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Phanhkongsy S, Suwannatrai A, Thinkhamrop K, Somlor S, Sorsavanh T, Tavinyan V, Sentian V, Khamphilavong S, Samountry B, Phanthanawiboon S. Spatial analysis of dengue fever incidence and serotype distribution in Vientiane Capital, Laos: A multi-year study. Acta Trop 2024; 256:107229. [PMID: 38768698 DOI: 10.1016/j.actatropica.2024.107229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/22/2024] [Accepted: 04/24/2024] [Indexed: 05/22/2024]
Abstract
Laos is a hyperendemic country of all 4 dengue serotypes. Various factors contribute to the spread of the disease including viral itself, vectors, and environment. This study aims to analyze dengue data and its incidence in nine districts of Vientiane Capital, Laos spanning from 2019 to 2021 by data collected from Mittaphab Hospital. The Maximum Entropy algorithm (MaxEnt) was applied to assess spatial distribution and identify high-probability locations for dengue occurrence by analyzing crucial environmental and climatic conditions. Dengue cases were more prominent in female (54.88 %) and highest case number was found in worker group (29.02 %) followed by student (28.47 %) and officer (16.92 %). In this study, the age group 21-30 years old had the highest infection rate (42.23 %), followed by 10-20 years old (24.21 %). Most of dengue cases was primary infection (91.61 %). Dengue serotype 2 predominated in 2019 and 2020 and substitute by serotype 1 in 2021. Across the nine districts of Vientiane Capital, the highest incidence of dengue was found in Xaythany district population in 2019, shifting to Chanthabouly district in 2020 and 2021. The MaxEnt revealed potentially most suitable areas for dengue were widely distributed central south part of Vientiane, Laos. Additionally, the best predictive variable for dengue occurrence was normalized difference vegetation index. Understanding of case characteristics and spatial distribution features of dengue will be helpful in effective surveillance and disease control in the future.
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Affiliation(s)
- Somsouk Phanhkongsy
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Apiporn Suwannatrai
- Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Kavin Thinkhamrop
- Faculty of Public Health, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Somphavanh Somlor
- Arbovirus & Emerging viral disease laboratory, Institute Pasteur du Laos, Samsenthai Rd, Ban Kao-ngot PO Box 3560, Vientiane, Lao People's Democratic Republic
| | - Thepphouthone Sorsavanh
- Department of Planning and Cooperation, Ministry of Health, Fa Ngoum Road, Thatkhao Village, Sisattanak District, Vientiane, Lao People's Democratic Republic
| | - Vanxay Tavinyan
- Microbiology Unit, Department of Medical Sciences, Faculty of Medicine, Ministry of Health, University of Health Sciences, Samsenthai Road, Ban Kao-ngot PO Box 7444 Vientiane, Lao People's Democratic Republic
| | - Virany Sentian
- Microbiology Unit, Department of Medical Sciences, Faculty of Medicine, Ministry of Health, University of Health Sciences, Samsenthai Road, Ban Kao-ngot PO Box 7444 Vientiane, Lao People's Democratic Republic
| | - Soulichanh Khamphilavong
- Microbiology Unit, Department of Medical Sciences, Faculty of Medicine, Ministry of Health, University of Health Sciences, Samsenthai Road, Ban Kao-ngot PO Box 7444 Vientiane, Lao People's Democratic Republic
| | - Bounthome Samountry
- Pathologist, Ministry of Health, University of Health Sciences, Samsenthai Road, Ban Koa-ngot PO Box 7444, Vientiane, Lao People's Democratic Republic
| | - Supranee Phanthanawiboon
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
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Man O, Kraay A, Thomas R, Trostle J, Lee GO, Robbins C, Morrison AC, Coloma J, Eisenberg JNS. Characterizing dengue transmission in rural areas: A systematic review. PLoS Negl Trop Dis 2023; 17:e0011333. [PMID: 37289678 PMCID: PMC10249895 DOI: 10.1371/journal.pntd.0011333] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023] Open
Abstract
Dengue has historically been considered an urban disease associated with dense human populations and the built environment. Recently, studies suggest increasing dengue virus (DENV) transmission in rural populations. It is unclear whether these reports reflect recent spread into rural areas or ongoing transmission that was previously unnoticed, and what mechanisms are driving this rural transmission. We conducted a systematic review to synthesize research on dengue in rural areas and apply this knowledge to summarize aspects of rurality used in current epidemiological studies of DENV transmission given changing and mixed environments. We described how authors defined rurality and how they defined mechanisms for rural dengue transmission. We systematically searched PubMed, Web of Science, and Embase for articles evaluating dengue prevalence or cumulative incidence in rural areas. A total of 106 articles published between 1958 and 2021 met our inclusion criteria. Overall, 56% (n = 22) of the 48 estimates that compared urban and rural settings reported rural dengue incidence as being as high or higher than in urban locations. In some rural areas, the force of infection appears to be increasing over time, as measured by increasing seroprevalence in children and thus likely decreasing age of first infection, suggesting that rural dengue transmission may be a relatively recent phenomenon. Authors characterized rural locations by many different factors, including population density and size, environmental and land use characteristics, and by comparing their context to urban areas. Hypothesized mechanisms for rural dengue transmission included travel, population size, urban infrastructure, vector and environmental factors, among other mechanisms. Strengthening our understanding of the relationship between rurality and dengue will require a more nuanced definition of rurality from the perspective of DENV transmission. Future studies should focus on characterizing details of study locations based on their environmental features, exposure histories, and movement dynamics to identify characteristics that may influence dengue transmission.
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Affiliation(s)
- Olivia Man
- Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Alicia Kraay
- Department of Kinesiology and Community Health, University of Illinois, Urbana, Illinois, United States of America
- Institution for Genomic Biology, University of Illinois, Urbana, Illinois, United States of America
| | - Ruth Thomas
- Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - James Trostle
- Department of Anthropology, Trinity College, Hartford, Connecticut, United States of America
| | - Gwenyth O. Lee
- Rutgers Global Health Institute, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
- Rutgers Department of Biostatistics and Epidemiology, School of Public Health, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
| | - Charlotte Robbins
- Department of Anthropology, Trinity College, Hartford, Connecticut, United States of America
| | - Amy C. Morrison
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America
| | - Josefina Coloma
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Joseph N. S. Eisenberg
- Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, United States of America
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Thisyakorn U, Saokaew S, Gallagher E, Kastner R, Sruamsiri R, Oliver L, Hanley R. Epidemiology and costs of dengue in Thailand: A systematic literature review. PLoS Negl Trop Dis 2022; 16:e0010966. [PMID: 36534668 PMCID: PMC9810168 DOI: 10.1371/journal.pntd.0010966] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 01/03/2023] [Accepted: 11/19/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Dengue is the fastest-spreading vector-borne viral disease worldwide. In Thailand, dengue is endemic and is associated with a high socioeconomic burden. A systematic literature review was conducted to assess and describe the epidemiological and economic burden of dengue in Thailand. METHODS Epidemiological and economic studies published in English and Thai between 2011-2019 and 2009-2019, respectively, were searched in MEDLINE, Embase, and Evidence-Based Medicines reviews databases. Reports published by the National Ministry of Public Health (MoPH) and other grey literature sources were also reviewed. Identified studies were screened according to predefined inclusion and exclusion criteria. Extracted data were descriptively summarised and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS A total of 155 publications were included in the review (39 journal articles and 116 grey literature). Overall, dengue incidence varied yearly, with the highest rates per 100,000 population in 2013 (dengue fever (DF) 136.6, dengue haemorrhagic fever (DHF) 100.9, dengue shock syndrome (DSS) 3.58) and 2015 (DF 133.1, DHF 87.4, DSS 2.14). Peak incidence coincided with the monsoon season, and annual mortality was highest for DSS, particularly in the age group 15-24-year-olds. The highest dengue incidence rates were reported in children (10-14-year-olds) and young adults (15-24-year-olds), irrespective of dengue case definition. Economic and societal burdens are extensive, with the average cost per case ranging from USD 41 to USD 261, total cost per year estimated at USD 440.3 million, and an average of 7.6 workdays lost for DHF and 6.6 days for DF. CONCLUSIONS The epidemiological, economic, and societal burden of dengue in Thailand is high and underreported due to gaps in national surveillance data. The use of expansion factors (EFs) is recommended to understand the true incidence of dengue and cost-benefit of control measures. Furthermore, as dengue is often self-managed and underreported, lost school and workdays result in substantial underestimation of the true economic and societal burden of dengue. The implementation of integrated strategies, including vaccination, is critical to reduce the disease burden and may help alleviate health disparities and equity challenges posed by dengue.
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Affiliation(s)
- Usa Thisyakorn
- Tropical Medicine Cluster, Chulalongkorn University, Bangkok, Thailand
| | - Surasak Saokaew
- Center of Health Outcomes Research and Therapeutic Safety (Cohorts), School of Pharmaceutical Sciences, University of Phayao, Phayao, Thailand
- Unit of Excellence on Clinical Outcomes Research and IntegratioN (UNICORN), School of Pharmaceutical Sciences, University of Phayao, Phayao, Thailand
- Division of Social and Administrative Pharmacy, Department of Pharmaceutical Care, School of Pharmaceutical Sciences, University of Phayao, Phayao, Thailand
| | | | - Randee Kastner
- Takeda Vaccines Inc., Cambridge, Massachusetts, United States of America
| | | | - Louisa Oliver
- Adelphi Values, Bollington, Macclesfield, United Kingdom
| | - Riona Hanley
- Takeda Pharmaceuticals International AG, Zurich, Switzerland
- * E-mail:
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Oo MC, Phongluxa K, Oo WH, Kounnavong S, Xayyavong S, Louangphaxay C, Htike W, Cutts JC, Thu KM, Hkawng GN, Fowkes FJI. Perspectives of health and community stakeholders on community-delivered models of malaria elimination in Lao People’s Democratic Republic: A qualitative study. PLoS One 2022; 17:e0264399. [PMID: 35271594 PMCID: PMC8912149 DOI: 10.1371/journal.pone.0264399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/10/2022] [Indexed: 11/22/2022] Open
Abstract
In the Lao People’s Democratic Republic (Lao PDR), village health volunteers play an important role in providing health services including those to reduce the burden of malaria. Over the last two decades, the volunteer network has expanded to bring malaria services closer to communities and contributed to the reduction of malaria cases. However, as malaria test positivity rates decreased, many volunteers have lost motivation to continue providing routine malaria services, and other services they provide may not reflect growing healthcare demands for common diseases in the community. This study explored the perspectives, knowledge and inputs of key health stakeholders and community members in southern Lao PDR on community-delivered models in order to refine the volunteer model in the context of Lao PDR’s primary health care sector and malaria elimination goals. Semi-structured interviews with multi-level health stakeholders, participatory workshops with community leaders, and focus group discussions with community members and current village health volunteers were conducted. Deductive followed by inductive thematic analysis was used to explore and categorise stakeholders’ perspectives on community-delivered models for malaria elimination. Both stakeholders and community members agreed that village health volunteers are essential providers of malaria services in rural communities. Apart from malaria, community members identified dengue, diarrhoea, influenza, skin infections and tuberculosis as priorities (in descending order of importance) and requested community-based primary health care for these diseases. Stakeholders and community members suggested integrating prevention, diagnosis, and treatment services for the five priority diseases into the current malaria volunteer model. A divergence was identified between community members’ expectations of health services and the services currently provided by village health volunteers. Stakeholders proposed an integrated model of healthcare to meet the needs of the community and help to maintain volunteers’ motivation and the long-term sustainability of the role. An evidence-based, integrated community-delivered model of healthcare should be developed to balance the needs of both community members and stakeholders, with consideration of available resources and current health policies in Lao PDR.
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Affiliation(s)
- May Chan Oo
- Health Security Program, Burnet Institute Myanmar, Yangon, Myanmar
- * E-mail: (MCO); (WHO)
| | | | - Win Han Oo
- Health Security Program, Burnet Institute Myanmar, Yangon, Myanmar
- Disease Elimination Program, Burnet Institute, Victoria, Australia
- * E-mail: (MCO); (WHO)
| | | | - Syda Xayyavong
- Lao Tropical and Public Health Institute, Vientiane, Lao PDR
| | | | - Win Htike
- Health Security Program, Burnet Institute Myanmar, Yangon, Myanmar
| | - Julia C. Cutts
- Disease Elimination Program, Burnet Institute, Victoria, Australia
| | - Kaung Myat Thu
- Health Security Program, Burnet Institute Myanmar, Yangon, Myanmar
| | - Galau Naw Hkawng
- Health Security Program, Burnet Institute Myanmar, Yangon, Myanmar
| | - Freya J. I. Fowkes
- Disease Elimination Program, Burnet Institute, Victoria, Australia
- Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia
- Department of Epidemiology and Preventive Medicine, Monash University, Victoria, Australia
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Long H, Zhang C, Chen C, Tang J, Zhang B, Wang Y, Pang J, Su W, Li K, Di B, Chen YQ, Shu Y, Du X. Assessment of the global circulation and endemicity of dengue. Transbound Emerg Dis 2021; 69:2148-2155. [PMID: 34197697 DOI: 10.1111/tbed.14211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/27/2021] [Indexed: 11/30/2022]
Abstract
Dengue is a significant public health issue, affecting hundreds of millions of people worldwide. As it is spreading from tropical and subtropical zones, some regions previously recognised as non-endemic are at risk of becoming endemic. However, the global circulation of dengue is not fully understood and quantitative measurements of endemicity levels are lacking, posing an obstacle in the precise control of dengue spread. In this study, a sequence-based pipeline was designed based on random sampling to study the transmission of dengue. The limited intercontinental transmission was identified, while regional circulation of dengue was quantified in terms of importation, local circulation and exportation. Additionally, hypo- and hyper-endemic regions were identified using a new metric, with the former characterised by low local circulation and increased importation, whereas the latter by high local circulation and reduced importation. In this study, the global circulation pattern of dengue was examined and a sequence-based endemicity measurement was proposed, which will be helpful for future surveillance and targeted control of dengue.
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Affiliation(s)
- Haoyu Long
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Chi Zhang
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Cai Chen
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Jing Tang
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Bing Zhang
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Yinghan Wang
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Jiali Pang
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Wenzhe Su
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Kuibiao Li
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Biao Di
- Guangzhou Center for Disease Control and Prevention, Guangzhou, China
| | - Yao-Qing Chen
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China
| | - Yuelong Shu
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Xiangjun Du
- School of Public Health (Shenzhen), Sun Yat-Sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
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Rahman MS, Overgaard HJ, Pientong C, Mayxay M, Ekalaksananan T, Aromseree S, Phanthanawiboon S, Zafar S, Shipin O, Paul RE, Phommachanh S, Pongvongsa T, Vannavong N, Haque U. Knowledge, attitudes, and practices on climate change and dengue in Lao People's Democratic Republic and Thailand. ENVIRONMENTAL RESEARCH 2021; 193:110509. [PMID: 33245883 DOI: 10.1016/j.envres.2020.110509] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 10/25/2020] [Accepted: 11/17/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Dengue is linked with climate change in tropical and sub-tropical countries including the Lao People's Democratic Republic (Laos) and Thailand. Knowledge about these issues and preventive measures can affect the incidence and outbreak risk of dengue. Therefore, the present study was conducted to determine the knowledge, attitudes, and practices (KAP) among urban and rural communities and government officials about climate change and dengue in Laos and Thailand. METHODS A cross-sectional KAP survey about climate change and dengue were conducted in 360 households in Laos (180 urban and 180 rural), 359 households in Thailand (179 urban and 180 rural), and 20 government officials (10 in each country) using structured questionnaires. Data analysis was undertaken using descriptive methods, principal component analysis (PCA), Chi-square test or Fisher's exact test (as appropriate), and logistic regression. RESULTS Significant differences among the selected communities in both countries were found in terms of household participant's age, level of education, socioeconomic status, attitude level of climate change and KAP level of dengue (PÂ <Â 0.05; 95% CI). Overall, participants' KAP about climate change and dengue were low except the attitude level for dengue in both countries. The level of awareness among government officials regarding the climatic relationship with dengue was also low. In Lao households, participants' knowledge about climate change and dengue was significantly associated with the level of education and socioeconomic status (SES) (PÂ <Â 0.01). Their attitudes towards climate change and dengue were associated with educational level and internet use (PÂ <Â 0.05). Householders' climate change related practices were associated with SES (PÂ <Â 0.01) and dengue related practices were associated with educational level, SES, previous dengue experience and internet use (PÂ <Â 0.01). In Thailand, participants' knowledge about climate change was associated with the level of education and SES (PÂ <Â 0.01). Their attitudes towards climate change were associated with residence status (urban/rural) and internet use (PÂ <Â 0.05); climate change related practices were associated with educational level and SES (PÂ <Â 0.05). Dengue related knowledge of participants was associated with SES and previous dengue experience (PÂ <Â 0.05); participants' dengue related attitudes and practices were associated with educational level (PÂ <Â 0.01). CONCLUSION The findings call for urgently needed integrated awareness programs to increase KAP levels regarding climate change adaptation, mitigation and dengue prevention to improve the health and welfare of people in these two countries, and similar dengue-endemic countries.
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Affiliation(s)
- Md Siddikur Rahman
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; Department of Statistics, Begum Rokeya University, Rangpur, Bangladesh
| | - Hans J Overgaard
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; Faculty of Science and Technology, Norwegian University of Life Sciences, P.O. Box 5003, Ã…s, Norway.
| | - Chamsai Pientong
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | - Mayfong Mayxay
- Institute of Research and Education Development (IRED), University of Health Sciences, Vientiane, Lao Democratic People's Republic; Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit (LOMWRU), Vientiane, Lao Democratic People's Republic; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Tipaya Ekalaksananan
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | - Sirinart Aromseree
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | - Supranee Phanthanawiboon
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; HPV & EBV and Carcinogenesis Research Group, Khon Kaen University, Khon Kaen, Thailand
| | | | - Oleg Shipin
- Asian Institute of Technology, Bangkok, Thailand
| | - Richard E Paul
- Institut Pasteur, Functional Genetics of Infectious Diseases Unit, UMR 2000 CNRS, Paris, France
| | - Sysavanh Phommachanh
- Institute of Research and Education Development (IRED), University of Health Sciences, Vientiane, Lao Democratic People's Republic
| | - Tiengkham Pongvongsa
- Savannakhet Provincial Health Office, Savannakhet Province, Lao Democratic People's Republic
| | | | - Ubydul Haque
- Department of Biostatistics and Epidemiology, University of North Texas Health Science Center, North, TX, Fort Worth, TX, 76107, USA
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Saeung M, Ngoen-Klan R, Thanispong K, Muenworn V, Bangs MJ, Chareonviriyaphap T. Susceptibility of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) to Temephos in Thailand and Surrounding Countries. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:1207-1220. [PMID: 32159772 DOI: 10.1093/jme/tjaa035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Indexed: 06/10/2023]
Abstract
Aedes-borne virus disease control relies on insecticides to interrupt transmission. Temephos remains a key chemical for control of immature stage Aedes in Thailand and much of Southeast Asia. However, repeated use of insecticides may result in selection for resistance in vector populations, thus compromising operational intervention. Herein, the phenotypic response to temephos by Aedes aegypti (L.) and Aedes albopictus (Skuse) collected in Thailand and surrounding countries is presented. Data from 345 collection sites are included: 283 from literature review (244 sites with Ae. aegypti, 21 with Ae. albopictus, and 18 having both species sampled), plus 62 locations with Ae. aegypti in Thailand conducted between 2014 and 2018. Susceptibility assays followed WHO guidelines using the recommended discriminating dose of temephos (0.012 mg/liter) against late third to early fourth instar Ae. aegypti. Findings revealed 34 locations with susceptible Ae. aegypti, 13 with suspected resistance, and 15 indicating resistance. Published data between 1999 and 2019 in Thailand found Ae. aegypti resistant in 73 of 206 collection sites, whereas 3 locations from 11 sampled with low-level resistant in Ae. albopictus. From surrounding countries conducting temephos assays (Cambodia, Lao PDR, Myanmar, Malaysia, and Singapore), resistance is present in Ae. aegypti and Ae. albopictus from 27 of 56 and 19 of 28 locations, respectively. Routine insecticide susceptibility monitoring should be an operational requirement in vector control programs. Given the wide distribution and apparent increase in temephos-resistance, alternative larvicidal compounds must be considered if chemical control is to remain a viable vector control strategy.
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Affiliation(s)
- Manop Saeung
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Ratchadawan Ngoen-Klan
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Kanutcharee Thanispong
- Division of Vector Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| | - Vithee Muenworn
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand
| | - Michael J Bangs
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
- Public Health & Malaria Control Department, PT Freeport Indonesia/International SOS, Kuala Kencana, Papua, Indonesia
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