Tawatchai Singhla

Background: Particulate matter (PM), particularly PM2.5 and PM10, is a major environmental health concern linked to respiratory diseases in humans and animals. Northern Thailand, especially Chiang Mai, experiences recurrent seasonal air pollution from biomass burning, exposing outdoor-housed livestock to elevated ambient PM levels. The bovine upper respiratory tract (URT) harbors both commensal and opportunistic microorganisms, and disruption of this microbiota may influence susceptibility to bovine respiratory disease (BRD). However, the impact of natural PM exposure on the bovine URT microbiota remains poorly understood. Results: Nasopharyngeal swabs from 25 clinically healthy dairy heifers were analyzed during low-PM and high-PM periods. During the high-PM period, peak PM2.5 levels exceeded 30 times the WHO 24-hour guideline. Alpha diversity, including observed features, Shannon diversity, and Simpson index, was significantly higher during the high-PM period than during the low-PM period. Beta diversity analysis showed significant differences in Bray–Curtis dissimilarity and Jaccard distance, indicating changes in both relative abundance-based community structure and presence–absence-based community membership. The high-PM period was characterized by altered taxonomic profiles, including higher proportions of Proteobacteria, Firmicutes, Gammaproteobacteria, and Bacilli, and lower proportions of Actinobacteriota, Bacteroidota, Actinobacteria, and Bacteroidia. Among selected dominant genera, Moraxella and Fusobacterium were significantly reduced during the high-PM period. BRD-associated genera, including Mycoplasma , Pasteurella , Mannheimia , and Histophilus , showed higher average relative abundances during the high-PM period; however, paired comparisons were not statistically significant. Conclusions: Seasonal high-PM exposure in Chiang Mai was associated with measurable changes in the nasopharyngeal microbiota of clinically healthy dairy heifers, including increased alpha diversity, altered beta diversity, changes in taxonomic profiles, and reductions in selected dominant genera. These findings suggest that ambient air pollution may contribute to respiratory microbiota restructuring in dairy heifers. Further longitudinal studies integrating microbiota composition, host immune responses, farm-level environmental monitoring, and clinical respiratory outcomes are needed to clarify whether PM-associated microbiota changes contribute to BRD susceptibility.

Background/Objectives: Bovine respiratory disease complex (BRDC) is commonly treated empirically, as etiological diagnosis is often impractical under field conditions. Comparative evidence on antimicrobial efficacy in undifferentiated BRDC remains limited. This study aimed to compare the therapeutic efficacy of tulathromycin and ceftiofur for treating undifferentiated BRDC in dairy cattle and to describe hematological and biochemical responses following a tulathromycin metaphylaxis program implemented during the seasonal high-PM2.5 period in northern Thailand. Methods: Thirty-eight Holstein–Friesian cattle with clinical BRDC were randomly assigned to receive tulathromycin (2.5 mg/kg, single subcutaneous dose; n = 20) or ceftiofur (2.2 mg/kg, intramuscularly for three consecutive days; n = 18). The clinical parameters of the surviving cattle were monitored for 5 days, and hematological and biochemical profiles were assessed on Days 1 and 5 in the surviving cattle. In addition, 87 pregnant dairy heifers were enrolled in a metaphylaxis trial and allocated to no injection, one tulathromycin injection, or two injections administered one month apart. Results: Cure rates were comparable between the tulathromycin and ceftiofur groups (90.0% vs. 88.9%), with similar case fatality rates (10.0% vs. 11.1%). No significant between-group differences were observed for clinical, hematological, or biochemical parameters. Both treatments resulted in significant within-group clinical and hematological improvement. During the metaphylaxis trial, no animals developed clinical BRDC; however, significant differences were observed in selected hematological parameters among injection groups. Conclusions: Tulathromycin and ceftiofur demonstrated comparable efficacy for treating undifferentiated BRDC in dairy cattle under field conditions. In the metaphylaxis component, conducted during the seasonal high-PM2.5 period, the absence of clinical BRDC cases did not allow for evaluation of preventive efficacy. Nevertheless, differences in selected blood parameters were observed among injection groups and should be interpreted cautiously, warranting further investigation in studies incorporating low- and high-PM2.5 comparisons.

Foot-and-mouth disease (FMD) significantly impacts global livestock industries, with raw milk transportation posing a recognized pathway for viral dissemination, particularly in endemic regions. This study aimed to evaluate the risk of FMD virus (FMDV) introduction and transmission to dairy farms via raw milk transportation in Ban Thi District, Thailand. A qualitative risk assessment methodology, adhering to WOAH guidelines, was employed. Data were collected through structured farmer surveys (n = 109), expert interviews (n = 12), and reviews of national disease surveillance data and scientific literature. The risk assessment, utilizing a scenario tree approach for domestic dairy cattle, revealed a moderate overall risk of FMDV transmission. This finding is primarily attributed to critical gaps in on-farm biosecurity practices, potential contamination at milk collection centers, and significant challenges in detecting subclinical carrier animals. While the qualitative approach presented inherent limitations and uncertainties, the study successfully highlighted key vulnerabilities. The results underscore the urgent necessity for implementing targeted biosecurity protocols, developing more robust surveillance strategies for FMDV carriers, and establishing standardized risk assessment frameworks to mitigate potential outbreaks and protect the regional dairy industry.

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.

Disease caused by elephant endotheliotropic herpesvirus (EEHV) infection is the most highly fatal hemorrhagic disease in Asian elephant calves worldwide. To date, adult elephants that have been infected with EEHV have predominantly displayed mild clinical signs, while they are believed to serve as EEHV shedders to other elephants. Hence, the diagnostic tools employed for monitoring EEHV-active infection are considered vitally important. In this study, partial EEHV-DNA polymerase (DNApol) nonstructural proteins (NSPs) were used to detect anti-EEHV antibodies through the use of an in-house indirect enzyme-linked immunosorbent assay (ELISA). The results were then compared to those obtained from a PCR test. In this study, a total of 175 serum samples were collected from Asian elephants living in elephant camps located in Chiang Mai and Lampang Provinces, Thailand. The elephants were aged between 2 and 80 years old. The overall percentages of positive samples by the PCR and EEHV-DNApol ELISA tests were 4% (21/175) and 12% (21/175), respectively. The ELISAs demonstrated values of 77.9% (95% posterior probability interval (PPI) = 52.5–95%) sensitivity and 87.7% (PPI = 82.5–91.9%) specificity, respectively. Accordingly, the sera obtained from the elephants exhibiting no clinical signs of EEHV infection, and those who were negative according to PCR tests, revealed a value of 14% seropositivity for EEHV-DNApol. Our results indicate that these asymptomatic, active EEHV-infected elephants could likely serve as a source of EEHV shedding within elephant herds. Consequently, the developed EEHV-DNApol NSPs-based ELISA test employed in the present study may be of use for routine monitoring and identification of EEHV shedders in elephant herds, and could be an alternative diagnostic tool for EEHV detection in Asian elephants.

This study aimed to estimate the sensitivity (Se) and specificity (Sp) of loop-mediated isothermal amplification (LAMP) and single intradermal tuberculin (SIT) tests for the diagnosis of bovine tuberculosis (bTB) in dairy cattle in Thailand using a Bayesian approach. The SIT test was performed in 203 lactating dairy cattle from nine dairy farms located in Chiang Mai province, Thailand. Milk samples were collected for the LAMP test. Kappa analysis was performed to determine the agreement between the two tests. A one-population conditional independence Bayesian model was applied to estimate the Se and Sp of the two tests. Of 203 dairy cattle, 2 were positive for the SIT test using standard interpretation, whereas 38 were positive for the LAMP test. A poor agreement (kappa = 0) was observed between the two tests. The median Se and Sp of the SIT test using standard interpretation were 63.5% and 99.1%, respectively. The median Se and Sp of the LAMP test were 67.2% and 82.0%, respectively. The estimated true prevalence of bTB was 3.7%. The LAMP test with milk samples can potentially be used as a non-invasive screening test for the diagnosis of bTB in dairy cattle.

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.

This study aimed to (1) investigate the prevalence of bovine tuberculosis (bTB) in slaughtered animals at the Chiang Mai Municipal abattoir in Chiang Mai, Thailand; (2) identify animal-level risk factors for bTB at the abattoir; and (3) evaluate the performance of techniques for bTB detection at the abattoir. From April 2020 to March 2021, 161 animals registered for slaughter were randomly selected for the study. Animal data including age, sex, species, body condition scores, and origins of the animals were collected. Meat inspection was performed by a trained meat inspector. Tissue samples of the lung, liver, and lymph nodes were collected for histopathological diagnosis and polymerase chain reaction (PCR) detection of Mycobacteria and specifically Mycobacterium bovis. The prevalence of bTB during meat inspection and PCR was calculated separately. Animal-level factors affecting bTB were determined using multivariate logistic regression analysis. The performance of meat inspection and PCR was evaluated using a Bayesian approach. The prevalence of bTB was 12.4% (20/161) and 34.8% (56/161) when the disease was diagnosed using meat inspection and PCR, respectively. Buffaloes had a significantly higher risk of being identified as bTB-positive using PCR compared to beef cattle (odds ratio = 2.19; confidence interval = 1.11–4.30). The median of posterior estimates of sensitivity (Se) and specificity (Sp) to detect bTB using meat inspection were 20.8% [95% posterior probability interval (PPI) = 9.1–36.5%] and 87.8% (95% PPI = 79.6–95.4%), respectively. The medians of the posterior estimates of Se and Sp for PCR were 88.6% (95% PPI = 70.5–98.3%) and 94.4% (95% PPI = 84.7–98.8%), respectively. These findings demonstrate that bTB is highly prevalent among slaughtered animals. PCR can be used as an ancillary test for bTB surveillance at abattoirs in Thailand.

Background: Foot-and-mouth disease (FMD) and Haemorrhagic septicemia (HS) are two important diseases that are known to have caused significant economic losses to the cattle industry. Accordingly, vaccinations have been recognized as an efficient method to control and prevent both of the above-mentioned diseases. This study aimed to determine the immune response to FMD virus antigens and the recombinant outer membrane protein of HS (rOmpH) of Pasteurella multocida in cattle administered as a combination vaccine and compare antibody titers with the two vaccines given independently, under field conditions. Dairy cattle were divided into three groups. Each group was immunized with different vaccine types according to the vaccination program employed in this study. Antibody responses were determined by indirect ELISA, liquid phase blocking ELISA (LPB-ELISA) and viral neutralization test (VNT). Furthermore, the cellular immune responses were measured by lymphocyte proliferation assay (LPA). Results: The overall antibody titers to HS and FMDV were above cut-off values for the combined FMD-HS vaccine in this study.The mean antibody titer against HS after the first immunization in the combined FMD-HS vaccine groups was higher than in the HS vaccine groups. However, no statistically significant differences (p > 0.05) were observed between groups. Likewise, the antibody titer to the FMDV serotypes O/TAI/189/87 and Asia 1/TAI/85 determined by LPB-ELISA in the combined vaccine were not statistically significantly different when compared to the FMD vaccine groups. However, the mean VNT antibody titer of combined vaccine against serotype O was significantly higher than the VN titer of FMD vaccine groups (p < 0.05). Moreover, the LPA results showed that all vaccinated groups displayed significantly higher than the negative control (p < 0.05). Nevertheless, no differences in the lymphocyte responses were observed in comparisons between the groups (p > 0.05). Conclusions: The combined FMD-HS vaccine formulated in this study could result in high both antibody and cellular immune responses without antigenic competition. Therefore, the combined FMD-HS vaccine can serve as an alternative vaccine against both HS and FMD in dairy cattle under field conditions.