Seroepidemiology of Foot and Mouth Disease using passive surveillance techniques in selected provinces of Lao PDR.

Foot and Mouth Disease (FMD) is a high-impact, contagious transboundary animal disease that is endemic in Southeast Asia. Abattoir samples were routinely collected in six selected provinces between March and December 2019. A total of 1280 samples of abattoir animals were tested for FMD Non-Structural Protein (NSP) antibodies to indicate natural infections. Overall, 22.8% were seropositive for FMD NSP antibodies while seroprevalence of cattle (n = 469), buffalo (n = 214), and pigs (n = 597) were 44.6%, 35.0%, and 1.3%, respectively. The highest seroprevalence destination province was Xiengkhouang (35.3% of 272 samples), followed by Savannakhet (27.0% of 244 samples). Risk factors for evidence of natural infection identified by a multivariate logistic regression model included age groups (p-value = 0.02) and origin provinces (p-value = 2.8 × 10-5) of the animals. There were significant differences of FMD NSP seroprevalence between age groups and origin provinces of the animals. The odds ratio of a seropositive result in the less than 1 year old group was 2.5 (95% CI; 1.4, 4.4) when compared to the 3-4 years old group, while the odds ratios for animals that originated from Khammouane and Xiengkhouang provinces were 4.5 (95% CI; 1.1, 18.7) and 2.4 (95% CI; 1.4, 4.1), respectively, when compared to Champasak province. Serotype-specific antibody ELISA for 44 NSP antibody-positive samples revealed evidence of FMD serotypes O and A virus circulation in some provinces. Despite the passive abattoir survey providing useful information on FMD virus previous exposure and geographic locations of the animals, timely information on FMD virus circulation and distribution is also crucial to an effective control program. Alternative approaches to increase the cost-effectiveness of the surveillance network are also discussed.

A history of FMD research and control programmes in Southeast Asia: lessons from the past informing the future.

Foot and mouth disease (FMD) is a major animal health problem within Southeast Asia (SEA). Although Indonesia and more recently the Philippines have achieved freedom from FMD, the disease remains endemic on continental SEA. Control of FMD within SEA would increase access to markets in more developed economies and reduce lost productivity in smallholder and emerging commercial farmer settings. However, despite many years of vaccination by individual countries, numerous factors have prevented the successful control of FMD within the region, including unregulated 'informal' transboundary movement of livestock and their products, difficulties implementing vaccination programmes, emergence of new virus topotypes and lineages, low-level technical capacity and biosecurity at national levels, limited farmer knowledge on FMD disease recognition, failure of timely outbreak reporting and response, and limitations in national and international FMD control programmes. This paper examines the published research of FMD in the SEA region, reviewing the history, virology, epidemiology and control programmes and identifies future opportunities for FMD research aimed at the eventual eradication of FMD from the region.

The Importance and Challenges of Implementing and Maintaining Biorepositories for High-Consequence Veterinary and One Health Pathogens in South-East Asia.

Introduction: Emerging infectious diseases pose a threat to public health and the economy, especially in developing countries. Southeast Asian veterinary laboratories handle numerous high-risk pathogens, making pathogen accountability crucial for safe handling and storage. Methods: Thirteen veterinary laboratories in Cambodia (n = 1), Lao People's Democratic Republic (n = 1), and Thailand (n = 11) participated in a study conducted between 2019 and 2020. Data were collected using a questionnaire, group discussions, and interviews. Conclusion: Significant gaps in biosecurity and biorepository management were recognized and discussed in the context of regional biosafety and biosecurity. Laboratories could use the findings and recommendations of the study to develop or improve their pathogen inventory and biosecurity systems. Governments play a significant role in setting standards and regulations and providing necessary support for laboratories to maintain inventory controls sustainably and have a very important role to play in ensuring biosafety and biosecurity compliance.

Biosafety and Biosecurity Challenges Facing Veterinary Diagnostic Laboratories in Lower-Middle Income Countries in Southeast Asia: A Case Study of Thailand.

INTRODUCTION: Global concerns over emerging and transboundary infectious zoonotic diseases have increased disease diagnostic demands, especially in the veterinary sector. In developing or newly developed countries where the sector often works under limited capacity, biosafety and biosecurity are unlikely to be high-priority issues. A recent development program supported by the Biological Threat Reduction Program of the Defense Threat Reduction Agency funded by the US government aimed to increase biosafety and biosecurity measures of government veterinary diagnostic and research laboratories in Thailand. OBJECTIVE: The purpose of this article is to identify biosafety and biosecurity challenges, opportunities, and recommendations. METHODS: Eleven government laboratory centers were assessed against the Biosafety in Microbiological and Biomedical Laboratories (BMBL) biosafety level 2 (BSL-2) requirements checklist. The BMBL assessment outcomes were then combined with the outcomes of discussion sessions, and the results of pre- and post-test questionnaires conducted during biosafety assessment workshops and self-evaluation reports using the Food and Agriculture Organization Biosafety Laboratory Mapping Tool of each laboratory center were reviewed and summarized. RESULTS: Despite established national policies on laboratory biosafety and biosecurity, major challenges included (1) harmonization and enforcement of these policies, especially at the regional level, and (2) engagement of personnel in implementations of biosafety and biosecurity measures. CONCLUSION: Consistent biosafety policy and allocated resources together with regular training are required to develop sustainable biosafety and biosecurity at the national level. Collaboration between regional countries, international organizations, and donors is essential for improving biosafety and biosecurity on a global scale through setting regional priorities, enacting regulatory standards, and providing technical and financial support.

UV inactivation and model of UV inactivation of foot-and-mouth disease viruses in suspension.

Foot-and-mouth disease virus (FMDV) causes one of the most contagious diseases affecting cloven-hoofed animals (e.g., cattle and swine) and causes severe economic loss for many countries. The resistance to UV irradiation of FMDV strains isolated from outbreaks in Thailand was investigated in phosphate-buffered saline at 25 degrees C. Since the regression coefficients of linear regression were large and root mean square errors were small, UV inactivation could be appropriately summarized and fitted well by a linear equation. The first-order kinetics then could describe UV inactivation, which was experimentally and mathematically shown in this study to be an effective means to inactivate FMDV in suspension. The decimal inactivation dose (DID) was modified from D value in traditional thermal-inactivation kinetics. The DID was the amount of UV irradiation required to reduce the number of microorganisms by a factor of 10, or by 90%. DIDs of FMDV serotypes O189, A132, A-Sakol, and AS1 ranged from 19.66 to 31.31 mWs/cm2. FMDV serotype AS1 was the most UV-resistant, and FMDV serotype A132 was the least UV-resistant. UV resistance of FMDV did not vary significantly among strains and serotypes (P value > 0.05). DID raw data were used to determine the fitted probability distributions by simulation software @Risk. The fitted distributions suggested were Exponential, Logistic, Normal, and LogNormal. Exponential distribution was the best fit by Chi-square test, Kolmogorov-Smirnov test, and Anderson-Darling test (P value >0.10). The parameter beta of the Exponential distribution, equivalent to the mean DID, was 24.173 mWs/cm2 as a first-order model. Poisson probability distribution described the uncertainty of parameter beta for the second-order model. After running simulations of both first-order and second-order models, the curves of both first-order and second-order models were overlaid on the same graph, which indicated that both models were only slightly different. This study concluded that FMDV in suspension was effectively inactivated by UV irradiation, the fitted probability distribution for UV inactivation was Exponential, and source of total uncertainty of this UV-inactivation model was not the uncertainty component.

Thermal inactivation of foot-and-mouth disease viruses in suspension.

The heat resistance of foot-and-mouth disease virus (FMDV) strains isolated from outbreaks in Thailand was investigated in phosphate-buffered saline (PBS) at 50, 60, 70, 80, 90, and 100 degrees C. The first-order kinetic model fitted most of the observed linear inactivation curves. The ranges of decimal-reduction time (D value) of FMDV strains at 50, 60, 70, 80, 90, and 100 degrees C were 732 to 1,275 s, 16.37 to 42.00 s, 6.06 to 10.87 s, 2.84 to 5.99 s, 1.65 to 3.18 s, and 1.90 to 2.94 s, respectively. The heat resistances of FMDV strains at lower temperature (50 degrees C) were not serotype specific. The effective inactivating temperature is approximately 60 degrees C. Heat resistances of FMDV strains at 90 and 100 degrees C were not statistically different (P > 0.05), while the FMDV serotype O (OPN) appeared to be the most heat resistant at 60 to 80 degrees C. The other observed inactivation curves were linear with shoulder or tailing (biphasic curves). The shoulder effect was mostly observed at 90 and 100 degrees C, while the tailing effect was mostly observed at 50 to 80 degrees C. The adjusted D values in the case of shoulder and tailing effects did not affect the overall estimated heat resistance of these FMDV strains, so even unadjusted D values of deviant inactivation curves were legitimate. The z values of FMDV serotypes O, A, and Asia 1 were 21.78 to 23.26, 20.75 to 22.79, and 19.87 degrees C, respectively. The z values of FMDV strains studied were not statistically significantly different (P > 0.05). The results of this study indicated that the heat resistance in PBS of FMDV strains from Thailand was much less than had been reported for foreign epidemic FMDV strains.