Victoria Iribarnegaray

Morbillivirus canis (canine distemper virus, CDV) remains a pathogen of major veterinary and conservation significance. Here, we summarize two decades of CDV surveillance in Uruguay by integrating laboratory-confirmed cases, diagnostic advances, molecular epidemiology, and neuropathological findings. Between 2006 and 2026, CDV infection was confirmed in 270 of 460 dogs submitted for diagnostic testing, supporting sustained transmission among clinically suspected cases. Confirmed infections were concentrated in young dogs and were more frequent during colder months, although the season was not significantly associated with diagnostic outcome. Dogs reported as vaccinated had a lower proportion of positive results than unvaccinated dogs; however, CDV infection was also detected in animals with reported vaccination history, suggesting that failures at some point in the immunization process cannot be ruled out and highlighting the need for improved records of vaccination protocols, immune status, and vaccine handling. Diagnostic capacity evolved from conventional RT-PCR to RT-qPCR, droplet digital PCR, and whole-genome sequencing, strengthening both clinical diagnosis and genomic surveillance. Phylogenetic analysis of the hemagglutinin gene showed that all Uruguayan strains characterized to date belong to the Europe/South America 1 lineage and revealed two locally differentiated clades, UY-I and UY-II, that co-circulated without clear temporal or geographic segregation in the available dataset. Comparative neuropathological analysis of fatal cases showed severe demyelinating lesions in both vaccinated and unvaccinated dogs, with no detectable differences in lesion pattern or stage in this limited series. These findings reveal sustained CDV transmission and local genetic structuring in Uruguay and support the need for continuous molecular and genomic surveillance, improved vaccination monitoring, and integrated One Health strategies to reduce the impact of CDV on domestic dogs and susceptible wildlife.

El virus del distemper canino (CDV) es una infección vírica muy contagiosa que causa inmunosupresión y afecta cánidos domésticos y salvajes con una elevada mortalidad. Este estudio analizó retrospectivamente casos diagnosticados de CDV remitidos al Laboratorio de Diagnóstico Microbiológico de la Facultad de Veterinaria de la Universidad de la República (Montevideo, Uruguay) entre 2021 y 2023. Se procesaron 251 muestras, sobre todo de Montevideo (85 %) y se detectó CDV en 119 mediante RT-qPCR. No hubo diferencias significativas por sexo, y los caninos menores de 2 años fueron más susceptibles (71,4 %). Un 60 % de los casos no estaban vacunados, mientras que un 28 % presentaban plan de vacunación completo, lo que sugiere posibles fallas vacunales. Los caninos mestizos fueron los más afectados, pero el CDV se detectó en varias razas. Los signos principales fueron nerviosos, seguidos por respiratorios, digestivos y dermatológicos; un 24 % presentó signos combinados. El análisis filogenético sugiere un linaje predominante de CDV en Uruguay, con algunas cepas divergentes. Comprender la epidemiología y la presentación clínica del CDV en Uruguay es fundamental para mejorar las estrategias de prevención, diagnóstico y tratamiento.

The purpose of this study was to examine the relationship between demyelination and cellular reactions in the cerebellum of Canine Distemper Virus (CDV)-infected dogs. We subdivided the disease staging by adding the degree of demyelination determined by Luxol Fast Blue staining to the previously reported disease staging from the acute stage to the chronic stage, and investigated the relationship between demyelination in the cerebellum and the number and histological changes in astroglia, microglia, and Purkinje cells in each stage. Reactions of astrocytes and microglia were observed at an early stage when demyelination was not evident. Changes progressed with demyelination. Demyelination initially began in the medulla adjoining the fourth ventricle and gradually spread to the entire cerebellum, including the lobes. CDV immune-positive granules were seen from the early stage, and inclusion bodies also appeared at the same time. CDV immune-positive reaction and inclusion bodies were observed in astrocytes, microglia, neurons, ependymal cells, and even leptomeningeal mononuclear cells. On the other hand, infiltration of CDV-immunoreactive particles from the pia mater to the gray matter and further into the white matter through the granular layer was observed from an early stage. Purkinje cells decreased from the intermediate stage, and a decrease in cells in the granular layer was also observed. There was no clear association between age and each stage, and the stages did not progress with age.

Canine distemper virus (CDV) poses a substantial threat to diverse carnivorans, leading to systemic and often fatal diseases. Accurate and prompt diagnosis is paramount for effective management and curbing further transmission. This study evaluates the diagnostic performance of droplet digital PCR (ddPCR) in comparison to conventional reverse-transcription (RT-PCR) and quantitative reverse-transcription real-time PCR (RT-qPCR). Seventy-six clinical samples were collected from dogs with CDV symptoms diagnosed by specialized veterinarians, and sixteen samples from apparently healthy individuals. Conventional PCR, quantitative real-time PCR, and ddPCR were deployed, and their diagnostic capabilities were meticulously assessed. DdPCR exhibited heightened analytical sensitivity, reaching a detection limit of 3 copies/μL, whereas RT-qPCR had a detection limit of 86 copies/μL. The comparative analysis between clinical diagnosis and molecular techniques, including RT-PCR and RT-qPCR, demonstrated low concordance, with Kappa coefficients of 0.268 and 0.324, respectively. In contrast, ddPCR showed a moderate concordance, with a Kappa coefficient of 0.477. The sensitivity was 42.4% for RT-PCR, 57.9% for RT-qPCR, and 72.4% for ddPCR, with 100% specificity for all methods. This study underscores ddPCR’s superior sensitivity and agreement with clinical CDV diagnosis, even at low viral concentrations, suggesting it as a promising alternative for CDV diagnosis.

The purpose of this study was to examine the relationship between demyelination and glial cell responses in the cerebellum of CDV-infected dogs. We subdivided the disease staging by adding the degree of demyelination determined by LFB staining to the previously reported disease staging from the acute stage to the chronic stage, and investigated the relationship between demyelination in cerebellum and the number and histological changes of astroglia, microglia and Purkinje cells in each stage. Reactions of astrocytes and microglia were observed at an early stage when demyelination was not evident. Changes progressed with demyelination. Demyelination initially began in the medulla adjoining the fourth ventricle and gradually spread to the entire cerebellum, including lobes. CDV immune-positive granules were seen from the early stage, and inclusion bodies also appeared at the same time. CDV immune-positive reaction and inclusion bodies were observed in astrocytes, microglia, neurons, ependymal cells, and even leptomenin-geal mononuclear cells. On the other hand, infiltration of CDV immunoreactive particles from the pia mater to the gray matter and further into the white matter through the granular layer was observed from an early stage. Purkinje cells decreased from the intermediate stage, and a decrease in cells in the granular layer was also observed. There was no clear association between age and each stage, and the stages did not progress with age.

Canine distemper virus (CDV) poses a substantial threat to diverse carnivores, leading to sys-temic and often fatal diseases. Accurate and prompt diagnosis is paramount for effective man-agement and curbing further transmission. This study evaluates the diagnostic efficacy of drop-let digital PCR (ddPCR) in comparison to conventional reverse transcription (RT-PCR) and quantitative reverse transcription real-time PCR (RT-qPCR). Seventy-six clinical samples were collected from dogs with CDV symptoms diagnosed by specialized veterinarians, and sixteen samples from asymptomatic individuals. Conventional PCR, quantitative real-time PCR, and ddPCR were deployed, and their diagnostic capabilities were meticulously assessed. DdPCR ex-hibited heightened analytical sensitivity, reaching a detection limit of 3 copies/μL, whereas RT-qPCR had a detection limit of 86 copies/μL. The comparative analysis between clinical diagnosis and molecular techniques, including RT-PCR and RT-qPCR, demonstrated low concordance, with Kappa coefficients of 0.268 and 0.324, respectively. In contrast, ddPCR, showed a moderate concordance, with a Kappa coefficient of 0.477. Sensitivity was 42.39% for RT-PCR, 57.89% for RT-qPCR and 72.37% for ddPCR, with 100% of specificity for all methods. This study under-scores ddPCR's superior sensitivity and concordance with clinical CDV diagnosis, even at low viral concentrations, suggesting it as a promising alternative for CDV diagnosis.

We describe the use of conventional histology and immunohistochemistry against canine distemper virus (CDV) to examine the brains of domestic dogs with a confirmed diagnosis of CDV infection. Histologically, to identify the main typical lesions, we used conventional H&E stain; to evaluate the progressive demyelination, we used Luxol Fast Blue stain; and to identify the presence of viral particles in these affected regions, we used immunohistochemistry against CDV. We confirm that the histopathological analysis of brains of distemper-infected dogs is a powerful tool to evaluate the typical brain lesions and could be used as an interesting natural model to continue studying the pathogenesis of canine distemper in different species and/or other morbillivirus infections, like measles.

Klebsiella pneumoniae is widely recognized as an opportunistic hospital and community pathogen. It is one of the priority microorganisms included in the ESKAPE group, and its antibiotic resistance related to extended-spectrum β-lactamases (ESBL) is a global public health concern. The multi-drug resistance (MDR) phenotype, in combination with pathogenicity factors, could enhance the ability of this pathogen to cause clinical infections. The aim of this study was to characterize pathogenicity factors and biofilm formation in ESBL-producing K. pneumoniae from pediatric clinical infections. Capsular types, virulence factors, and sequence types were characterized by PCR. Biofilm formation was determined by a semiquantitative microtiter technique. MDR phenotype and statistical analysis were performed. The K24 capsular type (27%), virulence factors related to iron uptake fyuA (35%) and kfuBC (27%), and sequence types ST14 (18%) and ST45 (18%) were the most frequently detected. Most of the strains were biofilm producers: weak (22%), moderate (22%), or strong (12%). In 62% of the strains, an MDR phenotype was detected. Strains with K24 capsular type showed an association with ST45 and the presence of fyuA; strains with kfuBC showed an association with moderate or strong biofilm production and belonging to ST14. Weak or no biofilm producers were associated with the absence of kfuBC. The MDR phenotype was associated with the main ESBL gene, bla_CTX-M-15. The high plasticity of K. pneumoniae to acquire an MDR phenotype, in combination with the factors exposed in this report, could make it even more difficult to achieve a good clinical outcome with the available therapeutics.