Research Interests: Epidemiology and Medicine
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ObjectiveTo characterise MDR‐TB outbreak and incorporate social network analysis with contact investigation to detect case–contact linkages and clusters.MethodsMDR‐TB cases registered in the district hospital between October 2012 and... more
ObjectiveTo characterise MDR‐TB outbreak and incorporate social network analysis with contact investigation to detect case–contact linkages and clusters.MethodsMDR‐TB cases registered in the district hospital between October 2012 and September 2015 were interviewed and their contacts were investigated. A relationship‐based weighted network was constructed.ResultsAmong 43 interviewed MDR‐TB cases, 20 (47%) were male, five (12%) were asymptomatic (and discovered incidentally) and 22 (51%) had underlying diseases. From the documented 115 contacts, 61 (53%) were household contacts and 49 (43%) were close (non‐household) contacts; 70 (61%) were screened for TB using various tests. In this network, we prioritised 37 contacts connected with more than one MDR‐TB patient. The largest cluster was identified in the pharmacy unit of the hospital.ConclusionThis investigation yielded a significant number of MDR‐TB contacts, and social network analysis facilitated the prioritisation for screening....
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Rabies is a fatal disease that has been a serious health concern, especially in developing countries. Although rabies is preventable by vaccination, the spread still occurs sporadically in many countries, including Thailand. Geographical... more
Rabies is a fatal disease that has been a serious health concern, especially in developing countries. Although rabies is preventable by vaccination, the spread still occurs sporadically in many countries, including Thailand. Geographical structures, habitats, and behaviors of host populations are essential factors that may result in an enormous impact on the mechanism of propagation and persistence of the disease. To investigate the role of geographical structures on the transmission dynamics of canine rabies, we developed a stochastic individual-based model that integrates the exact configuration of buildings and roads. In our model, the spatial distribution of dogs was estimated based on the distribution of buildings, with roads considered to facilitate dog movement. Two contrasting areas with high- and low-risk of rabies transmission in Thailand, namely, Hatyai and Tepha districts, were chosen as study sites. Our modeling results indicated that the distinct geographical structure...
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Background: Asian Openbills, Anastomus oscitans, have long been known to migrate from South to Southeast Asia for breeding and nesting. In Thailand, the first outbreak of H5N1 highly pathogenic avian influenza (HPAI) infection in the... more
Background: Asian Openbills, Anastomus oscitans, have long been known to migrate from South to Southeast Asia for breeding and nesting. In Thailand, the first outbreak of H5N1 highly pathogenic avian influenza (HPAI) infection in the Openbills coincided with the outbreak in the poultry. Therefore, the flyways of Asian Openbills was determined to study their role in the spread of H5N1 HPAI virus to poultry and wild birds, and also within their flocks. Results: Flyways of 5 Openbills from 3 colonies were monitored using Argos satellite transmitters with positioning by Google Earth Programme between 2007 and 2013. None of the Openbills tagged with satellite telemeters moved outside of Thailand. Their home ranges or movement areas varied from 1.6 to 23,608 km2 per month (95% utility distribution). There was no positive result of the viral infection from oral and cloacal swabs of the Openbills and wild birds living in the vicinity by viral isolation and genome detection during 2007 to 20...
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Figure S1. Percentage of flood area in 2012. Figure S2. The monthly rainfall of Thailand in 2012. Figure S3. Prediction of leptospirosis infection risk in 2016. The non-predicted districts are presented in white. Figure S4. Percentage of... more
Figure S1. Percentage of flood area in 2012. Figure S2. The monthly rainfall of Thailand in 2012. Figure S3. Prediction of leptospirosis infection risk in 2016. The non-predicted districts are presented in white. Figure S4. Percentage of Flood area in 2016.Figure S5. Maps of human density (people/km2) and livestock density (animal/km2). (DOCX 3416 kb)
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L’Influenza Aviaire Hautement Pathogène H5N1 (IAHP à H5N1) a été déclaré en Thaïlande lors de plusieurs vagues épidémiques puis lors de cas sporadiques entre 2004 et 2008, et le risque persiste encore en Thaïlande. La plupart des foyers... more
L’Influenza Aviaire Hautement Pathogène H5N1 (IAHP à H5N1) a été déclaré en Thaïlande lors de plusieurs vagues épidémiques puis lors de cas sporadiques entre 2004 et 2008, et le risque persiste encore en Thaïlande. La plupart des foyers confirmés d’IAHP à H5N1 en Thaïlande ont eu lieu dans les populations de volailles de basse-cour. Les poulets de basse-cour sont élevés pour de nombreuses raisons, y compris pour un revenu supplémentaire. Ce commerce est géré informellement par les collecteurs de volailles qui peuvent être classés en collecteur-abatteur (TS), sous-collecteur (HT) et collecteur de collecteurs (TT). Ces collecteurs se déplacent entre villages avec les mêmes véhicules et matériel non nettoyés. Nous avons mesuré leurs activités commerciales dans l'espace et le temps. Nous avons développé un modèle spatial dynamique compartimental et stochastique de la filière de poulet de basse-cour dans une province. Nos résultats indiquent que ces échanges commerciaux peuvent contr...
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Poor management of dog populations causes many problems in different countries, including rabies. To strategically design a dog population management, certain sets of data are required, such as the population size and spatial distribution... more
Poor management of dog populations causes many problems in different countries, including rabies. To strategically design a dog population management, certain sets of data are required, such as the population size and spatial distribution of dogs. However, these data are rarely available or incomplete. Hence, this study aimed to describe the characteristics of dog populations in Thailand, explore their spatial distribution and relevant factors, and estimate the number of dogs in the whole country. First, four districts were selected as representatives of each region. Each district was partitioned into grids with a 300-m resolution. The selected grids were then surveyed, and the number of dogs and related data were collected. Random forest models with a two-part approach were used to quantify the association between the surveyed dog population and predictor variables. The spatial distribution of dog populations was then predicted. A total of 1,750 grids were surveyed (945 grids with ...
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International audienc
Rabies, a fatal and infectious disease, is still endemic in all regions of Thailand. Domestic dogs are the most common reservoir of the virus. In a practical routine, it has a measure to control a disease with a mass vaccination, but... more
Rabies, a fatal and infectious disease, is still endemic in all regions of Thailand. Domestic dogs are the most common reservoir of the virus. In a practical routine, it has a measure to control a disease with a mass vaccination, but operation is not effective due to the large area of operation protocol and difficulty in tracking an infected dog. In order to make a tool to help tracking an epidemic area, this paper presents the implementation of rabies epidemic simulation. The world generation and spatial data are generated from Mapbox SDK in Unity engine. Dog behavior and homerange are determined from a normal distribution and kernel density estimation method. Rabies infected dogs are modeled in SEIR model and their behavior is determined from a normal distribution combined with a factor probability value calculated from the incline and home position. The result shows that the coverage area of epidemic can cover other reported cases with a shorter radius than a vaccination protocol but giving a high RO result due to the dog group sample and unpredictable repeat bite of infected dog.
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African swine fever (ASF) is a highly contagious disease that is caused by the ASF virus (ASFV) with a high fatality rate in domestic pigs resulting in a high socio-economic impact. The pig business in Vietnam was recently affected by ASF... more
African swine fever (ASF) is a highly contagious disease that is caused by the ASF virus (ASFV) with a high fatality rate in domestic pigs resulting in a high socio-economic impact. The pig business in Vietnam was recently affected by ASF for the first time. This study thus aimed to develop a disease dynamic model to explain how ASFV spreads in Vietnamese pig populations and suggest a protective vaccine coverage level required to prevent future outbreaks. The outbreak data were collected from ten private small-scale farms within the first wave of ASF outbreaks in Vietnam. Three methods were used to estimate the basic reproduction number (R0), including the exponential growth method, maximum likelihood method, and attack rate method. The average R0 values were estimated at 1.49 (95%CI: 1.05–2.21), 1.58 (95%CI: 0.92–2.56), and 1.46 (95%CI: 1.38–1.57), respectively. Based on the worst-case scenario, all pigs in a herd would be infected and removed within 50 days. We suggest vaccinating...
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Rabies is a deadly zoonotic disease responsible for almost 60,000 deaths each year, especially in Africa and Asia including Thailand. Dogs are the major reservoirs for rabies virus in these settings. This study thus used the concept of... more
Rabies is a deadly zoonotic disease responsible for almost 60,000 deaths each year, especially in Africa and Asia including Thailand. Dogs are the major reservoirs for rabies virus in these settings. This study thus used the concept of knowledge, attitudes, and practices (KAP) to identify socioeconomic factors that contribute to the differences in the canine rabies occurrences in high and low-risk areas which were classified by a Generalized Additive Model (GAM). Multistage sampling was then applied to designate the study locations and a KAP-based questionnaire was used to retrieve data and relevant perspectives from the respondents. Based on the responses from 476 participants living across four regions of Thailand, we found that the knowledge of the participants was positively correlated with their behaviors but negatively associated with the attitudes. Participants who are male, younger, educated at the level of middle to high school, or raising more dogs are likely to have negat...
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Campylobacter jejuni is one of the leading causes of foodborne illness worldwide. C. jejuni is commonly found in poultry. It is the most frequent cause of contamination and thus resulting in not only public health concerns but also... more
Campylobacter jejuni is one of the leading causes of foodborne illness worldwide. C. jejuni is commonly found in poultry. It is the most frequent cause of contamination and thus resulting in not only public health concerns but also economic impacts. To test for this bacterial contamination in food processing plants, this study attempted to employ a simple and rapid detection assay called loop-mediated isothermal amplification (LAMP). The best cutoff value for the positive determination of C. jejuni calculated using real-time LAMP quantification cycle (Cq) was derived from the receiver operating characteristic (ROC) curve modeling. The model showed an area under curve (AUC) of 0.936 (95% Wald CI: 0.903–0.970). Based on Youden’s J statistic, the optimal cutoff value which had the highest sensitivity and specificity from the model was calculated as 18.07. The LAMP assay had 96.9% sensitivity, 95.8% specificity, and 93.9 and 97.9% positive and negative predictive values, respectively, c...
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Additional file 1: Table S1. The list of high risk subdistricts for NiV occurrence at subdistrict level. Table S2. The list of medium risk subdistricts for NiV occurrence at subdistrict level. Table S3. The list of low risk subdistricts... more
Additional file 1: Table S1. The list of high risk subdistricts for NiV occurrence at subdistrict level. Table S2. The list of medium risk subdistricts for NiV occurrence at subdistrict level. Table S3. The list of low risk subdistricts for NiV occurrence at subdistrict level. Table S4. The list of very low risk subdistricts for NiV occurrence at subdistrict level.
Background: Asian Openbills, Anastomus oscitans, have long been known to migrate from South to Southeast Asia for breeding and nesting. In Thailand, the first outbreak of H5N1 highly pathogenic avian influenza (HPAI) infection in the... more
Background: Asian Openbills, Anastomus oscitans, have long been known to migrate from South to Southeast Asia for breeding and nesting. In Thailand, the first outbreak of H5N1 highly pathogenic avian influenza (HPAI) infection in the Openbills coincided with the outbreak in the poultry. Therefore, the flyways of Asian Openbills was determined to study their role in the spread of H5N1 HPAI virus to poultry and wild birds, and also within their flocks. Results: Flyways of 5 Openbills from 3 colonies were monitored using Argos satellite transmitters with positioning by Google Earth Programme between 2007 and 2013. None of the Openbills tagged with satellite telemeters moved outside of Thailand. Their home ranges or movement areas varied from 1.6 to 23,608 km2 per month (95% utility distribution). There was no positive result of the viral infection from oral and cloacal swabs of the Openbills and wild birds living in the vicinity by viral isolation and genome detection during 2007 to 20...
Table S1. Serosurveillance in the wild birds along the movement areas of Asian Openbills. Figure S1. The rice farming area nearby the large fresh marsh, the major habitat of the Asian Openbills. (PDF 1994Â kb)
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The main code for estimating the weekly biting rates and running the simulation is Estimate_Biting_Rate_Main_Code.m and Main_Code.m, respectively. (7Z 3143 kb)
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Background Thailand is among the top five countries with effective COVID-19 transmission control. This study examines how news of presence of COVID-19 in Thailand, as well as varying levels of government restriction on movement, affected... more
Background Thailand is among the top five countries with effective COVID-19 transmission control. This study examines how news of presence of COVID-19 in Thailand, as well as varying levels of government restriction on movement, affected human mobility in a rural Thai population along the border with Myanmar. Methods This study makes use of mobility data collected using a smartphone app. Between November 2019 and June 2020, four major events concerning information dissemination or government intervention give rise to five time intervals of analysis. Radius of gyration is used to analyze movement in each interval, and movement during government-imposed curfew. Human mobility network visualization is used to identify changes in travel patterns between main geographic locations of activity. Cross-border mobility analysis highlights potential for intervillage and intercountry disease transmission. Results Inter-village and cross-border movement was common in the pre-COVID-19 period. Rad...
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Table S1. Summary results of the univariable linear regression model (with binomial function and random effect). (DOCX 14 kb)
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The monitoring and surveillance of highly pathogenic avian influenza (HPAI) H5N1 virus in captive and wild birds at zoo in Suphan Buri province, Thailand was carried out under the disease surveillance program of the Monitoring and... more
The monitoring and surveillance of highly pathogenic avian influenza (HPAI) H5N1 virus in captive and wild birds at zoo in Suphan Buri province, Thailand was carried out under the disease surveillance program of the Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic animals from January 2009 to October 2010 by collecting tracheal swabs, cloacal swabs and serum. All 325 samples were found negative in viral detection with molecular technique, cell culture and serological methods. Although this study found no evidence of highly pathogenic avian influenza (HPAI) H5N1 in the area, the monitoring and surveillance for avian influenza should be continuously conducted.
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Leptospirosis is a zoonotic disease-causing illness in both humans and animals resulting in related economic impacts due to production loss as well as prevention and control efforts. Several mathematical models have been proposed to study... more
Leptospirosis is a zoonotic disease-causing illness in both humans and animals resulting in related economic impacts due to production loss as well as prevention and control efforts. Several mathematical models have been proposed to study the dynamics of infection but none of them has so far taken into account the dynamics of seroconversion. In this study, we have developed a general framework, based on the kinetic model for animal leptospirosis, that combines both the antibody (exposure marker) and infection dynamics to simultaneously follows both seroconversion and infection status of leptospirosis in a herd population. It is a stochastic compartmental model (for transition rates) with time delay (for seroconversion) which describes the progression of infection by a SEIRS (susceptible, exposed, infected, removed and susceptible) approach and seroconversion by four-state antibody kinetics (antibody negative and three antibody positive states of different antibody levels). The model...
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In Southeast Asia, traditional poultry marketing chains have been threatened by epidemics caused by the highly pathogenic avian influenza H5N1 (HPAI H5N1) virus. In Thailand, the trade of live backyard chickens is based on the activities... more
In Southeast Asia, traditional poultry marketing chains have been threatened by epidemics caused by the highly pathogenic avian influenza H5N1 (HPAI H5N1) virus. In Thailand, the trade of live backyard chickens is based on the activities of traders buying chickens from villages and supplying urban markets with chicken meat. This study aims to quantify the flows of chickens traded during a 1-year period in a province of Thailand. A compartmental stochastic dynamic model was constructed to illustrate trade flows of live chickens from villages to slaughterhouses. Live poultry movements present important temporal variations with increased activities during the 15 days preceding the Chinese New Year and, to a lesser extent, other festivals (Qingming Festival, Thai New Year, Hungry Ghost Festival, and International New Year). The average distance of poultry movements ranges from 4 to 25 km, defining a spatial scale for the risk of avian influenza that spread through traditional poultry marketing chains. Some characteristics of traditional poultry networks in Thailand, such as overlapping chicken supply zones, may facilitate disease diffusion over longer distances through combined expansion and relocation processes. This information may be of use in tailoring avian influenza and other emerging infectious poultry disease surveillance and control programs provided that the cost-effectiveness of such scenarios is also evaluated in further studies.
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Foot-and-mouth disease (FMD) is an important viral infection affecting productivity performance of many livestock species including cattle. Beef cattle are still traditionally raised in Thai households with small number of animals per... more
Foot-and-mouth disease (FMD) is an important viral infection affecting productivity performance of many livestock species including cattle. Beef cattle are still traditionally raised in Thai households with small number of animals per family. However, a number of cattle are imported from neighboring countries, especially Myanmar. This importation is managed to supply the needs of domestic consumption and also to convey animals to the third countries. Tak, a Thailand-Myanmar border province, is a major gateway importing cattle from Myanmar. The animals imported into the province are then widely distributed to different regions of Thailand [1]. Therefore, FMD virus may move across the border and further disseminate across the country. The present study hence tried to comprehend the cattle importation process and employed risk assessment technique to quantify the risk of FMD importation via transboundary cattle movement.
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Swamp buffalo population in Thailand has dramatically decreased in the last three decades. The present study was conducted to predict trends and future population size of swamp buffaloes and to formulate different interventions to prevent... more
Swamp buffalo population in Thailand has dramatically decreased in the last three decades. The present study was conducted to predict trends and future population size of swamp buffaloes and to formulate different interventions to prevent further decline and rejuvenate the existing population. The study is based on a questionnaire survey to access information regarding buffalo husbandry and marketing. Based on derived data, age-structured Leslie matrix population model was constructed to predict the population of the buffalo cows in the coming decades. Three different intervention models were subsequently proposed including Buffalo bank campaign, prohibition of slaughtering buffalo cows and the combination of these two interventions. A total of 398 farmers rearing buffaloes were interviewed and data encompassed information on 1,366 buffaloes (418 buffalo bulls and 948 cows) were retrieved. Initial buffalo cow population in Ubon Ratchathani province was estimated to be 42,766 heads. ...
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Biometrics have been widely used for human identification, including fingerprint, face and iris because they cannot be easily duplicated. Recently, biometrics have been also used for animal (i.e. cattle in this paper) identification.... more
Biometrics have been widely used for human identification, including fingerprint, face and iris because they cannot be easily duplicated. Recently, biometrics have been also used for animal (i.e. cattle in this paper) identification. Individual cattle identification is necessary for many important reasons including determining legal ownership, verifying transferred source, and implementing disease surveillance and control. Popular traditional methods for individual cattle identification are using plastic ear tags or microchips. However, the tag can be deduplicated and it can be dangerous and takes time for the human expert to place the microchip in the cattle. Also, it may hurt the cattle. Thus, in this paper, muzzle print is used as a biometric for automatic cattle identification. The fusion of texture features extracted from the muzzle image is used to represent individual cattle. They are Gabor feature and Local Binary Pattern (LBP) histogram. Gabor features were extracted at the...
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The study of flying fox (Pteropus spp.) distribution had been conducted during 2010 and 2011 in the central region of Thailand. This study was aimed to update the current status of flying foxis habitats and use as database for... more
The study of flying fox (Pteropus spp.) distribution had been conducted during 2010 and 2011 in the central region of Thailand. This study was aimed to update the current status of flying foxis habitats and use as database for epidemiological study in order to prevent their potential zoonoses. From our survey, we found 14 rooting sites including 10 previously reported and 4 newly discovered sites. These new sites were mangrove forest, Muang, Samut Sakorn, Banklong Thonglang, Banglen, Nakhon Pathom, Private area, Hanka, Chainat and Nongseedam Temple, Nongsaeng, Saraburi. Furthermore, it was also found that the distribution of flying fox covered 10 provinces of the central region, composing of Angthong, Suphanburi, Singburi, Ayutthaya, Samut Sakorn, Saraburi, Nakhon Nayok, Chainat, Nakhon Pathom, and Bangkok. Since more rooting sites and higher number of flying fox were discovered as well as their distributing areas has expanded, it was suggested that the overall population of flying ...
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This paper proposes a simulator to demonstrate dogs' behaviours considering individual and group habits, which is designed to be purposefully expandable for disease control. The proposed system is developed using Unity and Mapbox SDK.... more
This paper proposes a simulator to demonstrate dogs' behaviours considering individual and group habits, which is designed to be purposefully expandable for disease control. The proposed system is developed using Unity and Mapbox SDK. The normal distribution, kernel density method and probabilistic model are applied to simulate the movement behaviour, world interaction and behaviour rates, respectively. The simulation is validated on an area of Saibai, located in the north-western of Torres Strait islands, Australia. This reports a median tie-strength of 0.0106 which is slightly different from the value calculated from the GPS information of 0.0113. It thus contains the relative error of 6.19%. Then, the simulation is applied to three cities in Thailand. They are all reported with higher tie-strengths, when compared to Saibai. This is because of the significantly higher average numbers of dogs and group distances, with the larger connections between dogs and their communities.
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Animal movement is one of the most important risk factors for outbreaks of foot and mouth disease (FMD) in cattle. Likewise, FMD can spread to cattle farms via vehicles contaminated with the FMD virus. In Northern Thailand, the movement... more
Animal movement is one of the most important risk factors for outbreaks of foot and mouth disease (FMD) in cattle. Likewise, FMD can spread to cattle farms via vehicles contaminated with the FMD virus. In Northern Thailand, the movement of manure transport vehicles and the circulation of manure bags among cattle farms are considered as potential risk factors for FMD outbreaks among cattle farms. This study aimed to determine the characteristics and movement patterns of manure tradesman using social network analysis. A structured questionnaire was used to identify sequences of farms routinely visited by each tradesman. A total of 611 participants were interviewed, including 154 beef farmers, 407 dairy farmers, 36 tradesmen, and 14 final purchasers. A static weighted directed one-mode network was constructed, and the network metrics were measured. For the manure tradesman–cattle farmer network, the tradesman possessed the highest value of in- and out-degree centralities (71 and 4), be...
Highly pathogenic avian influenza H5N1 (HPAI H5N1) was recognized in Thailand by multiple epidemic waves and some sporadic cases between 2004 and 2008 but the risk of disease remerging in Thailand still remains up to present. Most of HPAI... more
Highly pathogenic avian influenza H5N1 (HPAI H5N1) was recognized in Thailand by multiple epidemic waves and some sporadic cases between 2004 and 2008 but the risk of disease remerging in Thailand still remains up to present. Most of HPAI H5N1 confirmed outbreaks in Thailand occurred in backyard chicken populations. Backyard chickens are reared for many purposes including for additional cash income. Backyard chicken trade is informally managed by poultry traders which can be categorized into trader–slaughterhouse (TS), household trader (HT) and trader of trader (TT). These traders roam around different villages with the same unclean vehicle and facilities. Thus, their trade patterns in space and time are necessary to be elaborately studied. In our study, we developed a spatial compartmental stochastic dynamic model of backyard chicken trade network in a province of Thailand. Our model results indicated that the structure of poultry networks may contribute to HPAI H5N1 spread through...
Foot and mouth disease (FMD) is recognized as an endemic disease in Thailand and throughout other countries in Southeast Asia. The underreporting of FMD outbreaks has affected the true status of the disease. This study aimed to determine... more
Foot and mouth disease (FMD) is recognized as an endemic disease in Thailand and throughout other countries in Southeast Asia. The underreporting of FMD outbreaks has affected the true status of the disease. This study aimed to determine the number of dairy farms in Chiang Mai that had experienced FMD outbreaks (FMD outbreak farm) during 2015-2016 using capture-recapture (CR) methods. Two independent FMD outbreak data sources including data from the livestock authorities and survey questionnaires were analyzed using Chapman estimator and Chao estimator. Results showed that the estimated number of FMD outbreak farms was 264 (95% CI = 250, 277) and 273 (95% CI = 259, 292) farms based on the Chapman estimator and Chao estimator, respectively. The estimated prevalence of FMD corresponding to the Chapman estimator was lower than the Chao estimator. The active approach of the survey method offered a higher degree of sensitivity compared to the passive method used by the livestock authorities. Estimations from the CR method provided an upper bound for the true number of outbreak farms. This study demonstrated the use of the CR method to estimate the true status of FMD outbreaks. Our proposed approach can potentially be used as a tool to enhance the accuracy and sensitivity of established monitoring and surveillance systems.
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The epidemic of leptospirosis in humans occurs annually in Thailand. In this study, we have developed mathematical models to investigate transmission dynamics between humans, animals, and a contaminated environment. We compared different... more
The epidemic of leptospirosis in humans occurs annually in Thailand. In this study, we have developed mathematical models to investigate transmission dynamics between humans, animals, and a contaminated environment. We compared different leptospire transmission models involving flooding and weather conditions, shedding and multiplication rate in a contaminated environment. We found that the model in which the transmission rate depends on both flooding and temperature, best-fits the reported human data on leptospirosis in Thailand. Our results indicate that flooding strongly contributes to disease transmission, where a high degree of flooding leads to a higher number of infected individuals. Sensitivity analysis showed that the transmission rate of leptospires from a contaminated environment was the most important parameter for the total number of human cases. Our results suggest that public education should target people who work in contaminated environments to prevent Leptospira in...
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Background 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... more
Background 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 acro...
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Seasonal influenza causes vast public health and economic impact globally. The prevention and control of the annual epidemics remain a challenge due to the antigenic evolution of the viruses. Here, we presented a novel modeling framework... more
Seasonal influenza causes vast public health and economic impact globally. The prevention and control of the annual epidemics remain a challenge due to the antigenic evolution of the viruses. Here, we presented a novel modeling framework based on changes in amino acid sequences and relevant epidemiological data to retrospectively investigate the competitive evolution and transmission of H1N1 and H3N2 influenza viruses in the United States during October 2002 and April 2019. To do so, we estimated the time-varying disease transmission rate from the reported influenza cases and the time-varying evolutionary rate of the viruses from the changes in amino acid sequences. By incorporating these time-varying rates into the transmission models, we found that the models could accurately capture the evolutionary transmission dynamics of influenza viruses in the United States. Our modeling results also showed that models incorporating evolutionary change of the virus could provide better model...
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A cross-sectional study was used to identify and assess prevalence and phenotypic antimicrobial resistance (AMR) profiles of Escherichia coli and other enterobacteria isolated from healthy wildlife and livestock cohabiting at a 10,000... more
A cross-sectional study was used to identify and assess prevalence and phenotypic antimicrobial resistance (AMR) profiles of Escherichia coli and other enterobacteria isolated from healthy wildlife and livestock cohabiting at a 10,000 acres game ranch near Lusaka, Zambia. Purposive sampling was used to select wildlife and livestock based on similarities in behavior, grazing habits and close interactions with humans. Isolates (n = 66) from fecal samples collected between April and August 2018 (n = 84) were examined following modified protocols for bacteria isolation, biochemical identification, molecular detection, phylogenetic analysis, and antimicrobial susceptibility testing by disc diffusion method. Data were analyzed using R software, Genetyx ver.12 and Mega 6. Using Applied Profile Index 20E kit for biochemical identification, polymerase chain reaction assay and sequencing, sixty-six isolates were identified to species level, of which Escherichia coli (72.7%, 48/66), E. ferguso...