Exploring the Forest Cover Changes and Influential Factors of Dongsithouane National Production Forest Area, Savannakhet Province, Lao PDR

The Dongsithouane National Production Forest (DNPF) is one of the largest natural forest areas in Savannakhet, Lao PDR, which has been a vital support for the local community’s livelihood, Recently, significant changes in land use and land cover (LULC) have been observed in this area, leading to a reduction of natural forests. There were two separate methods of this study: firstly, to identify LULC changes across three different periods, spectral imagery from the Landsat 5 Thematic Mapper (TM) for the years 2001 and 2011, and the Landsat 8 Operational Land Imager (OLI) for 2021 were used as the primary data sources. The satellite images were preprocessed for various forest classes, including pretreatment of the top of atmosphere reflectance by using QGIS software’s semi-automatic classification plug-in (SCP), and ArcGIS was used for post-classification. A supervised classification approach was applied to the satellite images from 2001, 2011, and 2021 to generate diverse maps of LULC. Secondly, a household survey dataset was used to investigate influential factors. Approximately 220 households were interviewed in order to collect socio-economic information (including data on population growth, increased business activities, location of the area, agriculture land expansion, and need for settlement land). Household survey data was analyzed by using SPSS. Descriptive statistics, including frequency distributions and percentages, were applied to observe characteristics. Additionally, a binary logistic regression model was used to analyze the socioeconomic factors related to LULC change in DNPF. Key findings indicated a decline in natural forest areas within the study site. Specifically, both dry dipterocarp forest (−11.35%) and mixed deciduous forest (−0.18%) decreased from 2001 to 2021. The overall accuracy of the LULC maps was 94%, 86%, and 89% for the years 2001, 2011, and 2021 respectively. In contrast, agricultural land increased significantly by 155.70%, while built-up land, and water bodies increased by 65.54% and 35.33%, respectively. The results also highlighted a significant increase in construction land, up to 65.54%. Furthermore, the study found a correlation between agricultural expansion and a reduction of forest areas, along with an increase in built-up land along the forest areas’ boundaries. Timber exploitation and charcoal production also contributed to the decline in forest cover. The logistic regression model identified significant determinants of LULC change, including the area’s location, agricultural land expansion, increased business activity, and the need for settlement land. These factors have influenced the management of DNPF. Urgent sustainable management practices and actions, including forest ecosystem protection, village agricultural zoning, water source and watershed protection and public awareness, are required to preserve the forest areas of DNPF.

Food Security of Shifting Cultivation Systems: Case Studies from Luang Prabang and Oudomxay Provinces, Lao PDR

The Government of the Lao PDR’s policy is to eliminate the cultivation of upland rice by means of ‘slash-and-burn’ cultivation and to replace it with more ecologically stable systems based on sustainable land use at the village and household level. The objectives of this policy are to alleviate poverty and to introduce more sustainable management of agricultural resources. In order to achieve these objectives, the government has initiated a program of relocation to upland ‘focal areas’ from which marketing, distribution and other services can be supplied, these being essential preconditions for effective agricultural development in these regions. This diagnostic study has examined communal and household strategies for addressing food security issues, and has highlighted the main problems encountered in the pursuit of food security on the local level. The specific objective was to conduct a broadly focused participatory problem diagnosis of the study areas in two districts Phonsay and Namo, in order to understand farmers’ problems, livelihood goals and how their perspectives on food security have changed, and to investigate food security in shifting cultivation systems in Luang Prabang andOudomxay provinces. Within these two provinces Phonsay and Namo districts were selected as the research areas. The two districts are the poorest districts in the Luang Prabang and Oudomxay provinces and two of ten priority poorest districts in the whole country. Semi-structured interviews were conducted for the study. The results of this study were reviewed against the sustainable land use systems strategy formulated from the Lao PDR policy. The study highlights both the benefits and stresses on household welfare, food insecurity conditions in the study areas, and interrelated problems of insufficient rice for household consumption. Finally based on these results the authors propose recommendations and future research indications.

Advocacy Coalition by External Actors and Strategies Used to Influence the Emergence of the National Nutrition Policy in Lao PDR

This article aims to explore the coalition of external actors and the strategies it deployed to influence the emergence of the National Nutrition Policy (NNP) in Lao People’s Democratic Republic (Lao PDR). The Advocacy Coalition Framework and the conceptual model of Effective Advocacy Strategies for Influencing Government Nutrition Policy were used to frame the data collection and their analysis. Sources of information were semi-structured interviews conducted with government and external actors, as well as all available documents on nutrition policy in Laos. The commitment of the government to achieve the Millennium Development Goals (MDGs) and to leave the Least Developed Country status created a favorable condition to support the emergence of the NNP in Laos. This context was a driving force for the building of an effective and convincing coalition of United Nations agencies able to accompany the government in redefining health priorities. Various strategies were used by the coalition to this end, including generating, disseminating, and using scientific evidence, assisting the government with a budget and technical expertise, providing decision-makers with opportunities to learn from other countries, and building relationships with the key actor. External actors can be a major force to support the emergence of a public policy in Laos, but this requires a window of opportunity like what the MDGs have been able to bring.

Changes of forest land use and ecosystem service values along Lao-Chinese border:A case study of Luang Namtha Province,Lao PDR

Forest cover and land use change directly impact biological diversity worldwide, contribute to climate change and affect the ability of biological systems to support human needs by altering ecosystem services. Given the forest land use characteristics and ecosystem types in Luang Namtha Province, Lao PDR, the forest cover and land cover category of Luang Namtha Province were divided into six classes, i.e., current forest （CF）, potential forest （PF）, other wooded areas （OW）, permanent agricultural land （PA）, other non-forest areas （NF） and water （W）. In first instance, earlier geographic information data （GIS data） of forest cover and land use during 1992 and 2002 was obtained from the Ministry of Agriculture and Forestry （MAF）, Lao PDR. Two steps of forest land use change assessment were conducted by the MAF, i.e., plot sampling on satellite image maps （SIMs） to detect the changes of forest cover and land use during 1992 and 2002 for the entire Luang Namtha Province and field verification in order to identify causes of the changes. Secondly, dynamic information of the forest land cover changes during this ten-year period was calculated by means of map algebra in ArcGIS 9.2. Thirdly, based on the theory of ecosystem service functions and the service function values of different global ecosystems, the value of the six forest cover and land use categories in the province was obtained. Finally, ecological environmental effects, produced by the regional land cover changes over the study period, were calculated.

Indigenous Knowledge on Soil Classification of Ethnic Groups in Luang Prabang Province of the Lao PDR

The objectives of this study were to demonstrate ethno-scientific elicitation techniques in retrieving indigenous knowledge at village-level, and to document the indigenous soil classification systems of different ethnic groups in Luang Prabang province in the Lao PDR. The study area comprised three villages – Nambo, Huaymaha and Thapo, in the Phonxay district of Luang Prabang province. Three ethnic groups were covered by the study – Hmong, Khmu and Lao Loum. All three ethnic groups used soil color as main criteria for soil classification. However, even within the same ethnic group, sometimes different villages have differences in the way they classify soils; this was apparent for the Hmong ethnic group in the villages of Huaymaha and Nambo. A significant difference of the Lao Loum ethnic group from the other two, was the emphasis used in classifying soil types according to their water holding capabilities. In contrast, the Khmu and Hmong classified many soil types in relation to their rock content (‘with rock’ or ‘pure rock’ sometimesbeing used). The results of the study suggest that the ethnic groups classify the soils in relation to their potential for different types of agricultural production.

Evaluation of the Environmental Impacts Assessment (EIA) System in Lao PDR

This study explores and seeks to explain the EIA procedures practice gap in Lao PDR. It reviews the literature and studies EIA legislation, administrative procedures, guidelines, and relevant documents by using a model proposed by Leu et al. (1996) and applying criteria proposed by Wood (1995) to evaluate the performance of EIA systems. Key EIA legislation in Lao PDR has many strengths, but also major weaknesses: Inadequate planning procedures, no secondary regulations, few trained and skilled personnel, inadequate public consultation, lack of environmental data, weak follow-up and monitoring, and no enforcement machinery. Additionally, the EIA approval procedure is very bureaucratic and easily derailed by political and economic pressures. In addition, coordination among EIA proponents, consultants, concerned ministries, local authorities, planners, and decision-makers is generally weak. This delays decision-making and hinders implementation of environmental regulations. Thus, procedures and evaluation are not always performed well. EIAs are more a project justification tool than a project planning tool for sustainable development. We conclude with recommendations to strengthen the system, such as improving capacity building, implementing an EIA consultants’ accreditation system, ensuring effective public participation and access to EIA reports, applying systematic EIAs, reviewing criteria, and promoting environmental awareness.

Detection of non-typhoid Salmonella infection by citrus and citrus extracts in Lao PDR

Objective:To know the current state of non-typhoid Salmonella infection in Laos.To examine the usefulness of new screening methods for Salmonella using citrus.Methods:Non-typhoid Salmonella infection of person in Lao PDR was studied in this research(2004-2009).The site was Vientiane capital city in 2004.Research from rural villages locating suburb of Vientiane during 2005-2008 was carried out.Rural villages in Attapu province where ethnic minorities were living was searched for this study in 2009.During this research,to detect Salmonella strain, a new method using citrus and citrus extract named MY phenomenon that observing black ring (MIDO ring) on DHL agar was tried.The slice lemon and lime were used for this trial in 2004. After 2005,disk of ascorbic acid and citric acid were used for the device instead of citrus fruits itself.Results:During this research,65 of 272 human samples(23.9%) were infected with non- typhoid Salmonella.Conclusions:During this study,the method using citrus and citrus extracts was accepted for the detection of Salmonella.This study shows that with citrus and citrus extract, detection of Salmonella is possible using only DHL media.Results suggest that infectious rate of non-typhoid Salmonella was high.

Climate change and groundwater resources in Lao PDR

The national economy of Lao PDR is highly dependent on water resources. Consequently, the sustainable management of groundwater and successful adaptations to future climate change are major concerns. Climate projections for Lao PDR predict increased rainfall and hot weather, with more intense rainfall events and more frequent and severe droughts and floods. Under climate change, reductions in the amount and quality of groundwater are two critical problems. Reductions of the groundwater level will restrict the access of local people to groundwater resources, thereby posing a threat to food security and livelihoods. Lao PDR suffers from a limited number of human resources with the requisite skills to perform groundwater investigations and provide sustainable management. For the successful implementation of groundwater management plans, limitations associated with funding and technology should be resolved via support from the government and international cooperation. Advanced action plans for capacity building and training courses should be established to strengthen administrative and individual capacities. Technical measures, such as groundwater monitoring, aquifer characterizations, and water treatment systems, should be implemented to manage future climate change and water resource security.

Malaria elimination in Lao PDR:the challenges associated with population mobility

Although the Lao People’s Democratic Republic(Lao PDR)is comparatively small landlocked country with patterns of both in-and out-migration,its human migration situation has been poorly studied.This is despite all of the country’s 18 provinces sharing both official and unofficial border checkpoints with neighboring countries.Economic reforms in the last decade have seen a gradual increase in the promotion of foreign investment,and main towns and transportation networks have been expanding thus offering new opportunities for livelihoods and economic activities.In the last decade,there has also been a significant reduction of reported malaria cases in Lao PDR and while this is an important prerequisite for eliminating malaria in the country,malaria outbreaks reported in the last four years suggest that population mobility,particularly in the south,is an important factor challenging current control efforts.Bolder investment in social sector spending should be geared towards improving health service provision and utilization,ensuring equitable access to primary health care(including malaria)through efforts to achieve universal health coverage targets.This should be extended to populations that are mobile and migrants.The local government plays a critical role in supporting policy and enforcement issues related to private sector project development in the provinces.Cross-border initiatives with neighboring countries,especially in terms of data sharing,surveillance,and response,is essential.Mechanisms to engage the private sector,especially the informal private sector,needs to be explored within the context of existing regulations and laws.Existing and new interventions for outdoor transmission of malaria,especially in forest settings,for high-risk groups including short-and long-term forest workers and their families,mobile and migrant populations,as well as the military must be combined into integrated packages with innovative delivery mechanisms through social marketing approaches.This should happen at multiple points in the mobility pathway and involve the private sector rather than being fully reliant on the national malaria vertical program This article based on the review of existing literature from abstracts and full texts,includes published,peer-reviewed English language literature sourced through PubMed and grey literature sources through Google and Google Scholar.The review included also case reports,sector reports,conference proceedings,research reports,epidemiology studies,qualitative studies,and census reports in both Lao and English languages.The authors used the search terms:malaria and mobile populations,malaria control program and elimination,health system performance,malaria outbreak,Lao PDR;and included articles published until June 2015.

Factors explaining the abundance of rodents in the city of Luang Prabang,Lao PDR,as revealed by field and household surveys

A field and a household survey, the latter of which included inspections and interviews with the residents of a totalof 1370 properties, were conducted in 2004 in 30 villages of the city of Luang Prabang, Lao PDR, in order to assessthe degree of rodent infestation and to identify potential factors influencing infestations. Roof rats, Rattus rattus,and the Polynesian rat, Rattus exulans, were the only rodents found in the city, and trapping results showed a cleardominance of roof rats (80–90% of all individuals). Measurements of rodent activity using tracking patchescorrelated positively with the trapping data, and revealed a significantly higher degree of rat infestation during therainy season (September) than during the dry season (November). If households in the vicinity of the samplinglocations were considered, villagers’ accounts of indoor rodent infestations recorded during the household surveycorrelated positively with measurements of rodent activity. At least every second household reported indoorinfestations. Using explorative statistical analyses (classification trees, factor analysis) we checked the predictiveor explanatory value of up to 28 variables assessed during household inspections for villagers’ observations onrodent infestation as the dependent variable. Trophic factors such as exposed food (indoors) and garbage (outdoors),and structural features such as open ceilings (indoors) and rat harborage in gardens (outdoors) ranked highest asexplanatory variables. Assessment of a small sample of roof rat droppings collected inside houses revealed thepresence of the potential disease agents Salmonella javiana, Cryptosporidium parvum, Giardia duodenalis and theparasitic nematode Calodium hepaticum (syn. Capillaria hepatica). These results underline the need for anappropriate rodent management strategy for the city, whereby simple sanitation and rodent-proofing measurescould be cheap means of reducing rat infestation rates.

Which Target Population for Promotion Programs on Health Infant Feeding Practice in Laos?

One of the determinants of the poor improvement in child nutrition indicators observed in Laos is mothers’ feeding practices. These practices are influenced by many socio-environmental factors and are expected to be targets of public health programs against malnutrition. The purpose of this work is to examine how the Lao National Nutrition Strategy (NNS) incorporates the issue of the determinants of the behavior of mothers of young children in its recommendations. We argue that the little consideration brought in the NNS to key determinants of women’s behavior is a major explanatory factor for the poor performance in improving the nutrition status of Lao under-five-year-old children.

Applying the Global Disturbance Index for Detecting Vegetation Changes in Lao Tropical Forests

Land cover change is a major challenge for many developing countries. Spatiotemporal information on this change is essential for monitoring global terrestrial ecosystem carbon, climate and biosphere exchange, and land use management. A combination of LST and the EVI indices in the global disturbance index (DI) has been proven to be useful for detecting and monitoring of changes in land covers at continental scales. However, this model has not been adequately applied or assessed in tropical regions. We aimed to demonstrate and evaluate the DI algorithm used to detect spatial change in land covers in Lao tropical forests. We used the land surface temperature and enhanced vegetation index of the Moderate Resolution Imaging Spectroradiometer time-series products from 2006-2012. We used two dates Google EarthTM images in 2006 and 2012 as ground truth data for accuracy assessment of the model. This research demonstrated that the DI was capable of detecting vegetation changes during seven-year periods with high overall accuracy;however, it showed low accuracy in detecting vegetation decrease.

Perceived ill-health and health seeking behavior in two communities in the nam theun 2 hydroelectric project area in Lao Peoples Democratic Republic

Objective:To compare perceived ill-health and health seeking behavior between two communities affected by the large Nam Theun 2 hydroelectric project in central Lao People’s Democratic Republic(PDR).Methods: Two different affected areas;Nakai plateaubeing remote,sparcely populated and mountainous,and Xe Bang Fai lowland plains,more densely populated and comparatively affluent were included.Data were obtained from two cross-sectional household-based health and socio-economic surveys.Results:We found pronounced differences in the frequency of self-reported fever,cough,headache and myalgia according to location.On the Nakai plateau,45.1%of the individuals with ill-health report(recall period;2 weeks) went to a local health volunteer compared to only 7.2%in the Xe Bang Fai area(P 【 0.001 ).In Nakai,there were disproportionately more illiterates seeking help from local health volunteers when compared to those who attended at least primary schooling(49.2%versus 17.5%,P 【0.01 ).Self-medication with antimalarials was more common in Xe Bang Fai than on Nakai(32.3%versus 7.0%,P 【 0.001).The mean amount of money spent per health consultation was US $ 1.7 in Nakai and US $ 7.2 in Xe Bang Fai.Conclusion:The observed differences in self-reported ill-health and health seeking behavior among these two Lao communities need to be considered when implementing setting-specific mitigation measures as part of the public health action plan of the Nam Theun 2 hydroelectric project.

老挝南部安东花岗闪长岩砖红土型风化壳分带及微量元素地球化学特征

在热带雨林特殊生态景观中和湿热气候条件下,老挝南部阿速波省(Attapeu)安东地区(Antoum)二叠纪花岗闪长岩形成了发育完整的砖红土型风化壳,该风化壳剖面分带明显,最下部为蚀变花岗闪长岩(基岩),往上依次为半风化蚀变花岗闪长岩→高岭石残积层带→砖红土带→森林表土带。测试了采集于红土型风化壳剖面不同分带样品的20种微量元素含量,微量元素可划分出6种变化模式,其中最明显的为Cu、Mo、As、B、iAu等在高岭土风化带上部显著富集。认为在今后土壤地球化学普查和详查中,经过加大采样深度,采用固定相态提取法或部分提取法可能是强化地球化学异常、探测深部找矿信息的有效途径。

老挝Boloven高原玄武岩风化壳中稀土元素富集与主量元素关系

老挝南部Champasak省东北部Boloven高原玄武岩喷发于晚中生代-新生代,在长期热带季风型气候和热带季雨林植被条件下,高原玄武岩上已经发育砖红壤型风化壳。在一条风化壳剖面上采集了11件样品并在室内细碎到200目,使用X射线荧光光谱仪分析了11个样品中的主量元素含量,使用ICP-MS分析了11件样品REE含量。结果表明,玄武岩风化壳中主量元素Na2O和MgO淋失量最大,K2O和CaO淋失量次之,并在淋失一定程度后淋失速度减慢;样品LR157和LR158中TiO2,P2O5分别为6.07%,1.45%和8.43%,0.82%,为整个剖面中的最高值;CaO的含量是松散风化产物中的最高值。风化玄武岩(LR140,LR141)的∑REE较低,为57.8×10-6和87.9×10-6;随着玄武岩风化程度和成壤作用的加强,∑REE逐渐富集,并在风化壳表土下(LR157,LR158)达到最高值1003×10-6和775×10-6。风化壳中LREE/HREE值为3.59～14.9,稀土元素分布型式属轻稀土富集型。随着风化程度加深,Ce由弱负异常逐渐变为强正异常,而Eu由弱正异常逐渐变小并呈现出强负异常,整个剖面中Ce正负异常和Eu正负异常的变化幅度较大。REE在剖面中的分布与含TiO2,P2O5的矿物有明显的相关关系,并且在TiO2,P2O5含量最高的样品LR157和LR158中最为富集。REE富集和Ce正异常出现在pH值为5.23～6.12的酸性和Fe2+/Fe3+为0.007～0.13的氧化环境下,证明在酸性氧化环境也能出现REE富集。

老挝南部Antoun地区花岗闪长岩风化壳中常量和稀土元素分布

应用岩石薄片鉴定、X射线粉晶衍射、X射线荧光光谱和ICP-MS等分析方法,研究了热带季风型气候条件下老挝Attapeu省Antoun地区二叠纪花岗闪长岩上发育的砖红土型风化壳矿物组成、常量元素和稀土元素地球化学特征。结果表明,风化产物呈酸性,风化壳表土上形成薄层硅质壳层,表土中石英含量最高、铁氧化物含量低和高岭石含量低,符合典型的灰化土特征。随着风化作用加强,Fe2O3、TiO2和Al2O3出现富集,K2O、Na2O、CaO和MgO出现淋失。石英出现富集原因可能是雨季降水冲刷和酸性水淋溶掉高岭石等黏土矿物,而旱季SiO2含量上升至地表富集形成硅质薄壳缘故。剖面稀土元素分布型式为轻稀土富集型,∑REE在风化壳中部达到最高值318 mg kg-1,剖面上Ce和Eu均呈正异常-负异常-正异常变化趋势,∑REE最高值出现在Ce和Eu负异常和(Fe2+/Fe3+)较高层位,∑REE与Fe2O3显著正相关。REE富集与铁铝氧化物和黏土矿物吸附有关,也与相对还原的酸性环境有关。

中国企业对老挝的直接投资及其影响

近年来,中国企业对老挝的直接投资呈加速发展态势,投资流量及存量的增长都在提速,已经成为老挝最重要的外资来源国之一。中国企业对老挝的直接投资在一定程度上促进了当地经济和社会的快速发展:提供了老挝经济发展所需要的资金;改善了老挝的基础设施;提升了老百姓的生活水平。但是,中国企业在老挝的投资也存在一些问题:投资的行业有些过于集中在资源领域;少数在老挝投资的中国企业或者个人存在着非法经营和非法用工现象;普遍缺乏与媒体的沟通能力和意愿。

中国、老挝、缅甸和泰国澜沧江—湄公河国际航运现状及未来发展趋势研究

澜沧江—湄公河国际航运是促进中国、老挝、缅甸和泰国4国经贸往来、区域开发以及人文交往的重要载体。本文在详细分析过去航运基础设施、运输能力、运输市场以及支持保障体系等现状的基础上,剖析当前4国国际航运发展面临的机遇与挑战,结合沿江经济现状及发展趋势,利用灰色多元线性回归分析方法,对2025年和2035年4国航运量进行客观预测,并对未来4国港口发展趋势进行研判。

水电行业非自愿移民政策——国际经验与老挝实践

针对近年中国企业在老挝投资开发水电项目面临非自愿移民政策解读和执行困扰,采用文献回顾、政策比较分析的方式对亚洲开发银行、中国和老挝非自愿移民政策的内容和要求进行深入解读和比较分析,剖析三方政策的异同点,重点介绍老挝非自愿移民实践的成功经验和不足之处,并针对以上述问题对中国企业提出建议。

Intestinal helminth infections and associated risk factors among adults in the Lao People’s Democratic Republic

Background Helminthiases are highly endemic in Southeast Asia,including the Lao People’s Democratic Republic(Lao PDR).This study aimed to assess the current intestinal helminth infections and the associated risk factors among adults across the Lao PDR.Methods A cross-sectional survey was conducted in 165 villages across 17 provinces and the Vientiane Capital,Lao PDR.A multi-stage sampling method was employed to select the adult study participants(≥18 years).Data collection included(1)interview of the study participants,(2)physical measurements,and(3)a fve gram of stool sample from each study participant was collected and preserved in 10%formalin solution for intestinal helminth detection using formalin-ether concentration technique(FECT).Descriptive analysis was used to describe the socio-demographic characteristics of study participants and the prevalence of intestinal helminth infections.Logistic regressions were applied to test the association between intestinal helminth infection and individual risk factors.A P-value below 0.05 was considered statistically signifcant.Results A total of 2800 study participants were enrolled.Their average age was 46.0 years;57.8%were female.Overall,30.9%,8.6%and 1.5%of study participants were infected with one,two,or three diferent intestinal helminth species,respectively.Among the study participants 21.6%were infected with hookworm,18.8%with Opisthorchis viverrini-like(Ov-like)infection,4.8%with Strongyloides stercoralis,2.3%with Ascaris lumbricoides,1.5%with Trichuris trichiura,and 3.3%with Taenia spp.Ov-like infection was of high prevalence in the southern(28.8%)and central(21.3%)provinces,while hookworm(26.3%),A.lumbricoides(7.3%),T.trichiura(3.1%),and Taenia spp.(4.2%)were prevalent in the northern provinces.Risk analysis showed that men were more likely to be infected with hookworm[adjusted odds ratio(aOR)=1.2,P=0.019].The Lao-Tai ethnic group had a 5.2-times(P<0.001)higher chance of having Ov-like infection than the minorities.Possession of toilet facility at home was associated with reduced odds for Ov-like(aOR=0.4,P<0.001)and hookworm(aOR=0.6,P<0.001)infections.Conclusions Our study provides a nationwide update of the intestinal helminth prevalence among adults in Lao PDR.To the best of our knowledge,this is the frst Lao nationwide survey on intestinal helminth infections and risk factors in adults.It provides crucial information for national control programs for intestinal helminth infections in Lao PDR.