Search Results (67)

African swine fever (ASF) is a transboundary viral disease that has heavily impacted Southeast Asia since its introduction in 2019. Smallholder pig production systems in Cambodia and the Lao People’s Democratic Republic (the Lao PDR), characterized by low biosecurity, free-ranging practices, and limited veterinary oversight, remain particularly vulnerable. To assess farmers’ awareness and practices regarding ASF, a knowledge, attitudes, and practices (KAP) survey was implemented between March and September 2023 by Agronomes et Vétérinaires Sans Frontières within the framework of the Biosecurity in Pig Farming (BIG) project. A total of 471 pig farmers, including 56% women, were interviewed across eight provinces using a standardized questionnaire (188 in Cambodia and 283 in the Lao PDR). Results showed that ASF awareness was generally high (92% in Cambodia, 66% in the Lao PDR), yet 15% of Cambodian and 30% of Lao respondents expressed doubts about the presence of ASF in their country. While recognition of ASF symptoms was moderate and positively correlated with farmers’ perceived capacity to identify the disease, knowledge of transmission pathways was low and often misaligned with perceptions. Airborne transmission was frequently cited as a risk, and the risks related to visitors and fomites were underestimated by more than 50% of the farmers. Implementation of biosecurity measures (BSM) was limited, with mean scores of 43% in Cambodia and 27% in the Lao PDR. Risky practices such as swill feeding, free-ranging, sharing of boars, traders, and inadequate carcass disposal remained widespread. Statistical analysis identified education level, herd size, knowledge, perceived risks, and perceived benefits of BSM as the main determinants of biosecurity implementation. Farmers with larger herds or stronger commercial orientation demonstrated higher biosecurity adoption, while misconceptions and knowledge gaps remained frequent among smallholder farmers. Strengthening awareness, promoting low-cost and feasible biosecurity practices, and integrating farmer-centred approaches are essential for reducing ASF transmission risks and improving the resilience of smallholder pig production systems in the region. Full article

Brucellosis remains a major zoonotic disease worldwide, with disproportionate burden in low- and middle-income countries where limited veterinary and healthcare infrastructure constrain effective control measures. However, its pathways of transmission are poorly understood. In pastoralist settings, we hypothesize that camels have a high burden of Brucella spp. and play a key role in spreading it to humans and other livestock. This manuscript presents a study protocol to quantify the relative contribution of various livestock species to brucellosis transmission and identify cost-effective control strategies in Kenya. Using probability-proportional-to-size sampling, we aimed to recruit a longitudinal cohort of 170 households and their herds per site in the Marsabit and Kajiado counties. Households rearing at least one livestock species (cattle, camels, goats, sheep) were eligible. Serum, milk, and vaginal swabs (from livestock), and serum (from humans) were collected for testing using Rose Bengal Test, ELISA, qPCR, and culture methods. Concurrently, surveillance for suspected brucellosis was conducted in study health facilities. A qualitative ethnographic study and livestock movement monitoring using GPS-collared animals were nested within the cohort. These data will be used to parameterize a multi-host, multi-species infectious disease model through Approximate Bayesian Computation. Through this One Health approach, our study will identify and optimize potential interventions and help inform the development of a comprehensive cost-effective national control program for brucellosis. Full article

Chronic wasting disease (CWD), a transmissible spongiform encephalopathy that targets cervids, has become a significant threat to both free-ranging and captive populations of Canadian white-tailed deer. In an effort to mitigate its spread, research in the past 20 years has demonstrated that the genetic background of deer may influence the pathogenesis of CWD. Specifically, variants located on the 95-, 96-, 116- and 226-codon of the prion protein gene seem to attenuate disease progression in white-tailed deer. The influence of these alleles on the likelihood of being found CWD-positive on Saskatchewan and Albertan farms was assessed using a Bayesian logistic regression model. To assess the presence of selection for favourable prion protein gene alleles, shifts in variant genotype frequencies were examined over the last seventeen years. Our results show that deer harboring the G96S allele have significantly lowered odds of infection within Canadian herds. Furthermore, the prevalence of this allele has increased significantly in farmed deer over the past seventeen years. Establishing the dynamic genetic background of Canadian deer populations will inform future disease management initiatives. Full article

A cross-sectional study was conducted in Bangladesh from January 2023 to December 2024 to assess the prevalence of BVDV antibodies and associated risk factors in dairy herds. Initially, 138 bulk milk samples were collected from herds across 14 districts and screened using a commercial ELISA for BVDV antibodies. Subsequently, 767 individual milk samples were tested from cows in herds that screened positive. The overall herd-level seroprevalence was 72.5% (95% CI: 64.1–79.6), while the cow-level seroprevalence was 93.3% (95% CI: 91.3–94.9%). Within-herd seroprevalence varied from 81.8% to 100%. Herds with more than 70 cows had 31.95 times higher odds of BVDV seropositivity than those with 13–23 cows. BVD seroprevalence was significantly higher in the third, fifth, and eighth semen sources compared to the reference source. Cows older than 8 years had 4.53 times higher odds of seropositivity than those aged up to 4 years. Cows in thin physical condition had 13.02 times higher odds of seropositivity than those in normal condition. Conversely, cows producing over 8.8 kg of milk daily had a significantly lower seroprevalence of BVDV compared to those producing less than 8.8 kg, with an odds ratio of 0.41 (95% CI: 0.17–0.98). These findings suggest that BVDV exposure is widespread in dairy herds in Bangladesh. Regular serological screening, the use of semen from BVD-free bulls, and prioritizing surveillance for thin cows and low milk producers are essential. Improving nutrition, herd management, and targeted monitoring may help reduce BVDV transmission and improve herd productivity. Full article

Surveillance of swine influenza A virus (swIAV) traditionally focuses on respiratory matrices, yet emerging evidence suggests that fecal shedding and secondary environmental contamination may also contribute to viral dissemination. In this study, we collected and analyzed nasal, rectal, environmental, milk, and colostrum samples from naturally infected pigs in a commercial farm in Minas Gerais, Brazil. IAV RNA was detected in 25% of samples, including 42% from asymptomatic animals, with nasal swabs showing higher detection rates (30%) than rectal swabs (20%), though rectal Ct values were consistently higher, indicative of lower viral loads. We successfully isolated viable viruses from feces and effluent samples. Whole-genome sequencing revealed co-circulation of enzootic pH1N1 clade #2 (HA) and pN1 clade #4 (NA), alongside human-origin H3N2 sequences clustering within clade 3C.2a1b.2a.2a.1, and N2 segments related to pre-3C human lineages from 2001 to 2002. Phylogenetic and p-distance analyses support both recent reverse zoonosis and historical transmission events. Detection of complete HA/NA sequences from rectal swabs and treated effluent further emphasizes the surveillance value of non-respiratory matrices. The integration of respiratory and fecal/environmental sampling appears important to achieve more comprehensive IAV monitoring in swine herds and may have significant implications for One Health strategies in Brazil and beyond. Full article

Quantum memory is essential for the prolonged storage and retrieval of quantum information. Nevertheless, no current studies have focused on the creation of effective quantum memory for continuous variables while accounting for the decoherence rate. This work presents an effective continuous-variable quantum key distribution method with parameter optimization utilizing the Elitist Elk Herd Random Immigrants Optimizer (2E-HRIO) technique. At the outset of transmission, the quantum device undergoes initialization and authentication via Compressed Hash-based Message Authentication Code with Encoded Post-Quantum Hash (CHMAC-EPQH). The settings are subsequently optimized from the authenticated device via 2E-HRIO, which mitigates the effects of decoherence by adaptively tuning system parameters. Subsequently, quantum bits are produced from the verified device, and pilot insertion is executed within the quantum bits. The pilot-inserted signal is thereafter subjected to pulse shaping using a Gaussian filter. The pulse-shaped signal undergoes modulation. Authenticated post-modulation, the prediction of link failure is conducted through an authenticated channel using Radial Density-Based Spatial Clustering of Applications with Noise. Subsequently, transmission occurs via a non-failure connection. The receiver performs channel equalization on the received signal with Recursive Regularized Least Mean Squares. Subsequently, a dataset for side-channel attack authentication is gathered and preprocessed, followed by feature extraction and classification using Adaptive Depthwise Separable Convolutional Neural Networks (ADS-CNNs), which enhances security against side-channel attacks. The quantum state is evaluated based on the signal received, and raw data are collected. Thereafter, a connection is established between the transmitter and receiver. Both the transmitter and receiver perform the scanning process. Thereafter, the calculation and correction of the error rate are performed based on the sifting results. Ultimately, privacy amplification and key authentication are performed using the repaired key via B-CHMAC-EPQH. The proposed system demonstrated improved resistance to decoherence and side-channel attacks, while achieving a reconciliation efficiency above 90% and increased key generation rate. Full article

Bovine leukemia virus (BLV) is classified as a Deltaretrovirus and shows close genomic and biological similarities with human T-cell leukemia viruses (HTLVs). It serves as the etiological agent for enzootic bovine leukosis (EBL), which stands as the most prevalent neoplastic disease affecting cattle globally. Additionally, BLV has been identified as a potential zoonotic pathogen, although the risk to human health remains a subject of ongoing research. The insidious nature of BLV lies in its predominantly subclinical presentation; the majority of BLV-infected cattle show no apparent symptoms. This subclinical nature poses challenges for disease detection and control, as infected animals can remain unnoticed carriers, contributing to the silent spread of the virus within herds. This characteristic also underscores the importance of surveillance and early detection strategies to monitor BLV prevalence and mitigate its spread. Despite concerted efforts in some regions to implement eradication programs, BLV continues to maintain a high prevalence worldwide. The persistence of BLV in cattle populations highlights the need for innovative and integrated approaches to control and manage the disease effectively. The development of a BLV vaccine represents a significant breakthrough in the fight against BLV transmission. A successful vaccine can not only reduce the incidence of BLV infection but also minimize the associated economic losses linked to reduced milk production, reproductive issues, and the premature culling of infected animals. Therefore, a comprehensive understanding of BLV, encompassing its origin, evolutionary patterns, epidemiology, risk factors, and control strategies, is pivotal. Such knowledge serves as the foundation for the development of effective vaccines, diagnostic tools, and control measures. Through this review, we aim to consolidate and present this multifaceted understanding of BLV, providing valuable insights and guidance for researchers, veterinarians, and policymakers involved in BLV prevention and control efforts globally. Full article

Introduction of African swine fever virus (ASFV) into pig herds can occur via virus-contaminated feed or other objects. Knowledge about ASFV survival in different matrices and under different conditions is required to understand indirect virus transmission. Maintenance of ASFV infectivity can occur for extended periods outside pigs. Current assays detecting ASFV have inherent disadvantages. Cell culture-based assays are labor-intensive and sensitive to contaminants while methods using qPCR detect ASFV DNA with high sensitivity and specificity, but this may not correspond to infectious virus. Here, we have combined the use of these assays to assess the replication of ASFV within cells and determined the effect of pig feces, straw, wood shavings, and mixed feed on ASFV infectivity. In porcine serum, infectious ASFV survived for at least 60 days at 4 °C, 22 °C, and 37 °C; for two days at 50 °C; one day at 60 °C; and ≤5 min at 70 °C. In the presence of feed, straw, or wood shavings, the survival of the virus wasmarkedly shortened. Samples remained positive in the qPCR assay despite the loss of virus infectivity. Thus, it was possible to distinguish between the presence of ASFV DNA and the survival of the infectious virus. Full article

Salmonella enterica infections can significantly impact the health and productivity of dairy cattle. Asymptomatic carriage of Salmonella can make it difficult to identify and monitor this pathogen across a herd. Therefore, a more focused Salmonella census on dairy farms is needed to better understand the dynamics of asymptomatic carriage. Here, we monitored the prevalence of Salmonella enterica on a dairy operation in Wisconsin, USA. Fecal samples were collected over 12 months from cattle and the farm environment, subjected to Salmonella isolation, serogrouped, and tested for antibiotic resistance. Salmonella was highly prevalent on this farm, with an average of 90% of the cattle being carriers. Total recovery of Salmonella from environmental samples ranged from 40 to 90%. Four serogroups were identified on the farm, with K being most common in cattle and C being most common in the environment. Antibiotic resistance was tested against eight antibiotics and was found to be highest for neomycin (44.5%) and sulfadimethoxine (86.3%). Our data show that serogroups associated with asymptomatic carriages are persistent and highly prevalent, with niche specificity to different locations. These results provide useful information for studying within-herd transmission of Salmonella and contributes to our understanding of transmission risks within the farm ecosystem. Full article

Enzootic bovine leukosis, a neoplastic disease caused by the bovine leukemia virus (BLV), was the primary cancer affecting cattle in China before 1985. Although its prevalence decreased significantly between 1986 and 2000, enzootic bovine leukosis has been re-emerging since 2000. This re-emergence has been largely overlooked, possibly due to the latent nature of BLV infection or the perceived lack of sufficient evidence. This study investigated the molecular epidemiology of BLV infections in dairy cattle in Henan province, Central China. Blood samples from 668 dairy cattle across nine farms were tested using nested polymerase chain reaction assays targeting the partial envelope (env) gene (gp51 fragment). Twenty-three samples tested positive (animal-level prevalence of 3.4%; 95% confidence interval: 2.2, 5.1). The full-length env gene sequences from these positive samples were obtained and phylogenetically analyzed, along with previously reported sequences from the GenBank database. The sequences from positive samples were clustered into four genotypes (1, 4, 6, and 7). The geographical annotation of the maximum clade credibility trees suggested that the two genotype 1 strains in Henan might have originated from Japan, while the genotype 7 strain is likely to have originated from Moldova. Subsequent Bayesian stochastic search variable selection analysis further indicated a strong geographical association between the Henan strains and Japan, as well as Moldova. The estimated substitution rate for the env gene ranged from 4.39 × 10⁻⁴ to 2.38 × 10⁻³ substitutions per site per year. Additionally, codons 291, 326, 385, and 480 were identified as positively selected sites, potentially associated with membrane fusion, epitope peptide vaccine design, and transmembrane signal transduction. These findings contribute to the broader understanding of BLV epidemiology in Chinese dairy cattle and highlight the need for measures to mitigate further BLV transmission within and between cattle herds in China. Full article

Bovine tuberculosis is caused by Mycobacterium bovis, a member of the M. tuberculosis complex of mycobacterial species that cause tuberculosis in humans and animals. Diagnosis of bovine tuberculosis has relied on examinations of cell-mediated immune responses to M. bovis proteins using tuberculin skin testing and/or interferon gamma release assays. Even when using these methods, disease detection during the earliest phases of infection has been difficult, allowing a window for cattle-to-cattle transmission to occur within a herd. Alternative means of diagnosis could include methods to detect M. bovis or M. bovis DNA in bodily fluids such as nasal secretions, saliva, or blood. During the first 8 weeks after experimental aerosol infection of 18 calves, M. bovis DNA was detected in nasal swabs from a small number of calves 5, 6, and 8 weeks after infection and in samples of saliva at 1, 7, and 8 weeks after infection. However, at no time could culturable M. bovis be recovered from nasal swabs or saliva. M. bovis DNA was not found in blood samples collected weekly and examined by real-time PCR. Interferon gamma release assays demonstrated successful infection of all calves, while examination of humoral responses using a commercial ELISA identified a low number of infected animals at weeks 4–8 after infection. Examination of disease severity through gross lesion scoring did not correlate with shedding in nasal secretions or saliva, and calves with positive antibody ELISA results did not have more severe disease than other calves. Full article

Diseases in the swine industry can cause significant economic and health impacts. This review examines R₀ estimates for respiratory diseases in pigs, assessing variations and comparing transmission risks within and between farms. A literature search of three databases aggregated peer-reviewed research articles on swine viral respiratory diseases’ R₀ values. The study focused on seven diseases: Aujeszky’s disease (AD), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Circovirus, Influenza A (IA), Encephalomyocarditis Virus (EV), Classical Swine Fever (CSF), and African Swine Fever (ASF). R₀ values were estimated for transmission within and between herds/farms using various methods, from complex mathematical models to simple calculations. Data primarily came from disease surveillance and laboratory experiments. The median R₀ for within-herd and between-herd transmission was 10 and 3.31 for AD, 2.78 and 1.14 for PRRSV, 5.9 and 0.89 for Circovirus, 1.75 and 1.6 for CSF, and 3.94 and 3.15 for ASF. For IA and EV, only within-herd R₀ values were estimated at 8.65 and 1.3, respectively. Diseases with high R₀ values highlight the need for prompt detection and response to outbreaks. Continuous monitoring and evaluation of pathogen transmissibility are crucial for enhancing disease surveillance and reducing the impact of livestock diseases. Full article

Trueperella (T.) pyogenes is a mastitis-causing pathogen formerly known to cause severe clinical mastitis (CM), especially during the summer, leading to milk losses and low recovery rates. Unfortunately, its transmission behavior within herds is unclear. The diversity and occurrence of T. pyogenes were monitored to gain an initial insight into the infection transmission behavior of T. pyogenes in dairy herds and to lay a foundation for following targeted investigations. CM milk samples were collected from German herds, and one Swedish farm was sampled for isolates from subclinical mastitis. All in all, 151 T. pyogenes isolates from 16 herds were isolated, identified by MALDI TOF analysis and typed with RAPD PCR. Of these, 17 isolates originated from subclinical mastitis cases. We found that T. pyogenes mastitis occurred year-round, and clinical mastitis cases were caused by multiple strains (31 affected animals/28 strains). Instances of multiple cows being infected with the same T. pyogenes strain were rare and typically only involved a small number of animals at a time. However, if several quarters of a cow were affected, it was likely the same strain. Unlike clinical infections, subclinical T. pyogenes infections, in one investigated farm, harbored a dominant strain. Additionally, we found that T. pyogenes infections tended to persist and stay within a herd for a minimum of 7 months in the same or different cows. Full article

Hemotrophic mycoplasmas (HMs) are highly host-adapted and specialized pathogens infecting a wide range of mammals including farm animals, i.e., pigs, cattle, sheep, and goats. Although HMs have been known for over 90 years, we still do not know much about the natural transmission routes within herds. Recently, it has been repeatedly discussed in publications that arthropod vectors may play a role in the transmission of HMs from animal to animal. This is mainly since several HM species could be detected in different potential arthropod vectors by PCR. This review summarizes the available literature about the transmission of bovine, porcine, ovine, and caprine HM species by different hematophagous arthropod vectors. Since most studies are only based on the detection of HMs in potential vectors, there are rare data about the actual vector competence of arthropods. Furthermore, there is a need for additional studies to investigate, whether there are biological vectors in which HMs can multiply and be delivered to new hosts. Full article

Porcine Reproductive and Respiratory Syndrome (PRRS) significantly impacts the pig farming industry globally, leading to economic losses due to reduced productivity. This study focuses on assessing the presence and impact of PRRS within Hungarian wild boar populations amidst efforts to eradicate the virus from domestic pig herds. We used a combination of serological and virological tests on samples collected from wild boars across Hungary to evaluate the prevalence of PRRS virus and its potential transmission risks to domestic pigs. Our findings reveal a low seropositivity rate in wild boars, suggesting a minimal role of wild boars in the transmission of PRRS to domestic pig populations. Moreover, no relationship was found between domestic pig and wild boar densities, emphasizing the limited interaction and consequent risk of disease spread between these populations. We confirm the effectiveness of Hungary’s PRRS eradication measures among domestic herds and highlight the negligible risk posed by wild boars in re-introducing the PRRS virus. Full article