Persistence of passive immunity in calves receiving colostrum from cows vaccinated with a live attenuated lumpy skin disease vaccine and the performance of serological tests.

This study aimed to determine the persistent duration of maternal immunity against lumpy skin disease virus (LSDV) in dairy calves born from vaccinated cows using a virus neutralization test (VNT). The performance of the VNT and an in-house-ELISA test was also determined. Thirty-seven pregnant cows from 12 LSD-free dairy farms in Lamphun province, Thailand were immunized with a homologous Neethling strain-based attenuated vaccine and calved from December 2021 to April 2022. Blood samples from dam-calve pairs were collected within the first week after calving. Subsequently, blood samples were taken from the calves at monthly intervals over a period of 4 months and tested for the humoral immune response using a VNT. The calf sera were also tested with an in-house ELISA test to estimate the accuracy of both tests using a Bayesian approach. For the results, antibodies against LSDV can persist in cows for 4-9 months post-vaccination. Moreover, neutralizing antibodies and LSDV-specific antibodies against LSDV were detected in the majority of calves (75.68%) during the first week after colostrum intake. However, the percentage of seropositive calves declined to zero by day 120, with seropositivity dropping below 50% after day 60. Only a small number of seropositive calves (approximately 13.51%) were observed on day 90. These findings indicated that passive immunity against LSDV can last up to 3 months. The median of posterior estimates for sensitivity (Se) and specificity (Sp) of the VNT were 87.3% [95% posterior probability interval (PPI) = 81.1-92.2%] and 94.5% (95% PPI = 87.7-98.3%), respectively. The estimated Se and Sp for the ELISA test were 83.1% (95% PPI = 73.6-92.6%) and 94.7% (95% PPI = 88.4-98.5%), respectively. In conclusion, this study illustrates the transfer and persistence of maternal passive immunity against LSDV to calves under field conditions. This highlights a potential three-month vaccination gap in calves born from vaccinated cows, while an in-house ELISA test can be used as an ancillary test for LSDV immune response detection. However, further research is required to assess the vaccination protocols for calves as young as 2 months old to precisely determine the duration of maternal immunity.

Identifying the patterns and sizes of the first lumpy skin disease outbreak clusters in Northern Thailand with a high degree of dairy farm aggregation using spatio-temporal models.

Lumpy skin disease (LSD) is one of the most important notifiable transboundary diseases affecting cattle in many parts of the world. In Thailand, LSD outbreaks in cattle farming areas have been reported in 69 out of 77 provinces, indicating a serious nationwide situation. Understanding the dynamics of spatial and temporal LSD epidemic patterns can provide important information on disease transmission and control. This study aims to identify spatial and temporal clusters in the first LSD outbreaks in dairy farming areas with a high degree of aggregation in Northern Thailand using spatio-temporal models. The data were obtained from an official LSD outbreak investigation conducted between June and August 2021 on dairy farms (n = 202). The outbreak of LSD was confirmed by employing clinical observations and laboratory analysis. The spatio-temporal models including space-time permutation (STP), Poisson, and Bernoulli were applied to the outbreak data with the settings of 10%, 25%, and 50%, respectively, for the maximum reported cluster size (MRCS). Overall, the number of most likely and secondary clusters varied depending on the model and MRCS settings. All MRCS settings in the STP model detected the most likely clusters in the same area and the Poisson models in different areas, with the largest being defined by a 50% MRCS. Although the sizes of the most likely clusters identified by the Bernoulli models were different, they all had the same cluster period. Based on the sizes of the detected clusters, strict LSD insect-vector control should be undertaken within one kilometer of the outbreak farm in areas where no LSD vaccination has been administered. This study determines the sizes and patterns of LSD outbreak clusters in the dairy farming area with a high degree of farm aggregation. The spatio-temporal study models used in this study, along with multiple adjusted MRCS, provide critical epidemiological information. These models also expand the options for assisting livestock authorities in facilitating effective LSD prevention and control programs. By prioritizing areas for resource allocation, these models can help improve the efficiency of such programs.

Development of in-house ELISA for detection of antibodies against lumpy skin disease virus in cattle and assessment of its performance using a bayesian approach.

Lumpy skin disease (LSD) is a contagious disease among cattle and buffalo worldwide. Currently, an enzyme-linked immunosorbent assay (ELISA) has been recognized as an efficient diagnostic tool that is less time-consuming and easier than the viral neutralization test to measure the antibody levels. In the present study, an in-house method of indirect ELISA was developed to detect the bovine antibodies against Lumpy skin disease virus (LSDV) and its performance was assessed using field samples. This in-house method has been compared with the commercial ELISA test kit for detection of bovine antibodies against LSDV. The sensitivity (Se) and the specificity (Sp) of the test were estimated using a Bayesian latent class model. Checkerboard titration was performed using the naturally LSDV-infected bovine sera and colostrum-deprived calf sera. The LSDV antigen concentrations (1 TCID50/mL), the sample serum (1:500), and goat anti-bovine immunoglobulin G (IgG) labeled with horseradish peroxidase (HRP) (1:10,000) were determined to be optimal for this assay. The calculated cut-off value was 0.067, and there were no differences in the results of tests that utilized positive and negative sera (p < 0.05). The characteristics of two diagnostic tests were evaluated using a conditional dependent and one-population Bayesian model. The Se value of an in-house indirect ELISA were almost similar to ELISA test kit. On the other hand, the Sp value of the in-house ELISA test was lower than that of the commercial ELISA test with the median values of 89% (95% PPI = 75.9-99.3%) and 91.4% (95% PPI = 85.3-95.5%), respectively. A posterior estimate for the prevalence was 66.9% (95% PPI = 60.8-83.3%) and higher than initially expected.

Molecular Characterization and Phylogenetic Analysis of Lumpy Skin Disease Virus Collected from Outbreaks in Northern Thailand in 2021.

Understanding molecular epidemiology is essential for the improvement of lumpy skin disease (LSD) eradication and control strategies. The objective of this study was to perform a molecular characterization and phylogenetic analysis of lumpy skin disease virus (LSDV) isolated from dairy cows presenting LSD-like clinical signs in northern Thailand. The skin nodules were collected from 26 LSD-suspected cows involved in six outbreaks during the period from July to September of 2021. LSDVs were confirmed from clinical samples using the polymerase chain reaction (PCR). The PCR-positive samples were subsequently amplified and sequenced using a G-protein-coupled chemokine receptor (GPCR) gene for molecular characterization and phylogenetic analyses. All 26 samples were positive for LSDV by PCR. A phylogenetic analysis indicated that the 24 LSDV isolates obtained from cattle in northern Thailand were closely related to other LSDV sequences acquired from Asia (China, Hong Kong, and Vietnam). On the other hand, two LSDV isolates of the cows presenting LSD-like clinical signs after vaccination were clustered along with LSDV Neethling-derived vaccines. The outcomes of this research will be beneficial in developing effective control strategies for LSDV.

Comparative occurrence and antibiogram of extended-spectrum ß-lactamase-producing Escherichia coli among post-weaned calves and lactating cows from smallholder dairy farms in a parallel animal husbandry area.

BACKGROUND AND AIM: Inappropriate overuse of antimicrobials might be associated with the spreading of antimicrobial-resistant bacteria in animal-based food products. Extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli have been recognized as an emerging global problem in a One Health approach. This study aimed to assess the occurrence and antimicrobial-susceptible profiles of ESBL-producing E. coli among post-weaned calves and lactating cows in a parallel animal husbandry area. MATERIALS AND METHODS: Seventy-two pool fecal samples were collected from 36 smallholder dairy farms registered in Ban Hong Dairy Cooperatives, Lamphun Province, Thailand. Pre-enriched fecal samples were cultured in MacConkey agar supplemented with cefotaxime. The potential E. coli isolates were identified by not only biochemical tests but also polymerase chain reaction assay of the 16S rRNA gene. ESBL production was confirmed by the combination disk test. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method. RESULTS: The occurrence of ESBL-producing E. coli at the farm level was 80.56%. The different phenotypic antibiogram of ESBL-producing E. coli was observed among post-weaned calf and lactating cow specimens. The most frequent resistance patterns of ESBL-producing isolates from both groups were amoxicillin-ceftiofur-cephalexin-cephalothin-cloxacillin-streptomycin-oxytetracycline-sulfamethoxazole/trimethoprim. For the median zone diameter, enrofloxacin-resistant isolates with narrow zone diameter values from lactating cow specimens were particularly more than post-weaned calf specimens (p<0.05). CONCLUSION: These findings revealed the dynamic changes in ESBL-producing E. coli from calves and lactating cows in Lamphun Province, posing the inevitability to prevent bacterial transmission and optimize antimicrobial therapy in dairy farming.

A Participatory System for Preventing Pandemics of Animal Origins: Pilot Study of the Participatory One Health Disease Detection (PODD) System.

BACKGROUND: Aiming for early disease detection and prompt outbreak control, digital technology with a participatory One Health approach was used to create a novel disease surveillance system called Participatory One Health Disease Detection (PODD). PODD is a community-owned surveillance system that collects data from volunteer reporters; identifies disease outbreak automatically; and notifies the local governments (LGs), surrounding villages, and relevant authorities. This system provides a direct and immediate benefit to the communities by empowering them to protect themselves. OBJECTIVE: The objective of this study was to determine the effectiveness of the PODD system for the rapid detection and control of disease outbreaks. METHODS: The system was piloted in 74 LGs in Chiang Mai, Thailand, with the participation of 296 volunteer reporters. The volunteers and LGs were key participants in the piloting of the PODD system. Volunteers monitored animal and human diseases, as well as environmental problems, in their communities and reported these events via the PODD mobile phone app. LGs were responsible for outbreak control and provided support to the volunteers. Outcome mapping was used to evaluate the performance of the LGs and volunteers. RESULTS: LGs were categorized into one of the 3 groups based on performance: A (good), B (fair), and C (poor), with the majority (46%,34/74) categorized into group B. Volunteers were similarly categorized into 4 performance groups (A-D), again with group A showing the best performance, with the majority categorized into groups B and C. After 16 months of implementation, 1029 abnormal events had been reported and confirmed to be true reports. The majority of abnormal reports were sick or dead animals (404/1029, 39.26%), followed by zoonoses and other human diseases (129/1029, 12.54%). Many potentially devastating animal disease outbreaks were detected and successfully controlled, including 26 chicken high mortality outbreaks, 4 cattle disease outbreaks, 3 pig disease outbreaks, and 3 fish disease outbreaks. In all cases, the communities and animal authorities cooperated to apply community contingency plans to control these outbreaks, and community volunteers continued to monitor the abnormal events for 3 weeks after each outbreak was controlled. CONCLUSIONS: By design, PODD initially targeted only animal diseases that potentially could emerge into human pandemics (eg, avian influenza) and then, in response to community needs, expanded to cover human health and environmental health issues.