Transboundary and Emerging Diseases最新文献

The complete mastitis control program is insufficient for the starting dairy industry country, and therefore it might cause emerging of new mastitis pathogens. This longitudinal study aimed to determine the association of the infected dynamic status of the main pathogens responsible for mastitis with seasonal variations, the proportions of transient and chronic intramammary infection (IMI) episodes, and the duration of IMI. This study was conducted on a training smallholder dairy farm in Phnom Penh, Cambodia, from January 2023 to July 2023. Trained veterinarians aseptically collected quarter milk samples from all milking cows (n = 21) every 2 weeks until the end of the study, accounting for 3–16 times of milk collection per cow based on their period of lactation. All collected milk samples (n = 812) were cultured, and subsequently, all bacterial colonies were identified using a MALDI-TOF mass spectrometer. An IMI episode is defined as a sequence of consecutive isolates of a specific bacterium from the same quarter. The duration of an episode is the time between the new IMI and its cure. Two types of IMI were defined as transient IMI and chronic IMI that lasted for 28 days or more. Results of the IMI episodes, distributions of no, single, double-mixed, and 3-mixed IMI were 61.1%, 31.9%, 6.3%, and 0.7%, respectively, in which the mixed IMI accounts for 18% of IMI samples. Streptococcus uberis, Staphylococcus chromogenes, and Streptococcus gallolyticus were the main organisms responsible for the mastitis epidemic on this farm. These bacteria had higher ratios of chronic episodes than the other mastitis bacteria found on this farm. In addition, results obtained from Cox’s model showed that S. chromogenes had a longer time to cure than pathogens other than S. uberis and S. gallolyticus, in which S. gallolyticus linked to colon neoplasia in humans. In conclusion, the lack of an optimal mastitis control program, in this case, provides information on the emerging mixed infections, emerging mastitis pathogens, and emerging chronic S. chromogenes infections.

The global rise in arboviral diseases can be attributed to the ongoing effects of climate change. Ross River virus (RRV) is an illustrative example of such diseases, with case reports in Australia experiencing a significant surge since 2020. RRV is transmitted to susceptible species, such as horses and humans, through multiple mosquito vectors, namely Culex annulirostris, Aedes camptorhynchus, and more recently Ae. notoscriptus. This disease is not only endemic to Australia but has caused outbreaks in surrounding countries such as Fiji and Papua New Guinea. Currently, there are no therapeutic regimes or vaccinations available for RRV, leaving public health warning systems and advice relying upon disease prediction and surveillance. Commonly utilised methods, such as predictive modelling, are experiencing challenges resulting from an increased mosquito presence and extreme weather patterns, often yielding inaccurate advice. Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) provided a promising solution to mitigate these challenges and is now considered the gold standard in many Australian states. However, this method must be performed in a laboratory setting and requires expensive machinery, thus rendering it inadequate for resource-poor or rural communities. Reverse-transcription loop-mediated isothermal amplification (RT-LAMP) serves as a simple and field-deployable substitute with comparable sensitivities and specificity to RT-qPCR, whilst possessing the ability to provide rapid results within 20 min. This paper describes a novel RRV RT-LAMP assay that can detect RRV in as little as one mosquito, with a limit of detection of 1 × 10⁻⁷ ng/µl (~620 copies/µl) and a clinical sensitivity of 84%. Through the addition of tetramethylammonium chloride (TMAC), our assay achieved a 100% specificity and was able to detect RRV RNA as early as 2 min in crude field samples. The simplistic sampling method coupled with our RRV RT-LAMP assay can provide an in-field and low-cost alternative to current routine surveillance techniques.

Prion diseases are fatal, irreversible, and infectious neurodegenerative diseases caused by proteinase K-resistant prion protein (PrP^Sc). Against PrP^Sc, several endogenous proteases involved in cellular degradation mechanisms can be activated to remove PrP^Sc. However, since PrP^Sc shows proteinase K resistance, we presumed that undegradable PrP^Sc induces positive feedback on the overactivation of the cellular degradation mechanisms and is correlated with proteolytic stress and exacerbation of the progression of prion diseases. We investigated the expression pattern of proteolytic stress-related proteins in the brains of ME7 scrapie-infected mice at 7 months postinfection and sporadic Creutzfeldt–Jakob disease (CJD) patients using western blotting and immunohistochemistry (IHC). In addition, we analyzed the 3D structure and binding complexes of prion protein (PrP) with nattokinase and lumbrokinase using in silico programs, including SWISS-MODEL and HawkDock. To fundamentally reduce proteolytic stress by the degradation of PrP^Sc, we performed an in vitro evaluation of the PrP^Sc degradation abilities of fibrinolytic enzymes, including nattokinase and lumbrokinase. Furthermore, we assessed the protective effects of nattokinase and lumbrokinase in ME7 scrapie-infected mice. We observed an abnormal accumulation of proteolytic stress-related proteins, including CD10, cathepsin B, cathepsin D, and matrix metalloproteinase 9 (MMP9), in the brains of ME7 scrapie-infected mice and sporadic CJD patients. In addition, we identified that nattokinase and lumbrokinase can stably bind to PrP. Furthermore, we identified significant in vitro degradation of PrP^Sc derived from ME7 scrapie-infected mice and sporadic CJD patients by nattokinase and lumbrokinase. Last, we found in vivo protective effects of nattokinase and lumbrokinase against prion disease in ME7 scrapie-infected mice. To the best of our knowledge, this is the first report on the identification of proteolytic stress-related novel potential biomarkers and the therapeutic potential of nattokinase and lumbrokinase for prion diseases.

Thailand was recognized as having the highest number of lumpy skin disease (LSD) outbreaks in Southeast Asia during 2021. Understanding how LSD outbreaks spread over time and space can provide detailed insight into the distribution and pattern of the disease, allowing for more precise identification of areas with high disease burden. This study aims to explore the spread of LSD among cattle in Thailand during 2021 using spatial and spatio-temporal analyses. Data were analyzed using spatial analysis techniques, including spatial autocorrelation and directional distribution. Additionally, the spatio-temporal models, including space–time permutation (STP) and Poisson with various maximum reported cluster size (MRCS) settings, were applied to the data to determine LSD outbreak clusters. Results showed that a total of 642 LSD outbreaks were reported from March to December 2021. Districts with confirmed cases exhibited spatial autocorrelation, indicating the interconnected spread of LSD across different geographic areas. Furthermore, the disease distribution pattern appeared to extend to the southern and southwestern regions from the northeast. Based on the spatio-temporal models, LSD outbreak clusters were identified in several regions. The STP model tended to identify more clusters with smaller radii compared to the Poisson model. The number of clusters detected varied according to both the model and MRCS setting, underscoring the importance of selecting the most relevant clusters for the effective implementation of disease control strategies. This study was the first of its kind to assess the spatial direction and spatio-temporal distribution of LSD outbreak clusters based on national-level data. Evaluating LSD occurrence through spatial and spatio-temporal analyses can provide valuable insight into its spatio-temporal dynamics, facilitating disease surveillance, control measures, and vector control strategies in Thailand.

Lumpy skin disease (LSD) is an important infectious disease that threatens the global cattle industry. Recently, LSD has occurred frequently in Asia. The attenuated goat poxvirus (GTPV) vaccine is widely used to prevent LSD in cattle in China; however, sporadic cases of LSD still occur in immunized cattle. This study aimed to investigate the genetic evolution of isolated LSD virus (LSDV) strain under GTPV heterologous vaccine immune pressure. We isolated a new strain of LSDV, named LSDV/China/SX/2023, from a cattle herd immunized with a GTPV-attenuated vaccine in Shaanxi Province, Northwest China, and conducted whole-genome sequencing and genetic evolution studies. There are several open reading frames (ORFs) differences between the isolated strain and the Chinese reference strains, among which truncated expression of the Kelch-like protein encoded by ORF 19 may affect its growth characteristics. Phylogenetic analysis revealed that the isolated strain is in the same evolutionary clade as previous isolates from China and Southeast Asia. RDP4 and Simplot simultaneously showed that all strains in this branch had the same 15 recombination events, and there was one recombination event associated with the GTPV. This study presents the recent genetic evolution of LSDV under GTPV vaccine immune pressure and discusses the viral recombination events that are thought to influence transmission which are critical for the control and purification of LSD.

During the winter of 2022/2023, Japan experienced its largest outbreak of high pathogenicity avian influenza (HPAI), affecting 84 poultry premises. In this study, we investigated the pathogenicity and antigenicity of A/chicken/Kagoshima/22A1T/2022 (Kagoshima/22A1T), a clade 2.3.4.4b H5N1 virus belonging to the G2b group. It was isolated from a poultry farm in Izumi City, where the largest number of consecutive cases was recorded. The 50% lethal dose, mean death time (MDT), amount of virus shed, and transmissibility in chickens of Kagoshima/22A1T were similar to those of A/chicken/Kagoshima/21A6T/2022 (Kagoshima/21A6T), the previous season’s isolate of the same group, indicating that their pathogenicities were comparable. However, the antigenicity of these isolates differed according to the hemagglutination inhibition (HI) test results. We found that the amino acid substitutions in residues 189 and 193, corresponding to antigenic site B in the H3 virus of the HA1 subunit, could have an impact on the HI cross-reactivity of Kagoshima/21A6T. This study provides important insights into the factors contributing to the consecutive HPAI outbreaks on poultry farms in Izumi City during the 2022/2023 season and the prediction of antigenic changes in G2b group HPAI viruses.

Invasive alien species pose a major threat to ecosystems by outcompeting native species for resources, altering habitats, enabling potential genetic hybridisation and introducing pathogens into the environment. An understanding of the factors that determine virus transfer between invasive and native species is crucial to the mitigation of the negative impact of the pathogens introduced. This study presents a comprehensive analysis of factors influencing Aleutian mink disease virus (AMDV) infection in native mustelids in Poland, following its introduction by feral American mink. AMDV seroprevalence in American mink varied spatially from 0 in the central and southern regions to 0.8 in the northern regions. Antibodies to AMDV were detected in all six studied mustelids, including a novel finding in weasels. AMDV seroprevalence in other mustelids correlated positively with its occurrence in American mink, and reached 0.54 in areas with the highest mink AMDV seroprevalence. Furthermore, in native mustelids, more closely phylogenetically related to mink, AMDV seroprevalence was higher (0.68 in polecats and weasels) compared to more distantly related species (0.37 in badgers). Over the 27-year study period, AMDV seroprevalence in mustelids has increased from 0.04 to 0.60, despite a decline in seroprevalence in feral mink in subsequent years. These findings suggest that the spread of viral infections as a result of the introduction of invasive species could affect mustelid species and may intensify over time.

Leptospirosis, a bacterial zoonosis with a worldwide distribution, represents a major public health challenge. It is caused by the spirochete Leptospira, whose main reservoir in urban environments is the brown rat (Rattus norvegicus). Understanding the transmission dynamics of this disease within a rat population is essential for controlling the risk of human infection. In this study, an original capture method was used to analyze variations in carriage and bacterial load according to age in two distinct populations of brown rats, to provide a better understanding of the transmission routes of Leptospira within a population. A total of 508 rats were captured from all age categories, from newborns to very young rats (representing 18% of the animals) to very old rats (representing 21% of the animals). The overall prevalence of leptospirosis was between 30% and 50%, depending on the population. A single strain was identified in both studied populations: Leptospira interrogans belonging to the Icterohaemorrhagiae serogroup and the Icterohaemorrhagiae serovar. Surprisingly, in both populations, our study reveals a sudden change in the prevalence at 300/400g, jumping from 20 to 30% to over 75%. Moreover, none of the 98 fetuses collected from 13 pregnant females infected with Leptospira was detected as infected. This sudden change and the absence of infected fetus demonstrate the major role of horizontal transmission in the dynamics of leptospirosis infections and minimize the importance of vertical transmission.

The high prevalence of enterotoxigenic Escherichia coli (ETEC) in nondiarrheic piglets contributes to its rapid spread; however, few studies have explored the effects of latent gastrointestinal pathogens on animal health. Therefore, using high-throughput sequencing approaches, we explored changes in entero-pulmonary microbiota and immune gene expression in healthy, asymptomatic, and diarrheic piglets. As expected, bacterial communities were less diverse in the respiratory tract than in the gut, with a site-specific composition that was more stable in the gut and highly variable in the lung among the investigated animals. Although no significant changes in diversity rates were seen based on ETEC-carrier state, our findings suggest that ETEC’s presence can cause dysbiosis in the gut and lung in asymptomatic and diarrheic piglets, reinforcing the crosstalk in the entero-pulmonary axis. We also identified potential bacterial biomarkers that can be used to monitor piglet health: Sphaerochaeta, Bacteroides, Butyricoccus, and Blautia were highly represented in the gut, while Streptococcus and Prevotellaceae NK3B31 group were enriched in the lungs of healthy piglets. In addition, most metabolic pathways predicted in the bacterial communities were shared despite the ETEC-carrier state, with differences observed only in the gut microbiota, suggesting that ETEC’s presence may impact substrate utilization. Finally, we observed shifts in the intestinal expression of tff2 and cd36 immune markers between healthy and diarrheic piglets, which might suggest their use as prognostic markers for postweaning diarrhea (PWD). Although the effect remains unclear, the ETEC-carrier state also altered the transcription of other markers locally (in the gut and lung) and systemically, which corroborates the shared mucosal immunity in the entero-pulmonary axis in piglets. Overall, despite limitations regarding sample size, our findings give clues about the entero-pulmonary dynamics in piglets in the presence of a gastrointestinal pathogen, representing a starting point for future research on this axis for veterinary purposes.

A growing number of studies has highlighted the importance of coinfections in eco-evolutionary processes underlying host–parasite interactions and the resulting epidemiology of zoonotic agents. Small mammals, and particularly rodents, are known to be important reservoirs of many zoonotic pathogens, such as Toxoplasma gondii and Trypanosoma lewisi, that are responsible for toxoplasmosis and atypical trypanosomiasis in humans, respectively. Laboratory experiments on rodent models have shown that primary infection with T. lewisi increases the host sensitivity to other parasites, including T. gondii, following an alteration in the immune response. However, data on potential interactions between these parasites in wild small mammals remain scarce. In this study, we determined the T. lewisi prevalence in 553 small mammals from four localities of Cotonou city, Benin. The results were then combined with T. gondii data previously collected for the same individuals in order to investigate the influence of T. lewisi on T. gondii infection, and vice versa, using co-occurrence tests and generalized linear mixed models (GLMMs). Despite quite high overall prevalence (32.5% and 15.2% for T. lewisi and T. gondii, respectively), we observed a clear and significant segregation between the two parasites. This may be explained by (i) differences in the species-specific receptivity and/or sensitivity of small mammal host species to infection by these two parasites, with Rattus rattus (Rra), Rattus norvegicus (Rno), and Mastomys natalensis (Mna) being the main hosts of T. lewisi, while Crocidura olivieri (Cro) and Mus musculus domesticus (Mus) were the main hosts for T. gondii; and/or (ii) a possibly high mortality in coinfected animals in the wild. Although dedicated experimental studies are required to confirm this pattern, as they stand, our data fail to support that in nature, the infection of small mammals by one of these two parasites favors widespread infection by the second one.