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Matsumoto-Takahashi ELA, Iwagami M, Oyoshi K, Sasaki Y, Hongvanthong B, Kano S. Deforestation inhibits malaria transmission in Lao PDR: a spatial epidemiology using Earth observation satellites. Trop Med Health 2023; 51:60. [PMID: 37915065 PMCID: PMC10621094 DOI: 10.1186/s41182-023-00554-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 10/26/2023] [Indexed: 11/03/2023] Open
Abstract
BACKGROUND The present study aimed to analyze the impact of deforestation on the malaria distribution in the Lao People's Democratic Republic (Lao PDR), with consideration of climate change. METHODS Malaria distribution data from 2002 to 2015 were obtained from the Ministry of Health of Lao PDR and each indicator was calculated. Earth observation satellite data (forested area, land surface temperature, and precipitation) were obtained from the Japan Aerospace Exploration Agency (JAXA). Structured equation modeling (SEM) was conducted to clarify the relationship between the malaria incidence and Earth observation satellite data. RESULTS As a result, SEM identified two factors that were independently associated with the malaria incidence: area and proportion of forest. Specifically, malaria was found to be more prevalent in the southern region, with the malaria incidence increasing as the percentage of forested land increased (both p < 0.01). With global warming steadily progressing, forested areas are expected to play an important role in the incidence of malaria in Lao PDR. This is believed because malaria in Lao PDR is mainly forest malaria transmitted by Anopheles dirus. CONCLUSION To accelerate the elimination of malaria in Lao PDR, it is important to identify, prevent, and intervene in places with increased forest coverage (e.g., plantations) and in low-temperature areas adjacent to malaria-endemic areas, where the vegetation is similar to that in malaria-endemic areas.
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Affiliation(s)
- Emilie Louise Akiko Matsumoto-Takahashi
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), 1-21-1 Toyama, Shinjuku-Ku, Tokyo, 162-8655, Japan
- Graduate School of Public Health, St. Luke's International University, Tokyo, Japan
| | - Moritoshi Iwagami
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), 1-21-1 Toyama, Shinjuku-Ku, Tokyo, 162-8655, Japan
- Parasitology Laboratory, Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Kei Oyoshi
- Earth Observation Research Center (EORC), Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
| | - Yoshinobu Sasaki
- Earth Observation Research Center (EORC), Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
| | - Bouasy Hongvanthong
- Center of Malariology, Parasitology and Entomology (CMPE), Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Shigeyuki Kano
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), 1-21-1 Toyama, Shinjuku-Ku, Tokyo, 162-8655, Japan.
- Parasitology Laboratory, Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao People's Democratic Republic.
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Kotepui M, Kotepui KU, Masangkay FR, Mahittikorn A, Wilairatana P. Prevalence and proportion estimate of asymptomatic Plasmodium infection in Asia: a systematic review and meta-analysis. Sci Rep 2023; 13:10379. [PMID: 37369862 DOI: 10.1038/s41598-023-37439-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 06/21/2023] [Indexed: 06/29/2023] Open
Abstract
Asymptomatic Plasmodium infection raises a problem for the persistent transmission of malaria in low-endemic areas such as Asia. This systematic review was undertaken to estimate the prevalence and proportion of asymptomatic Plasmodium infection in Asia. The systematic review was registered at PROSPERO (ID: CRD42022373664). The research followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. A comprehensive search of five databases, Ovid, Scopus, MEDLINE, PubMed, and Embase, was conducted to identify studies of asymptomatic Plasmodium infection in Asian countries. The pooled prevalence of asymptomatic Plasmodium infection, the pooled proportion of asymptomatic Plasmodium infection among all parasitised individuals, and the associated 95% confidence intervals were estimated using a random-effects model. A total of 916 articles were retrieved, and 87 articles that met the criteria were included in the systematic review. The pooled prevalence of asymptomatic Plasmodium infection among enrolled participants in Southeast Asia, South Asia, and Western Asia was 5.8%, 9.4%, and 8.4%, respectively. The pooled proportion of asymptomatic Plasmodium infection among all parasitised individuals in Southeast Asia, South Asia, and Western Asia was 89.3%, 87.2%, and 64.8%, respectively. There was a low prevalence of asymptomatic Plasmodium infection, but there was a high proportion of asymptomatic Plasmodium infection per all parasitised individuals in different parts of Asia. These results may support and facilitate elimination and control programs for asymptomatic Plasmodium infection in Asia.
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Affiliation(s)
- Manas Kotepui
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand.
| | - Kwuntida Uthaisar Kotepui
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand
| | | | - Aongart Mahittikorn
- Department of Protozoology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Polrat Wilairatana
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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3
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Survey of malaria vectors on the Cambodia, Thailand and China-Laos Borders. Malar J 2022; 21:399. [PMID: 36585690 PMCID: PMC9801360 DOI: 10.1186/s12936-022-04418-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 12/15/2022] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Anopheles maculatus, Anopheles minimus and Anopheles dirus are the major vectors of malaria transmission in the Greater Mekong Subregion (GMS). The malaria burden in this region has decreased significantly in recent years as all GMS countries progress towards malaria elimination. It is necessary to investigate the Anopheles diversity and abundance status and assess the Plasmodium infection rates to understand the malaria transmission potential of these vector species in GMS countries to guide the development of up-to-date vector control strategies and interventions. METHODS A survey of mosquitoes was conducted in Stung Treng, Sainyabuli and Phongsaly Provinces on the Cambodia-Laos, Thailand-Laos and China-Laos borders, respectively. Mosquito collection was done by overnight trapping at sentinel sites in each province. After morphological identification, the 18S rRNA-based nested-PCR was performed to detect malaria parasites in the captured Anopheles mosquitoes. RESULTS A total of 18 965 mosquitoes comprising of 35 species of 2 subgenera (Subgenus Anopheles and Subgenus Cellia) and 4 tribes (Tribes Culicini, Aedini, Armigerini and Mansoniini) were captured. Tribe Culicini accounted for 85.66% of captures, followed by Subgenus Anopheles (8.15%). Anopheles sinensis dominated the Subgenus Anopheles by 99.81%. Plasmodium-infection was found in 25 out of the 1 683 individual or pooled samples of Anopheles. Among the 25 positive samples, 19, 5 and 1 were collected from Loum, Pangkhom and Siem Pang village, respectively. Eight Anopheles species were found infected with Plasmodium, i.e., An. sinensis, Anopheles kochi, Anopheles vagus, An. minimus, Anopheles annularis, Anopheles philippinensis, Anopheles tessellatus and An. dirus. The infection rates of Plasmodium falciparum, Plasmodium vivax and mixture of Plasmodium parasite species were 0.12% (2/1 683), 1.31% (22/1 683) and 0.06% (1/1 683), respectively. CONCLUSIONS Overall, this survey re-confirmed that multiple Anopheles species carry malaria parasites in the international border areas of the GMS countries. Anopheles sinensis dominated the Anopheles collections and as carriers of malaria parasites, therefore may play a significant role in malaria transmission. More extensive investigations of malaria vectors are required to reveal the detailed vector biology, ecology, behaviour, and genetics in GMS regions in order to assist with the planning and implementation of improved malaria control strategies.
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4
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Kagaya W, Takehara I, Kurihara K, Maina M, Chan CW, Okomo G, Kongere J, Gitaka J, Kaneko A. Potential application of the haematology analyser XN-31 prototype for field malaria surveillance in Kenya. Malar J 2022; 21:252. [PMID: 36050757 PMCID: PMC9434510 DOI: 10.1186/s12936-022-04259-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 08/09/2022] [Indexed: 11/10/2022] Open
Abstract
Background Simple and accurate diagnosis is a key component of malaria control programmes. Microscopy is the current gold standard, however it requires extensive training and the results largely rely on the skill of the microscopists. Malaria rapid diagnostic tests (RDT) can be performed with minimal training and offer timely diagnosis, but results are not quantitative. Moreover, some Plasmodium falciparum parasites have evolved and can no longer be detected by existing RDT. Developed by the Sysmex Corporation, the XN-31 prototype (XN-31p) is an automated haematology analyser capable of detecting Plasmodium-infected erythrocytes and providing species differentiation and stage specific parasite counts in venous blood samples without any preparation in approximately one minute. However, factors such as stable electricity supply in a temperature-controlled room, cost of the instrument and its initial set-up, and need for proprietary reagents limit the utility of the XN-31p across rural settings. To overcome some of these limitations, a hub and spoke diagnosis model was designed, in which peripheral health facilities were linked to a central hospital where detection of Plasmodium infections by the XN-31p would take place. To explore the feasibility of this concept, the applicability of capillary blood samples with the XN-31p was evaluated with respect to the effect of sample storage time and temperature on the stability of results. Methods Paired capillary and venous blood samples were collected from 169 malaria-suspected outpatients in Homa Bay County Referral Hospital, Kenya. Malaria infections were diagnosed with the XN-31p, microscopy, RDT, and PCR. Capillary blood samples were remeasured on the XN-31p after 24 h of storage at either room (15–25 °C) or chilled temperatures (2–8 °C). Results Identical results in malaria diagnosis were observed between venous and capillary blood samples processed immediately after collection with the XN-31p. Relative to PCR, the sensitivity and specificity of the XN-31p with capillary blood samples were 0.857 and 1.000, respectively. Short-term storage of capillary blood samples at chilled temperatures had no adverse impact on parasitaemia and complete blood counts (CBC) measured by the XN-31p. Conclusion These results demonstrate the potential of the XN-31p to improve routine malaria diagnosis across remote settings using a hub and spoke model. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04259-7.
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Affiliation(s)
- Wataru Kagaya
- Department of Virology and Parasitology/Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, 1-4-3, Asahimachi, Abeno-ku, Osaka, 545-8585, Japan.,Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, NagasakiNagasaki, 852-8523, Japan
| | - Ikki Takehara
- Sysmex Corporation, 4-4-4 Takatsukadai, Nishiku, Kobe, Hyogo, 651-2271, Japan
| | - Kyoko Kurihara
- Sysmex Corporation, 4-4-4 Takatsukadai, Nishiku, Kobe, Hyogo, 651-2271, Japan
| | - Michael Maina
- Department of Clinical Medicine, Mount Kenya University, PO Box 342-01000, Thika, Kenya
| | - Chim W Chan
- Department of Virology and Parasitology/Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, 1-4-3, Asahimachi, Abeno-ku, Osaka, 545-8585, Japan
| | | | - James Kongere
- Nairobi Research Station, Nagasaki University Institute of Tropical Medicine-Kenya Medical Research Institute (NUITM-KEMRI) Project, Institute of Tropical Medicine (NEKKEN), Nagasaki University, PO Box 19993-00202, Nairobi, Kenya.,Department of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, 1-4-3, Asahimachi, Abeno-ku, Osaka, 545-8585, Japan
| | - Jesse Gitaka
- Department of Clinical Medicine, Mount Kenya University, PO Box 342-01000, Thika, Kenya.,Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, NagasakiNagasaki, 852-8523, Japan.,Centre for Malaria Elimination, Mount Kenya University, P.O. Box 342-01000, Thika, Kenya
| | - Akira Kaneko
- Department of Virology and Parasitology/Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, 1-4-3, Asahimachi, Abeno-ku, Osaka, 545-8585, Japan. .,Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, NagasakiNagasaki, 852-8523, Japan. .,Island Malaria Group, Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Biomedicum, Solnavägen 9, Solna, 171 65, Stockholm, Sweden.
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5
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Komaki-Yasuda K, Kutsuna S, Kawaguchi M, Kamei M, Uchihashi K, Nakamura K, Nakamoto T, Ohmagari N, Kano S. Clinical performance testing of the automated haematology analyzer XN-31 prototype using whole blood samples from patients with imported malaria in Japan. Malar J 2022; 21:229. [PMID: 35907857 PMCID: PMC9338637 DOI: 10.1186/s12936-022-04247-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 07/20/2022] [Indexed: 11/10/2022] Open
Abstract
Background The automated haematology analyzer XN-31 prototype (XN-31p) is a new flow cytometry-based device developed to measure the number and the ratio of malaria-infected red blood cells (MI-RBC) with a complete blood count (CBC). The XN-31p can provide results in about one minute and also can simultaneously provide information on the malaria parasite (Plasmodium) species. In this study, clinical testing of the XN-31p was performed using blood samples from patients with imported malaria in Japan. Methods Blood samples were collected from 80 patients who visited the hospital of the National Center for Global Health and Medicine, Tokyo, Japan, for malaria diagnosis from January 2017 to January 2019. The test results by the XN-31p were compared with those by other standard methods, such as microscopic observation, rapid diagnostic tests and the nested PCR. Results Thirty-three patients were diagnosed by the nested PCR as being malaria positive (28 Plasmodium falciparum, 2 Plasmodium vivax, 1 Plasmodium knowlesi, 1 mixed infection of P. falciparum and Plasmodium malariae, and 1 mixed infection of P. falciparum and Plasmodium ovale), and the other 47 were negative. The XN-31p detected 32 patients as “MI-RBC positive”, which almost matched the results by the nested PCR and, in fact, completely matched with the microscopic observations. The ratio of RBCs infected with malaria parasites as determined by the XN-31p showed a high correlation coefficient of more than 0.99 with the parasitaemia counted under microscopic observation. The XN-31p can analyse the size and nucleic acid contents of each cell, and the results were visualized on a two-dimensional cytogram termed the “M scattergram”. Information on species and developmental stages of the parasites could also be predicted from the patterns visualized in the M scattergrams. The XN-31p showed a positive coincidence rate of 0.848 with the nested PCR in discriminating P. falciparum from the other species. Conclusions The XN-31p could rapidly provide instructive information on the ratio of MI-RBC and the infecting Plasmodium species. It was regarded to be of great help for the clinical diagnosis of malaria. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04247-x.
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Affiliation(s)
- Kanako Komaki-Yasuda
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Satoshi Kutsuna
- Disease Control and Prevention Center of National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Miki Kawaguchi
- Sysmex Corporation, 4-4-4 Takatsukadai, Nishi-ku, Kobe, 651-2271, Japan
| | - Mina Kamei
- Sysmex Corporation, 4-4-4 Takatsukadai, Nishi-ku, Kobe, 651-2271, Japan
| | - Kinya Uchihashi
- Sysmex Corporation, 4-4-4 Takatsukadai, Nishi-ku, Kobe, 651-2271, Japan
| | - Keiji Nakamura
- Disease Control and Prevention Center of National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Takato Nakamoto
- Disease Control and Prevention Center of National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Norio Ohmagari
- Disease Control and Prevention Center of National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Shigeyuki Kano
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan.
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Ong KIC, Khattignavong P, Keomalaphet S, Iwagami M, Brey P, Kano S, Jimba M. Health-seeking behaviours in a malaria endemic district in Lao People's Democratic Republic: a mixed methods study. BMJ Open 2021; 11:e055350. [PMID: 34903551 PMCID: PMC8671991 DOI: 10.1136/bmjopen-2021-055350] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES This mixed methods study was conducted to explore the barriers and facilitators for health-seeking behaviours in a malaria endemic district in Lao PDR. DESIGN A convergent mixed methods design. SETTING Two malaria endemic villages in Thapangthong district, Savannakhet Province, Lao PDR. PARTICIPANTS Villagers and healthcare workers in the two villages in Thapangthong district. METHODS In the quantitative part, a pretested questionnaire was used to identify the health-seeking behaviours of the villagers. In the qualitative part, focus group discussions were employed to explore health-seeking behaviours of the villagers and in-depth interviews were used to explore the perceptions of the healthcare workers. Descriptive statistics were computed and multiple logistic regressions were used to identify the factors associated with perceived severity and perceived susceptibility. Thematic analysis was used to analyse the qualitative data. Quantitative and qualitative results were integrated in joint displays. RESULTS In the quantitative part, data were collected from 313 villagers from both villages. For malaria, 96.0% and 98.2% of villagers from villages A and B, respectively, would first seek treatment at public health facilities. Villagers who have not experienced malaria before were more likely to perceive that the consequences of malaria were serious compared with those who have experienced malaria before (adjusted OR=1.69, 95% CI: 1.03 to 2.75). However, qualitative data showed that villagers faced problems such as lack of medicines and medical equipment. Healthcare workers also mentioned the lack of manpower and equipment in the in-depth interviews. Nevertheless, villagers still preferred to seek treatment at the health center as the National Health Insurance was introduced. CONCLUSIONS Public health facility usage was high but barriers existed. Effective policy and enabling environment such as the introduction of the National Health Insurance could help accelerate the progress towards the malaria elimination goal. Moreover, the benefits could go beyond the context of malaria.
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Affiliation(s)
- Ken Ing Cherng Ong
- Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | | | - Moritoshi Iwagami
- Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
- Department of Tropical Medicine and Malaria, National Center for Global Health and Medicine, Research Institute, Tokyo, Japan
| | - Paul Brey
- Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
| | - Shigeyuki Kano
- Institut Pasteur du Laos, Vientiane, Lao People's Democratic Republic
- Department of Tropical Medicine and Malaria, National Center for Global Health and Medicine, Research Institute, Tokyo, Japan
| | - Masamine Jimba
- Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Masunaga Y, Muela Ribera J, Nguyen TT, Tesfazghi K, Peeters Grietens K. In search of the last malaria cases: ethnographic methods for community and private-sector engagement in malaria elimination in Vietnam, Laos, and Cambodia. Malar J 2021; 20:370. [PMID: 34535133 PMCID: PMC8447739 DOI: 10.1186/s12936-021-03903-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 09/02/2021] [Indexed: 08/21/2023] Open
Abstract
Background Despite significant strides made in reducing malaria morbidity and mortality in the Greater Mekong Subregion, malaria transmission continues amongst the most ‘hard-to-reach’, such as forest-goers and mobile and migrant populations, who face access obstacles to malaria diagnosis and treatment. As such, regional malaria elimination strategies endeavour to incorporate the private sector and local communities in improving surveillance and detection of the last malaria cases in remote forested areas. The question remains, however, whether such strategies can reach these hard-to-reach populations and effectively reduce their disproportionate burden of malaria. This paper evaluates the strategy of community and private sector engagement in a malaria elimination project in Vietnam, Laos, and Cambodia. Methods Ethnographic research, incorporating in-depth interviews, participant observations with informal discussions, and group discussions were conducted in Bu Gia Map commune, Binh Phuc province of Vietnam; in Phouvong district, Attapeu province of Laos; and, in nine newly established and informal communities in the provinces of Mondul Kiri, Steung Treng, Kratie, Kampong Thom, and Prah Vihear of Cambodia. Results Different types of factors limited or enhanced the effectiveness of the participatory approaches in the different settings. In Vietnam, inter-ethnic tensions and sensitivity around forest-work negatively affected local population’s health-seeking behaviour and consequent uptake of malaria testing and treatment. In Laos, the location of the project collaborative pharmacies in the district-centre were a mismatch for reaching hard-to-reach populations in remote villages. In Cambodia, the strategy of recruiting community malaria-workers, elected by the community members, did manage to reach the remote forested areas where people visited or stayed. Conclusions ‘Hard-to-reach’ populations remain hard to reach without proper research identifying the socio-economic-political environment and the key dynamics determining uptake in involved communities and populations. Solid implementation research with a strong ethnographic component is required to tailor malaria elimination strategies to local contexts.
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Affiliation(s)
- Yoriko Masunaga
- Socio-Ecological Health Research Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium. .,Faculty of Social and Behavioural Science, Department of Sociology and Anthropology, University of Amsterdam, Amsterdam, The Netherlands.
| | - Joan Muela Ribera
- PASS Suisse, Neuchâtel, Switzerland.,Universitat Rovira i Virgili, Tarragona, Spain
| | - Thuan Thi Nguyen
- Socio-Ecological Health Research Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.,Faculty of Social and Behavioural Science, Department of Sociology and Anthropology, University of Amsterdam, Amsterdam, The Netherlands.,National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | | | - Koen Peeters Grietens
- Socio-Ecological Health Research Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
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Survey of asymptomatic malaria and mosquito vectors in Muang Khua District of Phongsaly Province, China-Laos Border. Int J Infect Dis 2020; 96:141-147. [PMID: 32251803 DOI: 10.1016/j.ijid.2020.03.066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/22/2020] [Accepted: 03/25/2020] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVES The China-Laos border has been identified as an important origin of imported malaria outside China. The aim of this study was to describe the asymptomatic malaria infections and epidemic trend of malaria in the China-Laos border region. METHODS A prevalence survey and surveillance of mosquito vectors was conducted in Muang Khua District of Phongsaly Province, China-Laos border, to determine the parasite carriage rate using nested PCR and microscopy. The species composition of malaria vectors was determined by overnight trapping. Blood samples were collected from 354 local residents aged 1-72 years in Sankang village in 2016. A total of 2430 adult mosquitoes were collected from four other villages in Muang Khua District from June to August 2016. RESULTS The parasite carriage rate was 7.63% (27/354) by microscopy or 7.91% (28/354) by nested PCR. The results of surveillance of the mosquito vectors revealed that the predominant genera of adult mosquitoes were Culex (69.92%, 1699/2430) and Anopheles (21.48%, 522/2430). Anopheles sinensis (82.95%, 433/522) was identified as the predominant species among the seven members of Anopheles found in this border region. CONCLUSIONS A high prevalence of asymptomatic malaria was present and the most important malaria vector was Anopheles sinensis, suggesting that the malaria epidemic situation on the China-Laos border is serious.
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Kaehler N, Adhikari B, Cheah PY, von Seidlein L, Day NPJ, Paris DH, Tanner M, Pell C. Prospects and strategies for malaria elimination in the Greater Mekong Sub-region: a qualitative study. Malar J 2019; 18:203. [PMID: 31221145 PMCID: PMC6585139 DOI: 10.1186/s12936-019-2835-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 06/09/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND As malaria elimination becomes a goal in malaria-endemic nations, questions of feasibility become critical. This article explores the potential challenges associated with this goal and future strategies for malaria elimination in the Greater Mekong Sub-region. METHODS Thirty-two semi-structured interviews were conducted with policy makers (n = 17) and principal investigators (n = 15) selected based on their involvement in malaria prevention, control and elimination in the GMS. Interviews were audio-recorded and transcribed for qualitative content (thematic) analysis using QSR NVivo. RESULTS All respondents described current malaria control and elimination strategies, such as case detection and management, prevention and strengthening of surveillance systems as critical and of equal priority. Aware of the emergence of multi-drug resistance in the GMS, researchers and policy makers outlined the need for additional elimination tools. As opposed to a centralized strategy, more targeted and tailored approaches to elimination were recommended. These included targeting endemic areas, consideration for local epidemiology and malaria species, and strengthening the peripheral health system. A decline in malaria transmission could lead to complacency amongst funders and policy makers resulting in a reduction or discontinuation of support for malaria elimination. Strong commitment of policymakers combined with strict monitoring and supervision by funders were considered pivotal to successful elimination programmes. CONCLUSION Against a backdrop of increasing anti-malarial resistance and decreasing choices of anti-malarial regimens, policy makers and researchers stressed the urgency of finding new malaria elimination strategies. There was consensus that multi-pronged strategies and approaches are needed, that no single potential tool/strategy can be appropriate to all settings. Hence there is a need to customize malaria control and elimination strategies based on the better surveillance data.
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Affiliation(s)
- Nils Kaehler
- Swiss Tropical and Public Health Institute, Basel, Switzerland.
- University of Basel, 4051, Basel, Switzerland.
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Bipin Adhikari
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Phaik Yeong Cheah
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
- The Ethox Centre, Nuffield Department of Population Health, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK
| | - Lorenz von Seidlein
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Nicholas P J Day
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Daniel H Paris
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, 4051, Basel, Switzerland
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, 4051, Basel, Switzerland
| | - Christopher Pell
- Amsterdam Institute for Global Health and Development (AIGHD), Amsterdam, The Netherlands
- Centre for Social Science and Global Health, University of Amsterdam, Amsterdam, The Netherlands
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Duanguppama J, Mathema VB, Tripura R, Day NPJ, Maxay M, Nguon C, von Seidlein L, Dhorda M, Peto TJ, Nosten F, White NJ, Dondorp AM, Imwong M. Polymorphisms in Pvkelch12 and gene amplification of Pvplasmepsin4 in Plasmodium vivax from Thailand, Lao PDR and Cambodia. Malar J 2019; 18:114. [PMID: 30940150 PMCID: PMC6444602 DOI: 10.1186/s12936-019-2749-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 03/26/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutations in Pfkelch13 and Pfplasmepsin2/3 gene amplification are well-established markers for artemisinin and piperaquine resistance in Plasmodium falciparum, a widespread problem in the Greater Mekong Subregion (GMS). The Plasmodium vivax parasite population has experienced varying drug pressure dependent on local drug policies. We investigated the correlation between drug pressure from artemisinins and piperaquine and mutations in the P. vivax orthologous genes Pvkelch12 and Pvplasmepsin4 (Pvpm4), as candidate resistance markers. METHODS Blood samples from 734 P. vivax patients were obtained from Thailand (n = 399), Lao PDR (n = 296) and Cambodia (n = 39) between 2007 and 2017. Pvkelch12 and Pvpm4 was amplified and sequenced to assess gene mutations. To assess PvPM4 gene amplification, a Taqman® Real-Time PCR method was developed and validated. Selection of non-synonymous mutations was assessed by its ratio with synonymous mutations (Ka/Ks ratios). Mutation rates were compared to the estimated local drug pressure. RESULTS Polymorphisms in Pvkelch12 were rare. Pvkelch12 mutations V552I, K151Q and M124I were observed in 1.0% (7/734) of P. vivax samples. V552I was the most common mutation with a frequency of 0.7% (5/734), most of which (4/5) observed in Ubon Ratchathani, Thailand. Polymorphisms in Pvpm4 were more common, with a frequency of 40.3% (123/305) in 305 samples from Thailand, Lao PDR and Cambodia, but this was not related to the estimated piperaquine drug pressure in these areas (Pearson's χ2 test, p = 0.50). Pvpm4 mutation V165I was most frequent in Tak, Thailand (40.2%, 43/107) followed by Pailin, Cambodia (43.5%, 37/85), Champasak, Lao PDR (40.4%, 23/57) and Ubon Ratchathani, Thailand (35.7%, 20/56). Pvpm4 amplification was not observed in 141 samples from Thailand and Cambodia. For both Pvkelch12 and Pvpm4, in all areas and at all time points, the Ka/Ks values were < 1, suggesting no purifying selection. CONCLUSIONS A novel real-time PCR-based method to assess P. vivax Pvpm4 gene amplification was developed. Drug pressure with artemisinins and piperaquine in the GMS was not clearly related to signatures of selection for mutations in the P. vivax orthologous resistance genes Pvkelch12 and Pvpm4 in areas under investigation. Current resistance of P. vivax to these drugs is unlikely and additional observations including analysis of associated clinical data from these regions could further clarify current findings.
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Affiliation(s)
- Jureeporn Duanguppama
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Vivek Bhakta Mathema
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rupam Tripura
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Mayfong Maxay
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Lao People's Democratic Republic.,Institute of Research and Education Development, University of Health Sciences, Vientiane, Lao People's Democratic Republic
| | - Chea Nguon
- National Centre for Parasitology, Entomology & Malaria Control, Ministry of Health, Phnom Penh, Cambodia
| | - Lorenz von Seidlein
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Mehul Dhorda
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Thomas J Peto
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Francois Nosten
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine, Churchill Hospital, Oxford, UK.,Shoklo Malaria Research Unit, Mae Sot, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine, Churchill Hospital, Oxford, UK
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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11
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Ong KIC, Iwagami M, Araki H, Khattignavong P, Soundala P, Keomalaphet S, Prasayasith P, Lorpachan L, Xangsayalath P, Pongvongsa T, Hongvanthong B, Brey PT, Kano S, Jimba M. Prevalence of G6PD Viangchan variant in malaria endemic areas in Lao PDR: an implication for malaria elimination by 2030. Malar J 2019; 18:75. [PMID: 30866940 PMCID: PMC6416863 DOI: 10.1186/s12936-019-2715-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 03/08/2019] [Indexed: 11/16/2022] Open
Abstract
Background Primaquine is effective against the latent liver stage of Plasmodium vivax. Eliminating the latent liver stage of P. vivax is one of the necessary conditions to achieve the goal of malaria elimination in Lao People’s Democratic Republic (PDR) by 2030. However, people with glucose-6-phosphate dehydrogenase (G6PD) deficiency are at risk of haemolysis when ingesting primaquine. The aim of this study was to detect the prevalence of the G6PD Viangchan variant, which is said to be common in Lao PDR and which can result in severe haemolysis in patients exposed to primaquine. Methods Blood samples were collected from villagers in three malaria endemic provinces: Champasak and Savannakhet in the south, and Phongsaly in the north. Each blood sample was semi-quantitatively assayed for G6PD enzyme activity using the G6PD Assay Kit-WST Lyophilized (DOJINDO Laboratories, Japan). Blood samples that were found to be G6PD deficient were sequenced to detect G6PD Viangchan mutation. Results In total, 2043 blood samples were collected from Phongsaly (n = 426, 20.9%), Savannakhet (n = 924, 45.2%), and Champasak (n = 693, 33.9%) provinces in Lao PDR from 2016 to 2017. Of these, 964 (47.2%) were taken from male villagers and 1079 (52.8%) were taken from female villagers. G6PD Viangchan mutation was not detected in Phongsaly province in this study. In Savannakhet province, 48 of the 924 samples (45 males, 3 females) had the G6PD Viangchan mutation (n = 48, 5.2%). In Champasak province, 42 of the 693 samples (18 males, 24 females) had the G6PD Viangchan mutation (n = 42, 6.1%). Conclusions G6PD Viangchan variant, which can cause severe haemolysis in the carrier when exposed to primaquine, was detected among 6.1% of the villagers in Champasak and 5.2% in Savannakhet but not in Phongsaly in this study. G6PD Viangchan variant might be common in the south of Laos but not so in the north. In the north, other G6PD deficiency variants might be more prevalent. However, in order not to overlook anyone and ensure a safe primaquine therapy for people living in malaria endemic areas in Lao PDR, G6PD testing is necessary. Electronic supplementary material The online version of this article (10.1186/s12936-019-2715-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ken Ing Cherng Ong
- Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic
| | - Moritoshi Iwagami
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Department of Tropical Medicine and Malaria, Research Institute, National Centre for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo, 162-8655, Japan.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Hitomi Araki
- Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic
| | - Phonepadith Khattignavong
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Pheovaly Soundala
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Sengdeuane Keomalaphet
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Phoyphaylinh Prasayasith
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Lavy Lorpachan
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Phonepadith Xangsayalath
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic.,National Institute of Public Health, Ministry of Health, Vientiane, Lao People's Democratic Republic.,National Center for Laboratory and Epidemiology, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Tiengkham Pongvongsa
- Savannakhet Provincial Health Department, Kaysone-Phomvihan District, Savannakhet, Lao People's Democratic Republic
| | - Bouasy Hongvanthong
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Paul T Brey
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Shigeyuki Kano
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Department of Tropical Medicine and Malaria, Research Institute, National Centre for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo, 162-8655, Japan.,Institut Pasteur du Laos, Ministry of Health, Samsenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Masamine Jimba
- Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. .,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.
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12
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Vilay P, Nonaka D, Senamonty P, Lao M, Iwagami M, Kobayashi J, Hernandez PM, Phrasisombath K, Kounnavong S, Hongvanthong B, Brey PT, Kano S. Malaria prevalence, knowledge, perception, preventive and treatment behavior among military in Champasak and Attapeu provinces, Lao PDR: a mixed methods study. Trop Med Health 2019; 47:11. [PMID: 30700970 PMCID: PMC6347756 DOI: 10.1186/s41182-019-0138-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/14/2019] [Indexed: 11/10/2022] Open
Abstract
Background Malaria is a major health problem in Lao People's Democratic Republic (Lao PDR) with high transmission in remote and forest areas, particularly in the South. The military is at risk of malaria infection especially those deployed in forest areas. This study determined the prevalence of malaria infection and assessed knowledge, perception, and preventive and treatment behavior regarding malaria among military personnel in two southern provinces in Lao PDR. Methods Quantitative and qualitative approaches were undertaken in Champasak and Attapeu provinces in 2017. From 313 military personnel, quantitative data were collected through questionnaire-based interviews and blood samples used for parasite detection by polymerase chain reaction (PCR). Qualitative data were collected through 7 focus group discussions and 17 in-depth interviews among 49 military personnel. Fisher's exact test and Mann-Whitney U test were used to assess the association between malaria infection and participant characteristics. Content analysis for qualitative data was performed to explore perception and treatment behaviors regarding malaria. Results The prevalence of malaria infection was 11.2% (Plasmodium falciparum: 1.3%, Plasmodium vivax: 9.3% and mixed infections: 0.6%). Many participants understood that malaria is transmitted through mosquito bites, although they did not necessarily know the name of vector mosquitoes (Anopheles). Surprisingly, more than a half also believed that malaria is transmitted through drinking stream water. One-third of the participants used long-lasting insecticidal nets. Due to limited supply, participants were often unable to use mosquito repellent and coils when necessary. Because participants were unable to receive timely diagnosis and appropriate treatment for malaria in their camps, they commonly practiced self-treatment using antibiotics, painkillers, and/or traditional medicines. They only go to a healthcare facility through their supervisor if their conditions worsen. Conclusions The prevalence of symptomatic and asymptomatic malaria was conspicuous among military in forest areas. Many participants believed that malaria is transmitted not only by mosquito bites but also from drinking stream water. Preventive equipment was often insufficient. Self-treatment was practiced before referring to healthcare facility. To further prevent military from contracting malaria, the National Malaria Control Program and military body should provide adequate and suitable health education, protective equipment, and on-site malaria case management.
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Affiliation(s)
- Phoutnalong Vilay
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,2Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao PDR.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Daisuke Nonaka
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Phosadeth Senamonty
- Military Institute of Diseases Prevention, Department of Military Medical, Ministry of Defense, Vientiane, Lao PDR
| | - Malayvanh Lao
- Military Institute of Diseases Prevention, Department of Military Medical, Ministry of Defense, Vientiane, Lao PDR
| | - Moritoshi Iwagami
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,5Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655 Japan.,6Institut Pasteur du Laos, Ministry of Health, Vientiane, Lao PDR
| | - Jun Kobayashi
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Paul Michael Hernandez
- 1Department of Global Health, Graduate School of Health Sciences, University of the Ryukyus, 207 Uehara-cho, Okinawa, 903-0215 Japan.,7Department of Environmental and Occupational Health, College of Public Health, University of the Philippines Manila, 625 Pedro Gil Street, Ermita, 1000 Manila, Philippines
| | | | - Sengchanh Kounnavong
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,9Lao Tropical and Public Health Institute, Ministry of Health, Vientiane, Lao PDR
| | - Bouasy Hongvanthong
- 2Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao PDR.,SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR
| | - Paul T Brey
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,6Institut Pasteur du Laos, Ministry of Health, Vientiane, Lao PDR
| | - Shigeyuki Kano
- SATREPS Project for Parasitic Diseases, Vientiane, Lao PDR.,5Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655 Japan
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13
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Iwagami M, Nakatsu M, Khattignavong P, Soundala P, Keomalaphet S, Lorpachan L, Xangsayalath P, Matsumoto-Takahashi E, Pommelet V, Hongvanthong B, Brey PT, Kano S. Heterogeneous distribution of k13 mutations in Plasmodium falciparum in Laos. Malar J 2018; 17:483. [PMID: 30587196 PMCID: PMC6307170 DOI: 10.1186/s12936-018-2625-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 12/11/2018] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND The emergence and transnational spread of artemisinin resistance in Plasmodium falciparum in the Greater Mekong Sub-region (GMS) is a serious threat to malaria elimination in the region and could present a threat to malaria control in Africa. Recently, the Lao Government adopted the goal of malaria elimination by 2030, for which monitoring of artemisinin-resistant malaria within the country is indispensable. This study's objectives were to assess the distribution of k13 mutations in Laos. METHODS Plasmodium falciparum isolates (n = 1151) were collected from five southern provinces in Laos between 2015 and 2016, and three isolates from the northernmost province bordering China in 2017. Polymorphisms of the k13 gene and two flanking regions were analysed to estimate relationship among the isolates. RESULTS In the five southern provinces, overall 55.5% of the isolates possessed artemisinin-resistant mutations of the k13 gene (C580Y, P574L, R539T, Y493H). The C580Y was the predominant mutation (87.2%). The frequencies of the k13 mutations were heterogeneous in the five southern provinces, but with a clear tendency showing the highest frequency in the south (72.5%) and to a lower degree when moving northward (28.0%). The three isolates from the Lao-Chinese border also possessed the C580Y mutation. Analysis of the flanking loci demonstrated that these three isolates were genetically very close to resistant strains originating from western Cambodia. CONCLUSIONS Artemisinin resistance was observed to be rapidly increasing and spreading northwards through Laos and has now reached the Chinese border. The Lao and Chinese governments, as well as the international community, should make dedicated efforts to contain the spread of k13 mutations within Laos and in the GMS.
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Affiliation(s)
- Moritoshi Iwagami
- Department of Tropical Medicine and Malaria, Research Institute, National Centre for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo, 162-8655, Japan.,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Masami Nakatsu
- Department of Tropical Medicine and Malaria, Research Institute, National Centre for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo, 162-8655, Japan.,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic
| | - Phonepadith Khattignavong
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Pheovaly Soundala
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Sengdeuane Keomalaphet
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Lavy Lorpachan
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Phonepadith Xangsayalath
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,National Institute of Public Health, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Emilie Matsumoto-Takahashi
- Department of Tropical Medicine and Malaria, Research Institute, National Centre for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo, 162-8655, Japan.,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic
| | - Virginie Pommelet
- Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic
| | - Bouasy Hongvanthong
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic.,Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Paul T Brey
- SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic. .,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic.
| | - Shigeyuki Kano
- Department of Tropical Medicine and Malaria, Research Institute, National Centre for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo, 162-8655, Japan. .,SATREPS Project (JICA/AMED) for Parasitic Diseases, Vientiane, Lao People's Democratic Republic. .,Institut Pasteur du Laos, Ministry of Health, Sansenthai Road, Ban Kao-Gnot, Sisattanak District, P.O. Box 3560, Vientiane, Lao People's Democratic Republic.
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14
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Adhikari B, Phommasone K, Pongvongsa T, Soundala X, Koummarasy P, Henriques G, Peto TJ, von Seidlein L, White NJ, Day NPJ, Dondorp AM, Newton PN, Cheah PY, Mayxay M, Pell C. Perceptions of asymptomatic malaria infection and their implications for malaria control and elimination in Laos. PLoS One 2018; 13:e0208912. [PMID: 30533024 PMCID: PMC6289463 DOI: 10.1371/journal.pone.0208912] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 11/26/2018] [Indexed: 11/29/2022] Open
Abstract
Background In the Greater Mekong Sub-region (GMS), malaria elimination efforts are targeting the asymptomatic parasite reservoirs. Understanding community perceptions about asymptomatic malaria infections and interventions that target this reservoir is critical to the design of community engagement. This article examines knowledge, attitudes, perceptions and practices related to asymptomatic malaria infections and mass drug administration (MDA) in malaria-endemic villages in southern Savannakhet Province, Laos. Methods A questionnaire consisting of questions on socio-demographic characteristics, knowledge, attitudes, perceptions and practices on malaria and MDA was administered to each household head or representative (n = 281) in four villages. These topics were also further discussed in 12 single-gender focus group discussions (FGDs). The FGDs were conducted in all four villages and consisted of eight to 10 participants. Results A minority (14.2%; 40/281) of respondents agreed that a seemingly healthy person could have malaria parasite in his or her blood. Half (52%; 146/281) disagreed and one third (33.8%, 95/281) were unsure. Respondents who responded that “MDA aims to cure everyone” [AOR = 4.6; CI: 1.6–13.1], “MDA is to make our community malaria free” [AOR = 3.3; CI: 1.3–8.1] and “I will take part in future MDA” [AOR = 9.9; CI: 1.2–78.8] were more likely to accept the idea of asymptomatic malaria. During FGDs, respondents recalled signs and symptoms of malaria (fever, chills and headache), and described malaria as a major health problem. Symptomatic and asymptomatic malaria infections were associated with their work in the forest and living conditions. Measures described to eliminate malaria included using mosquito nets, wearing long-sleeved clothes and taking medicine when symptomatic. Most respondents were unaware of MDA as a tool to eliminate malaria. Conclusions Awareness of asymptomatic malaria infections, and MDA as a tool to eliminate malaria, was low. With the need to target asymptomatic malaria carriers for elimination efforts in the GMS, as well as informing target groups about asymptomatic infection, accompanying community engagement must build trust in interventions through the active collaboration of government stakeholders, key local persons and community members. This entails training and devolving responsibilities to the community members to implement and sustain the control and elimination efforts.
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Affiliation(s)
- Bipin Adhikari
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
- Kellogg College, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Koukeo Phommasone
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Tiengkham Pongvongsa
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Savannakhet Provincial Health Department, Savannakhet Province, Laos
| | - Xayaphone Soundala
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Palingnaphone Koummarasy
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Gisela Henriques
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Life Science, Imperial College London, London, United Kingdom
| | - Thomas J. Peto
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
| | - Lorenz von Seidlein
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
| | - Nicholas J. White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
| | - Arjen M. Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
| | - Paul N. Newton
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
| | - Phaik Yeong Cheah
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
- The Ethox Centre, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
| | - Mayfong Mayxay
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Churchill Hospital, Oxford, United Kingdom
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Microbiology Laboratory, Mahosot Hospital, Vientiane, Laos
- Institute of Research and Educational Development, University of Health Sciences, Vientiane, Laos
| | - Christopher Pell
- Centre for Social Science and Global Health, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Institute for Global Health and Development, Amsterdam, The Netherlands
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15
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Iwagami M, Tangpukdee N, Wilairatana P, Krudsood S, Dao LD, Nakazawa S, Sinuon M, Socheat D, Yasuoka J, Jimba M, Watanabe H, Kobayashi J, Toma H, Vanisaveth V, Hongvanthong B, Brey PT, Kano S. Pfcrt genotypes and related microsatellite DNA polymorphisms on Plasmodium falciparum differed among populations in the Greater Mekong Subregion. Parasitol Int 2018; 67:816-823. [PMID: 30165262 DOI: 10.1016/j.parint.2018.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 05/16/2018] [Accepted: 08/26/2018] [Indexed: 10/28/2022]
Abstract
Malaria morbidity and mortality have decreased gradually in the Greater Mekong Subregion (GMS). Presently, WHO sets a goal to eliminate malaria by 2030 in the GMS. However, drug-resistant malaria has been reported from several endemic areas. To achieve the goal of elimination, the status of the emergence and spread of drug resistance should be monitored. In this study, the genotype of the Plasmodium falciparum chloroquine (CQ) resistance transporter gene (pfcrt) and 6 microsatellite DNA loci flanking the gene were examined. P. falciparum isolates (n = 136) was collected from malaria patients in Thailand (n = 50, 2002-2005), Vietnam (n = 39, 2004), Laos (n = 15, 2007) and Cambodia (n = 32, 2009). Amino acid sequences at codons 72-76 on the gene were determined. All of the isolates from Thailand were CQ-resistant (CVIET), as were all of the isolates from Cambodia (CVIET, CVIDT). Thirteen of the 15 isolates (87%) from Laos were CQ-resistant (CVIET, CVIDT), whereas the other 2 (13%) were CQ-susceptible (CVMNK). In contrast, 27 of the 39 isolates (69%) from Vietnam were CQ-susceptible (CVMNK), whereas the other 12 (31%) were CQ-resistant (CVIET, CVIDT, CVMDT) or mixed (CVMNK/CVIDT). The mean of expected heterozygosity of the microsatellite loci was 0.444 in the Thai population, 0.482 in the Cambodian population, and 0.734 in the Vietnamese population. Genetic diversity in the Thai population was significantly lower than that in the Vietnamese population. These results suggested that chloroquine selective pressure on P. falciparum populations is heterogeneous in the GMS. Therefore, further examination to understand the mechanisms behind the emergence and spread of drug-resistant malaria are needed.
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Affiliation(s)
- Moritoshi Iwagami
- Department of Tropical Medicine and Malaria, National Center for Global Health and Medicine, Research Institute, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan; Ministry of Health, Institut Pasteur du Laos, Vientiane, Laos; SATREPS Project for Parasitic Diseases, Vientiane, Laos
| | - Noppadon Tangpukdee
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Polrat Wilairatana
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Srivicha Krudsood
- Department of Tropical Hygiene, Mahidol University, Bangkok, Thailand
| | - Le Duc Dao
- Molecular Biology Department, Parasitology and Entomology, National Institute of Malariology, Hanoi, Viet Nam
| | - Shusuke Nakazawa
- Department of Protozoology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Muth Sinuon
- National Centre for Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia
| | - Duong Socheat
- National Centre for Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia
| | - Junko Yasuoka
- Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masamine Jimba
- SATREPS Project for Parasitic Diseases, Vientiane, Laos; Department of Community and Global Health, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hisami Watanabe
- Division of Cellular and Molecular Immunology, Center of Molecular Biosciences, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa 903-0215, Japan
| | - Jun Kobayashi
- Department of Global Health, School of Health Sciences, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
| | - Hiromu Toma
- Department of Parasitology and Immunopathoetiology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa 903-0215, Japan
| | - Viengxay Vanisaveth
- Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Laos
| | - Bouasy Hongvanthong
- SATREPS Project for Parasitic Diseases, Vientiane, Laos; Center of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Laos
| | - Paul T Brey
- Ministry of Health, Institut Pasteur du Laos, Vientiane, Laos; SATREPS Project for Parasitic Diseases, Vientiane, Laos
| | - Shigeyuki Kano
- Department of Tropical Medicine and Malaria, National Center for Global Health and Medicine, Research Institute, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan; Ministry of Health, Institut Pasteur du Laos, Vientiane, Laos; SATREPS Project for Parasitic Diseases, Vientiane, Laos.
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