Thailand-Cambodia Border Research Articles

Tracking Origins and Spread of Sulfadoxine-Resistant Plasmodium falciparum dhps Alleles in Thailand

The emergence and spread of drug-resistant Plasmodium falciparum have been a major impediment for the control of malaria worldwide. Earlier studies have shown that similar to chloroquine (CQ) resistance, high levels of pyrimethamine resistance in P. falciparum originated independently 4 to 5 times globally, including one origin at the Thailand-Cambodia border. In this study we describe the origins and spread of sulfadoxine-resistance-conferring dihydropteroate synthase (dhps) alleles in Thailand. The dhps mutations and flanking microsatellite loci were genotyped for P. falciparum isolates collected from 11 Thai provinces along the Burma, Cambodia, and Malaysia borders. Results indicated that resistant dhps alleles were fixed in Thailand, predominantly being the SGEGA, AGEAA, and SGNGA triple mutants and the AGKAA double mutant (mutated codons are underlined). These alleles had different geographical distributions. The SGEGA alleles were found mostly at the Burma border, while the SGNGA alleles occurred mainly at the Cambodia border and nearby provinces. Microsatellite data suggested that there were two major genetic lineages of the triple mutants in Thailand, one common for SGEGA/SGNGA alleles and another one independent for AGEAA. Importantly, the newly reported SGNGA alleles possibly originated at the Thailand-Cambodia border. All parasites in the Yala province (Malaysia border) had AGKAA alleles with almost identical flanking microsatellites haplotypes. They were also identical at putatively neutral loci on chromosomes 2 and 3, suggesting a clonal nature of the parasite population in Yala. In summary, this study suggests multiple and independent origins of resistant dhps alleles in Thailand.

Origin and Evolution of Sulfadoxine Resistant Plasmodium falciparum

The Thailand-Cambodia border is the epicenter for drug-resistant falciparum malaria. Previous studies have shown that chloroquine (CQ) and pyrimethamine resistance originated in this region and eventually spread to other Asian countries and Africa. However, there is a dearth in understanding the origin and evolution of dhps alleles associated with sulfadoxine resistance. The present study was designed to reveal the origin(s) of sulfadoxine resistance in Cambodia and its evolutionary relationship to African and South American dhps alleles. We sequenced 234 Cambodian Plasmodium falciparum isolates for the dhps codons S436A/F, A437G, K540E, A581G and A613S/T implicated in sulfadoxine resistance. We also genotyped 10 microsatellite loci around dhps to determine the genetic backgrounds of various alleles and compared them with the backgrounds of alleles prevalent in Africa and South America. In addition to previously known highly-resistant triple mutant dhps alleles SGEGA and AGEAA (codons 436, 437, 540, 581, 613 are sequentially indicated), a large proportion of the isolates (19.3%) contained a 540N mutation in association with 437G/581G yielding a previously unreported triple mutant allele, SGNGA. Microsatellite data strongly suggest the strength of selection was greater on triple mutant dhps alleles followed by the double and single mutants. We provide evidence for at least three independent origins for the double mutants, one each for the SGKGA, AGKAA and SGEAA alleles. Our data suggest that the triple mutant allele SGEGA and the novel allele SGNGA have common origin on the SGKGA background, whereas the AGEAA triple mutant was derived from AGKAA on multiple, albeit limited, genetic backgrounds. The SGEAA did not share haplotypes with any of the triple mutants. Comparative analysis of the microsatellite haplotypes flanking dhps alleles from Cambodia, Kenya, Cameroon and Venezuela revealed an independent origin of sulfadoxine resistant alleles in each of these regions.

Increased Tolerance to Artemisinin in Plasmodium falciparum Is Mediated by a Quiescence Mechanism

Artemisinin (ART)-based combination therapies (ACTs) are the first-line drugs-and often the last treatments-that can effectively cure Plasmodium falciparum infections. Unfortunately, the decreased clinical efficacy of artesunate, one of the major ART derivatives, was recently reported along the Thailand-Cambodia border. Through long-term artemisinin pressure in vitro, we have obtained an ART-tolerant strain that can survive extremely high doses of ART. We showed that drug pressure could induce a subpopulation of ring stages into developmental arrest, which can explain the ART tolerance in P. falciparum. We also observed interesting transcriptomic modifications possibly associated with the acquisition of ART tolerance. These modifications include the overexpression of heat shock and erythrocyte surface proteins and the downexpression of a cell cycle regulator and a DNA biosynthesis protein. This study highlights a new phenomenon in the Plasmodium response to ART that may explain the delayed clearance of parasites after artesunate treatment observed on the Thailand-Cambodia border and that provides important information for achieving a better understanding of the mechanisms of antimalarial resistance.

SPATIO-TEMPORAL DISTRIBUTION OF PLASMODIUM FALCIPARUM AND P. VIVAX MALARIA IN THAILAND

Malaria incidence data at the district level from 1997 to 2002 and total malaria case data from 1965 to 2002 in Thailand were analyzed to determine the spatial and temporal dynamics of Plasmodium falciparum and P. vivax malaria incidence. Over the 37-year period, there was a 35-fold reduction in the incidence rates of P. falciparum malaria (11.86% in 1965 versus 0.34% in 2002) and a 7-fold reduction in P. vivax malaria (2.89% in 1965 versus 0.40% in 2002). The incidence ratio of P. falciparum to P. vivax malaria was reduced from 4.1 to 0.8 during this period. Malaria incidence rate exhibited the most rapid reduction between 1975 and 1985, coinciding with the introduction of a combination of antifolate drugs (sulfadoxine-pyrimethamine). The distribution maps of P. falciparum and P. vivax malaria incidence rates indicated a high spatial heterogeneity. The Thailand-Myanmar and Thailand-Cambodia border areas, where migration of foreign workers was pronounced, had the highest incidence rates for P. falciparum, P. vivax, and mixed-species infections. Transition probability analysis based on the malaria incidence rate among Thai residents indicated that there was an overall trend of decrease in the number of malaria cases and the number of high incidence districts between 1997 and 2002. High spatial variation in malaria incidence and local human migration patterns suggest that malaria control measures need to be adjusted according to local environmental and demographic settings.

The Trauma Story: A Phenomenological Approach to the Traumatic Life Experiences of Refugee Survivors

The Trauma Story: A Phenomenological Approach to the Traumatic Life Experiences of Refugee SurvivorsRichard F. MollicaRichard F. MollicaSearch for more papers by this authorPublished Online:June 2005https://doi.org/10.1521/psyc.64.1.60.18242PDFPDF PLUS ShareShare onFacebookTwitterLinkedInRedditEmail ToolsAdd to favoritesDownload CitationsTrack Citations AboutReferencesAllport , G. The Use of Personal Documents in Psychological Science. Social Science Research Council, 1942. Google ScholarCrapanzano , Vincent. The life history in Anthropological field work. Anthropology and Humanism Quarterly (1977) 2, No. 2–3, 3–7. Google ScholarFrank , G. Life histories in gerontology: The subjective side to aging. In C. L. Fry and J. Keith, eds., New Methods for Old Age Research (pp. 155–176). Loyola University of Chicago, Center for Urban Policy, 1980. Google ScholarGee , J. The narrativization of experience in the oral style. Journal of Education (1985) 167(1): 9–34. 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Invisible wounds Scientific American (2000a) 282(6):54–7. Crossref Medline, Google ScholarMollica , R. F. The special psychiatric problems of refugees. In M. Gelder, J. Lopez-Ibor, and N. Andreason, eds. New Oxford Textbook of Psychiatry (Vol. 2, pp. 1595–1601). Oxford University Press, 2000b. Google ScholarMollica , R. F., and Caspi-Yavin, Y. Measuring torture and torture-related symptoms. Psychological Assessment (1991) 3(4):581–7. Crossref, Google ScholarMollica , R. F, Donelan, K., Tor, S., Lavelle, J., Ellas, C., Frankel, M., and Blendon, R. The effect of trauma and confinement on functional health and mental health status of Cambodians living in Thailand-Cambodia border camps. Journal of the American Medical Association (1993) 270(5):581–6. Crossref, Google Scholar Previous article Next article FiguresReferencesRelatedDetails Cited byCited by1. Psychotherapy for refugees and other populations exposed to conflictOnline publication date: Go to citation Crossref Google Scholar2. Online publication date: Go to citation Crossref Google Scholar3. Does social capital protect mental health among migrants in Sweden?Online publication date: 4 June 2015. Go to citation Crossref Google Scholar4. Not the Promised LandOnline publication date: 6 February 2015. Go to citation Crossref Google Scholar5. The Refugee-Mental Health Assessment Package (R-MHAP); rationale, development and first-stage testing amongst West Papuan refugeesOnline publication date: 10 July 2015. Go to citation Crossref Google Scholar6. Holding Harm: Narrative Methods in Mental Health Research on Refugee TraumaOnline publication date: 27 July 2010. Go to citation Crossref Google Scholar7. Traumatised refugees: An integrated dance and verbal therapy approachOnline publication date: Go to citation Crossref Google Scholar8. CLINICAL PERSPECTIVES ON TRAUMAOnline publication date: Go to citation Crossref Google Scholar9. The Psychological Effects of Exposure to Wartime Trauma in Bosnian Residents and Refugees: Implications for Treatment and Service ProvisionOnline publication date: 9 November 2006. Go to citation Crossref Google Scholar10. Gay Men Tortured on the Basis of HomosexualityOnline publication date: Go to citation Crossref Google Scholar11. Female genital mutilationOnline publication date: Go to citation Crossref Google Scholar12. Review of Child and Adolescent Refugee Mental HealthOnline publication date: Go to citation Crossref Google Scholar13. Online publication date: Go to citation Crossref Google Scholar14. Posttraumatic Suffering as a Source of Transformation: A Clinical PerspectiveOnline publication date: Go to citation Crossref Google Scholar Volume 64Issue 1Mar 2001 Information© Guilford Publications Inc.PDF download

Transnational Advocacy, Global Civil Society? Emerging Evidence from the Field of Education

L'objectif des auteurs de cet article est double. Il s'agit d'une part de presenter une etude exploratoire sur les tendances actuelles temoignant de l'emergence d'un nouvel activisme non gouvernemental dans le champ de l'education et d'autre part de dresser un cadre analytique afin d'evaluer l'importance de cet activisme, en elaborant des concepts bases sur les recherches ayant porte sur les nouveaux mouvements sociaux et les debats theoriques actuels a propos de la societe civile mondiale.

Transnational Advocacy, Global Civil Society? Emerging Evidence from the Field of Education

Transnational Advocacy, Global Civil Society? Emerging Evidence from the Field of Education

The Effect of Trauma and Confinement on Functional Health and Mental Health Status of Cambodians Living in Thailand-Cambodia Border Camps

To assess the long-term impact of trauma and confinement on the functional health and mental health status of Cambodian displaced persons living on the Thailand-Cambodia border. Household survey of 993 adults randomly selected from household rosters. Household sample selection by multistage area probability sample. Site 2, the largest Cambodian displaced-persons camp on the Thailand-Cambodia border. Adults 18 years of age and older selected at random within households; 98% of eligible persons selected agreed to participate. From 1975 through 1979 (Khmer Rouge regime), more than 85% reported lack of food, water, shelter, and medical care, brainwashing, and forced labor; 54% reported murder of a family member or friend; 36% reported torture; 18% reported head injury; and 17% reported rape or sexual abuse. During the refugee period between 1980 and 1990, 56% reported lack of food or water, 44% reported lack of shelter, 28% reported lack of medical care, 24% reported brainwashing, and 8% reported torture. Since 1980, reports of murder of a family member, head injury, and rape/sexual abuse have decreased to 5%. Reports of experiencing combat situations and shelling attacks have remained consistent between the two time periods, approximately 44% and 30%, respectively. From 1989 to 1990, 25% reported experiencing lack of food or water, and 5% to 10% reported serious injury, combat, and shelling conditions. More than 80% said they were in fair or poor health, felt depressed, and had a number of somatic complaints despite good access to medical services. Fifty-five percent and 15% had symptom scores that correlate with Western criteria for depression and posttraumatic stress disorder, respectively. Fifteen percent to 20% reported health impairments limiting activity, and moderate or severe bodily pain. Despite reported high levels of trauma and symptoms, social and work functioning were well preserved in the majority of respondents. Reports of extensive trauma, poor health status, and depressive symptoms of this population are of concern in predicting future morbidity and mortality. The health and mental health needs of Cambodian displaced persons and their impact on social and economic behavior should be addressed now that the Cambodians have been repatriated.

The effect of trauma and confinement on functional health and mental health status of Cambodians living in Thailand-Cambodia border camps

The effect of trauma and confinement on functional health and mental health status of Cambodians living in Thailand-Cambodia border camps