Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers

Abstract Background Foreign migrant workers from malaria-endemic regions play a critical factor in the transmission of malaria to non-endemic areas, mainly due to their mobility while seeking employment opportunities. This risk is particularly heightened in areas where malaria vectors are present. M...

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Main Authors: Nurhadi Eko Firmansyah, Thaksaporn Thongseesuksai, Thidarut Boonmars, Porntip Laummaunwai
Format: Article
Language:English
Published: BMC 2025-01-01
Series:Malaria Journal
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Online Access:https://doi.org/10.1186/s12936-025-05253-5
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author Nurhadi Eko Firmansyah
Thaksaporn Thongseesuksai
Thidarut Boonmars
Porntip Laummaunwai
author_facet Nurhadi Eko Firmansyah
Thaksaporn Thongseesuksai
Thidarut Boonmars
Porntip Laummaunwai
author_sort Nurhadi Eko Firmansyah
collection DOAJ
description Abstract Background Foreign migrant workers from malaria-endemic regions play a critical factor in the transmission of malaria to non-endemic areas, mainly due to their mobility while seeking employment opportunities. This risk is particularly heightened in areas where malaria vectors are present. Methods This study aimed to investigate the malaria vectors in two sub-districts in Khon Kaen Province, known for their factory areas and the significant presence of Myanmar migrant worker communities. The collection was carried out from June 2020 to May 2021. The black light traps (BLT) operated continuously from 6:00 pm to 6:00 am (12 h) and Kelambu trap (KT) were set up from 6:00 pm to 9:00 pm, with both traps set up once a month. A total of 679 female Anopheles mosquitoes were collected near the workplaces and dormitories of these workers. Subsequently, the collected female mosquitoes underwent morphological identification using Standard Thailand keys and polymerase chain reaction analysis with rDNA ITS2 primers. Results Morphological identification revealed that 201 (29.6%) belonged to the Barbirostris complex. The remaining Anopheles mosquitoes are in the subgroup Cellia, comprised 437 (64.4%) Anopheles vagus, 39 (5.7%) Anopheles subpictus, and 2 (0.3%) Anopheles annularis. To distinguish the Barbirostris complex, multiplex PCR based on ITS-2 sequences was conducted. Out of the 201 specimens examined, 153 (76.1%) as Anopheles campestris, 36 (17.9%) as Anopheles wejchoochotei, and 12 (6%) as Anopheles dissidens. Additionally, the subgroup Anopheles Cellia was confirmed using specific primers based on ITS-2 sequences. Conclusions From the obtained results, An. campestris, An. wejchoochotei, An. vagus and An. annularis are reported as the malaria vectors in Thailand. The findings emphasized the important of addressing the presence of Anopheles malaria vectors, especially in the substantial migrant worker population originating from endemic areas. This situation raises concerns regarding the potential transmission of malaria infections to regions not traditionally affected by the disease. Epidemiological studies on malaria vectors should not solely concentrate on endemic regions but also extend to non-endemic areas because of the mobility of migrant workers throughout the country. This broader approach is crucial for implementing an effective malaria surveillance strategy. Graphical Abstract
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spelling doaj-art-77125bc624d34c0e94eea4ab16ab09c42025-01-26T12:15:56ZengBMCMalaria Journal1475-28752025-01-0124111010.1186/s12936-025-05253-5Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workersNurhadi Eko Firmansyah0Thaksaporn Thongseesuksai1Thidarut Boonmars2Porntip Laummaunwai3Department of Parasitology, Faculty of Medicine, Khon Kaen UniversityDepartment of Parasitology, Faculty of Medicine, Khon Kaen UniversityDepartment of Parasitology, Faculty of Medicine, Khon Kaen UniversityDepartment of Parasitology, Faculty of Medicine, Khon Kaen UniversityAbstract Background Foreign migrant workers from malaria-endemic regions play a critical factor in the transmission of malaria to non-endemic areas, mainly due to their mobility while seeking employment opportunities. This risk is particularly heightened in areas where malaria vectors are present. Methods This study aimed to investigate the malaria vectors in two sub-districts in Khon Kaen Province, known for their factory areas and the significant presence of Myanmar migrant worker communities. The collection was carried out from June 2020 to May 2021. The black light traps (BLT) operated continuously from 6:00 pm to 6:00 am (12 h) and Kelambu trap (KT) were set up from 6:00 pm to 9:00 pm, with both traps set up once a month. A total of 679 female Anopheles mosquitoes were collected near the workplaces and dormitories of these workers. Subsequently, the collected female mosquitoes underwent morphological identification using Standard Thailand keys and polymerase chain reaction analysis with rDNA ITS2 primers. Results Morphological identification revealed that 201 (29.6%) belonged to the Barbirostris complex. The remaining Anopheles mosquitoes are in the subgroup Cellia, comprised 437 (64.4%) Anopheles vagus, 39 (5.7%) Anopheles subpictus, and 2 (0.3%) Anopheles annularis. To distinguish the Barbirostris complex, multiplex PCR based on ITS-2 sequences was conducted. Out of the 201 specimens examined, 153 (76.1%) as Anopheles campestris, 36 (17.9%) as Anopheles wejchoochotei, and 12 (6%) as Anopheles dissidens. Additionally, the subgroup Anopheles Cellia was confirmed using specific primers based on ITS-2 sequences. Conclusions From the obtained results, An. campestris, An. wejchoochotei, An. vagus and An. annularis are reported as the malaria vectors in Thailand. The findings emphasized the important of addressing the presence of Anopheles malaria vectors, especially in the substantial migrant worker population originating from endemic areas. This situation raises concerns regarding the potential transmission of malaria infections to regions not traditionally affected by the disease. Epidemiological studies on malaria vectors should not solely concentrate on endemic regions but also extend to non-endemic areas because of the mobility of migrant workers throughout the country. This broader approach is crucial for implementing an effective malaria surveillance strategy. Graphical Abstracthttps://doi.org/10.1186/s12936-025-05253-5Malaria vectorsAnophelesForeign migrant workersNon-endemic areaMolecular identification
spellingShingle Nurhadi Eko Firmansyah
Thaksaporn Thongseesuksai
Thidarut Boonmars
Porntip Laummaunwai
Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers
Malaria Journal
Malaria vectors
Anopheles
Foreign migrant workers
Non-endemic area
Molecular identification
title Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers
title_full Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers
title_fullStr Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers
title_full_unstemmed Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers
title_short Investigation of malaria vectors Anopheles in non-endemic areas of Thailand: in proximity to workplaces housing foreign migrant workers
title_sort investigation of malaria vectors anopheles in non endemic areas of thailand in proximity to workplaces housing foreign migrant workers
topic Malaria vectors
Anopheles
Foreign migrant workers
Non-endemic area
Molecular identification
url https://doi.org/10.1186/s12936-025-05253-5
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