzyme-linked immunosorbent assays using anti-canine IgG and protein G as secondary reagents. Sera from bears had variable reactivity to antigens, and there was no difference among bears that had a history of coming near the town of Churchill, Manitoba, and bears that did not.

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This study combined a social network analysis and whole-genome sequencing (WGS) to test for general patterns of contagious spread of a mycobacterial infection for which pathways of disease acquisition are not well understood. Our population included 275 cases diagnosed with avian mycobacteriosis that were nested in a source population of 16,430 birds at San Diego Zoo Wildlife Alliance facilities from 1992 through mid-2014. Mycobacteria species were determined using conventional methods and whole genome sequencing (WGS).

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The Mojave Desert tortoise (Gopherus agassizii), federally listed as threatened, has suffered habitat loss and fragmentation due to human activities. Upper respiratory tract disease (URTD), a documented health threat to desert tortoises, has been detected at the Large-Scale Translocation Study Site (LSTS) in southwestern Nevada, US, a fenced recipient site for translocated animals. Our study aimed to 1) estimate prevalence of URTD and Mycoplasma infection at LSTS and three nearby unfenced sites; 2) assess whether Mycoplasma infection status was associated with developing clinical signs of URTD; and 3) determine whether such an association differed between LSTS and unfenced areas.

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Gammaherpesvirus infections are ubiquitous in captive and free-ranging ruminants and are associated with a variety of clinical diseases ranging from subclinical or mild inflammatory syndromes to fatal diseases such as malignant catarrhal fever. Gammaherpesvirus infections have been fully characterized in only a few ruminant species, and the overall diversity, host range, and biologic effects of most are not known. This study investigated the presence and host distribution of gammaherpesviruses in ruminant species at two facilities, the San Diego Zoo and San Diego Zoo Safari Park.

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Background: Koalas are infected with the koala retrovirus (KoRV) that exists as exogenous or endogenous viruses. KoRV is genetically diverse with co-infection with up to ten envelope subtypes (A-J) possible; KoRV-A is the prototype endogenous form. KoRV-B, first found in a small number of koalas with an increased leukemia prevalence at one US zoo, has been associated with other cancers and increased chlamydial disease.

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Disease transmission can be identified in a social network from the structural patterns of contact. However, it is difficult to separate contagious processes from those driven by homophily, and multiple pathways of transmission or inexact information on the timing of infection can obscure the detection of true transmission events. Here, we analyze the dynamic social network of a large, and near-complete population of 16,430 zoo birds tracked daily over 22 years to test a novel "friends-of-friends" strategy for detecting contagion in a social network.

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A 3-year-old female Bruce's green pigeon () was presented with granulomatous inflammation of the cere and underlying tissues with osteomyelitis and bone proliferation of the dorsal premaxilla. Biopsy and culture revealed the presence of complex, and multi-antimicrobial treatment was initiated with clarithromycin, ethambutol, rifabutin, and enrofloxacin. The cere lesion improved and no evidence of systemic granulomas was observed over 4 months of treatment, although leukocytosis and monocytosis persisted.

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A histopathologic study of free-ranging hummingbirds found in California, US was performed to identify mortality trends. Tissues from 61 wild hummingbirds representing five native California species collected by the San Diego Zoo from 1996 to 2016 or the Lindsay Wildlife Experience from 2015 to 2017 were histologically examined. Birds were either found dead or moribund at the time of submission or were euthanized due to unresolvable health issues.

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Background: Passive acoustic telemetry using coded transmitter tags and stationary receivers is a popular method for tracking movements of aquatic animals. Understanding the performance of these systems is important in array design and in analysis. Close proximity detection interference (CPDI) is a condition where receivers fail to reliably detect tag transmissions.

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Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic, progressive bacterial enteritis of ruminants that can cause serious losses in both livestock and exotic species. Infection risk in exotic ruminants is associated with maternal infection status, but the effect of other herdmates on risk of infection has not been reported, to our knowledge.

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Article Synopsis
  • A study was conducted to analyze the incidence and risk factors of feline herpesvirus (FHV) infection among zoo-housed cheetah cubs, involving a cohort of 144 cubs born between 1988 and 2007.
  • The study found that 35% of the cubs developed clinical FHV infection, with various risk factors influencing susceptibility, particularly related to the mother's vaccination status and litter size.
  • Notably, the health of the mother (dam) did not significantly impact the likelihood of infection in the cubs, providing new insights for managing this disease in captive cheetahs.
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Although Salmonella spp. infection has been identified in captive and free-ranging rhinoceros, clinical cases in black rhinoceros ( Diceros bicornis ) calves have not been described. This case series describes clinical salmonellosis in four black rhinoceros calves.

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Methods: Mycobacteria isolated from more than 100 birds diagnosed with avian mycobacteriosis at the San Diego Zoo and its Safari Park were cultured postmortem and had their whole genomes sequenced. Computational workflows were developed and applied to identify the mycobacterial species in each DNA sample, to find single-nucleotide polymorphisms (SNPs) between samples of the same species, to further differentiate SNPs between as many as three different genotypes within a single sample, and to identify which samples are closely clustered genomically.

Results: Nine species of mycobacteria were found in 123 samples from 105 birds.

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The preshipment examination, with associated transmissible disease testing, has become standard practice in the movement of animals between zoos. An alternative disease risk-based approach, based on a comprehensive surveillance program including necropsy and preventive medicine examination testing and data, has been in practice since 2006 between the San Diego Zoo and San Diego Zoo Safari Park. A retrospective analysis, evaluating comprehensive necropsy data and preshipment testing over a 5-yr study period, was performed to determine the viability of this model for use with sending animals to other institutions.

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Quarantine is designed primarily to prevent the introduction of transmissible diseases to zoological collections. Improvements in preventive medicine, disease eradication, and comprehensive pathology programs call into question current industry quarantine standards. Disease risk analysis was used at the San Diego Zoo (SDZ) and the SDZ Safari Park to eliminate quarantine isolation and transmissible disease testing for animals transferred between the two institutions.

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The echolocation system of the Risso's dolphin (Grampus griseus) remains poorly studied compared to other odontocete species. In this study, echolocation signals were recorded from a stationary Risso's dolphin with an array of 16 hydrophones and the two-dimensional beam shape was explored using frequency-dependent amplitude plots. Click source parameters were similar to those already described for this species.

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Throughout the world, populations of scavenger birds are declining rapidly with some populations already on the brink of extinction. Much of the current research into the factors contributing to these declines has focused on exposure to drug residues, lead, and other toxins. Despite increased monitoring of these declining populations, little is known about infectious diseases affecting scavenger bird species.

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Abstract Mycoplasmas are an important cause of upper respiratory tract disease (URTD) in desert tortoises (Gopherus agassizii) and have been a main focus in attempts to mitigate disease-based population declines. Infection risk can vary with an animal's population of origin, making screening tests popular tools for determining infection status in individuals and populations. To provide additional methods for investigating URTD we developed quantitative PCR (qPCR) assays specific for agents causing clinical signs of URTD: Mycoplasma agassizii, Mycoplasma testudineum, and Testudinid herpesvirus 2 (TeHV2) and tested necropsied desert tortoises housed at the Desert Tortoise Conservation Center in Las Vegas, Nevada, USA, as well as wild desert tortoises (n=3), during 2010.

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A 10-month-old, female African pygmy falcon (Polihierax semitorquatus) hatched and housed at the San Diego Zoo developed neurologic signs and died from a cerebral infection with the rat lungworm Angiostrongylus cantonensis. There was an associated mild nonsuppurative meningoencephalitis. This infection was diagnosed on histology and confirmed by detection of species-specific A.

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