CRYPTOSPORIDIUM AND GIARDIA RISK IN THAILAND
May 2016. The collaborative work between the Wetlab, Duke-NUS, and Universiti Malaya, Malaysia on Cryptosporidium and Giardia risk in northern Thailand was published in Science of the Total Environment (Joon Chuah, primary author). The catchment-scale investigation of the prevalence of Cryptosporidium and Giardia in the Kuang River Basin was carried out during the dry and rainy seasons. Water samples were collected from the Kuang River and its tributaries as well as a major irrigation canal at the study site. We also investigated the prevalence of gastrointestinal parasitic infection among dairy and beef cattle hosts. Cryptosporidium and/or Giardia were detected in all the rivers considered for this study, reflecting their ubiquity within the Kuang River Basin. The high prevalence of Cryptosporidium/Giardia in the upper Kuang River and Lai River is of a particular concern as both drain into the Mae Kuang Reservoir, a vital source of drinking-water to many local towns and villages at the research area. We did not, however, detected neither Cryptosporidium nor Giardia were in the irrigation canal. The frequency of Cryptosporidium/Giardia detection nearly doubled during the rainy season compared to the dry season, highlighting the importance of water as an agent of transport. In addition to the overland transport of these protozoa from their land sources (e.g. cattle manure, cess pits), Cryptosporidium/Giardia may also be re-suspended from the streambeds (a potentially important repository) into the water column of rivers during storm events. Faecal samples from dairy and beef cattle showed high infection rates from various intestinal parasites — 97% and 94%, respectively. However, Cryptosporidium and Giardia were only detected in beef cattle. The difference in management style between beef (freeranging) and dairy cattle (confined) may account for this disparity. Finally, phylogenetic analyses revealed that the Cryptosporidium/Giardia-positive samples contained C. ryanae (non-zoonotic) as well as Giardia intestinalis assemblages B (zoonotic) and E (non-zoonotic). With only basic water treatment facilities afforded to them, the communities of the rural area relying on these water supplies are highly at risk to Cryptosporidium/Giardia infections.
DISENTANGLING THE OPISTHORCHIS HOCUS POCUS
Feb 2016. The joint collaborative research between NUS and Khon Kaen University is beginning to pay off. Our recent paper published in Ecohealth demonstrates how a transdisciplinary learning approach provided new insights for explaining persistent Opisthorchis viverrini infection in northern Thailand, as well as elucidating problems of focusing solely on the parasite as a means of addressing high prevalence of cholangiocarcinoma. In the work, researchers from diverse backgrounds collaborated to design an investigative homestay program for 72 Singaporean and Thai university students in five northeast Thai villages. The students explored how liverfluke infection and potential cholangiocarcinoma development is influenced by local landscape dynamics, aquatic ecology, livelihoods, food culture, and health education. Qualitative fieldwork was guided daily by the researchers in a collaborative, co-learning process that led to viewing this health issue as a complex system, influenced by interlinked multidimensional factors. Our transdisciplinary experience has led us to believe that an incomplete understanding of these linkages may reduce the efficacy of interventions. Further, viewing liver fluke infection and cholangiocarcinoma as the same issue is inadvisable. Although O. viverrini infection is an established risk factor for the development of cholangiocarcinoma, multiple factors are known to influence the likelihood of acquiring either. Understanding the importance of the current livelihood transition, landscape modification and the resulting mismatch between local cultures and new socio-ecological settings on cholangiocarcinoma initiation and liver fluke transmission is of critical importance as it may help readjust our view of the respective role of O. viverrini and other socio-economic risk factors in cholangiocarcinoma etiology and refine intervention strategies. As demonstrated in this study, transdisciplinary approaches have the potential to yield more nuanced perspectives to complex diseases than research that focuses on specific aspects of their epidemiology. They may therefore be valuable when designing effective solutions to context-sensitive diseases such as liverfluke infection and cholangiocarcinoma.
FLUOROSIS RISK IN THAILAND
JAN 2016. Joon Chuah's first paper came out in Science of the Total Environment (see below). The paper synthesizes his field data and the findings in Lye Han Rui's honors thesis to explain the physical mechanisms associated with the fluoride hotspot in Chiang Mai Basin in northern Thailand. Unsurprising is that anthropogenic activities potentially exacerbate this naturally-occurring health hazard.
FLUOROSIS RISK IN THAILAND
JAN 2016. Joon Chuah's first paper can out in Science of the Total Environment. The paper synthesizes his field data with the findings in Lye Han Rui's honors thesis to explain the physical mechanisms associated with the fluoride hotspot in Chiang Mai Basin in northern Thailand. Unsurprising is that anthropogenic activities potentially exacerbate this naturally-occurring health hazard.
Nov 2014 - Joon Chuah won the Niloufer Chinoy Award for his oral presentation at the 32nd Conference of the International Society for Fluoride Research. Joon's talk was entitled 'Fluoride in the Water Resources of Northern Thailand: Source, Transport, Distribution and Water Management Implications'. Conference was organized by The International Society for Fluoride Research with the Department of Health, Ministry of Public Health, Thailand.
Fluoride Officially Classified as a Neurotoxin
THE GREAT ELEPHANT-CORAL CONUNDRUM
Dec 2016. Ruins of brick and stone religious monuments, brick city walls, and earthworks and moats are the enduring relics of northern Thailand’s great early kingdoms. ADZ teamed with Spencer Wood and Layle Wood to study several enigmatic earthwork trench systems in northern Thailand. The trenches were built on hillsides and could not possibly hold water, and therefore are not former moats. Evidence suggests that some encircling entrenchments may have been for the capture or containment of elephants, probably 800–1200 years ago.
The paper on this study was recently published in the Journal of Field Archaeology.
MUCH (MORE) ADO ABOUT CARBON
Nov 2015. Tak Fung joined forces with Jiaqi and ADZ on a review of allometric equations for major land covers in SE Asia. The paper is a series of four related to Jiaqi's MSc degree and the Wet Lab's ongoing interest in understanding the impacts of land-cover/land-use change on carbon stocks in SE Asia.
Aug 2015. Dan Friess, of Mangrove Lab fame, joined Jiaqi in the opportunistic biomass sampling of a fallen tree on campus (photo to the left).
A CLEAR AND PRESENT DANGER: FLASH FLOODS AND DEBRIS FLOWS IN LADAKH
Aug 2015. Sebastian Cantatero, Robert Wasson, and ADZ hooked up with Pradeep Srivastava from the Wadia Institute of Himalayan Geology to begin an investigation of the recent spate of deadly floods and debris flows in the Ladakh Area of India. Along the way we ran into local archeologist Sonam Spalzin, who provided some local context. Hidden in the stratigraphy of the flood plains of many mountain streams is a record of many huge events occurring in the past. Rapid and widespread development largely in response to tourism is increasing the vulnerability of many residents to flash floods and debris flows.
The photos were taken in the Ladakh and Zangskar Valleys in August 2015.
Sebastian Cantarero is currently a research assistant at the National University of Singapore
Session on Swamp Forest Ecology and Hydrology
2-7 August 2015. Dan Friess and Situ Nurhidayu Abu Bakar and hosted a session on Tropical Swamp Forest Ecology and Hydrology at the 2015 AOGS annual meeting, which was held in Singapore from 2-7 August, 2015. Details are at the conference www site.
The wetlab contributed 5 papers:
Nguyen, TTC, RA Wasson, SH Win, K Pai, MH Lim, AD Ziegler. 2015. Heavy Metal Distributions in a Tropical Forest Catchment. Presentation IG03-D3-PM2-329-009.
Win, SH, TTC Nguyen, K Pai, MW Lim, RA Wasson, AD Ziegler. 2015. Water Quality and Hydrologic Conditions in the Nee Soon Freshwater Swamp Forest, Singapore: Implications for Ecological Systems. Presentation IG03-D4-PM2-P-016.
Win, SH., RA Wasson, T O’Dempsey, TTC Nguyen, AD Ziegler. 2015. History of Land Use / Land Cover Changes in the Nee Soon Swamp Forest, Singapore: Combined Inventory of Historical and Contemporary Mapping Products. Presentation IG03-D4-PM2-P-017.
Wasson, RA, AD Ziegler, K Pai, KNBM Ramdzan, RYT Koh, TTC Nguyen. 2015. Erosion and Recovery Regimes in the Nee Soon Swamp Forest Catchment, Singapore. Presentation IG03-D3-PM2-329-010.
Wasson, RA, AD Ziegler, TTC Nguyen, K Pai, SH Win. 2015. Disturbance Regimes at the Interface of Geomorphology and Ecology at Nee Soon and Johor. Presentation IG03-D3-PM2-329-01.
RUBBER EXPANSION THREATENS BIODIVERSITY AND LIVELIHOODS
July 2015. Antje Ahrends of the Royal Botanic Garden Edinburgh lead the charge in the Wetlab's recent analysis of the impacts of rubber expansion in SE Asia. The paper, published in Global Environmental Change, shows that between 2005 and 2010 rubber has been planted into increasingly sub-optimal environments in SE Asia. in 2015, 72% of plantation area is in environmentally marginal zones where reduced yields are likely. An estimated 57% of the area is susceptible to insufficient water availability, erosion, frost, or wind damage, all of which may make long-term rubber production unsustainable. Other plantations are in locations at risk to damage from tropical storms. Further, future climate change may lead to a net exacerbation of environmental marginality for both current and predicted future rubber plantation area. New rubber plantations are also frequently placed on lands that are important for biodiversity conservation and ecological functions. For example, between 2005 and 2010, more than 2500 km2 of natural tree cover and 610 km2 of protected areas were converted to plantations. Overall, expansion into marginal areas creates potential for loss-loss scenarios: clearing of high-biodiversity value land for economically unsustainable plantations that are poorly adapted to local conditions and alter landscape functions (e.g. hydrology, erosion) – ultimately compromising livelihoods, particularly when rubber prices fall. The paper expands upon an earlier analysis of livelihood and environmental impacts of rubber expansion in the region, lead by Jefferson Fox (East-West Center) and Jean-Christophe Castella (IRD France) in 2014.
FLOODS AND THE FUTURE
Feb 2015. Under the Auspices of the NUS Environment Clusters and the Institute of Water Policy at the LKY School of Public Policy, Bob Wasson and ADZ organized a region workshop aimed at reducing the uncertainty in predicting future floods in the area. The workshop united diverse groups of people from the insurance industry, historians, scientists, and policy makers during the two day event held at NUS.
Five wet lab students complete MSc degrees in 2014 (in order from left to right)
Michelle Quak, who by the way absolutely does not look like a moose, finished her MSc degree in July 2014. She was the first to graduate from the WETlab! She used a multiproxy sediment fingerprinting approach to determine the impact of land-cover change on seagrass meadows on Koh Yao Yai, Island (Thailand). She is currently writing up the work for publication...and working for a living now, learning to be a (urban) geospatial analyst. She still loves trees.
Lucy G Gillis, completed a dissertation entitle "Facilitation beyond diversity: self facilitation of mangrove-seagrass-coral ecosystems". Officially enrolled at NIOZ (The Netherlands), she worked with ADZ on a project sponsored by the Singapore-Delft Water Alliance. Several chapters of her dissertation have already been published (see pub hub).
Shamraz Anver finished an excellent thesis looking at artificial intelligence methods for gap filling of stream discharge time series. He plans to write this work for publication soon (hint hint). During his stay he won an award for the best presentation at the 8th Mathematics and Physical Science Graduate Congress, December 2012, Bangkok, Thailand. His presentation was on "using artificial intelligence models for gap filling in hydrologic time series".
James Bramante finished his MSc in December, and has moved away from NUS to begin a PhD at Woods Hole. His MSc Thesis investigated novel non-destructive ways of determining seagrass biomass from remote sensing imagery.
Rutger Hofste completed "Comparative analysis among near-operational evapotranspiration products for the basin based on earth observations". His degree was a double Master of Science in Hydraulic Engineering and Water Resources Management at the Delft University of Technology and the National University of Singapore (Co-supervised with Wim Bastiaanssen, Delft University of Technology).
A DECADE OF DATA COLLECTION PAYING OFF
Dec 2014. Ten years ago we initiated hydrological monitoring in the Mae Sa Catchment in northern Thailand. At times the network consisted of three climate stations, 6 soil moisture stations, eleven rain guages, and one stream flow station within the 84-ha catchment. The first two of several expected articles came out in 2014 - on on bedload estimates and the other on turbidity-suspended sediment relationships. A third paper on nutrient transport is in revision, and expected out next year.
GE5211 Assault on the Ping River
October 2014. ADZ, Grahame Oliver, and Robert Wasson led five NUS graduate students to northern Thailand for a week to look at strategraphical evidence of large historical floods on the Ping River. The great Chris Morely came along for a day to help us sort out the rocks on the Doi Suthep metomorphic core complex. And of course, what would a trip to Mae Sa catchment be without Oliver droning on about Sibumasu!
DEMISE OF AN ANCIENT LANNA CAPITAL
1 Oct 2014. The much anticipated paper in Natural Hazards by Serene Ng on her interpretation of the when and how of the demise of the old Lanna capital Wiang Khum Kam is now out. This paper demonstrates that the importance of rivers in northern Thailand was anchored upon society’s dependence on them for sustenance and defense. Concurrently, rivers were also of deep religious and cultural significance. Hence, many northern Thai settlements were located near rivers. This resulted in their susceptibility to flood hazards. Our study investigates the interactions between the Ping River and the population of Wiang Kum Kam. Wiang Kum Kam was one of the former capitals of the Lanna Kingdom, a thirteenth- to sixteenth-century polity in northern Thailand. Described as the ‘Atlantis’ of the Lanna kingdom, the city was buried under flood sediments several centuries ago. Based on the floodplain sediments excavated, we argue that the city was abandoned after a large flood. Radiocarbon dating of charcoal found in the coarse sand layer deposited by the flood suggests that the deposition occurred sometime after ca. 1477 AD–1512 AD. Prior to this large flood, persisting floods in the city were noted in the Chiang Mai Chronicle and were also recorded in the floodplain stratigraphy. We show that an elongated mound on the floodplain in Wiang Kum Kam was a dyke constructed after ca. 1411 AD to alleviate the effects of persisting floods. From this story of paleofloods and Wiang Kum Kam, we conclude with two lessons for the management of modern floods in urban Thailand. (Thanks to Spen Woods for getting us involved in this work).
DATING IN INDIA
1 Aug 2014. From March to July 2014, Lim Han She and Elisha Teo were based in Ahmedabad, India to date flood deposits from Thailand. They trained in optically stimulated luminescence (OSL) dating with Dr Ashok Singhvi at his lab in the Physical Research Laboratory (unit of the Indian Department of Space). OSL dating is a really interesting process that involves treating the sediment with lots of acids, tools and machinery… all whilst in the dark (the dates are dependent on the exposure to light). All in all it was an amazing learning experience that will not be forgotten!"
Giardia & Cryptosporidium: The Deadly Duo
September, 2014. After months of anxious search and sampling literally truck loads of water in Northern Thailand, Joon has finally found the elusive Giardia and Cryptosporidium - possibly the two of the most dangerous waterborne parasites to mankind but rarely studied in developing nations - in the the rivers of Chiang Mai and Lamphun. He has since proceeded to map the spatial distribution of these protozoa in selected parts of the Ping river basin and investigated the seasonal effects to their presence in the precious drinking water supplies of the region.
Parasites in Poo-radise
Summer 2014. Nabila and some of the #WETlab crew have been going around villages in Thailand collecting copious amounts of cow manure. The very noble Nabila is studying the prevalence of potentially pathogenic gastro-intestinal parasites in dairy and free-ranging cattle. Samples collected are analysed under the supervision of the incomparable Prof. Yvonne Lim in her laboratory at the University Malaya.
Of Water and Bacteria...
1 Sept 2014. Esther Tan is investigating the bacteria, Burkholderia pseudomallei, in the wetlands of Northeast Thailand. The bacteria is responsible for a disease called Melioidosis, for which there are about 2,000 cases annually with a 40% mortality rate. Most people, especially rice farmers, are infected with the bacteria through environmental (soil and water) exposure. Her work included fieldwork in Thailand with several members of the wetlab, as well as laboratory work in Dr. Rasana Wongratanacheewin's laboratory at the Melioidosis Research Center (MRC) at Khon Kaen University in Thailand.
Kedarnath Tragedy (re)visited
July 2014. ADZ, Bob Wasson, and Alok Bhardwaj visited the Uttarakand region and the Mandakani Tributary where devastating landslides and floods killed thousands of people in June of 2013. Alok will be studying the rainfall and landslide triggers to flood on the Mandakani River, for which the Kedarnath temple sits at the headwaters. To date, our team has conducted two field trips to the Mandakini catchment during February and June, 2014. The first trip was aimed to perform a general survey to qualitatively estimate the factors and level of destruction. Few interviews with the local people were conducted to ascertain the depth of sediment deposition along the river course and their experiences of the calamity. During the follow up trip in June, our team hiked approx. 20 Km to reach and survey Kedarnath at about 3500m asl, the worst flood affected area in June 2013 floods. Additionally, the attributes of both large and medium natural and anthropogenic landslides such as GPS coordinates, landslide boundary coordinates and distance of landslides from river were measured in the Mandakini catchment.
Teaching Public Health Research
May 2014. May 2014, students from the National University of Singapore (NUS) and Khon Kaen University (KKU) were placed in homestays within five villages: Non Kradao, Chi Kok Kho, Lawa, Ban Don
Tum, and Pho Tak, all located in Khon Kaen province of northeast Thailand. Through extended homestays, the students sought to understand issues surrounding the chronic problem of OV-related
cholangiocarcinoma within the region. The students addressed four major themes: (1) landscape dynamics; (2) livelihoods; (3) food culture; and (4) health education. The main modes of
enquiry were participant observation and informal interviews. The inclusion of local Thai students in each group precluded the need for interpreters. This field-based investigative approach
cemented our emerging beliefs that the linkage between opistorchiasis and the development of cholangiocarcima (CCA) in high-risk areas of Thailand involves a complex web of environmental, social,
cultural, and behavior drivers. While not quantitatively robust, the process provided fresh insights that allow for a state-of-the-art commentary on contemporary drivers of opistorchiasis
and the development of cholangiocarcima in the area, and likely the region. The results cement our belief that development of CCA from OV infection is not simply a linear function of
consuming improperly cooked fish infected with the OV parasite.
the life cycle of Opisthorchis viverrini, human infection occurs when cyprinid fish bearing metacercariae in their tissues and organs are consumed raw or partially cooked
(including smoked, pickled and salted) (Grundy-Warr et al., 2012). Metacercariae in the fish excyst in the duodenum and enter the bile ducts, where they mature sexually. The adult worms produce
eggs which are passed out in faeces. When freshwater bithynia snails ingest the eggs, miracidium hatch and develop into sporocysts, then redia. The life cycle closes when free-swimming cercariae
penetrate the tissues and skin of cyprinid fish, and become infective metacercariae. (Sithithaworn et al., 2014; Sripa et al., 2011). Bithynia snails and cyprinid fish are common in Mekong
wetlands that are crucial to rural livelihoods (Petney et al., 2012). Chronic opisthorchiasis is a primary risk factor for debilitating CCA, among others.
What gets inside us?
1 May 2014. Jiaqi Yuen is into bioavailability. She has crafted a gizmo that simulates how your stomach process soil if ingested, thereby releasing harmful contaminants in the body.
Carrying on from Jiaqi's mometum, Honours student Lim Wan Lin will investigate heavy metal accumulation in housefhold dust in Singapore. Wan Lin is a final year student for 2014.
Big Catch 2014
April 2014. drZ supervised six Honors students in AY2013-14: Rachel Koh, Anna Yeo, Candice Soh, Chiam Gui Ping, Aricia Tan, and Lye Han Rui.
Thanks to Grahame Oliver, Robert Wasson, David Higgitt, and Joon Chuah for the help...
- Rachel: A sedimentary record of land use change and heavy metal deposition in Nee Soon Swamp Forest, Singapore.
- Anna: Biogeochemistry of aluminum in the acidified streams of Bukit Timah Nature Reserve Singapore.
- Candice: Rainfall partitioning in a montane bamboo-dominated stand, northern Thailand.
- Gui Ping: Geologic controls of drainage systems and channel morphology in Doi Suthep metamorphic core complex, northern Thailand.
- Aricia: Limitations to using neodymium, strontium, and lead isotopes for sediment tracing in small catchments: a case study of Mae Sa Catchment, northern Thailand.
- Han Rui: The F word: groundwater fluoride contamination in Chiang Mai, northern Thailand.
Joon is off to Chiang Mai for fieldwork - and won't be back for many a day. He has a new 'house'! And he has started a new project looking at fluoride contamination in groundwater of the Chiang Mai basin, along with Han Rui and drZ.
He's also brought along a copy of Thoreau's Walden with him.
Serene Ng won the FASS Outstanding Undergraduate Researcher (OUR) Prize for year 2011/2012 for her Honour's thesis, "The Role of Rivers in Northern Thai History: A Study of Paleofloods at Wiang Kum Kam."
She also graduated first class honors. Yeah!
Nick has started a spin-off lab! The Auto Geo Systems Laboratory - check it out!
He also captured the most amazing 23 seconds of aerial photography ever collected --twice. Once by balloon over drZ's house in Chiang Mai, the other we are told, on Yao Yai Island by model plane. Details await!
The 2012 Dream Team set the world record for highest jump shot at dr Z's in Chiang Mai in August. One is now a cop; one is a double naught spy; and the third, a scholar in the making...
Mandy Song: Biophysical impacts of elephant trampling in Thailand.
Serene Ng: Flooding effects on location of Wat Wiang Khum Kam, Chiang Mai, Thailand
Ang Zuo Jin: Sediment Fingerprinting in Mae Sa Catchment, Chiang Mai, Thailand.