Nipah virus (NiV) is a fatal zoonotic agent that was first identified amongst pig farmers in Malaysia in 1998, in an outbreak that resulted in 105 fatal human cases. That epidemic arose from a chain ...of infection, initiating from bats to pigs, and which then spilled over from pigs to humans. In Thailand, bat-pig-human communities can be observed across the country, particularly in the central plain. The present study therefore aimed to identify high-risk areas for potential NiV outbreaks and to model how the virus is likely to spread. Multi-criteria decision analysis (MCDA) and weighted linear combination (WLC) were employed to produce the NiV risk map. The map was then overlaid with the nationwide pig movement network to identify the index subdistricts in which NiV may emerge. Subsequently, susceptible-exposed-infectious-removed (SEIR) modeling was used to simulate NiV spread within each subdistrict, and network modeling was used to illustrate how the virus disperses across subdistricts.
Based on the MCDA and pig movement data, 14 index subdistricts with a high-risk of NiV emergence were identified. We found in our infectious network modeling that the infected subdistricts clustered in, or close to the central plain, within a range of 171 km from the source subdistricts. However, the virus may travel as far as 528.5 km (R
= 5).
In conclusion, the risk of NiV dissemination through pig movement networks in Thailand is low but not negligible. The risk areas identified in our study can help the veterinary authority to allocate financial and human resources to where preventive strategies, such as pig farm regionalization, are required and to contain outbreaks in a timely fashion once they occur.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Thailand's Central Plain is identified as a contact zone between pigs and flying foxes, representing a potential zoonotic risk. Nipah virus (NiV) has been reported in flying foxes in Thailand, but it ...has never been found in pigs or humans. An assessment of the suitability of NiV transmission at the spatial and farm level would be useful for disease surveillance and prevention. Multi-criteria decision analysis (MCDA), a knowledge-driven model, was used to map contact zones between local epizootic risk factors as well as to quantify the suitability of NiV transmission at the pixel and farm level.
Spatial risk factors of NiV transmission in pigs were identified by experts as being of three types, including i) natural host factors (bat preferred areas and distance to the nearest bat colony), ii) intermediate host factors (pig population density), and iii) environmental factors (distance to the nearest forest, distance to the nearest orchard, distance to the nearest water body, and human population density). The resulting high suitable areas were concentrated around the bat colonies in three provinces in the East of Thailand, including Chacheongsao, Chonburi, and Nakhonnayok. The suitability of NiV transmission in pig farms in the study area was quantified as ranging from very low to medium suitability.
We believe that risk-based surveillance in the identified priority areas may increase the chances of finding out NiV and other bat-borne pathogens and thereby optimize the allocation of financial resources for disease surveillance. In the long run, improvements of biosecurity in those priority areas may also contribute to preventing the spread of potential emergence of NiV and other bat-borne pathogens.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Unexpected pathogen transmission between animals, humans and their shared environments can impact all aspects of society. The Tripartite organisations—the Food and Agriculture Organization of the ...United Nations (FAO), the World Health Organization (WHO), and the World Organisation for Animal Health (WOAH)—have been collaborating for over two decades. The inclusion of the United Nations Environment Program (UNEP) with the Tripartite, forming the ‘Quadripartite’ in 2021, creates a new and important avenue to engage environment sectors in the development of additional tools and resources for One Health coordination and improved health security globally. Beginning formally in 2010, the Tripartite set out strategic directions for the coordination of global activities to address health risks at the human-animal-environment interface. This paper highlights the historical background of this collaboration in the specific area of health security, using country examples to demonstrate lessons learnt and the evolution and pairing of Tripartite programmes and processes to jointly develop and deliver capacity strengthening tools to countries and strengthen performance for iterative evaluations. Evaluation frameworks, such as the International Health Regulations (IHR) Monitoring and Evaluation Framework, the WOAH Performance of Veterinary Services (PVS) Pathway and the FAO multisectoral evaluation tools for epidemiology and surveillance, support a shared global vision for health security, ultimately serving to inform decision making and provide a systematic approach for improved One Health capacity strengthening in countries. Supported by the IHR-PVS National Bridging Workshops and the development of the Tripartite Zoonoses Guide and related operational tools, the Tripartite and now Quadripartite, are working alongside countries to address critical gaps at the human-animal-environment interface.
A workforce with the adequate field epidemiology knowledge, skills and abilities is the foundation of a strong and effective animal health system. Field epidemiology training is conducted in several ...countries to meet the increased global demand for such a workforce. However, core competencies for field veterinary epidemiology have not been identified and agreed upon globally, leading to the development of different training curricula. Having a set of agreed core competencies can harmonize field veterinary epidemiology training. The Food and Agriculture Organization of the United Nations (FAO) initiated a collective, iterative, and participative process to achieve this and organized two expert consultative workshops in 2018 to develop core competencies for field veterinary epidemiology at the frontline and intermediate levels. Based on these expert discussions, 13 competencies were identified for the frontline and intermediate levels. These competencies were organized into three domains: epidemiological surveillance and studies; field investigation, preparedness and response; and One Health, communication, ethics and professionalism. These competencies can be used to facilitate the development of field epidemiology training curricula for veterinarians, adapted to country training needs, or customized for training other close disciplines. The competencies can also be useful for mentors and employers to monitor and evaluate the progress of their mentees, or to guide the selection process during the recruitment of new staff.
Abstract
Background
Nipah virus (NiV) infection causes encephalitis and has > 75% mortality rate, making it a WHO priority pathogen due to its pandemic potential. There have been NiV outbreak(s) in ...Malaysia, India, Bangladesh, and southern Philippines. NiV naturally circulates among fruit bats of the genus
Pteropus
and has been detected widely across Southeast and South Asia. Both Malaysian and Bangladeshi NiV strains have been found in fruit bats in Thailand. This study summarizes 20 years of pre-emptive One Health surveillance of NiV in Thailand, including triangulated surveillance of bats, and humans and pigs in the vicinity of roosts inhabited by NiV-infected bats.
Methods
Samples were collected periodically and tested for NiV from bats, pigs and healthy human volunteers from Wat Luang village, Chonburi province, home to the biggest
P. lylei
roosts in Thailand, and other provinces since 2001. Archived cerebrospinal fluid specimens from encephalitis patients between 2001 and 2012 were also tested for NiV. NiV RNA was detected using nested reverse transcription polymerase chain reaction (RT-PCR). NiV antibodies were detected using enzyme-linked immunosorbent assay or multiplex microsphere immunoassay.
Results
NiV RNA (mainly Bangladesh strain) was detected every year in fruit bats by RT-PCR from 2002 to 2020. The whole genome sequence of NiV directly sequenced from bat urine in 2017 shared 99.17% identity to NiV from a Bangladeshi patient in 2004. No NiV-specific IgG antibodies or RNA have been found in healthy volunteers, encephalitis patients, or pigs to date. During the sample collection trips, 100 community members were trained on how to live safely with bats.
Conclusions
High identity shared between the NiV genome from Thai bats and the Bangladeshi patient highlights the outbreak potential of NiV in Thailand. Results from NiV cross-sectoral surveillance were conveyed to national authorities and villagers which led to preventive control measures, increased surveillance of pigs and humans in vicinity of known NiV-infected roosts, and increased vigilance and reduced risk behaviors at the community level. This proactive One Health approach to NiV surveillance is a success story; that increased collaboration between the human, animal, and wildlife sectors is imperative to staying ahead of a zoonotic disease outbreak.
We describe 2-season, risk-based, virological surveillance for zoonotic avian influenza in Myanmar and report the first detection of influenza A subtypes H5N6 and H9N2 in Myanmar. The study focused ...mainly on the live bird markets in border townships, where illegal poultry importation from China usually takes place. The objective was to enhance early warning for low pathogenic avian influenza A(H7N9) incursion. The study followed the guidelines of the Food and Agriculture Organization (FAO) of the United Nations for influenza A(H7N9) surveillance in uninfected countries. The sampling strategy was risk-based at all sampling levels. Sample collection and laboratory analysis were carried out with the government of the Union of the Republic of Myanmar. Laboratory testing was according to a previously published FAO laboratory protocol and algorithm designed to detect a range of influenza A subtypes. Challenges to implementation are outlined. The study provided evidence that the H7N9 subtype had not entered Myanmar but detected other subtypes, including H5N6 and H9N2. Although there were logistical difficulties associated with nation-related issues, the results highlight the importance and feasibility of this risk-based active surveillance, which should be urgently established in other countries, especially those located at the east-southeast influenza epicenter.
To assess the likelihood of an introduction of foot-and-mouth disease (FMD) into the Malaysia-Thailand-Myanmar (MTM) peninsula through terrestrial movement of livestock.
89,294 cattle and buffalo ...legally moved into the MTM peninsula.
A quantitative risk assessment was conducted by use of a stochastic simulation. Patterns of livestock movement were ascertained through review of relevant governmental records and regulations and by interviewing farmers, traders, and local officers when the records did not exist. Parameters identified in the process were the probabilities of livestock having FMD and of FMD infection going undetected during import processes. The probability of an animal accepted for import having FMD was also assessed. Sensitivity analysis was performed to determine the effects that each parameter had on the model.
The simulation yielded an average consignment prevalence of 10.95%. Typically, each animal in a quarantine facility had a 2.7% chance of having an inapparent form of FMD infection; hence, it was likely an animal would not be identified as infected. Findings revealed that the mean probability of an animal accepted for import having FMD was 2.9%, and the risk was as high as 11%.
Results of the model allowed for the evaluation of movement regulations currently imposed in the MTM peninsula. Evidence from the study suggested that current practices in animal movement were far from efficient in preventing introduction of FMD-infected animals into the MTM region, and additional measures will be necessary.
Objective--To assess the impacts of the introduction of foot-and-mouth disease (FMD) and various FMD control programs in southern Thailand. Animals--A native population of 562,910 cattle and 33,088 ...buffalo as well as 89,294 animals legally transported into southern Thailand. Procedures--A quantitative risk assessment was used to ascertain the probability of FMD introduction, and an intrinsic dynamic model was used to assess impacts. Value for the transmission rate (β) was estimated. Five scenarios created to assess the impacts of nonstructural protein (NSP) testing, mass vaccination, and culling were examined. Impacts were assessed through an examination of the estimated annual cumulative incidence (ACI) of FMD. The ACIs of various scenarios were compared by use of the Tukey Studentized range technique. Results--β was estimated at 0.115. Approximately 35,000 cases of FMD would be expected from the baseline situation. A 30% reduction of ACI was detected with the introduction of NSP antibody testing. Prophylactic vaccination resulted in an 85% reduction of ACI. Concurrent use of NSP antibody testing and vaccination reduced the ACI by 96%, and the addition of an eradication policy resulted in a slightly greater decrease in the ACI (98%). Conclusions and Clinical Relevance--The study used epidemiologic models to investigate FMD control interventions. Results suggested that vaccination has more impact than the use of NSP testing. Use of the NSP test reduced ACI during peak seasons, whereas vaccination diminished the underlying incidence. The best mitigation plan was an integrated and strategic use of multiple control techniques.
A quantitative risk assessment (QRA) study was conducted in the Malaysia-Thailand-Myanmar (MTM) peninsular to assess the likelihood of an introduction of FMD through importation of livestock. The ...simulation yielded the most-likely prevalence at 8%. On average, each livestock in a quarantine station would have 2.7% chance of having unapparent form of FMD infection. Given the current movement patterns and import regulations, the average probability of a livestock accepted for import carrying FMD was 2.9%, and the risk was as high as 11%. From the sensitivity analysis, the correlation between the sensitivity of the screening processes and the risk of FMD introduction was substantial. A compartmental model was developed to assess the impacts of the FMD introduction and control programs in Southern Thailand. The transmission rate (β) value was acknowledged by comparing observed (outbreak reports) to expected outbreak data (from the simulation) using least square estimation; and β was estimated at 0.115. The sensitivity analysis for the annual cumulative incidence (ACI) was performed; and the effects of vaccination (ϵ), stamping-out policy (κ), and sensitivity of screening processes during quarantine (pS) were examined using a partial rank correlation coefficient method. The results showed that all parameters revealed negative correlations with the ACI, but only pS was considered strongly significant. Five scenarios were created to imitate different FMD control strategies in Southern Thailand. The baseline scenario (BS) emulated current strategy, and was the comparison point for all other subsequent scenarios. Eradication Scenario (ES) I investigated the assimilation of NSP test during quarantine. Assumedly 80% livestock were randomly vaccinated in the ESII. ESIII evaluated an integrated use of NSP test and vaccines; and ESIV investigated an addition of the stamping-out policy to the ESIII. About 30% and 85% reduction in ACI from the BS were observed for the ESI and ESII, respectively. ESIII resulted in the 96% ACI reduction; and slightly more drop (98%) was seen in the ESIV. The results suggested that the vaccination had more impact on the ACT than the use of NSP test. However, the best mitigation strategy was the integrated and strategic use of control techniques.
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