Northern Laos Research Articles

Swidden Agriculture Landscape Mapping Using MODIS Vegetation Index Time Series and Its Spatio-Temporal Dynamics in Northern Laos

Swidden agriculture or shifting cultivation is still being widely practiced in tropical developing countries and Laos has spared no effort to eradicate it since the mid-1990s. So far, the development of swidden agriculture in this land-locked mountainous country during the 2000–2020 bi-decade remains poorly examined. Moderate-resolution Imaging Spectroradiometer (MODIS) time-series products have shown potential in monitoring vegetative status; however, only extremely limited cases of remote sensing of swidden agriculture landscapes have been reported. Taking northern Laos as a study area and using 2001–2020 MODIS vegetation indices products, the Savitzky–Golay filter, the Mann–Kendall trend test and a threshold method were employed to delineate and monitor annual patterns and dynamics of swidden agriculture landscape at the village level. The results showed that: MODIS Normalized Difference Vegetation Index (NDVI) time series perform better in delineating the temporal development of swidden agriculture. The swidden agriculture landscape has shown a general descending trend in the past decades, especially in the 2010s, with an annual average of 14.70 × 104 ha. The total number of swidden-practicing villages (or districts) also displayed a declining trend and there were 957 villages or 91 districts practicing it continuously between 2001 and 2020. An average of 32 villages per year or two districts per decade highlights the difficulty in ending swidden agriculture in Laos, although the government of Laos has established a number of policies for the eradication of swidden agriculture by 2020. This study provides a necessary methodological reference for monitoring a two-decade evolution and transformation of swidden agriculture in the tropics.

Monitoring ecological and environmental stress patterns over the past two decades in the Mekong River basin

ABSTRACT Among the most biodiverse environments in the world, the Mekong River Basin has experienced extensive socio-economic development in the past few decades resulting in land use change and associated ecological and environmental stresses. To assess possible impacts on sensitive ecosystems and their services in the Lower Mekong River Basin (LMB), we examine spatial and temporal changes in forest community extent, as well as tree density and canopy coverage, in relation to carbon uptake and climate change. We employed the Mann–Kendall test to identify regions of likely significant ecological and environmental change within forest ecosystems. We developed a new approach to eliminate the classification of false positives and false negatives. We quantified the annual rate of ecological changes using Sen’s slope. Ordinary Least Squares (OLS) regression analysis was performed to analyze the impact of tree and leaf density changes on the regional environment, particularly with regard to net primary productivity (NPP) and surface temperature trends. Across the LMB, a total of 2.81% of forest extent has been lost. Cambodia experienced the most prominent forest loss among all countries, while Thailand and Myanmar had net forest gain. NPP trends were starkly divergent from the north to the south and declined across the majority of northern Laos. The LMB region experienced increasing trends for both daytime and nighttime temperatures except for small portions of Thailand and Vietnam. An annual 0.0876°C increase in surface temperature can be expected for every 1% decrease in tree density in forest degraded regions, while a substantial annual carbon productivity increase can be expected in reforested regions. In addition, the effectiveness of policy enforcement at the government level is critical for reforestation in LMB.

Decadal changes in premature mortality associated with exposure to outdoor PM2.5 in mainland Southeast Asia and the impacts of biomass burning and anthropogenic emissions

In mainland Southeast Asia (SEA), a rapid increase of fossil fuel consumption and massive particulate matter emissions from biomass burning (BB) are severely threatening the health of local inhabitants. In this study, surface PM2.5 data, satellite fire observations and emission inventories were integrated with the Global Exposure Mortality Model (GEMM) to estimate premature mortality attributable to PM2.5 exposure from 1990 through 2019 and to explore and quantify the health burden associated with BB and anthropogenic emissions in mainland SEA. BB in mainland SEA has remained intense over the past decades. Owing to a lack of effective control measures, emission inventory and satellite-observed data both showed that BB has markedly intensified in several regions, including northern Cambodia and northern Laos. The multiannual average (1997–2015) BB PM2.5 emission was 1.6 × 106 t/yr, which is much higher than that of anthropogenic (fossil fuel combustion) PM2.5 emission. GEMM results indicated that PM2.5-related premature mortality in mainland SEA more than doubled from 100 (95 % confidence interval [CI], 88–112) thousand in 1990 to 257 (95 % CI, 228–286) thousand in 2019. Decomposition analysis revealed that variations in population size and age structure also promoted this increase of PM2.5-related deaths. Given that mainland SEA is a rapidly developing region, it is expected that local public health will face increasing challenges due to population growth, population ageing, and increased anthropogenic emissions. Therefore, it is imperative for policymakers to consider these influential factors, set practical mitigation targets, and explore how to effectively and systematically combine BB with anthropogenic emission controls to maximize the health benefits.

Exploration of the Contribution of Fire Carbon Emissions to PM2.5 and Their Influencing Factors in Laotian Tropical Rainforests

It is of great significance to understand the drivers of PM2.5 and fire carbon emission (FCE) and the relationship between them for the prevention, control, and policy formulation of severe PM2.5 exposure in areas where biomass burning is a major source. In this study, we considered northern Laos as the area of research, and we utilized space cluster analysis to present the spatial pattern of PM2.5 and FCE from 2003–2019. With the use of a random forest and structural equation model, we explored the relationship between PM2.5 and FCE and their drivers. The key results during the target period of the study were as follows: (1) the HH (high/high) clusters of PM2.5 concentration and FCE were very similar and distributed in the west of the study area; (2) compared with the contribution of climate variables, the contribution of FCE to PM2.5 was weak but statistically significant. The standardized coefficients were 0.5 for drought index, 0.32 for diurnal temperature range, and 0.22 for FCE; (3) climate factors are the main drivers of PM2.5 and FCE in northern Laos, among which drought and diurnal temperature range are the most influential factors. We believe that, as the heat intensifies driven by climate in tropical rainforests, this exploration and discovery can help regulators and researchers better integrate drought and diurnal temperature range into FCE and PM2.5 predictive models in order to develop effective measures to prevent and control air pollution in areas affected by biomass combustion.

Estimating the burden of hepatitis B virus infection in Laos between 2020 and 2021: A cross-sectional seroprevalence survey.

SummaryBackgroundLaos is considered highly endemic for persistent infection with hepatitis B virus (HBV). To eliminate this burden, it has gradually implemented universal anti-hepatitis B immunisation of newborns over the past two decades.MethodsUsing VIKIA® HBsAg, a rapid test for the qualitative detection of the HBV surface antigen, we conducted between Sep 1st, 2020 and Aug 31st, 2021 the largest prospective prevalence survey ever in Laos. This survey included blood donors (BD, n = 42,277), patients attending care in capital and provincial hospitals (n = 37,347) including attending mothers (n = 20,548), HIV-infected patients (n = 7439, recruited from 2009 to 2020), students from the Health Sciences University (n = 609), and outpatients (n = 350) coming for diagnosis at the Center Infectiology Lao-Christophe Mérieux in Vientiane. In total, 88,022 persons were tested, representing approximately 1.22% of the national population. To reach a reasonable estimate of HBsAg prevalence in Laos, we segmented the population according to three variables, age (≤20 years as a cut-off), sex, and geographical origin. BD values were used to estimate HBsAg prevalence in patients aged <20 while hospital survey prevalence was used to estimate the prevalence in those aged older than 20 years.FindingsWe observed an HBsAg seroprevalence ranging from 2.6% in blood donors to 8.0% in HIV-infected patients. In BD, men were significantly more at risk to be carriers than women (RR = 1.2, P = 0.00063). For BD, attending mothers, or HIV-infected patients, HBsAg was significantly more prevalent in northern Laos (5.1–8.4%) than in central (2.0–8.1%) or southern parts of the country (2.2–6.9%), thereby delineating a North-to-South gradient.InterpretationWe considered that HBsAg prevalence probably ranges between 5.0% and 6.0% of the total population. Thus, we consider that Laos may no longer be highly endemic for chronic HBV infection but rather a country with intermediate endemicity.FundingThe funding sources were the Agence Universitaire de la Francophonie, the French Government, the French Institute for Sustainable Development (IRD), and European Union’s Horizon 2020 Marie Sklodowska-Curie Actions (MSCA) – Research and Innovation Staff Exchange - (RISE) under grant agreement N° 823935.

Diet and prey selection of clouded leopards and tigers in Laos.

In Southeast Asia, conservation of ‘Vulnerable’ clouded leopards (Neofelis nebulosa) and ‘Endangered’ tigers (Panthera tigris) might depend on the management of their preferred prey because large felid populations are limited by the availability of suitable prey. However, the diet of clouded leopards has never been determined, so the preferred prey of this felid remains unknown. The diet of tigers in the region has been studied only from one protected‐area complex in western Thailand, but prey preferences were not determined. To better understand the primary and preferred prey of threatened felids, we used DNA‐confirmed scats and prey surveys to determine the diet and prey selection of clouded leopards and tigers in a hilly evergreen forest in northern Laos. For clouded leopards, the primary prey was wild pig (Sus scrofa; 33% biomass consumed), followed by greater hog badger (Arctonyx collaris; 28%), small rodents (15%), and mainland serow (Capricornis sumatraensis; 13%; hereafter, serow). For tigers, the primary prey was wild pig (44%), followed by serow (18%), sambar (Rusa unicolor; 12%), and Asiatic black bear (Ursus thibetanus; 10%). Compared to availability, serow was positively selected by both clouded leopards (D = 0.69) and tigers (0.61), whereas all other ungulate species were consumed in proportion to the availability or avoided. Our results indicate that clouded leopards are generalist predators with a wide prey spectrum. Nonetheless, mid‐sized ungulates (50–150 kg) comprised nearly half of their diet, and were the preferred prey, supporting a previous hypothesis that the enlarged gape and elongated canines of clouded leopards are adaptations for killing large prey. Because serow was the only ungulate preferred by both felids, we recommend that serow populations be monitored and managed to help conservation efforts for clouded leopards and tigers, at least in hilly evergreen forests of Southeast Asia.

The Impact of Unimplemented Large-Scale Land Development Deals

Although many land deals are never implemented to production stage, little is known about how abandoned projects affect local communities and the government agencies that promote them. This article analyses the effects on local actors, their land access, land use and tenure security of a large-scale bio-fuel land deal in northern Laos that a Chinese company initiated but subsequently abandoned before reaching the planting and production stage. The project left local people bound by contracts without cancellation clauses and with livelihood losses, until the investment contract eventually was annulled by Lao state actors. The deal has prepared the provincial government to receive new investors to further the modernization of agriculture and a land-based economic growth, both in terms of identifying land for development, and experiences gained of how to handle international investors. However, it seems unlikely that local actors can decline future projects when interests of investors and government actors overlap–interests that may not be limited to those officially stated as the objectives of the land deal. A more accurate terminology and additional research is needed to shed light on the outcomes of land deals that for some reason never reach a production stage, whether as a “virtual,” or “failed” land deal.

Population genetic structure and evolutionary genetics of Anopheles sinensis based on knockdown resistance (kdr) mutations and mtDNA-COII gene in China–Laos, Thailand–Laos, and Cambodia–Laos borders

BackgroundVector control is still a pivotal method for preventing malaria, and its potency is weakened by the increasing resistance of vectors to chemical insecticides. As the most abundant and vital malaria vector in Southeast Asia, the chemical insecticide resistance status in Anopheles sinensis remains elusive in Laos, which makes it imperative to evaluate the true nature of chemical insecticide resistance-associated genetic mutations in An. sinensis in Laos.MethodsAdult An. sinensis were collected from three border regions in Laos. DNA was extracted from individual mosquitoes. PCR amplification and DNA sequencing of a fragment containing codon 1014 of the voltage-gated sodium channel (vgsc) gene were completed to study the kdr allele frequency distribution, kdr intron polymorphism, population genetic diversity, and the evolutionary status of the kdr codon. The mitochondrial cytochrome c oxidase subunit II gene (COII) was amplified and sequenced to examine population variations, genetic differentiation, spatial population structure, population expansion, and gene flow patterns.ResultsNine wild kdr haplotypes of the vgsc gene were detected in this study, and eight of them, namely 1014L1, 1014L2, 1014L4, 1014L7, 1014L9, 1014L10, 1014L11, and 1014L21, were discovered in the China–Laos border (northern Laos), while 1014L3 was only detected in the Thailand–Laos border (northwestern Laos) and Cambodia–Laos border (southern Laos). The newly identified haplotype, 1014L21, was uniquely distributed in the China–Laos border and was not identified in other countries. Based on sequence analysis of the mitochondrial COII genes, significant genetic differentiation and limited gene flow were detected between the China–Laos and Cambodia–Laos An. sinensis populations, which suggested that those two regions were genetically isolated. The distinct distribution of the kdr haplotype frequencies is probably the result of geographical isolation in mosquito populations.ConclusionsLack of kdr mutations in the vgsc gene was probably due to genetic isolation and the absence of intense selection pressure in the three border regions of Laos. This study reveals that pyrethroid-based chemical insecticides are still appropriate for battling An. sinensis in parts of Laos, and routine monitoring of chemical insecticide resistance should be continuously implemented and focused on more restricted areas as part of chemical insecticide resistance management.Graphical

Two new species of the nominotypical subgenus Gonioctena Chevrolat, 1836, from China and Laos, and a proposed new species-group (Coleoptera: Chrysomelidae: Chrysomelinae).

The Gonioctena kanfani species-group of the nominotypical subgenus Gonioctena Chevrolat, 1836 is proposed and reviewed. This group comprises the following five species, including two new to science, distributed in eastern China and northern Laos: G. kanfani (Chen, 1941), G. kamikawai (Chj, 1958), G. fujiana Cho Borowiec, 2016, G. jolantae new species, and G. lukasi new species. Members of this species-group are easily distinguished from other species by their metallic lustre, two yellowish-brown markings on the elytral humeri, and the trifurcated tip of the flagellum of the aedeagus. Photographs of habitus, illustrations of male genitalia, and diagnostic characters for each species are given. A distribution map and literature records are also provided.

A Middle Pleistocene Denisovan molar from the Annamite Chain of northern Laos

The Pleistocene presence of the genus Homo in continental Southeast Asia is primarily evidenced by a sparse stone tool record and rare human remains. Here we report a Middle Pleistocene hominin specimen from Laos, with the discovery of a molar from the Tam Ngu Hao 2 (Cobra Cave) limestone cave in the Annamite Mountains. The age of the fossil-bearing breccia ranges between 164–131 kyr, based on the Bayesian modelling of luminescence dating of the sedimentary matrix from which it was recovered, U-series dating of an overlying flowstone, and U-series–ESR dating of associated faunal teeth. Analyses of the internal structure of the molar in tandem with palaeoproteomic analyses of the enamel indicate that the tooth derives from a young, likely female, Homo individual. The close morphological affinities with the Xiahe specimen from China indicate that they belong to the same taxon and that Tam Ngu Hao 2 most likely represents a Denisovan.

Satellite observations reveal 13 years of reservoir filling strategies, operating rules, and hydrological alterations in the Upper Mekong River basin

Abstract. The current situation in the Lancang–Mekong River basin is emblematic of the issues faced by many transboundary basins around the world: riparian countries prioritize national water–energy policies and provide limited information on how major infrastructures are operated. In turn, such infrastructures and their management become a source of controversy. Here, we turn our attention to the Upper Mekong River, or Lancang, where a system of 11 mainstream dams controls about 55 % of the annual flow to Northern Thailand and Laos. Yet, assessing their actual impact is a challenging task because of the chronic lack of data on reservoir storage and dam release decisions. To overcome this challenge, we focus on the 10 largest reservoirs and leverage satellite observations to infer 13-year time series of monthly storage variations. Specifically, we use area–storage curves (derived from a digital elevation model) and time series of water surface area, which we estimate from Landsat images through a novel algorithm that removes the effects of clouds and other disturbances. We also use satellite radar altimetry water level data (Jason and Sentinel-3) to validate the results obtained from satellite imagery. Our results describe the evolution of the hydropower system and highlight the pivotal role played by Xiaowan and Nuozhadu reservoirs, which make up to ∼ 85 % of the total system's storage in the Lancang River basin. We show that these two reservoirs were filled in about 2 years and that their operations were marginally affected by the drought that occurred in the region in 2019–2020. Deciphering these operating strategies will help enrich existing monitoring tools and hydrological models, thereby supporting riparian countries in the design of more cooperative water–energy policies.

The effects of season, geography, and urbanization on the diversity of edible insects at food markets in Laos.

Laos, a mountainous and landlocked country located in Southeast Asia, has the highest percentage of people using insects as food in the world. Lao people obtain edible insects through harvesting in the natural environment and purchasing at food markets. There has been no comprehensive survey about sales of insects at food markets in the wider areas, and our understanding of sales of insects in Laos is limited. Our study aims to identify environmental factors affecting the sales and the diversity of edible insects sold at food markets in Laos. We visited 37 and 55 markets, during the dry and rainy seasons respectively, in northern Laos to record species of sold insects. We then analyzed the correlations between insect sales and three potential factors (seasons, provinces, and urbanization indices around the markets). There was no significant difference in the percentage of markets selling insects between in the dry and rainy seasons; 40–50% of the markets sold insects in both seasons. The composition of sold insects differed between in the dry and rainy seasons, which reflects the seasonality and life history of each insect species. There tended to be more groups of insects for sale in the Vientiane capital than in the other provinces in both seasons. This trend may reflect that it is more difficult to obtain edible insects through wild harvesting in highly urbanized Vientiane capital than in the other provinces, and the commercial demand for insects is increasing. This possibility is directly supported by the positive correlation between the urbanization index and the insect sales in the rainy season. Laos has recently undergone rapid urbanization, particularly in the Vientiane capital, and we predict that commercial demand for edible insects will be much higher in the Vientiane capital and the urbanized cities in the future.

Public health and economic impact assessment of PM2.5 from open biomass burning over countries in mainland Southeast Asia during the smog episode

PM2.5 is considered the principal air pollutant caused by open biomass burning (OBB) in Mainland Southeast Asia (MSEA) and significant adverse health effects and economic burdens. The goals of this work are to conduct a literature review on relative measures of the effect associated with the exposure to OBB emission in MSEA, to analyze the impact of OBB emission on PM2.5 concentration in MSEA using the dispersion model, and to estimate the public health and economic impacts associated with the exposure to PM2.5 from OBB on regional and national scales using Environmental Benefits Mapping and Analysis Program during a smog episode. This work found that OBB was the largest emission source in MSEA, contributing 57% to the PM2.5 concentrations, with the substantial OBB impact was found in Northern Laos and Eastern Myanmar. As a result, the exposure to PM2.5 from OBB was estimated to contribute a substantial number of deaths regarding all-cause (78,276 cases - 95% CI: 62,915–92,629), respiratory disease (6,716 cases – 95% CI: 3,639–9,482), and cardiovascular disease (1,076 cases – 95% CI: 490-1,615). The economic impact was estimated at 23.28 billion (95% CI: 18.69–27.57), 1.90 billion (95% CI: 0.88–2.40), and 0.44 billion (95% CI: 0.20–0.67) USD, respectively. OBB emission caused the greatest public health and economic impact in Myanmar, while the smallest impact was found in Cambodia. Our study provides policymakers with quantitative estimates of the OBB impacts so that they can develop appropriate control measures at the regional and national levels in MSEA.

The 2014 Northern Thailand Mw 6.1 Earthquake and its Seismogenic Tectonics

AbstractOn May 5, 2014, an earthquake with a magnitude of Mw 6.1 (the largest earthquake in Thailand so far) occurred in Chiang Rai of the Golden Triangle area in northern Thailand. We had an opportunity to conduct field survey immediately after the earthquake. Serious damage to buildings and casualties of lives were observed, and the estimated Maximum Mercalli Intensity (MMI) of the earthquake is VIII (evaluated according to the MMI scale of the Chinese Standard). No long continuous ground ruptures were produced during the earthquake, but in the epicenter (commonly within MMI VIII extent), massive small linear ruptures (usually several tens of meters long) developed and displayed intriguing structural features, offsetting many roads several centimeters left laterally on NE trending cracks or offsetting right laterally on NW trending ones. The focal mechanism solution of earthquake shows that this is a pure strike‐slip event, and two nodal planes in NW and NE directions had the same motion senses respectively as those of breakage associated with the earthquake. The long axis of the isoseismals and aftershock distributions are in NE direction, which is consistent with the strike of Luang Namtha fault. The 230‐km‐long Luang Namtha fault which starts from the border of China and Laos, runs through northern Laos, and terminates at Chiang Rai of Thailand is predominated by left‐lateral strike‐slip and active in late Quaternary, and two earthquakes over Ms 6.0 occurred along the fault in 1925 and 2007 respectively. This Mw 6.1 earthquake occurred at the southwestern end of the fault. All related features such as evident structural rupturing, elongated orientation of MMI and aftershock distribution, as well as the location of the epicenter, suggest that the Luang Namtha fault may be responsible for the 2014 Northern Thailand earthquake.

BRI as cognitive empire: Epistemic violence, ethnonationalism and alternative imaginaries in Zomian highlands

China's Belt and Road Initiative (BRI) has become the lodestar of Beijing's efforts to increase its global political and economic influence. This article interrogates BRI discourse, arguing that the normative adoption of BRI narratives as a means for making sense of connectivities between China and other places risks producing new forms of epistemic violence against subaltern populations. The empirical focus of this paper is on China‐Laos relations, and the epistemic positioning of highland ethnic minority groups in northern Laos. This context offers a valuable case study for examining BRI discourse due to: (a) the profound effects of Chinese investment in Laos; (b) the geostrategic importance of Laos as a BRI ‘gateway’ between China and Southeast Asia; (c) the deep histories of ethnic minority engagements across China and Laos; and (d) the limited extant research on both China‐Laos relations and the more localized effects of Chinese actors within the highland border regions.

Equilibrium moisture content map for Laos

Providing the equilibrium moisture content values for territories is important for avoiding major problems due to dimensional changes in wooden products. This study evaluated the average equilibrium moisture content values for twelve months (from 1981 to 2020) for Laos and produced an equilibrium moisture content map. A model was used to generate the equilibrium moisture content values based on temperature and relative humidity data obtained from the POWER Data Access Viewer v2.0.0. for 18 provinces (148 districts) based on the geographic coordinates of each district in Laos. The lowest equilibrium moisture content (12% to 13%) values were found in Vientiane Capital City, Vientiane province, Louangprabang, Bokeo, Attapeu, Louang Namtha, Oudomxay, Houaphan, Sayaburi, Savannakhet, Salavan, and Champasak province. The rest of the districts, which had an equilibrium moisture content ranging from 13% to 16%, were mostly found on the eastern part of Laos and a small part of Northern Laos. The monthly swinging average value of the equilibrium moisture content ranged from 10% to 18% across the country. The equilibrium moisture content values for each district in Laos were also defined.

Landscape heterogeneity, basis risk and the feasibility of index insurance: An analysis of rice in upland regions of Southeast Asia

Despite its promise, the adoption of index insurance has been hindered by the extent of basis risk, the additional variability introduced by its reliance on a signal correlated with losses rather than losses themselves. We examine the feasibility of substantially reducing basis risk by accounting for heterogeneity in production conditions via clustering data into more homogeneous groups. We exemplify this approach using data from a sample of rice producers in northern Laos, using Normalized Difference Vegetation Index (NDVI) data as the index on which the contract is defined. Our results show that accounting for landscape heterogeneity substantially improves the insurance contracts that can be offered to rice producers.

Divergence in Nutritional Intake and Physical Activity Patterns Among Households in a Village of Ethnic Minorities in Northern Laos at the Initial Stage of Health Transition

Divergence in Nutritional Intake and Physical Activity Patterns Among Households in a Village of Ethnic Minorities in Northern Laos at the Initial Stage of Health Transition

Positioning kindness and care at the centre of health services: A case study of an informal health and development programme oriented to surviving well collectively

AbstractThe mainstream development agenda highlights how important access to health care is for poorer regions of the world. In the area of maternal health, this is expressed in a concern to drive down rates of maternal morbidity and improve access to maternal health care services. While important, the focus on metrics misses the way that relations of care are fundamental to good health. This paper takes an example of a project which is offering a different approach to health and development in the resource scarce environment of Luang Prabang Province, in northern Laos. Here, a group of antipodean midwives has partnered with provincial health authorities to offer a midwifery training programme to health workers posted in remote rural health centres. Supported by the analytical tools of diverse economies, this paper explores how this programme centres relationality, collectivity and an ethic of kindness, and discusses the advantages of being relationship based, small and informal. The paper concludes that this training programme can be understood as an example of a community economy of care: based on global networks of care instead of formal development programmes built on global networks of bureaucracy.

Bat coronaviruses related to SARS-CoV-2 and infectious for human cells.

The animal reservoir of SARS-CoV-2 is unknown despite reports of SARS-CoV-2-related viruses in Asian Rhinolophus bats1-4, including the closest virus from R. affinis, RaTG13 (refs. 5,6), and pangolins7-9. SARS-CoV-2 has a mosaic genome, to which different progenitors contribute. The spike sequence determines the binding affinity and accessibility of its receptor-binding domain to the cellular angiotensin-converting enzyme 2 (ACE2) receptor and is responsible for host range10-12. SARS-CoV-2 progenitor bat viruses genetically close to SARS-CoV-2 and able to enter human cells through a human ACE2 (hACE2) pathway have not yet been identified, although they would be key in understanding the origin of the epidemic. Here we show that such viruses circulate in cave bats living in the limestone karstic terrain in northern Laos, in the Indochinese peninsula. We found that the receptor-binding domains of these viruses differ from that of SARS-CoV-2 by only one or two residues at the interface with ACE2, bind more efficiently to the hACE2 protein than that of the SARS-CoV-2 strain isolated in Wuhan from early human cases, and mediate hACE2-dependent entry and replication in human cells, which is inhibited by antibodies that neutralize SARS-CoV-2. None of these bat viruses contains a furin cleavage site in the spike protein. Our findings therefore indicate that bat-borne SARS-CoV-2-like viruses that arepotentially infectious for humans circulate in Rhinolophus spp. in the Indochinese peninsula.