Browsing by Author "Sopon Iamsirithaworn"

Filter results by typing the first few letters
Now showing 1 - 20 of 23
  • No Thumbnail Available
    PublicationMetadata only
    Accuracy of dengue clinical diagnosis with and without NS1 antigen rapid test: Comparison between human and Bayesian network model decision
    (2018-06-01) Chaitawat Sa-ngamuang; Peter Haddawy; Viravarn Luvira; Watcharapong Piyaphanee; Sopon Iamsirithaworn; Saranath Lawpoolsri; Thailand Ministry of Public Health; Mahidol University
    © 2018 Sa-ngamuang et al. http://creativecommons.org/licenses/by/4.0/ Differentiating dengue patients from other acute febrile illness patients is a great challenge among physicians. Several dengue diagnosis methods are recommended by WHO. The application of specific laboratory tests is still limited due to high cost, lack of equipment, and uncertain validity. Therefore, clinical diagnosis remains a common practice especially in resource limited settings. Bayesian networks have been shown to be a useful tool for diagnostic decision support. This study aimed to construct Bayesian network models using basic demographic, clinical, and laboratory profiles of acute febrile illness patients to diagnose dengue. Data of 397 acute undifferentiated febrile illness patients who visited the fever clinic of the Bangkok Hospital for Tropical Diseases, Thailand, were used for model construction and validation. The two best final models were selected: one with and one without NS1 rapid test result. The diagnostic accuracy of the models was compared with that of physicians on the same set of patients. The Bayesian network models provided good diagnostic accuracy of dengue infection, with ROC AUC of 0.80 and 0.75 for models with and without NS1 rapid test result, respectively. The models had approximately 80% specificity and 70% sensitivity, similar to the diagnostic accuracy of the hospital’s fellows in infectious disease. Including information on NS1 rapid test improved the specificity, but reduced the sensitivity, both in model and physician diagnoses. The Bayesian network model developed in this study could be useful to assist physicians in diagnosing dengue, particularly in regions where experienced physicians and laboratory confirmation tests are limited.
  • Thumbnail Image
    PublicationOpen Access
    Amino acid substitutions in hemagglutinin of the 2009 pandemic influenza A(H1N1) viruses that might affect the viral antigenicity
    (2014) Nathamon Kosoltanapiwat; Usa Boonyuen; Phisanu Pooruk; Sopon Iamsirithaworn; Anek Mungaomklang; Kulkanya Chokephaibulkit; Prasert Auewarakul; Pilaipan Puthavathana; Mahidol University. Faculty of Medicine Siriraj Hospital. Department of Microbiology
    Background: During 2009 to 2012, Thailand had encountered 4 distinctive waves of the 2009 pandemic influenza A(H1N1) (H1N1pdm) outbreaks. Considering the RNA nature of the influenza viral genome, a mutation in hemagglutinin (HA) gene which led to change in antigenicity of the strains circulating during those epidemic periods is anticipated. It is also uncertain whether the A/California/07/2009 (H1N1) (CA/07) vaccine strain still confers protective immunity against those evolved viruses, the causative agents of the later epidemic waves. Methods: HA gene segments of 10 H1N1pdm isolates obtained during 2009 to 2012 were sequenced and phylogenetically analysed using ClustalW and MEGA5 programs. A total of 124 convalescent serum samples collected from patients naturally infected during 3 epidemic waves were employed as tools to investigate for antigenic change in HA of these 10 circulating H1N1pdm viruses by hemagglutination inhibition (HI) assay. Results: A phylogenetic analysis showed that the 10 virus isolates were grouped into 4 clusters corresponding to the time of 4 consecutive outbreaks. An accumulation of amino acid substitutions in HA was observed in viruses derived from the late epidemic waves. Significantly lower antibody titers were observed when CA/07 was tested against convalescent sera collected from the 3 waves (p < 0.05) compared to most of Thai isolates; and significantly lower antibody titers were also obtained when virus isolates, retrieved from the third epidemic wave were tested against convalescent sera collected during the first and second wave. These results were suggestive of change in antigenicity of the evolved viruses. Our results also showed some mutation position residing outside the previously reported antigenic site that may involve in an alteration of the viral antigenicity. Conclusions: Our study demonstrated that convalescent sera collected from individuals naturally infected with H1N1pdm virus were successfully used to reveal a statistically significant change in antibody titers against the currently evolved H1N1pdm viruses as determined by HI assay. Nevertheless, the antibody titers of individual serum against various viruses were less than 4-folded difference as compared to that against the CA/07 vaccine strain. Therefore, CA/07 is still a potent vaccine strain for those evolved H1N1pdm viruses.
  • No Thumbnail Available
    PublicationMetadata only
    Amino acid substitutions in hemagglutinin of the 2009 pandemic influenza A(H1N1) viruses that might affect the viral antigenicity
    (2014-12-23) Nathamon Kosoltanapiwat; Usa Boonyuen; Phisanu Pooruk; Sopon Iamsirithaworn; Anek Mungaomklang; Kulkanya Chokephaibulkit; Prasert Auewarakul; Pilaipan Puthavathana; Mahidol University; Thailand Ministry of Public Health; Thepparat-Nakhonratchasima Hospital
    © 2014 Kosoltanapiwat et al.; licensee BioMed Central. Background: During 2009 to 2012, Thailand had encountered 4 distinctive waves of the 2009 pandemic influenza A(H1N1) (H1N1pdm) outbreaks. Considering the RNA nature of the influenza viral genome, a mutation in hemagglutinin (HA) gene which led to change in antigenicity of the strains circulating during those epidemic periods is anticipated. It is also uncertain whether the A/California/07/2009 (H1N1) (CA/07) vaccine strain still confers protective immunity against those evolved viruses, the causative agents of the later epidemic waves. Methods: HA gene segments of 10 H1N1pdm isolates obtained during 2009 to 2012 were sequenced and phylogenetically analysed using ClustalW and MEGA5 programs. A total of 124 convalescent serum samples collected from patients naturally infected during 3 epidemic waves were employed as tools to investigate for antigenic change in HA of these 10 circulating H1N1pdm viruses by hemagglutination inhibition (HI) assay. Results: A phylogenetic analysis showed that the 10 virus isolates were grouped into 4 clusters corresponding to the time of 4 consecutive outbreaks. An accumulation of amino acid substitutions in HA was observed in viruses derived from the late epidemic waves. Significantly lower antibody titers were observed when CA/07 was tested against convalescent sera collected from the 3 waves (p < 0.05) compared to most of Thai isolates; and significantly lower antibody titers were also obtained when virus isolates, retrieved from the third epidemic wave were tested against convalescent sera collected during the first and second wave. These results were suggestive of change in antigenicity of the evolved viruses. Our results also showed some mutation position residing outside the previously reported antigenic site that may involve in an alteration of the viral antigenicity. Conclusions: Our study demonstrated that convalescent sera collected from individuals naturally infected with H1N1pdm virus were successfully used to reveal a statistically significant change in antibody titers against the currently evolved H1N1pdm viruses as determined by HI assay. Nevertheless, the antibody titers of individual serum against various viruses were less than 4-folded difference as compared to that against the CA/07 vaccine strain. Therefore, CA/07 is still a potent vaccine strain for those evolved H1N1pdm viruses.
  • No Thumbnail Available
    PublicationMetadata only
    Automating the Generation of Antimicrobial Resistance Surveillance Reports: Proof-of-Concept Study Involving Seven Hospitals in Seven Countries
    (2020-10-02) Cherry Lim; Thyl Miliya; Vilada Chansamouth; Myint Thazin Aung; Abhilasha Karkey; Prapit Teparrukkul; Batra Rahul; Nguyen Phu Huong Lan; John Stelling; Paul Turner; Elizabeth Ashley; H. Rogier van Doorn; Htet Naing Lin; Clare Ling; Soawapak Hinjoy; Sopon Iamsirithaworn; Susanna Dunachie; Tri Wangrangsimakul; Viriya Hantrakun; William Schilling; Lam Minh Yen; Le Van Tan; Htay Htay Hlaing; Mayfong Mayxay; Manivanh Vongsouvath; Buddha Basnyat; Jonathan Edgeworth; Sharon J. Peacock; Guy Thwaites; Nicholas Pj Day; Ben S. Cooper; Direk Limmathurotsakul; Oxford University Clinical Research Unit; Friends of Patan Hospital Nepal; Hospital for Tropical Diseases Vietnam; University of Cambridge; Brigham and Women's Hospital; Thailand Ministry of Public Health; Mahosot Hospital, Lao; Mahidol University; Nuffield Department of Medicine; Guy's and St Thomas' NHS Foundation Trust; University of Health Sciences; Myanmar Oxford Clinical Research Unit; Sunpasitthiprasong Hospital; North Okkalapa General Hospital; Angkor Hospital for Children
    ©Cherry Lim, Thyl Miliya, Vilada Chansamouth, Myint Thazin Aung, Abhilasha Karkey, Prapit Teparrukkul, Batra Rahul, Nguyen Phu Huong Lan, John Stelling, Paul Turner, Elizabeth Ashley, H Rogier van Doorn, Htet Naing Lin, Clare Ling, Soawapak Hinjoy, Sopon Iamsirithaworn, Susanna Dunachie, Tri Wangrangsimakul, Viriya Hantrakun, William Schilling, Lam Minh Yen, Le Van Tan, Htay Htay Hlaing, Mayfong BACKGROUND: Reporting cumulative antimicrobial susceptibility testing data on a regular basis is crucial to inform antimicrobial resistance (AMR) action plans at local, national, and global levels. However, analyzing data and generating a report are time consuming and often require trained personnel. OBJECTIVE: This study aimed to develop and test an application that can support a local hospital to analyze routinely collected electronic data independently and generate AMR surveillance reports rapidly. METHODS: An offline application to generate standardized AMR surveillance reports from routinely available microbiology and hospital data files was written in the R programming language (R Project for Statistical Computing). The application can be run by double clicking on the application file without any further user input. The data analysis procedure and report content were developed based on the recommendations of the World Health Organization Global Antimicrobial Resistance Surveillance System (WHO GLASS). The application was tested on Microsoft Windows 10 and 7 using open access example data sets. We then independently tested the application in seven hospitals in Cambodia, Lao People's Democratic Republic, Myanmar, Nepal, Thailand, the United Kingdom, and Vietnam. RESULTS: We developed the AutoMated tool for Antimicrobial resistance Surveillance System (AMASS), which can support clinical microbiology laboratories to analyze their microbiology and hospital data files (in CSV or Excel format) onsite and promptly generate AMR surveillance reports (in PDF and CSV formats). The data files could be those exported from WHONET or other laboratory information systems. The automatically generated reports contain only summary data without patient identifiers. The AMASS application is downloadable from https://www.amass.website/. The participating hospitals tested the application and deposited their AMR surveillance reports in an open access data repository. CONCLUSIONS: The AMASS is a useful tool to support the generation and sharing of AMR surveillance reports.
  • No Thumbnail Available
    PublicationMetadata only
    Case report: Walking pneumonia in novel coronavirus disease (COVID-19): Mild symptoms with marked abnormalities on chest imaging
    (2020-01-01) Chaisith Sivakorn; Viravarn Luvira; Sant Muangnoicharoen; Pittaya Piroonamornpun; Tharawit Ouppapong; Anek Mungaomklang; Sopon Iamsirithaworn; The Hospital for Tropical Diseases, Bangkok; Thailand Ministry of Public Health; Mahidol University
    © 2020 by The American Society of Tropical Medicine and Hygiene This case report underlines the appearance of a “walking pneumonia” in a novel coronavirus disease (COVID-19) patient, with evidence of progressive lung involvement on chest imaging studies. The patient traveled from Wuhan, Hubei, China, to Thailand in January 2020. One of her family members was diagnosed with COVID-19. She presented to the hospital because of her concern, but she was without fever or any respiratory symptoms. Three days earlier, her nasopharyngeal and throat swabs revealed a negative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Her initial chest radiography was abnormal, and her first sputum SARS-CoV-2 test yielded inconclusive results. A subsequent sputum test was positive for SARS-CoV-2. Diagnosis in this patient was facilitated by chest imaging and repeat viral testing. Thus, chest imaging studies might enhance capabilities for early diagnosis of COVID-19 pneumonia.
  • No Thumbnail Available
    PublicationMetadata only
    Contact mixing patterns and population movement among migrant workers in an urban setting in Thailand
    (2020-04-01) Wiriya Mahikul; Somkid Kripattanapong; Piya Hanvoravongchai; Aronrag Meeyai; Sopon Iamsirithaworn; Prasert Auewarakul; Wirichada Pan-Ngum; London School of Hygiene & Tropical Medicine; Chulalongkorn University; Thailand Ministry of Public Health; Mahidol University; Burapha University; Bureau of Epidemiology
    © 2020 by the authors. Licensee MDPI, Basel, Switzerland. Data relating to contact mixing patterns among humans are essential for the accurate modeling of infectious disease transmission dynamics. Here, we describe contact mixing patterns among migrant workers in urban settings in Thailand, based on a survey of 369 migrant workers of three nationalities. Respondents recorded their demographic data, including age, sex, nationality, workplace, income, and education. Each respondent chose a single day to record their contacts; this resulted in a total of more than 8300 contacts. The characteristics of contacts were recorded, including their age, sex, nationality, location of contact, and occurrence of physical contact. More than 75% of all contacts occurred among migrants aged 15 to 39 years. The contacts were highly clustered in this age group among migrant workers of all three nationalities. There were far fewer contacts between migrant workers with younger and older age groups. The pattern varied slightly among different nationalities, which was mostly dependent upon the types of jobs taken. Half of migrant workers always returned to their home country at most once a year and on a seasonal basis. The present study has helped us gain a better understanding of contact mixing patterns among migrant workers in urban settings. This information is useful both when simulating disease epidemics and for guiding optimal disease control strategies among this vulnerable section of the population.
  • No Thumbnail Available
    PublicationMetadata only
    Current status of helminthiases in Thailand: A cross-sectional, nationwide survey, 2019
    (2021-11-01) Oranard Wattanawong; Sopon Iamsirithaworn; Thongroo Kophachon; Worayuth Nak-ai; Ampas Wisetmora; Thitima Wongsaroj; Paron Dekumyoy; Choosak Nithikathkul; Apiporn T. Suwannatrai; Banchob Sripa; Faculty of Tropical Medicine, Mahidol University; Praboromarajchanok Institute; Faculty of Medicine, Khon Kaen University; Thailand Ministry of Public Health; Mahasarakham University
    Helminthiases are common neglected tropical diseases in Thailand, thus regular surveillance is necessary for their control. During fiscal year 2019, the Thailand Ministry of Public Health carried out a cross-sectional nationwide survey in people of all age groups from the 12 Regional Health Offices in 76 provinces of Thailand. Multi-stage cluster random sampling design was employed to assess the prevalence of helminth infections and certain behavioural risk factors. A total of 16,187 stool samples and demographic data were obtained from the participants. Stool examination was done and parasite eggs/lavae were identified microscopically by experienced technicians. Positive stool samples for Opisthorchis viverrini, hookworms, or Ascaris lumbricoides were further quantified and expressed in eggs per gram feces (EPG). The results revealed an overall prevalence of helminthic infections of 9.79% with over 14 species identified. The highest prevalence was hookworms (4.47%) followed by O. viverrini (2.2%) with mean infection intensities of 222.7 EPG and 120.9, respectively. The majority of the infections were low intensity (97.4% for hookworms and 99.1% for O. viverrini). Similarly for A. lumbricoides, 93.9% of the positive cases were low infections. Two major helminthiases caused by hookworms and O. viverrini were highlighted in this report. While the liver fluke was highly endemic in Northeast Thailand, the hookworms were prevalent in the southmost region of the country. Association with demographic characteristics and risk behaviors of the two parasites were analyzed and presented in this study. Overall, this countrywide survey provides basic information of the current status of helminth infections in Thailand. Moreover, the data clearly indicates a dramatic reduction of O. viverrini prevalence likely due to extensive control activities under the national campaign against the liver fluke over the past five years.
  • No Thumbnail Available
    PublicationMetadata only
    Delayed care-seeking and outcome of dengue-infected patients
    (2018-01-01) Nantawan Wongchidwan; Yupaporn Wattanagoon; Viravarn Luvira; Sopon Iamsirithaworn; Thailand Ministry of Public Health; Mahidol University
    © 2017, © The Author(s) 2017. A retrospective cohort study was conducted to assess the effect of early (1–4 days after fever onset) and delayed (≥5 days) care-seeking on outcomes of dengue-infected patients. We used data of adult dengue-infected patients treated in Bangkok, Thailand between June 2012 and September 2013. There were 110 patients in the early care-seeking group and 100 in the delayed care-seeking group. There were no deaths. Bleeding complications were not significantly different between the two groups while the latter group had a significantly higher rate of admission compared with the former (98% versus 91.8%, respectively; P = 0.04). Being female was the only factor significantly associated with delayed care-seeking (63.0% versus 45.5%; P = 0.01).
  • No Thumbnail Available
    PublicationMetadata only
    Evaluation of different platforms for the detection of anti-SARS coronavirus-2 antibodies, Thailand
    (2021-12-01) Hatairat Lerdsamran; Anek Mungaomklang; Sopon Iamsirithaworn; Jarunee Prasertsopon; Kriengkrai Prasert; Poj Intalapaporn; Nirada Siriyakorn; Witthawat Wiriyarat; Nattakan Thinpan; Suteema Sawadpongpan; Somrak Sirikhetkon; Noparat Mongkalangoon; Suwanna Petto; Pilaipan Puthavathana; Thailand Ministry of Public Health; Mahidol University; Rajavithi Hospital
    Background: Antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) help determine previous infection in individuals, regardless of whether they are asymptomatic or symptomatic. The detection of antibodies serves several purposes, including supporting other assays for disease diagnosis, conducting seroepidemiological studies, and evaluating vaccines. Many platforms of immunological methods for anti-SARS-CoV-2 antibody detection and their performance require validation. Methods: This study evaluated the test performance of three autoanalyzer-based assays (Architect IgG, Vitros IgG, and Vitros total Ig) and one manual ELISA (Wantai total Ig) against a microneutralization (microNT) assay on the detection of SARS-CoV-2 antibodies. Furthermore, an indirect immunofluorescence assay verified the discordant results between the microNT and commercial assays. The test sensitivity, specificity, positive predictive value, and negative predictive value were determined based on four groups of 1005 serum samples: 102 COVID-19 prepandemic sera, 45 anti-SARS-CoV-2 positive sera, 366 sera of people at risk, and 492 sera of citizens returning from countries with a high prevalence of infection. Results: The analyses as a whole showed that the performance of these commercial assays was comparable. Each group was also analysed separately to gain further insight into test performance. The Architect did not detect two positive sera of people at risk (prevalence of infection 0.55%). The other methods correctly identified these two positive sera but yielded varying false-positive results. The group of returning travellers with an infection rate of 28.3% (139 of 492) better differentiated the test performance of individual assays. Conclusions: High-throughput Architect and Vitros autoanalyzers appear appropriate for working on large sample sizes in countries that can afford the cost. The Wantai ELISA, while requiring more individual time and technical skill, may provide reliable results at a lower cost. The selection of assays will depend on the laboratory facilities and feasibility.
  • No Thumbnail Available
    PublicationMetadata only
    First pandemic A (H1N1) pdm09 outbreak in a private school, Bangkok, Thailand, June 2009
    (2014-01-01) Kanlaya Jongcherdchootrakul; Alden K. Henderson; Sopon Iamsirithaworn; Charin Modchang; Potjaman Siriarayapon; Phramongkutklao College of Medicine; Centers for Disease Control and Prevention; Thailand Ministry of Public Health; Mahidol University
    © 2014, Medical Association of Thailand. All Rights Reserved. Objective: On June 9, 2009, the Thailand Ministry of Public Health received their first report of an outbreak of the pandemic A (H1N1) pdm09 that occurred in a school. The authors conducted a study to describe the epidemiological characteristics of the outbreak and its resurgence, estimate the basic reproduction number (R0) and review recommendations for prevention and control. Material and Method: Active case finding in the school and reviewing reports to the national surveillance system identified 184 students infected by the new virus. A survey described the illness in the students and the prevention and control measures taken by the school. The basic reproduction number was estimated from data in the early epidemic phase. The other survey was done to assess factors contributing to the resurgence of the outbreak. Results: Students with the pandemic A (H1N1) pdm09 had a mild illness resembling seasonal influenza. Overcrowding in the classroom and activities that mixed students from different classes contributed to transmission in the school. The basic reproduction number for this school-based setting is 3.58. The second outbreak occurred because of poor monitoring of absenteeism and management of ill students. Conclusion: This was the first outbreak of the pandemic A (H1N1) pdm09 in Thailand. The source could not be identified. Effective control measures monitoring, screening, strict personal hygiene and proper management of ill students.
  • No Thumbnail Available
    PublicationMetadata only
    The impact of rainfall and temperature on the spatial progression of cases during the chikungunya re-emergence in Thailand in 2008-2009
    (2016-01-04) Sudarat Chadsuthi; Sopon Iamsirithaworn; Wannapong Triampo; Derek A.T. Cummings; Mahidol University; Thailand Ministry of Public Health; South Carolina Commission on Higher Education; Centre of Excellence in Mathematics CHE; Johns Hopkins Bloomberg School of Public Health; University of Florida
    © The Author 2016. Background: In 2008, chikungunya virus (CHIKV) re-emerged in Thailand aftermore than a decade of absence. Cases first appeared in the extreme southern region of the country and advanced northward approx. 300 kmover the next 18 months. The spatial advance of CHIKV cases appeared to occur at two rates, initially progressing slowly and then increasing in speed. We hypothesize that climatic variation affected the transmission of CHIKV in the country. Methods: To determine the effect of climate on CHIKV transmission, we evaluatedmodelswhere climate affects the transmission rate from mosquitoes to humans; extrinsic incubation period; fertility rate ofmosquitoes; and the mortality rate of mosquito larvae. We compared these models to models that did not include climate effects. Results: The inclusion of climate data greatly improvedmodel fit withmodels assuming climate affected the fertility rate of mosquitoes providing the best fit to data. Conclusion: These results suggest that climatic variation contributed to the slower rate of incidence observed inMarch 2009. Overall, a gradient in transmission probability and mortality and fertility rates of mosquito is observed over the entire area with the most southern districts experiencing the most efficient transmission.
  • No Thumbnail Available
    PublicationMetadata only
    Kinetics, longevity, and cross-reactivity of antineuraminidase antibody after natural infection with influenza a viruses
    (2017-12-01) Don Changsom; Li Jiang; Hatairat Lerdsamran; Sopon Iamsirithaworn; Rungrueng Kitphati; Phisanu Pooruk; Prasert Auewarakul; Pilaipan Puthavathana; Mahidol University; Thailand Ministry of Public Health; Thailand Government Pharmaceutical Organization
    © 2017 American Society for Microbiology. All Rights Reserved. The kinetics, longevity, and breadth of antibodies to influenza virus neuraminidase (NA) in archival, sequential serum/plasma samples from influenza A virus (IAV) H5N1 infection survivors and from patients infected with the 2009 pandemic IAV (H1N1) virus were determined using an enzyme-linked lectin-based assay. The reverse-genetics-derived H4N1 viruses harboring a hemagglutinin (HA) segment from A/duck/Shan Tou/461/2000 (H4N9) and an NA segment derived from either IAV H5N1 clade 1, IAV H5N1 clade 2.3.4, the 2009 pandemic IAV (H1N1) (H1N1pdm), or A/Puerto Rico/8/1934 (H1N1) virus were used as the test antigens. These serum/ plasma samples were also investigated by microneutralization (MN) and/or hemagglutination inhibition (HI) assays. Neuraminidase-inhibiting (NI) antibodies against N1 NA of both homologous and heterologous viruses were observed in H5N1 survivors and H1N1pdm patients. H5N1 survivors who were never exposed to H1N1pdm virus developed NI antibodies to H1N1pdm NA. Seroconversion of NI antibodies was observed in 65% of the H1N1pdm patients at day 7 after disease onset, but an increase in titer was not observed in serum samples obtained late in infection. On the other hand, an increase in seroconversion rate with the HI assay was observed in the follow-up series of sera obtained on days 7, 14, 28, and 90 after infection. The study also showed that NI antibodies are broadly reactive, while MN and HI antibodies are more strain specific.
  • No Thumbnail Available
    PublicationMetadata only
    Modeling Seasonal Influenza Transmission and Its Association with Climate Factors in Thailand Using Time-Series and ARIMAX Analyses
    (2015-01-01) Sudarat Chadsuthi; Sopon Iamsirithaworn; Wannapong Triampo; Charin Modchang; Naresuan University; Thailand Ministry of Public Health; Mahidol University; South Carolina Commission on Higher Education
    © 2015 Sudarat Chadsuthi et al. Influenza is a worldwide respiratory infectious disease that easily spreads from one person to another. Previous research has found that the influenza transmission process is often associated with climate variables. In this study, we used autocorrelation and partial autocorrelation plots to determine the appropriate autoregressive integrated moving average (ARIMA) model for influenza transmission in the central and southern regions of Thailand. The relationships between reported influenza cases and the climate data, such as the amount of rainfall, average temperature, average maximum relative humidity, average minimum relative humidity, and average relative humidity, were evaluated using cross-correlation function. Based on the available data of suspected influenza cases and climate variables, the most appropriate ARIMA(X) model for each region was obtained. We found that the average temperature correlated with influenza cases in both central and southern regions, but average minimum relative humidity played an important role only in the southern region. The ARIMAX model that includes the average temperature with a 4-month lag and the minimum relative humidity with a 2-month lag is the appropriate model for the central region, whereas including the minimum relative humidity with a 4-month lag results in the best model for the southern region.
  • No Thumbnail Available
    PublicationMetadata only
    Modeling seasonal leptospirosis transmission and its association with rainfall and temperature in Thailand using time-series and ARIMAX analyses
    (2012-07-01) Sudarat Chadsuthi; Charin Modchang; Yongwimon Lenbury; Sopon Iamsirithaworn; Wannapong Triampo; Mahidol University; South Carolina Commission on Higher Education; Thailand Ministry of Public Health
    Objective: To study the number of leptospirosis cases in relations to the seasonal pattern, and its association with climate factors. Methods: Time series analysis was used to study the time variations in the number of leptospirosis cases. The Autoregressive Integrated Moving Average (ARIMA) model was used in data curve fitting and predicting the next leptospirosis cases. Results: We found that the amount of rainfall was correlated to leptospirosis cases in both regions of interest, namely the northern and northeastern region of Thailand, while the temperature played a role in the northeastern region only. The use of multivariate ARIMA (ARIMAX) model showed that factoring in rainfall (with an 8 months lag) yields the best model for the northern region while the model, which factors in rainfall (with a 10 months lag) and temperature (with an 8 months lag) was the best for the no rtheastern region. Conclusion: The models are able to show the trend in leptospirosis cases and closely fit the recorded data in both regions. The models can also be used to predict the next seasonal peak quite accurately. © 2012 Hainan Medical College.
  • No Thumbnail Available
    PublicationMetadata only
    A modeling study of school closure to reduce influenza transmission: A case study of an influenza A (H1N1) outbreak in a private Thai school
    (2012-02-01) Charin Modchang; Sopon Iamsirithaworn; Prasert Auewarakul; Wannapong Triampo; Mahidol University; Thailand Ministry of Public Health; Faculty of Medicine, Thammasat University; South Carolina Commission on Higher Education
    The A/H1N1 influenza pandemic has been in the spotlight since the virus was first detected in Mexico in early 2009. To prevent the repetition of the 1918 influenza pandemic, the global response to this pandemic has been strong. In Thailand and in many other countries, schools have been a major source of outbreaks, which then spreads to the general population. Understanding the dynamics of school outbreaks and the impact of disease intervention in school settings is crucial for the effective mitigation of a pandemic. Using data from outbreaks in School G, a private school in Bangkok where detailed epidemiological data were collected, we estimated the basic reproduction number (R 0 ) to be 3.58 [95% confidence interval: 2.88 to 4.28]. We then modeled outbreaks in school settings with Susceptible-Exposed-Infectious-Recovered (SEIR) equations and tested various interventions such as school closure and student screenings. We found that closing the school on the date with the peak number of daily incidences usually appeared to be effective in preventing further outbreaks. However, if the school was closed too early, subsequent cases would appear after reopening. With no intervention, the number of total cases reaches 83%. Individual student screenings appeared to reduce the number of total cases by up to 40%. In a situation in which the widespread outbreak of a mild disease is unavoidable and in which the goal is to slowly reach sufficient herd immunity while minimizing the number of cases, closing the school at the predicted date with the peak number of daily incidences and screening for respiratory symptoms appear to be the most appropriate intervention methods. © 2011 Elsevier Ltd.
  • No Thumbnail Available
    PublicationMetadata only
    Non-linear effect of different humidity types on scrub typhus occurrence in endemic provinces, Thailand
    (2021-02-01) Bhophkrit Bhopdhornangkul; Aronrag Cooper Meeyai; Waranya Wongwit; Yanin Limpanont; Sopon Iamsirithaworn; Yongjua laosiritaworn; Kraichat Tantrakarnapa; Thailand Ministry of Public Health; Mahidol University; Nuffield Department of Medicine
    Background: Reported monthly scrub typhus (ST) cases in Thailand has an increase in the number of cases during 2009–2014. Humidity is a crucial climatic factor for the survival of chiggers, which is the disease vectors. The present study was to determine the role of humidity in ST occurrence in Thailand and its delayed effect. Methods: We obtained the climate data from the Department of Meteorology, the disease data from Ministry of Public Health. Negative binomial regression combined with a distributed lag non-linear model (NB-DLNM) was employed to determine the non-linear effects of different types of humidity on the disease. This model controlled overdispersion and confounder, including seasonality, minimum temperature, and cumulative total rainwater. Results: The occurrence of the disease in the 6-year period showed the number of cases gradually increased summer season (Mid-February – Mid-May) and then reached a plateau during the rainy season (Mid-May – Mid-October) and then steep fall after the cold season (Mid-October – Mid-February). The high level (at 70%) of minimum relative humidity (RHmin) was associated with a 33% (RR 1.33, 95% CI 1.13–1.57) significant increase in the number of the disease; a high level (at 14 g/m3) of minimum absolute humidity (AHmin) was associated with a 30% (RR 1.30, 95% CI 1.14–1.48); a high level (at 1.4 g/kg) of minimum specific humidity (SHmin) was associated with a 28% (RR 1.28, 95% CI 1.04–1.57). The significant effects of these types of humidity occurred within the past month. Conclusion: Humidity played a significant role in enhancing ST cases in Thailand, particularly at a high level and usually occurred within the past month. NB-DLNM had good controlled for the overdispersion and provided the precise estimated relative risk of non-linear associations. Results from this study contributed the evidence to support the Ministry of Public Health on warning system which might be useful for public health intervention and preparation in Thailand.
  • Thumbnail Image
    PublicationOpen Access
    Pandemic influenza H1N1 2009 in Thailand
    (2012) Aronrag Meeyai; Ben Cooper; Richard Coker; Wirichada Pan-ngum; Pasakorn Akarasewi; Sopon Iamsirithaworn; อรุณรักษ์ คูเปอร์ มีใย; Aronrag Meeyai; Mahidol university. Faculty of Public Health. Department of Epidemiology; Mahidol university. Faculty of Tropical Medicine. Department of Tropical Hygiene; Mahidol university. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit
    Background: Developing a quantitative understanding of pandemic influenza dynamics in South- East Asia is important for informing future pandemic planning. Hence, transmission dynamics of influenza A/H1N1 were determined across space and time in Thailand. Methods: Dates of symptom onset were obtained for all daily laboratory-confirmed cases of influenza A/H1N1pdm in Thailand from 3 May 2009 to 26 December 2010 for four different geographic regions (Central, North, North-East, and South). These data were analysed using a probabilistic epidemic reconstruction, and estimates of the effective reproduction number, R(t), were derived by region and over time. Results: Estimated R(t) values for the first wave peaked at 1.54 (95% CI: 1.42-1.71) in the Central region and 1.64 (95% CI: 1.38-1.92) in the North, whilst the corresponding values in the North-East and the South were 1.30 (95% CI: 1.17-1.46) and 1.39 (95% CI: 1.32-1.45) respectively. As the R(t) in the Central region fell below one, the value of R(t) in the rest of Thailand increased above one. R(t) was above one for 30 days continuously through the first wave in all regions of Thailand. During the second wave R(t) was only marginally above one in all regions except the South. Conclusions: In Thailand, the value of R(t) varied by region in the two pandemic waves. Higher R(t) estimates were found in Central and Northern regions in the first wave. Knowledge of regional variation in transmission potential is needed for predicting the course of future pandemics and for analysing the potential impact of control measures.
  • No Thumbnail Available
    PublicationMetadata only
    Predicting factors of treatment failure in smear positive pulmonary tuberculosis: A retrospective cohort study in Bangkok using a combination of symptoms and sputum smear/chest radiography
    (2018-01-01) Najeebullah Rahimy; Viravarn Luvira; Prakaykaew Charunwatthana; Sopon Iamsirithaworn; Maleerat Sutherat; Weerapong Phumratanaprapin; Thavisakdi Bamrungtrakul; Benjaluck Phonrat; Thailand Ministry of Public Health; Mahidol University; Prasarnmit Hospital; Kandahar University
    © 2018, Medical Association of Thailand. All rights reserved. Background: A successful outcome of smear positive pulmonary tuberculosis [SPPTB] used as an indicator of TB control program performance is necessary for monitoring program achievement. Objective: To study outcomes of SPPTB and to investigate factors associated with treatment failure. Materials and Methods: A retrospective study was conducted to identify outcomes and factors associated with failure in HIV-seronegative, SPPTB adult patients at Prasarnmit Hospital, Bangkok, Thailand between 2003 and 2012. Results: Two hundred ninety-one patients were enrolled. The following outcomes were notes, 78.7% cure, 1.7% completed treatment, 5.5% failure, 10% transfer out, 3.8% default, and 0.3% died. In multiple logistic regression, the failures were statistically associated with age over 50 years (OR 3.99, 95% CI 1.06 to 15.07), sputum smear 3+ at diagnosis (OR 6.34, 95% CI 1.71 to 23.55), and drug resistance (OR 23.58, 95% CI 6.11 to 90.97). To predict failure, symptoms and basic laboratory results as well as sputum smear and chest radiography [CXR] were combined. The symptoms of cough, fever, and hemoptysis plus sputum smear 3+ showed high odd ratios of 5.17 (95% CI 1.50 to 18.67), 8.88 (95% CI 1.46 to 68.75), and 18.57 (95% CI 1.82 to 456.86), respectively. When combining symptoms with cavitary lesion(s) in CXR, only hemoptysis in combination with cavitary lesion(s) showed a significant association with failure (OR 8.54, 95% CI 0.87 to 205.19). Conclusion: The WHO goal of success rate in SPPTB was not achieved. However, the risk factors of failure were identified by using symptoms plus simple laboratory tests, which can be useful in resource-limited areas.
  • Thumbnail Image
    PublicationOpen Access
    The Reproduction Number of Hepatitis A in Thailand: a 10 Year-period Estimate Using the National Diseases Surveillance Data
    (2019) Thapakorn Gonthongkum; Prapassorn Pechgit; Kitiphong Harncharoen; Sopon Iamsirithaworn; Aronrag Cooper Meeyai; ฐาปกรณ์ ก้อนทองคำ; ประภัสสร เพ็ชรกิจ; กิติพงษ์ หาญเจริญ; โสภณ เอี่ยมศิริถาวร; อรุณรักษ์ คูเปอร์ มีใย; Mahidol University. Faculty of Public Health. Department of Epidemiology; Mahidol University. Faculty of Public Health. Department of Parasitology and Entomology
    The reproduction number, R, is the actual average number of secondary cases per primary case which is the useful information for understanding epidemic. If R exceeds 1, the epidemic is growing, while R less than 1, the epidemic decline or end. The cases of hepatitis A in the national disease surveillancefrom 2005 to 2014 were used to estimate the R by a likelihood-based estimationprocedure and characterise the epidemic. The results showed that R of hepatitis A in Thailand are varied by provinces. An overall average R was 1.19 (95%CI=1.10-1.28). In endemic areas (low effective transmission), the R was 0.95 (95%CI=0.94-0.97). While in outbreak areas (high effective transmission), the R was 1.29 (95%CI=1.19-1.38). These findings suggest that the control measures for hepatitis A are highly required in the outbreakareas as soon as possible in order to control the transmission of hepatitis A viruses.However, estimation of R from epidemic curvescan be underestimate as those asymptomaticinfections were not included.
  • No Thumbnail Available
    PublicationMetadata only
    Seasonal influenza vaccine effectiveness among individuals with copd in thailand: A retrospective national cohort study of 2011-2013 influenza seasons
    (2021-05-17) Kriengkrai Prasert; Jayanton Patumanond; Jarawee Rattanayot; Jutatip Thungthong; Manash Shrestha; Sutthinan Chawalchitiporn; Sutthichai Nakphook; Somrak Sirikhetkon; Sopon Iamsirithaworn; National Health Security Office; Thailand Ministry of Public Health; Mahidol University; Chiang Mai University; Nakhon Phanom Provincial Hospital
    The effectiveness of trivalent inactivated influenza vaccine against respiratory illness outpatient visits and hospitalizations among patients with chronic obstructive pulmonary disease (COPD) is less established in Thailand. Using the Thailand National Health Security Office’s database, we assembled a retrospective cohort of Thai adults aged ≥18 years with COPD before each of the 2011 to 2013 influenza seasons. We used ICD-10 codes (J40, J41, and J44.1) to identify participants from all public COPD clinics in Thailand, and abstracted data on COPD history, hospital visits and admissions, and influenza vaccination status. Influenza vaccine effectiveness (VE) was estimated by comparing ICD-10 coded discharge diagnosis for influenza and pneumonia (J9-J18) and COPD exacerbations (J44.1) in each season between vaccinated and unvaccinated COPD patients using Poisson regression analysis. Propensity scores were used to match vaccinated with unvaccinated patients with COPD by age, sex, smoking status, severity of COPD, and numbers of COPD exacerbations and hospitalizations in the previous year. Overall, 117,894 patients with COPD were included in the cohort; the median age was 70 years (inter-quartile range 61-77) and 90,161 (77%) were male. Influenza vaccination coverage was 35% in 2011 and 41% in 2012 and 2013. The predominant circulating strain in 2011 and 2013 was A(H3N2), well-matched by the vaccine strain. In 2012, the predominant circulating strain was influenza B, but the vaccine strain had a poor antigenic match. Overall, the pooled VE for three years against ICD-coded influenza, pneumonia, and COPD exacerbations were estimated at 20% (95% confidence interval [CI], 6%-34%), 35% (95% CI, 34%-36%), and 38.8% (95% CI, 38.3%-39.3%), respectively. Overall, influenza vaccination was associated with a modest protection among people with COPD against ICD-10 coded influenza, pneumonia, and COPD exacerbations. However, despite propensity score matching, our results may have been affected by residual confounding and some measurement bias.