A one-health review on brucellosis in the United States.

Brucellosis is a highly infectious zoonotic disease of global significance due to its adverse impact on public health, economics, and trade. Despite being one of the most prevalent zoonoses worldwide, attention given to global brucellosis control and prevention has been inadequate. Brucella species of greatest one-health relevance in the US include those infecting dogs (Brucella canis), swine (Brucella suis), and cattle and domestic bison (Brucella abortus). Although not endemic in the US, Brucella melitensis warrants awareness as it poses a risk to international travelers. While brucellosis has been eradicated from domestic livestock in the US, its detection in US companion animals (B canis) and US wildlife reservoirs (B suis and B abortus) and enzootic presence internationally pose a threat to human and animal health, warranting its spotlight on the one-health stage. The challenges of B canis diagnosis in humans and dogs is addressed in more detail in the companion Currents in One Health by Guarino et al, AJVR, April 2023. Human consumption of unpasteurized dairy products and occupational exposure of laboratory diagnosticians, veterinarians, and animal care providers are responsible for human exposures reported to the US CDC. Diagnosis and treatment of brucellosis is challenging due to the limitations of diagnostic assays and the tendency of Brucella spp to produce nonspecific, insidious clinical signs and evade antimicrobial therapy, making prevention essential. This review will focus on zoonotic considerations for Brucella spp found within the US along with their epidemiology, pathophysiology, clinical presentation, treatment, and control strategies.

Improved molecular detection of Neorickettsia risticii with a duplex real-time PCR assay in the diagnosis of Potomac horse fever.

Neorickettsia risticii, an obligate intracellular bacterium, is the causative agent of Potomac horse fever (PHF). Diagnosis of PHF is based on demonstration of serum antibodies, isolation of N. risticii, and/or detection of nucleic acid by a PCR assay. An existing real-time PCR assay targeting the N. risticii 16S rRNA has been validated using blood samples from horses with colitis, and snails; to our knowledge, the performance of the assay for other sample types has not been reported. We describe here a modification of the 16S rRNA gene assay by the addition of a set of primers and probe targeting the N. risticii p51 gene to form a duplex assay. We validated the new assay using diagnostic specimens from 56 horses with suspected PHF. The assay consistently detected down to 5 copies of synthetic targets, and did not show any cross-reaction with common equine enteric pathogens. Although we did not establish the diagnostic sensitivity and specificity of the duplex assay, results for both gene targets were in complete agreement, with the exception of 4 fecal samples that tested positive for the 16S rRNA gene only. Further analysis indicated that testing of fecal samples using our 16S rRNA gene assay alone can produce a false-positive result.

Particle Size Distribution of Plasma Lipoproteins in Donkeys from Death Valley Compared to a Sampling of Horses.

The clinical evaluation of lipid metabolism in equids is often limited to the measurement of total cholesterol and triglyceride concentrations. This provides a limited picture of metabolic state and general health, given the continuous exchange of lipid species between various lipoproteins. Major lipoprotein classes in equids include high-density lipoprotein (HDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and chylomicrons (CM). Unlike large breed horses, donkeys are highly susceptible to hepatic lipidosis. Currently, serum triglyceride concentrations serve as a surrogate marker of hepatic lipid exportation. Both VLDL, indicative of hepatic exportation, and its metabolic end-product, LDL, are rich in triglycerides, and contribute to this value. Diagnostic assays that distinguish VLDL from LDL could be useful in better recognizing the hepatic pathology in donkeys. The compositional differences of lipoproteins across species limit the use of commercially available assays developed for the measurement of human lipoproteins in domestic animals. In this study, we evaluated a high-resolution polyacrylamide gel electrophoresis method (Lipoprint®) for separating major lipoprotein classes and sub-fractionating LDL and HDL based on particle size in a large group of donkeys, and compared the pattern to a representative set of horses. Donkeys proved an HDL-rich species, with HDL accounting for the bulk of all lipoproteins (average 78.45%, SD 6.6%, range 92.2-55%). VLDL accounted for a large portion of the total (average 21.6%, SD 6.6%, range 37.1-7.8%), with minimal amounts of LDL detected. The horses tested had higher proportions of VLDL as compared to donkeys (31.7% and 21.6%, respectively p = 0.00008). The later finding draws into question the purported relationship between VLDL, high triglycerides, and hepatic lipidosis, given the incidence of the disease in donkeys is far higher than in horses.

SARS-CoV-2 B.1.1.7 Variant Infection in Malayan Tigers, Virginia, USA.

We report infection of 3 Malayan tigers with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.7 (Alpha) variant at a zoologic park in Virginia, USA. All tigers exhibited respiratory signs consistent with SARS-CoV-2 infection. These findings show that tigers are susceptible to infection with the SARS-CoV-2 B.1.1.7 variant.

Severe SARS-CoV-2 Infection in a Cat with Hypertrophic Cardiomyopathy.

Coronavirus disease 19 (COVID-19), has claimed millions of human lives worldwide since the emergence of the zoonotic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China in December 2019. Notably, most severe and fatal SARS-CoV-2 infections in humans have been associated with underlying clinical conditions, including diabetes, hypertension and heart diseases. Here, we describe a case of severe SARS-CoV-2 infection in a domestic cat (Felis catus) that presented with hypertrophic cardiomyopathy (HCM), a chronic heart condition that has been described as a comorbidity of COVID-19 in humans and that is prevalent in domestic cats. The lung and heart of the affected cat presented clear evidence of SARS-CoV-2 replication, with histological lesions similar to those observed in humans with COVID-19 with high infectious viral loads being recovered from these organs. The study highlights the potential impact of comorbidities on the outcome of SARS-CoV-2 infection in animals and provides important information that may contribute to the development of a feline model with the potential to recapitulate the clinical outcomes of severe COVID-19 in humans.

Infectious disease surveillance of apparently healthy horses at a multi-day show using a novel nanoscale real-time PCR panel.

In the United States, horses are used for a variety of purposes including recreation, exhibition, and racing. As farm, performance, and companion animals, horses are a unique species from a zoonotic disease risk perspective, and the risks of subclinical infections spreading among horses can pose challenges. Using a nanoscale real-time PCR platform, we investigated the prevalence of 14 enteric pathogens, 11 Escherichia coli genes, and 9 respiratory pathogens in fecal samples from 97 apparently healthy horses at a multi-day horse event. In addition, sugar flotation test was performed for fecal parasites. E. coli f17 was commonly detected, prevalent in 59% of horses, followed closely by Streptococcus equi subsp. zooepidemicus (55%). Additional pathogens recognized included betacoronavirus, Campylobacter jejuni, Cryptosporidium sp., E. coli O157, equine adenovirus 1, equine rhinitis B virus, and others. The use of PCR data may overestimate the true prevalence of these pathogens but provides a sensitive overview of common pathogens present in healthy horses. Our results prompt the continued need for practical biosecurity measures at horse shows, both to protect individuals interacting with these horses and to minimize transmission among horses.

A Pilot Serosurvey for Selected Pathogens in Feral Donkeys (Equus asinus).

Recent removal and relocation of feral donkeys from vast public lands to more concentrated holding pens, training facilities, and offsite adoption locations raises several health and welfare concerns. Very little is known regarding the common equid pathogens that are circulating within the feral donkey population in and around Death Valley National Park, California, USA. The aim of this study was to utilize serologic assays to assess previous exposure of these donkeys to equine herpesvirus 1 (EHV-1), equine influenza (EIV), West Nile virus (WNV), and Borrelia burgdorferi (the causative agent of Lyme disease). The results of this study indicate that this feral equid population is mostly naïve and likely susceptible to these common equid pathogens upon removal from the wild.

Clinical Pathology of Donkeys and Mules.

Given the stoic nature of donkeys and their hybrids, it is important to consider the significance of diagnostic testing modalities that can provide objective health status information beyond the basic physical examination findings. However, clinical pathology assays are also fraught with significant limitations because the results for donkeys, mules, and hinnies can be difficult to interpret, and transference of data from the horse is not always applicable. This article presents considerations for sample collection, storage, analysis, and interpretation strategies for clinical pathology testing of donkeys and their hybrids based on the limited information available in the literature.