Early warning systems for malaria outbreaks in Thailand: an anomaly detection approach.

BACKGROUND: Malaria continues to pose a significant health threat. Rapid identification of malaria infections and the deployment of active surveillance tools are crucial for achieving malaria elimination in regions where malaria is endemic, such as certain areas of Thailand. In this study, an anomaly detection system is introduced as an early warning mechanism for potential malaria outbreaks in countries like Thailand. METHODS: Unsupervised clustering-based, and time series-based anomaly detection algorithms are developed and compared to identify abnormal malaria activity in Thailand. Additionally, a user interface tailored for anomaly detection is designed, enabling the Thai malaria surveillance team to utilize these algorithms and visualize regions exhibiting unusual malaria patterns. RESULTS: Nine distinct anomaly detection algorithms we developed. Their efficacy in pinpointing verified outbreaks was assessed using malaria case data from Thailand spanning 2012 to 2022. The historical average threshold-based anomaly detection method triggered three times fewer alerts, while correctly identifying the same number of verified outbreaks when compared to the current method used in Thailand. A limitation of this analysis is the small number of verified outbreaks; further consultation with the Division of Vector Borne Disease could help identify more verified outbreaks. The developed dashboard, designed specifically for anomaly detection, allows disease surveillance professionals to easily identify and visualize unusual malaria activity at a provincial level across Thailand. CONCLUSION: An enhanced early warning system is proposed to bolster malaria elimination efforts for countries with a similar malaria profile to Thailand. The developed anomaly detection algorithms, after thorough comparison, have been optimized for integration with the current malaria surveillance infrastructure. An anomaly detection dashboard for Thailand is built and supports early detection of abnormal malaria activity. In summary, the proposed early warning system enhances the identification process for provinces at risk of outbreaks and offers easy integration with Thailand's established malaria surveillance framework.

Home as a new physical workplace: a causal model for understanding the inextricable link between home environment, work productivity, and well-being.

The home has become a new physical workplace, and can therefore influence the work, health, and life of workers. This cross-sectional study aimed to evaluate the chronology of the effects of work hazards at home on factors such as workers' health, productivity, and well-being (WB). Information on novice working-from-home (WFH) workers was derived from the "Occupational health of WFH" project. The selected variables in the hypothesis model comprised problems such as perceived indoor environmental quality (IEQ), working conditions (WC), sick house syndrome (SHS), occupational stress (OS), work productivity (WP), and WB. The relationship between these variables was analyzed using a structural equation model. The group analysis results showed the following significant indirect path effects from work environment through WP: IEQ-> SHS->OS->WP. A non-significant direct effect was observed between IEQ and WP. While WC problems could also have a significant direct effect on WP, or be mediated by OS, WP is a significant consequence and a direct effect of WB. In conclusion, the WFH model's causal impact between home environment, WP, and WB is a physiopsychological pathway. Therefore, creating a healthy home environment and WC, along with OS management, comprise important issues for improving productivity and WB for this new work style.

Five years of post-validation surveillance of lymphatic filariasis in Thailand.

BACKGROUND: The World Health Organization (WHO) validated Thailand in 2017 as having eliminated lymphatic filariasis (LF) as a public health problem with recommendations for continued surveillance. This article describes measures and progress made in Thailand with post-validation surveillance (PVS) of LF from 2018 until 2022. METHODS: The implementation unit (IU) is a sub-village in 11 former LF endemic provinces. Human blood surveys are targeted in 10% of IUs each year. In Wuchereria bancrofti areas, filaria antigen test strips (FTS) are used, and in Brugia malayi areas, antibody test kits (Filaria DIAG RAPID) are used. Positive cases are confirmed by thick blood film (TBF) and polymerase chain reaction (PCR). Vector surveys for mosquito species identification and dissection for microfilaria (Mf)/filarial larvae are done in 1% of IUs where human blood surveys are conducted. Human blood surveys using FTS are conducted among migrants in five provinces. Surveillance of cats is done in areas that previously recorded > 1.0% Mf rate among cats. Morbidity management and disability prevention (MMDP) are done every 2 years in LF-endemic areas where chronic disease patients reside. RESULTS: From 2018 to 2022, in a total of 357 IUs in 11 provinces, human blood surveys were conducted in 145 IUs (41%) with an average population coverage of 81%. A total of 22,468 FTS and 27,741 FilariaDIAG RAPID were performed. 27 cases were detected: 3 cases of W. bancrofti in Kanchanaburi province and 24 cases of B. malayi in Narathiwat province. 4 cases of W. bancrofti were detected in two provinces through routine public health surveillance. Vector surveys in 47 IUs detected B. malayi Mf filarial larvae only in Narathiwat province. Chronic LF patients reduced from 114 in 2017 to 76 in 2022. Surveys among 7633 unregistered migrants yielded 12 cases of W. bancrofti. Mf rate among cats in Narathiwat province declined from 1.9% in 2018 to 0.7% in 2022. MMDP assessments revealed gaps in healthcare provider's management of chronic cases due to staff turnover. CONCLUSIONS: In 2022, after 5 years of PVS, Thailand re-surveyed 41% of its previously endemic IUs and demonstrated ongoing transmission in only one province of Narathiwat, where Mf prevalence is below the WHO provisional transmission threshold of 1%. This study highlights the importance of continued disease surveillance measures and vigilance among health care providers in LF receptive areas.

Projecting malaria elimination in Thailand using Bayesian hierarchical spatiotemporal models.

Thailand has set a goal of eliminating malaria by 2024 in its national strategic plan. In this study, we used the Thailand malaria surveillance database to develop hierarchical spatiotemporal models to analyze retrospective patterns and predict Plasmodium falciparum and Plasmodium vivax malaria incidences at the provincial level. We first describe the available data, explain the hierarchical spatiotemporal framework underlying the analysis, and then display the results of fitting various space-time formulations to the malaria data with the different model selection metrics. The Bayesian model selection process assessed the sensitivity of different specifications to obtain the optimal models. To assess whether malaria could be eliminated by 2024 per Thailand's National Malaria Elimination Strategy, 2017-2026, we used the best-fitted model to project the estimated cases for 2022-2028. The study results based on the models revealed different predicted estimates between both species. The model for P. falciparum suggested that zero P. falciparum cases might be possible by 2024, in contrast to the model for P. vivax, wherein zero P. vivax cases might not be reached. Innovative approaches in the P. vivax-specific control and elimination plans must be implemented to reach zero P. vivax and consequently declare Thailand as a malaria-free country.

Characteristics of COVID-19 infection clusters occurring among workers in several Asia-Pacific countries.

The types of workplaces and occupations with coronavirus 2019 (COVID-19) clusters vary between countries and periods. We aimed to characterize major occupational groups with mass outbreaks of COVID-19 infections in several Asia-Pacific countries. Data on the major occupations or workplaces reporting COVID-19 cases in workplaces from January 2020 to July 2021 was collected from industrial hygiene professionals in nine countries. The proportion of workers accounted for 39.1 to 56.6% of the population in each country. The number of workers covered in the national statistics varies among nations based on their definition of a worker. None of the countries examined here have systematically collected occupational data on COVID-19 illnesses and deaths classified by type of industry, occupation, or job. Most countries experienced COVID-19 clusters among health and social care workers (HSCW) in hospitals or long-term care facilities. The types of occupations or workplaces with virus clusters in some participating countries included prisons, call centers, workplaces employing immigrants, garment facilities, grocery stores, and the military, which differed among countries, except for a few common occupations such as HSCW and those populated by immigrants. Further study is necessary in order to seek ways to control infection risks, including revisions to industrial-health-related laws.

Preliminary study on assessment of lead exposure in Thai children aged between 3-7 years old who live in Umphang district, Tak Province.

BACKGROUND: Centers of Disease Control of the United States of America (CDC) informs Ministry of Public Health, Thailand that up to 13% of Burmese refugee children who are transferred to the United States of America during 2007-2009 have elevated blood lead levels (EBLL, Blood Lead Level > or = 10 microg/dl). These are children from a number of refugee camps in Tak Province; two camps are near Umphang but other camps are not. In June 2008, CDC, the result of investigation of Centers for Disease Control/Thailand Ministry of Public Health Collaboration (CDC/TUC) and International Organization for Migration, Thailand indicates that 33 of 64 children aged 6 months to 15 years (5.1%) who live in Mae La, Umpiem and Nupo camps have elevated blood lead level. However, no study on how Thai children who live nearby those camps are exposed to lead. Subsequently, Queen Sirikit National Institute of Child Health, Bangkok, Thailand contacts relevant organizations in Tak Province in order to investigate lead exposure and evaluate health status of Thai children who live close to Burmese refugee camps. OBJECTIVE: 1) Evaluation of lead exposure of Thai children who live nearby Burmese refugee camps; 2) Assessment of risk factors on lead exposure of the children as mentioned above. MATERIAL AND METHOD: The present study adopts a retrospective study based on information gathered from health assessment on 213 Thai children aged between 3-7 years old who live nearby Burmese refugee camps. The health assessment was conducted from April 30th, 2010 to May 5th, 2010. The information is from 3 sources. The first source is from blood sampling in order to assess lead level and ferritin level. The next source is from interview of persons who provide primary care in order to identify risk factors on lead exposure of target children. The last source is from physical examination and developmental assessment conducted by pediatricians and special nurses for child development in order to identify health and developmental problems. RESULTS: The population of the present study was 213 of Thai children are 3-7 years old, average age is 54.54 +/- 12.41 months-old. The average blood lead level is 7.71 +/- 4.62 microg/dl (range = 3-25 microg/dl). Elevated blood lead levels of all populations show that 57 children (26%) have blood lead level at 10 microg/dl or more. Analysis of odds by controlling all risk factors (adjusted OR) that effect on blood lead level (> or =10 microg/dl) indicates that only gender and source of drinking water are risk factors. To clarify, male children would have 2.8 times higher risk than female children. Children who drink water from tap and canal have 15 times and 72 times, respectively, higher risk than children drinking from bottle water. CONCLUSION: The result of the present study shows that 1 of 4 of Thai children at Umphang district, Tak Province who lived near Burmese refugee camps aged between 3-7 years old have blood lead level higher than concerning level. Thus, it is necessary to identify risk factors on lead exposure and policy of blood lead screening in some areas in Thailand.

Occupational Health Problems and Lifestyle Changes Among Novice Working-From-Home Workers Amid the COVID-19 Pandemic.

BACKGROUND: Social distancing by working-from-home is an effective measure to decrease the spread of COVID-19. However, this new work pattern could also affect the well-being of workers. Therefore, the aim of the study was to study the magnitude of occupational health problems and lifestyle changes among workers who have only recently started working from home. METHODS: A cross-sectional study was conducted using online self-administered questionnaires during the coronavirus disease 2019 pandemic in the Bangkok metropolitan area, Thailand. The participants were from any organization that allowed working from home. The demographic data including the analysis of the characteristics of working from home, the occurrence of occupational health problems, and the lifestyle changes caused by working from home were analyzed. RESULTS: A total of 869 workers were included as study participants. The highest prevalence of physical health problems among all workers was identified to be weight gain at a rate of 40.97% (95% confidence interval = 37.69-44.24), and the highest prevalence of psychosocial problems was identified to be cabin fever at a rate of 31.28% (95% confidence interval = 26.66-35.90%) among full-time working-from-home workers. The health effects that were significantly related to the intensity of working from home (p for trends <0.05), either positively or negatively, included body weight changes, ergonomic problems, indoor environmental problems, and psychosocial problems. Meanwhile, the lifestyle changes related to work intensity included eating pattern, sleep habits, and exercise. CONCLUSIONS: Working from home can affect workers' well-being in various aspects. Hence, occupational health providers must prepare for risk prevention and health promotion in this "new normal" working life pattern and for future pandemics.

Overview of Legal Measures for Managing Workplace COVID-19 Infection Risk in Several Asia-Pacific Countries.

BACKGROUND: Despite the lack of official COVID-19 statistics, various workplaces and occupations have been at the center of COVID-19 outbreaks. We aimed to compare legal measures and governance established for managing COVID-19 infection risks at workplaces in nine Asia and Pacific countries and to recommend key administrative measures. METHODS: We collected information on legal measures and governance from both general citizens and workers regarding infection risks such as COVID-19 from industrial hygiene professionals in nine countries (Indonesia, India, Japan, Malaysia, New Zealand, Republic of the Philippines, Republic of Korea, Taiwan, and Thailand) using a structured questionnaire. RESULTS: A governmental body overseeing public health and welfare was in charge of containing the spread and occurrence of infectious diseases under an infectious disease control and prevention act or another special act, although the name of the pertinent organizations and legislation vary among countries. Unlike in the case of other traditional hazards, there have been no specific articles or clauses describing the means of mitigating virus risk in the workplace that are legally required of employers, making it difficult to define the responsibilities of the employer. Each country maintains own legal systems regarding access to the duration, administration, and financing of paid sick leave. Many workers may not have access to paid sick leave even if it is legally guaranteed. CONCLUSION: Specific legal measures to manage infectious disease risks, such as providing proper personal protective equipment, education, engineering control measures, and paid sick leave are recommended to be stipulated in Industrial safety and health-related acts.

Occupational accidents and injuries in Thailand.

The Workers' Compensation Fund (WCF) represents only a limited fraction of work-related injuries in the Thai workforce. This cross-sectional study examined 258,986 records from the Thai National Injury Surveillance (NIS) system collected during 2001-2004, focusing on 17,538 injuries coded as work-related. NIS records provided information generally not represented in WCF statistics, such as construction and agriculture. The reported mechanisms in 129 work-related fatalities were particularly informative, including electrical current (27%), transport accidents (20%), and falls (15%). Mortality in transport accidents was dramatically higher when seat belts or motorcycle helmets were not used, whether work-related or not. The findings emphasize the need to use multiple sources of information for a complete picture of work-related injuries in Thailand, and possibly in other countries. The mechanisms of fatal injury indicate areas where focused efforts are warranted.

Cadmium-exposed population in Mae Sot District, Tak Province: 1. Prevalence of high urinary cadmium levels in the adults.

BACKGROUND: In Mae Sot District, Tak Province, Thailand, the paddy fields receiving irrigation from the two creeks and crops grown in the areas were found to contain markedly elevated cadmium levels during the surveys in 2001-2004. OBJECTIVE: The present report carried out a survey in 2004 to determine urinary cadmium, a good index of excessive cadmium exposure and body burden, among the exposed residents aged 15 years and older in these contaminated areas. MATERIAL AND METHOD: Morning urine samples were collected from the subjects and then kept frozen until cadmium analysis. Urinary cadmium was determined using the atomic absorption spectrometry and urinary creatinine was determined using a method of reaction with picric acid at alkaline pH and colorimetry. RESULTS: Of the 7,697 persons surveyed, only 45.6% had urinary cadmium levels < 2 microg/g creatinine. About 4.9% were between 5 and 10 microg/g creatinine and 2.3% had cadmium concentrations > 10. The urinary cadmium level was greater among women than men and increased with increasing age. Smokers were more likely to have high urinary cadmium than non-smokers. Persons who mainly consumed rice grown locally in the contaminated areas had higher urinary cadmium than those who did not. CONCLUSION: Persons who had high urinary cadmium levels and might have cadmium-induced toxic effects should be screened for early detection of chronic cadmium toxicity. Smoking cessation programs should be one component of preventive action beneficial for the study population. The production of rice and other crops for human consumption should be prohibited to prevent further accumulation of cadmium in the body of the exposed population.

Predictors of elevated blood lead level in Thai children: a pilot study using risk assessment questionnaire.

INTRODUCTION: In the era post leaded-gasoline use, the risk of exposure to environmental lead in Thai children is not well described. This is a pilot study using a risk assessment questionnaire to identify children with elevated blood lead level. MATERIAL AND METHOD: Children from 4 communities, 2 in the Bangkok metropolitan area and 2 in Kanchanaburi province, were recruited during their well child visits. Blood lead levels were obtained in all children and parents are asked to fill out a 25-item risk assessment questionnaire. STATISTICAL ANALYSIS: The relationship between the blood lead level and dependent variables were tested using linear regression and one-way analysis of variance (ANOVA) as appropriate. RESULTS: There were 296 children included in the study; 33 from Klong Toey and 114 from Siriraj community in Bangkok while 149 were from two different communities in Kanchanaburi province. The average blood lead level was 5.65 +/- 3.05 mcg/dL. The overall prevalence of children with blood lead level > 10 mcg/dL was 8.1%, while that of the Klong Toey community was 12.5%. The questionnaire identified 3 independent predictors of elevated blood lead levels; the presence of peeling paint in or outside the house, eating paints chips, and the geographic location of children. CONCLUSION: Using a risk assessment questionnaire, together with obtaining blood lead level has proven effective in identifying key environmental features associated with elevated blood lead level in children from sampled Thai communities. The challenge now is to conduct a larger epidemiological study of a similar type in order to guide the screening and preventive efforts.

Additional Burden of Diseases Associated with Cadmium Exposure: A Case Study of Cadmium Contaminated Rice Fields in Mae Sot District, Tak Province, Thailand.

The cadmium (Cd) contaminated rice fields in Mae Sot District, Tak Province, Thailand has been one of the major environmental problems in Thailand for the last 10 years. We used disability adjusted life years (DALYs) to estimate the burden of disease attributable to Cd in terms of additional DALYs of Mae Sot residents. Cd exposure data included Cd and ß2-microglobulin (ß2-MG) in urine (as an internal exposure dose) and estimated cadmium daily intake (as an external exposure dose). Compared to the general Thai population, Mae Sot residents gained 10%-86% DALYs from nephrosis/nephritis, heart diseases, osteoporosis and cancer depending on their Cd exposure type and exposure level. The results for urinary Cd and dietary Cd intake varied according to the studies used for risk estimation. The ceiling effect was observed in results using dietary Cd intake because of the high Cd content in rice grown in the Mae Sot area. The results from ß2-MG were more robust with additional DALYs ranging from 36%-86% for heart failure, cerebral infraction, and nephrosis/nephritis. Additional DALYs is a useful approach for assessing the magnitude of environmental Cd exposure. The Mae Sot population lost more healthy life compared to populations living in a non- or less Cd polluted area. This method should be applicable to various types of environmental contamination problems if exposure assessment information is available.

Generalized eruption accompanied by hepatitis in two Thai metal cleaners exposed to trichloroethylene.

Two female workers, aged 23 and 24, engaged in cleaning metal straps with trichloroethylene (TCE) in a watch manufacturing plant, experienced generalized eruption, mucosal lesion, fever and hepatitis. The first case suffered fulminant hepatitis and died from liver failure in two weeks after the first symptom appearance. The second case, whose onset of generalized eruption, mucosal lesion and hepatitis without jaundice was nine days after that of the first case, however, recovered in 2 wk. Because the result of working environment measurement suggested heavy exposure to TCE, we deemed that there would be a causal relationship between TCE exposure and the illness. Although there have been considerable number of papers describing the above-mentioned relationship, the fact is not well recognized even among medical personnel in Thailand. Taking the wide use of TCE into account, the prevention of this illness would be very important especially in rapidly industrializing countries.

The management of environmental lead exposure in the pediatric population: lessons from Clitty Creek, Thailand.

UNLABELLED: During the month of September-October 1997, a depression storm caused massive flooding in the area of western Kanchanaburi province, Thailand, causing lead-contaminated water from a nearby lead refinery plant to spill into the surrounding areas of Clitty Creek; exposing the village downstream to large amounts of lead. The Ministry of Public Health, together with the Ministry of Science, the Ministry of Industry, and officials from the Kanchanaburi Office of Public Health, began measures for environmental deleading and assessment of exposure and health risks of the population. METHOD: This was a retrospective cohort study of the effects that environmental remediation and chelation therapy had on the blood lead levels of children residing in Lower Clitty Creek Village during the period between 1997-2001. Sixty-eight children were followed yearly for their blood lead levels and hematocrit, beginning in early 1998. Simultaneously, programs for environmental remediation had begun. The blood lead levels (BLLs) of children were followed over a 3-year period. The BLLs during the 2 year period of environmental remediation alone were compared. Subsequently, when chelation therapy was instituted, levels pre and post chelation therapy, as well as the efficacy of the two different chelation methods were compared using standard 2-tailed t-test. RESULTS: The initial average BLL was 27.75 +/- 5.4 mg/dl (1998). After environmental remediation began, BLL at one year (1999) was 30.64 +/- 4.49 mg/dl (p = 0.072), and at two years (2000) was 30.30 +/- 5.1 mg/dl (p = 0.537). There were 18 children with BLLs > 25 who were elected to receive chelation therapy with CaNa2EDTA (11) and DMSA (7). Post chelation average BLL was 18.73 +/- 7.50 mg/dl. The difference between pre and post chelation BLL was statistically significant (p < 0.001: paired t-test). The differences in average BLLs between pre and post chelation for the EDTA group was 15.37 mg/dl and for the DMSA group it was 8.91 mg/dl. Children treated with EDTA appeared, on average, to have 6.47 mg/dl (p < 0.05: 95% CI (0.821-12.12)) lower BLL than those treated with DMSA. CONCLUSION: The incident at Clitty Creek serves to illustrate the importance of environmental remediation as a priority to treating lead poisoning in children. Only when effective environmental deleading has taken place can medical intervention in the form of chelation therapy begin.

Risk of aplastic anemia and pesticide and other chemical exposures.

Risk of aplastic anemia (AA) from occupational exposures to pesticides and industrial chemicals was evaluated in a hospital-based case control study in Thailand (541 cases of AA and 2261 controls). Exposure data were obtained via participants' self-reports and by experts' assessments and the data from these 2 exposure assessment methods were compared. There was an increased risk of AA associated with several classes of pesticides measured by either self-report or expert assessment. The strongest associations were seen in those whose exposures were identified both by self-report and by expert assessment. Comparing very high/high to no exposure, odds ratios (95% confidence intervals) were as follows: for organophosphates 3.20 (1.87-5.46), carbamates 4.75 (1.92-11.75), organochlorines 6.04 (1.31-27.84), and paraquat 2.17 (1.11-4.25). There were correlations among the pesticides because many types were used in the same job, so it was not possible to determine whether these risks were independent or because of confounding of one by another.

Cadmium induced renal dysfunction among residents of rice farming area downstream from a zinc-mineralized belt in Thailand.

High levels of cadmium (Cd) in paddy soil and rice, and a concurrent increase in urinary Cd of inhabitants in the Mae Sot District, Tak Province, Thailand first emerged in 2003. Risk factors such as occupation, sources of staple food and drinking water as well as biomarkers of adverse renal effects of the increased body burden of Cd were investigated in 795 residents, 30 years or older, whose urinary Cd levels were between 0.02 and 106mug/g creatinine. Farmers who consumed their own rice and residents who sourced drinking water from wells and/or the river demonstrated increased urinary Cd. Age-adjusted mean urinary cadmium for male and female subjects who consumed well water was 5.7mug/g vs. 6.1mug/g creatinine while the corresponding value for male and female subjects who did not consume well water was 3.7mug/g vs. 4.8mug/g creatinine, respectively. Increased urinary levels of beta(2)-microglobulin and N-acetyl-beta-d-glucosaminidase were observed with the increase in urinary Cd, indicating tubular dysfunction and renal damage associated with increase in Cd body burden. Consumption of well water and rice grown in the contaminated area increase the body burden of Cd. Cessation of exposure is essential to prevent and possibly recover from Cd toxicity, especially among the residents whose kidney damage and malfunction may be reversible.

Spectrophotometric determination of plasma and red blood cell cholinesterase activity of 53 fruit farm workers pre- and post-exposed chlorpyrifos for one fruit crop.

We sought to investigate the early biological effects of chlorpyrifos among 53 Thai fruit farm workers by measuring the plasma cholinesterase (PChE) and red blood cell cholinesterase (AChE) activities, a biomarker of organophosphate (OPs) pesticide during one fruit crop. The ChE activity (V(m)/K(m)) was spectrophotometrically analyzed before and after exposing to chlorpyrifos. The V(m)/K(m) values of both non-spraying and spraying seasons are found as normal distribution pattern. The median PChE and AChE activities among farm workers in the non-spraying season were 2.3 x 10(-3) s(-1) and 7.26 x 10(-5) s(-1), respectively. The median PChE and AChE activities of the farm workers in the spraying season were 2.02 x 10(-3) s(-1) and 5.95 x 10(-5) s(-1), respectively. The mean V(m)/K(m) values of PChE shifted left (t-test, p=0.013), indicating a decrease in PChE activity in the farm workers exposed to chlorpyrifos. However, the V(m)/K(m) values of AChE in nonspraying season and in the spraying season were not different (t-test, p=0.246). We propose that PChE activity can be used as a biomarker for monitoring early toxicity induced by chlorpyrifos insecticide.