Publications by authors named "Le Xuan Hung"

24 Publications

  • Page 1 of 1

Factors associated with the duration of hospitalisation among COVID-19 patients in Vietnam: A survival analysis.

Epidemiol Infect 2020 06 10;148:e114. Epub 2020 Jun 10.

Institute of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Vietnam.

Background: The median duration of hospital stays due to COVID-19 has been reported in several studies on China as 10-13 days. Global studies have indicated that the length of hospitalisation depends on different factors, such as the time elapsed from exposure to symptom onset, and from symptom onset to hospital admission, as well as specificities of the country under study. The goal of this paper is to identify factors associated with the median duration of hospital stays of COVID-19 patients during the second COVID-19 wave that hit Vietnam from 5 March to 8 April 2020.

Method: We used retrospective data on 133 hospitalised patients with COVID-19 recorded over at least two weeks during the study period. The Cox proportional-hazards regression model was applied to determine the potential risk factors associated with length of hospital stay.

Results: There were 65 (48.9%) females, 98 (73.7%) patients 48 years old or younger, 15 (11.3%) persons with comorbidities, 21 (16.0%) severely ill patients and 5 (3.8%) individuals with life-threatening conditions. Eighty-two (61.7%) patients were discharged after testing negative for the SARS-CoV-2 virus, 51 were still in the hospital at the end of the study period and none died. The median duration of stay in a hospital was 21 (IQR: 16-34) days. The multivariable Cox regression model showed that age, residence and sources of contamination were significantly associated with longer duration of hospitalisation.

Conclusion: A close look at how long COVID-19 patients stayed in the hospital could provide an overview of their treatment process in Vietnam, and support the country's National Steering Committee on COVID-19 Prevention and Control in the efficient allocation of resources over the next stages of the COVID-19 prevention period.
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http://dx.doi.org/10.1017/S0950268820001259DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306545PMC
June 2020

Knowledge, Attitude, and Practice Regarding Breast Cancer Early Detection Among Women in a Mountainous Area in Northern Vietnam.

Cancer Control 2019 Jan-Dec;26(1):1073274819863777

1 Institute of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Vietnam.

Breast cancer is the most common cancer in women all over the world, also in Vietnam. In recent years, the incidence of breast cancer has been increasing in Vietnam, and most cases are diagnosed at late stages, making treatment more difficult. More and better early detection could help more women to survive. The aim of this study was to identify the current knowledge, attitude and practice about early detection of breast cancer as well as potential predictors of breast cancer screening among women aged 20 to 49 year in a mountainous commune in Thanh Hoa Province, Vietnam, in a largely ethnic Muong population. Women aged 20 to 49 years were selected by systematic random sampling to participate in a cross sectional study in October 2017. They were interviewed with a closed questionnaire about their knowledge of breast cancer, its risk factors, and warning signs. A checklist for performance of breast self-examination was also applied. Three hundred six women agreed to participate in the study. More than half had a low level of knowledge, and were weak in attitude and practice about breast self-examination, clinical breast examination, breast ultrasound, and mamography. Among women who had practiced at least 1 screening method, 17.0% mentioned clinical breast examination, and only 13.8% reported practicing breast self-examination. Factors associated with practice included knowledge about breast cancer early detection (BCED), ethnicity, income, the BCED information approach, and the BCED screening programs approach. The finding of a very low proportion of women in the mountainous setting with good awareness and practice on early detection of breast cancer is important evidence to inform the BCED intervention program developers about where and how to target which information, especially to reach more ethnic minority women.
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http://dx.doi.org/10.1177/1073274819863777DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651667PMC
January 2020

Fabrication and vibration characterization of curcumin extracted from turmeric (Curcuma longa) rhizomes of the northern Vietnam.

Springerplus 2016 22;5(1):1147. Epub 2016 Jul 22.

Institute of Materials Science, Vietnam Academy of Science and Technology (VAST), 18, Hoang Quoc Viet Road, Cau Giay Dist., Hanoi, Vietnam.

In this report, we present the research results on using the conventional method and microwave technology to extract curcuminoid from turmeric roots originated in different regions of Northern Vietnam. This method is simple, yet economical, non-toxic and still able to achieve high extraction performance to get curcuminoid from turmeric roots. The detailed results on the Raman vibration spectra combined with X-ray powder diffraction and high-performance liquid chromatography/mass spectrometry allowed the evaluation of each batch of curcumin crystalline powder sample received, under the conditions of applied fabrication technology. Also, the absorption and fluorescence spectroscopies of the samples are presented in the paper. The information to be presented in this paper: absorption and fluorescence spectroscopies of the samples; new experimental study results on applied technology to mass-produce curcumin from turmeric rhizomes; comparative study results between fabricated samples and marketing curcumin products-to state the complexity of co-existing crystalline phase in curcumin powder samples. We noticed that, it is possible to use the vibration line at ~959 cm(-1)-characteristic of the ν C=O vibration, and the ~1625 cm(-1) line-characteristic of the ν C=O and ν C=C vibration in curcumin molecules, for preliminary quality assessment of naturally originated curcumin crystalline powder samples. Data on these new optical spectra will contribute to the bringing of detailed information on natural curcumin in Vietnam, serving research purposes and applications of natural curcumin powder and nanocurcumin in Vietnam, as well as being initial materials for the pharmaceutical, cosmetics or functional food industries.
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http://dx.doi.org/10.1186/s40064-016-2812-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956636PMC
August 2016

Confirmed Plasmodium vivax Resistance to Chloroquine in Central Vietnam.

Antimicrob Agents Chemother 2015 Dec 21;59(12):7411-9. Epub 2015 Sep 21.

Institute of Tropical Medicine, Antwerp, Belgium.

Plasmodium vivax resistance to chloroquine (CQ) is currently reported in almost all countries where P. vivax is endemic. In Vietnam, despite a first report on P. vivax resistance to chloroquine published in the early 2000s, P. vivax was still considered sensitive to CQ. Between May 2009 and December 2011, a 2-year cohort study was conducted in central Vietnam to assess the recommended radical cure regimen based on a 10-day course of primaquine (0.5 mg/kg/day) together with 3 days of CQ (25 mg/kg). Here we report the results of the first 28-day follow-up estimating the cumulative risk of P. vivax recurrences together with the corresponding CQ blood concentrations, among other endpoints. Out of 260 recruited P. vivax patients, 240 completed treatment and were followed up to day 28 according to the WHO guidelines. Eight patients (3.45%) had a recurrent P. vivax infection, at day 14 (n = 2), day 21 (n = 1), and day 28 (n = 5). Chloroquine blood concentrations, available for 3/8 recurrent infections (days 14, 21, and 28), were above the MIC (>100 ng/ml whole blood) in all of these cases. Fever and parasitemia (both sexual and asexual stages) were cleared by day 3. Anemia was common at day 0 (35.8%), especially in children under 10 years (50%), and hemoglobin (Hb) recovery at day 28 was substantial among anemic patients (median change from day 0 to 28, +1.7 g/dl; interquartile range [IQR], +0.7 to +3.2). This report, based on CQ blood levels measured at the time of recurrences, confirms for the first time P. vivax CQ resistance in central Vietnam and calls for further studies using standardized protocols for accurately monitoring the extent and evolution of P. vivax resistance to chloroquine in Vietnam. These results, together with the mounting evidence of artemisinin resistance in central Vietnam, further highlight the increasing threat of antimalarial drug resistance to malaria elimination in Vietnam.
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http://dx.doi.org/10.1128/AAC.00791-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4649222PMC
December 2015

Identifying Effective Approaches for Dissemination of Clinical Evidence--Correlation Analyses on Promotional Activities and Usage of a Guideline-Driven Interactive Case Simulation Tool in a Statewide HIV-HCV-STD Clinical Education Program.

Stud Health Technol Inform 2015 ;216:515-9

University of Rochester Medical Center, Rochester, NY, USA.

Dissemination of the latest clinical evidence to community-based healthcare providers is a critical step to translate biomedical knowledge into clinical practice. We performed a study to analyze the correlations between the promotional activities and the usage of a guideline-driven interactive case simulation tool (ICST) for insomnia screening and treatment in a statewide HIV-HCV-STD clinical education program. For this purpose, we tracked users' interactions with the ICST and the sending of promotional email newsletters during a study period of 44 weeks. Results showed that promotional activities were strongly correlated with the number of audience as well as the intensity of use of the target resource. The strength of correlation varied in specific use contexts. Strong correlations were found between the sending of email newsletters and the intensity of resource use by promotion recipients, by new users, and through the most convenient access channel associated with the promotion. Selection of approaches for resource dissemination should consider the potentials and limitations of use contexts to make them more effective.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6606052PMC
December 2016

Evaluation of an Enhanced Role-Based Access Control model to manage information access in collaborative processes for a statewide clinical education program.

J Biomed Inform 2014 Aug 25;50:184-95. Epub 2013 Nov 25.

University of Rochester Medical Center, Rochester, NY 14642, USA. Electronic address:

Background: Managing information access in collaborative processes is a critical requirement to team-based biomedical research, clinical education, and patient care. We have previously developed a computation model, Enhanced Role-Based Access Control (EnhancedRBAC), and applied it to coordinate information access in the combined context of team collaboration and workflow for the New York State HIV Clinical Education Initiative (CEI) program. We report in this paper an evaluation study to assess the effectiveness of the EnhancedRBAC model for information access management in collaborative processes when applied to CEI.

Methods: We designed a cross-sectional study and performed two sets of measurement: (1) degree of agreement between EnhancedRBAC and a control system CEIAdmin based on 9152 study cases, and (2) effectiveness of EnhancedRBAC in terms of sensitivity, specificity, and accuracy based on a gold-standard with 512 sample cases developed by a human expert panel. We applied stratified random sampling, partial factorial design, and blocked randomization to ensure a representative case sample and a high-quality gold-standard.

Results: With the kappa statistics of four comparisons in the range of 0.80-0.89, EnhancedRBAC has demonstrated a high level of agreement with CEIAdmin. When evaluated against the gold-standard, EnhancedRBAC has achieved sensitivities in the range of 97-100%, specificities at the level of 100%, and accuracies in the range of 98-100%.

Conclusions: The initial results have shown that the EnhancedRBAC model can be effectively used to manage information access in the combined context of team collaboration and workflow for coordination of clinical education programs. Future research is required to perform longitudinal evaluation studies and to assess the effectiveness of EnhancedRBAC in other applications.
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http://dx.doi.org/10.1016/j.jbi.2013.11.007DOI Listing
August 2014

A modified semi-nested multiplex malaria PCR (SnM-PCR) for the identification of the five human Plasmodium species occurring in Southeast Asia.

Am J Trop Med Hyg 2013 Oct 26;89(4):721-723. Epub 2013 Aug 26.

We have modified an existing semi-nested multiplex polymerase chain reaction (PCR) by adding one Plasmodium knowlesi-specific nested PCR, and validated the latter against laboratory and clinical samples. This new method has the advantage of being relatively affordable in low resource settings while identifying the five human Plasmodium species with a three-step PCR.
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http://dx.doi.org/10.4269/ajtmh.13-0027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3795103PMC
October 2013

Assessing the usage of a guideline-driven interactive case simulation tool for insomnia screening and treatment in an HIV clinical education program.

Stud Health Technol Inform 2013 ;192:323-7

University of Rochester Medical Center, Rochester, NY, USA.

Interactive case simulation tools (ICSTs) are important vehicles to disseminate medical knowledge. We conducted a study to examine the usage of an insomnia screening and treatment case simulation tool in an HIV clinical education program. Using system usage diagrams (SUDs) as an instrument, we quantified visit frequency and length of stay for different types of system resources. Preliminary results have shown that both recommendations and interactive decision diagrams were frequently used, with the former having a longer length of stay but fewer visits. Case simulation functions seemed to be able to engage users. Future research is required to verify the generalizability of the identified usage patterns, to investigate issues in usability design, and to perform correlation analyses on system usage and context parameters.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001658PMC
April 2015

Cost-effectiveness of long-lasting insecticide-treated hammocks in preventing malaria in South-central Vietnam.

PLoS One 2013 11;8(3):e58205. Epub 2013 Mar 11.

LSE Health, London School of Economics & Political Science, London, United Kingdom.

Background: Despite much success in reducing the burden of malaria in Vietnam, pockets of malaria persist and eliminating them remains an important development goal. In central Vietnam, insecticide-treated hammocks have recently been introduced to help counter the disease in the highly forested, mountainous areas, where other measures have so far been unsuccessful. This study assesses the cost-effectiveness of using long-lasting insecticide-treated hammocks in this area.

Methods And Findings: This cost-effectiveness study was run alongside a randomized control trial testing the efficacy of the long-lasting insecticide-treated hammocks. Data were collected through an exit survey, a household survey, expenditure records and key informant interviews. The study estimates that under normal (non-trial) conditions the total net societal cost per malaria episode averted in using long-lasting insecticide-treated hammocks in this area was 126 USD. Cost per hammock, including insecticidal netting, sewing, transport, and distribution was found to be approximately 11.76 USD per hammock. Average savings per episode averted were estimated to be $14.60 USD for the health system and 14.37 USD for households (including both direct and indirect cost savings). The study estimates that the annual financial outlay required of government to implement this type of programme to be 3.40 USD per person covered per year.

Conclusion: The study finds that the use of a hammock intervention could represent good value for money to help prevent malaria in more remote areas, where traditional control measures such as insecticide-treated bednets and indoor residual spraying are insufficient or inappropriate to control malaria. However, the life span of the hammock-the number of years over which it effectively deters mosquitoes-has a significant impact on the cost-effectiveness of the intervention and study results should be interpreted in light of the evidence on effectiveness gathered in the years to come.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0058205PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3594234PMC
December 2013

Marked age-dependent prevalence of symptomatic and patent infections and complexity of distribution of human Plasmodium species in central Vietnam.

Am J Trop Med Hyg 2012 Dec 5;87(6):989-995. Epub 2012 Nov 5.

In Vietnam, Plasmodium falciparum and P. vivax are responsible for most malaria infections, and P. malariae and P. ovale infections are rarely reported. Nevertheless, species-specific polymerase chain reaction analysis on 2,303 blood samples collected during a cross-sectional survey conducted in a forest area of central Vietnam identified 223 (9.7%) P. falciparum, 170 (7.4%) P. vivax, 95 (4.1%) P. malariae, and 19 (0.8%) P. ovale mono-infections and 164 (7.1%) mixed infections. Of the 671 Plasmodium-positive samples by polymerase chain reaction, only 331 were detected by microscopy. Microscopy poorly diagnosed P. malariae, P. ovale, and mixed infections. Clinical and sub-clinical infections occurred in all age groups. The risk for infection and disease decreased with age, probably because of acquired partial immunity. The common occurrence of sub-patent infections seems to indicate that the malaria burden is underestimated and that diagnostic and therapeutic policies should be adapted accordingly.
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http://dx.doi.org/10.4269/ajtmh.2012.12-0047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3516102PMC
December 2012

An enhancement of the role-based access control model to facilitate information access management in context of team collaboration and workflow.

J Biomed Inform 2012 Dec 23;45(6):1084-107. Epub 2012 Jun 23.

University of Rochester Medical Center, Rochester, NY 14642, USA.

Although information access control models have been developed and applied to various applications, few of the previous works have addressed the issue of managing information access in the combined context of team collaboration and workflow. To facilitate this requirement, we have enhanced the Role-Based Access Control (RBAC) model through formulating universal constraints, defining bridging entities and contributing attributes, extending access permissions to include workflow contexts, synthesizing a role-based access delegation model to target on specific objects, and developing domain ontologies as instantiations of the general model to particular applications. We have successfully applied this model to the New York State HIV Clinical Education Initiative (CEI) project to address the specific needs of information management in collaborative processes. An initial evaluation has shown this model achieved a high level of agreement with an existing system when applied to 4576 cases (kappa=0.801). Comparing to a reference standard, the sensitivity and specificity of the enhanced RBAC model were at the level of 97-100%. These results indicate that the enhanced RBAC model can be effectively used for information access management in context of team collaboration and workflow to coordinate clinical education programs. Future research is required to incrementally develop additional types of universal constraints, to further investigate how the workflow context and access delegation can be enriched to support the various needs on information access management in collaborative processes, and to examine the generalizability of the enhanced RBAC model for other applications in clinical education, biomedical research, and patient care.
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http://dx.doi.org/10.1016/j.jbi.2012.06.001DOI Listing
December 2012

Towards smart homes using low level sensory data.

Sensors (Basel) 2011 12;11(12):11581-604. Epub 2011 Dec 12.

OS Lab, Department of Computer Engineering, Kyung Hee University, Yongin-Si, 446-701, Korea.

Ubiquitous Life Care (u-Life care) is receiving attention because it provides high quality and low cost care services. To provide spontaneous and robust healthcare services, knowledge of a patient's real-time daily life activities is required. Context information with real-time daily life activities can help to provide better services and to improve healthcare delivery. The performance and accuracy of existing life care systems is not reliable, even with a limited number of services. This paper presents a Human Activity Recognition Engine (HARE) that monitors human health as well as activities using heterogeneous sensor technology and processes these activities intelligently on a Cloud platform for providing improved care at low cost. We focus on activity recognition using video-based, wearable sensor-based, and location-based activity recognition engines and then use intelligent processing to analyze the context of the activities performed. The experimental results of all the components showed good accuracy against existing techniques. The system is deployed on Cloud for Alzheimer's disease patients (as a case study) with four activity recognition engines to identify low level activity from the raw data captured by sensors. These are then manipulated using ontology to infer higher level activities and make decisions about a patient's activity using patient profile information and customized rules.
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http://dx.doi.org/10.3390/s111211581DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3251999PMC
June 2012

High complexity of Plasmodium vivax infections in symptomatic patients from a rural community in central Vietnam detected by microsatellite genotyping.

Am J Trop Med Hyg 2010 Feb;82(2):223-7

Department of Parasitology, Institute of Tropical Medicine, Nationalestraat 155, Antwerp, Belgium.

Fourteen published and three newly identified polymorphic microsatellites were used to genotype 69 Plasmodium vivax samples obtained from 39 patients detected over a period of two years who lived in a rural community of central Vietnam. All samples were polyclonal with an average expected heterozygosity of 0.86. Among the 39 patients, 16 experienced 1-5 recurrent episodes of P. vivax malaria, most of them (83%) with a different genotype profile compared with previous infections. The minimal set of microsatellites required for differentiating the genotype profiles of the recurrent infections compared with the full set of 17 microsatellites was explored. A combination of five markers was sufficient to identify all recurrent infections with an unrelated or different genotype profile compared with all previous episodes.
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http://dx.doi.org/10.4269/ajtmh.2010.09-0458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813161PMC
February 2010

Low perception of malaria risk among the Ra-glai ethnic minority in south-central Vietnam: implications for forest malaria control.

Malar J 2010 Jan 20;9:23. Epub 2010 Jan 20.

Institute of Tropical Medicine, Antwerp, Belgium.

Background: Despite Vietnam's success in reducing malaria mortality and morbidity over the last decade, malaria persists in the forested and mountainous areas of the central and southern provinces, where more than 50% of the clinical cases and 90% of severe cases and malaria deaths occur.

Methods: Between July 2005 and September 2006, a multi-method study, triangulating a malariometric cross-sectional survey and qualitative data from focused ethnography, was carried out among the Ra-glai ethnic minority in the hilly forested areas of south-central Vietnam.

Results: Despite the relatively high malaria burden among the Ra-glai and their general awareness that mosquitoes can transmit an unspecific kind of fever (84.2%), the use of bed nets, distributed free of charge by the national malaria control programme, remains low at the farmers' forest fields where the malaria risk is the highest. However, to meet work requirements during the labour intensive malaria transmission and rainy season, Ra-glai farmers combine living in government supported villages along the road with a second home or shelter at their slash and burn fields located in the forest. Bed net use was 84.6% in the villages but only 52.9% at the forest fields; 20.6% of the respondents slept unprotected in both places. Such low use may be explained by the low perception of the risk for malaria, decreasing the perceived need to sleep protected. Several reasons may account for this: (1) only 15.6% acknowledged the higher risk of contracting malaria in the forest than in the village; (2) perceived mosquito biting times only partially coincided with Anopheles dirus ss and Anopheles minimus A true biting times; (3) the disease locally identified as 'malaria' was hardly perceived as having an impact on forest farmers' daily lives as they were unaware of the specific kind of fevers from which they had suffered even after being diagnosed with malaria at the health centre (20.9%).

Conclusions: The progressive confinement of malaria to minority groups and settings in the Greater Mekong sub-region implies that further success in malaria control will be linked to research into these specific socio-cultural contexts. Findings highlight the need for context sensitive malaria control policies; not only to reduce the local malaria burden but also to minimize the risk of malaria spreading to other areas where transmission has virtually ceased.
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http://dx.doi.org/10.1186/1475-2875-9-23DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2823606PMC
January 2010

Plasmodium knowlesi malaria in Vietnam: some clarifications.

Malar J 2010 Jan 18;9:20. Epub 2010 Jan 18.

Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium.

A recently published comment on a report of Plasmodium knowlesi infections in Vietnam states that this may not accurately represent the situation in the study area because the PCR primers used may cross-hybridize with Plasmodium vivax. Nevertheless, P. knowlesi infections have been confirmed by sequencing. In addition, a neighbour-joining tree based on the 18S S-Type SSUrRNA gene shows that the Vietnamese samples clearly cluster with the P. knowlesi isolates identified in Malaysia and are distinct from the corresponding P. vivax sequences. All samples came from asymptomatic individuals who did not consult for fever during the months preceding or following the survey, indicating that asymptomatic P. knowlesi infections occur in this population, although this does not exclude the occurrence of symptomatic cases. Large-scale studies to determine the extent and the epidemiology of P. knowlesi malaria in Vietnam are further needed.
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http://dx.doi.org/10.1186/1475-2875-9-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2817702PMC
January 2010

Human Plasmodium knowlesi infections in young children in central Vietnam.

Malar J 2009 Oct 30;8:249. Epub 2009 Oct 30.

Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium.

Background: Considering increasing reports on human infections by Plasmodium knowlesi in Southeast Asian countries, blood samples collected during two large cross-sectional malariometric surveys carried out in a forested area of central Vietnam in 2004 and 2005 were screened for this parasite.

Methods: Blood samples collected at the 2004 survey and positive for Plasmodium malariae were randomly selected for PCR analysis detecting P. knowlesi. Blood samples collected in 2005 from the same individuals were screened again for P. knowlesi. Positive samples were confirmed by sequencing. Family members of positive cases who participated in both surveys were also screened.

Results: Ninety-five samples with P. malariae mono- or mixed infections identified by species-specific PCR were screened for P. knowlesi. Among the five (5.2%) positive samples by PCR, three were confirmed to be P. knowlesi infections by sequencing, two young children (<5 years old) and a young man, all asymptomatic at the time of the survey and for the next six months after the survey. One of the two children was still positive one year later. No infection was found among the family members.

Conclusion: Plasmodium knowlesi infections in humans can be found in central Vietnam. A small child was positive for P. knowlesi in both surveys at one year interval, though it is unclear whether it was the same or a new infection.
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http://dx.doi.org/10.1186/1475-2875-8-249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2773789PMC
October 2009

Long-Lasting Insecticidal Hammocks for controlling forest malaria: a community-based trial in a rural area of central Vietnam.

PLoS One 2009 Oct 7;4(10):e7369. Epub 2009 Oct 7.

National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam.

Background: In Vietnam, malaria remains a problem in some remote areas located along its international borders and in the central highlands, partly due to the bionomics of the local vector, mainly found in forested areas and less vulnerable to standard control measures. Long Lasting Insecticidal Hammocks (LLIH), a tailored and user-friendly tool for forest workers, may further contribute in reducing the malaria burden. Their effectiveness was tested in a large community-based intervention trial carried out in Ninh Thuan province in Central Vietnam.

Methods And Findings: Thirty villages (population 18,646) were assembled in 20 clusters (1,000 individuals per cluster) that were randomly allocated to either the intervention or control group (no LLIH) after stratification according to the pre-intervention P. falciparum antibody prevalence (<30%; > or =30%). LLIH were distributed to the intervention group in December 2004. For the following 2 years, the incidence of clinical malaria and the prevalence of infection were determined by passive case detection at community level and by bi-annual malariometric surveys. A 2-fold larger effect on malaria incidence in the intervention as compared to the control group was observed. Similarly, malaria prevalence decreased more substantially in the intervention (1.6-fold greater reduction) than in the control group. Both for incidence and prevalence, a stronger and earlier effect of the intervention was observed in the high endemicity stratum. The number of malaria cases and infections averted by the intervention overall was estimated at 10.5 per 1,000 persons and 5.6/100 individuals, respectively, for the last half of 2006. In the high endemicity stratum, the impact was much higher, i.e. 29/1000 malaria cases and 15.7 infections/100 individuals averted.

Conclusions: LLIH reduced malaria incidence and prevalence in this remote and forested area of Central Vietnam. As the targets of the newly-launched Global Malaria Action Plan include the 75% reduction of the global malaria cases by 2015 and eventually the elimination/eradication of malaria in the long term, LLIH may represent an additional tool for reaching such objectives, particularly in high endemicity areas where standard control tools have a modest impact, such as in remote and forested areas of Southeast Asia and possibly South America.

Trial Registration: ClinicalTrials.gov NCT00853281.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0007369PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2752990PMC
October 2009

Risk factors for malaria infection among ethnic minorities in Binh Phuoc, Vietnam.

Southeast Asian J Trop Med Public Health 2009 Jan;40(1):18-29

Department of Medical Entomology, Institute of Tropical Medicine, Nagasaki University, Sakamoto, Nagasaki, Japan.

A cross-sectional study was undertaken to identify the prevalence of malaria infection, behavioral patterns of inhabitants and risk factors for malaria infection in a minority village in an area endemic for malaria in Vietnam. The target population were all the inhabitants of a village in Binh Phuoc Province, Vietnam. Interviews using a structured questionnaire and blood examination for malaria infection were conducted in house-to-house visits. Relationships between malaria infection and variables were examined using uni- and multivariate adjusted analysis. A total of 682 individuals from 159 households participated in both the interview and blood examinations. All households earned income through farming without forest activities at night, and the socio-economic status was generally not very low. The total prevalence of malaria infection was 6.2%, with a peak among 3- to 5-year-old children. Univariate analysis identified 3 - 5 year olds, a family size of > or =5 people, sleeping with >3 people in a bed, and living in a wooden/bamboo house as factors associated with malaria infection. Multivariate adjusted analysis after variable selection identified age 3 - 5 years old, a family size of > or =5 people and living in a wooden/bamboo house were significantly related to malaria infection. Malaria in this area can be controlled by basic activities, such as early diagnosis and treatment and prevention using bednets, since risk factors for malaria infection did not include forest activities, but were young age, living in a wooden/bamboo house and belonging to a large family. Continuous and intensive expansion of existing malaria control activities are required.
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January 2009

Rapid decrease of malaria morbidity following the introduction of community-based monitoring in a rural area of central Vietnam.

Malar J 2009 Jan 5;8. Epub 2009 Jan 5.

National Institute of Malariology, Parasitology and Entomology, Tu Liem district, Hanoi, Vietnam.

Background: Despite a successful control programme, malaria has not completely disappeared in Vietnam; it remains endemic in remote areas of central Vietnam, where standard control activities seem to be less effective. The evolution of malaria prevalence and incidence over two and half years in a rural area of central Vietnam, after the introduction of community-based monitoring of malaria cases, is presented.

Methods: After a complete census, six cross-sectional surveys and passive detection of malaria cases (by village and commune health workers using rapid diagnostic tests) were carried out between March 2004 and December 2006 in Ninh-Thuan province, in a population of about 10,000 individuals. The prevalence of malaria infection and the incidence of clinical cases were estimated.

Results: Malaria prevalence significantly decreased from 13.6% (281/2,068) in December 2004 to 4.0% (80/2,019) in December 2006. Plasmodium falciparum and Plasmodium vivax were the most common infections with few Plasmodium malariae mono-infections and some mixed infections. During the study period, malaria incidence decreased by more than 50%, from 25.7/1,000 population at risk in the second half of 2004 to 12.3/1,000 in the second half of 2006. The incidence showed seasonal variations, with a yearly peak between June and December, except in 2006 when the peak observed in the previous years did not occur.

Conclusion: Over a 2.5-year follow-up period, malaria prevalence and incidence decreased by more than 70% and 50%, respectively. Possibly, this could be attributed to the setting up of a passive case detection system based on village health workers, indicating that a major impact on the malaria burden can be obtained whenever prompt diagnosis and adequate treatment are available.
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http://dx.doi.org/10.1186/1475-2875-8-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2657912PMC
January 2009

An Energy-Efficient Secure Routing and Key Management Scheme for Mobile Sinks in Wireless Sensor Networks Using Deployment Knowledge.

Sensors (Basel) 2008 Dec 3;8(12):7753-7782. Epub 2008 Dec 3.

Dept. of Computer Science and Engineering, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-713, Korea.

For many sensor network applications such as military or homeland security, it is essential for users (sinks) to access the sensor network while they are moving. Sink mobility brings new challenges to secure routing in large-scale sensor networks. Previous studies on sink mobility have mainly focused on efficiency and effectiveness of data dissemination without security consideration. Also, studies and experiences have shown that considering security during design time is the best way to provide security for sensor network routing. This paper presents an energy-efficient secure routing and key management for mobile sinks in sensor networks, called SCODE. It is a significant extension of our previous study in five aspects: (1) Key management scheme and routing protocol are considered during design time to increase security and efficiency; (2) The network topology is organized in a hexagonal plane which supports more efficiency than previous square-grid topology; (3) The key management scheme can eliminate the impacts of node compromise attacks on links between non-compromised nodes; (4) Sensor node deployment is based on Gaussian distribution which is more realistic than uniform distribution; (5) No GPS or like is required to provide sensor node location information. Our security analysis demonstrates that the proposed scheme can defend against common attacks in sensor networks including node compromise attacks, replay attacks, selective forwarding attacks, sinkhole and wormhole, attacks, HELLO flood attacks. Both mathematical and simulation-based performance evaluation show that the SCODE significantly reduces the communication overhead, energy consumption, packet delivery latency while it always delivers more than 97 percent of packets successfully.
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http://dx.doi.org/10.3390/s8127753DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3790987PMC
December 2008

The economic burden of malaria on the household in south-central Vietnam.

Malar J 2008 Aug 27;7:166. Epub 2008 Aug 27.

LSE Health, London School of Economics, Houghton Street, London, UK.

Background: Each year, several thousand cases of malaria occur in south-central Vietnam. Evidence from elsewhere suggests that malaria can have an economic impact on the household as the illness prevents households from completing their normal, physically demanding, productive duties such as tending crops and animals. The economic impact of malaria on households was explored within the Raglay ethnic minority living in the montainous and forested area of south-central Vietnam (Ninh Thuan Province).

Methods: Two-hundred fifty-one malaria patients were identified and interviewed in an exit survey at Community Health Centres. The same patient sample was then re-interviewed in a household survey two to four weeks later. Survey data were complemented by approximately 40 informal discussions with health workers, vendors, patients, and community leaders.

Results: Each episode of malaria was estimated to cost the patient's household an average of 11.79 USD (2005 prices), direct costs for travel and treatment representing 6% of the total while the remainder was loss in annual income.

Conclusion: Whilst government provision of malaria treatment keeps the direct costs relatively low, the overall loss in income due to illness can still be significant given the poverty amongst this population, especially when multiple cases of malaria occur annually within the same household.
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http://dx.doi.org/10.1186/1475-2875-7-166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2546429PMC
August 2008

Malaria in central Vietnam: analysis of risk factors by multivariate analysis and classification tree models.

Malar J 2008 Jan 30;7:28. Epub 2008 Jan 30.

National Institute of Malariology, Parasitology and Entomology, Luong The Vinh street, BC 10200 Tu Liem district, Hanoi, Vietnam.

Background: In Central Vietnam, forest malaria remains difficult to control due to the complex interactions between human, vector and environmental factors.

Methods: Prior to a community-based intervention to assess the efficacy of long-lasting insecticidal hammocks, a complete census (18,646 individuals) and a baseline cross-sectional survey for determining malaria prevalence and related risk factors were carried out. Multivariate analysis using survey logistic regression was combined to a classification tree model (CART) to better define the relative importance and inter-relations between the different risk factors.

Results: The study population was mostly from the Ra-glai ethnic group (88%), with both low education and socio-economic status and engaged mainly in forest activities (58%). The multivariate analysis confirmed forest activity, bed net use, ethnicity, age and education as risk factors for malaria infections, but could not handle multiple interactions. The CART analysis showed that the most important risk factor for malaria was the wealth category, the wealthiest group being much less infected (8.9%) than the lower and medium wealth category (16.6%). In the former, forest activity and bed net use were the most determinant risk factors for malaria, while in the lower and medium wealth category, insecticide treated nets were most important, although the latter were less protective among Ra-glai people.

Conclusion: The combination of CART and multivariate analysis constitute a novel analytical approach, providing an accurate and dynamic picture of the main risk factors for malaria infection. Results show that the control of forest malaria remains an extremely complex task that has to address poverty-related risk factors such as education, ethnicity and housing conditions.
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http://dx.doi.org/10.1186/1475-2875-7-28DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2267804PMC
January 2008

Epidemiology of forest malaria in central Vietnam: a large scale cross-sectional survey.

Malar J 2005 Dec 8;4:58. Epub 2005 Dec 8.

Prince Leopold Institute of Tropical Medicine, Nationalestraat 155, 2000 Antwerp, Belgium.

In Vietnam, a large proportion of all malaria cases and deaths occurs in the central mountainous and forested part of the country. Indeed, forest malaria, despite intensive control activities, is still a major problem which raises several questions about its dynamics.A large-scale malaria morbidity survey to measure malaria endemicity and identify important risk factors was carried out in 43 villages situated in a forested area of Ninh Thuan province, south central Vietnam. Four thousand three hundred and six randomly selected individuals, aged 10-60 years, participated in the survey. Rag Lays (86%), traditionally living in the forest and practising "slash and burn" cultivation represented the most common ethnic group. The overall parasite rate was 13.3% (range [0-42.3] while Plasmodium falciparum seroprevalence was 25.5% (range [2.1-75.6]). Mapping of these two variables showed a patchy distribution, suggesting that risk factors other than remoteness and forest proximity modulated the human-vector interactions. This was confirmed by the results of the multivariate-adjusted analysis, showing that forest work was a significant risk factor for malaria infection, further increased by staying in the forest overnight (OR= 2.86; 95%CI [1.62; 5.07]). Rag Lays had a higher risk of malaria infection, which inversely related to education level and socio-economic status. Women were less at risk than men (OR = 0.71; 95%CI [0.59; 0.86]), a possible consequence of different behaviour. This study confirms that malaria endemicity is still relatively high in this area and that the dynamics of transmission is constantly modulated by the behaviour of both humans and vectors. A well-targeted intervention reducing the "vector/forest worker" interaction, based on long-lasting insecticidal material, could be appropriate in this environment.
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http://dx.doi.org/10.1186/1475-2875-4-58DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1325238PMC
December 2005

KAP surveys and malaria control in Vietnam: findings and cautions about community research.

Southeast Asian J Trop Med Public Health 2005 May;36(3):572-7

National Institute of Malariology, Parasitology and Entomology Tu Liem, Hanoi, Vietnam.

The malaria disease burden is increasing in many countries despite the existence of effective preventative strategies and antimalarial drugs. An understanding of community perspectives and practices is one of the essential components of a successful malaria control program. This paper reports on a KAP (Knowledge, Attitudes and Practices) survey among the Raglai ethnic minority population in Ninh Thuan Province, Vietnam, which in 2003 had one of the country's highest confirmed rates of malaria. We found high levels of correct knowledge about malaria's transmission and symptoms, and self-reports of adequate bed net usage and appropriate health-seeking behavior. While the survey generated useful findings, an initial, qualitative investigation (eg, observation and focus group discussions) to explore the large numbers of potential influences on behavior and exposure risk would have provided a more robust underpinning for the design of survey questions. This would have strengthened its validity and generated additional information. The adoption of rigorous, multi-disciplinary research methods offers the best chance of contributing to the development of successful malaria control programs and effective policies.
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May 2005