Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia
Abstract Background After a marked reduction in malaria burden in Cambodia over the last decades, case numbers increased again in 2017–2018. In light of the national goal of malaria elimination by 2025, remaining pockets of high risk need to be well defined and strategies well-tailored to identify a...
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| Format: | Article |
| Language: | English |
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BMC
2020-11-01
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| Series: | Malaria Journal |
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| Online Access: | http://link.springer.com/article/10.1186/s12936-020-03482-4 |
| _version_ | 1818530304517734400 |
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| author | Mirco Sandfort Amélie Vantaux Saorin Kim Thomas Obadia Anaïs Pepey Soazic Gardais Nimol Khim Dysoley Lek Michael White Leanne J. Robinson Benoit Witkowski Ivo Mueller |
| author_facet | Mirco Sandfort Amélie Vantaux Saorin Kim Thomas Obadia Anaïs Pepey Soazic Gardais Nimol Khim Dysoley Lek Michael White Leanne J. Robinson Benoit Witkowski Ivo Mueller |
| author_sort | Mirco Sandfort |
| collection | DOAJ |
| description | Abstract Background After a marked reduction in malaria burden in Cambodia over the last decades, case numbers increased again in 2017–2018. In light of the national goal of malaria elimination by 2025, remaining pockets of high risk need to be well defined and strategies well-tailored to identify and target the persisting burden cost-effectively. This study presents species-specific prevalence estimates and risk stratification for a remote area in Cambodia. Methods A cross-sectional survey was conducted in 17 villages in the high-incidence province Mondulkiri in the dry season (December 2017 to April 2018). 4200 randomly selected participants (2–80 years old) were tested for Plasmodium infection by PCR. Risk of infection was associated with questionnaire-derived covariates and spatially stratified based on household GPS coordinates. Results The prevalence of PCR-detectable Plasmodium infection was 8.3% (349/4200) and was more than twice as high for Plasmodium vivax (6.4%, 268) than for Plasmodium falciparum (3.0%, 125, p < 0.001). 97.8% (262/268) of P. vivax and 92.8% (116/125, p < 0.05) of P. falciparum infections were neither accompanied by symptoms at the time of the interview nor detected by microscopy or RDT. Recent travels to forest sites (aOR 2.17, p < 0.01) and forest work (aOR 2.88, p < 0.001) were particularly strong risk factors and risk profiles for both species were similar. Large village-level differences in prevalence of Plasmodium infection were observed, ranging from 0.6% outside the forest to 40.4% inside. Residing in villages at the forest fringe or inside the forest compared to outside was associated with risk of infection (aOR 2.14 and 12.47, p < 0.001). Villages inside the forest formed spatial hotspots of infection despite adjustment for the other risk factors. Conclusions Persisting pockets of high malaria risk were detected in forested areas and in sub-populations engaging in forest-related activities. High levels of asymptomatic infections suggest the need of better case detection plans and the predominance of P. vivax the implementation of radical cure. In villages inside the forest, within-village exposure was indicated in addition to risk due to forest activities. Village-level stratification of targeted interventions based on forest proximity could render the elimination efforts more cost-effective and successful. |
| first_indexed | 2024-12-11T17:18:01Z |
| format | Article |
| id | doaj.art-4f30aaf46fbe493991690b40545854f7 |
| institution | Directory Open Access Journal |
| issn | 1475-2875 |
| language | English |
| last_indexed | 2024-12-11T17:18:01Z |
| publishDate | 2020-11-01 |
| publisher | BMC |
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| series | Malaria Journal |
| spelling | doaj.art-4f30aaf46fbe493991690b40545854f72022-12-22T00:57:14ZengBMCMalaria Journal1475-28752020-11-0119111210.1186/s12936-020-03482-4Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, CambodiaMirco Sandfort0Amélie Vantaux1Saorin Kim2Thomas Obadia3Anaïs Pepey4Soazic Gardais5Nimol Khim6Dysoley Lek7Michael White8Leanne J. Robinson9Benoit Witkowski10Ivo Mueller11Malaria: Parasites and Hosts Unit, Institut PasteurMalaria Molecular Epidemiology Unit, Institut Pasteur du CambodgeMalaria Molecular Epidemiology Unit, Institut Pasteur du CambodgeMalaria: Parasites and Hosts Unit, Institut PasteurMalaria Molecular Epidemiology Unit, Institut Pasteur du CambodgeMalaria: Parasites and Hosts Unit, Institut PasteurMalaria Molecular Epidemiology Unit, Institut Pasteur du CambodgeNational Centre for Parasitology, Entomology, and Malaria ControlMalaria: Parasites and Hosts Unit, Institut PasteurPopulation Health & Immunity, Walter and Eliza Hall InstituteMalaria Molecular Epidemiology Unit, Institut Pasteur du CambodgeMalaria: Parasites and Hosts Unit, Institut PasteurAbstract Background After a marked reduction in malaria burden in Cambodia over the last decades, case numbers increased again in 2017–2018. In light of the national goal of malaria elimination by 2025, remaining pockets of high risk need to be well defined and strategies well-tailored to identify and target the persisting burden cost-effectively. This study presents species-specific prevalence estimates and risk stratification for a remote area in Cambodia. Methods A cross-sectional survey was conducted in 17 villages in the high-incidence province Mondulkiri in the dry season (December 2017 to April 2018). 4200 randomly selected participants (2–80 years old) were tested for Plasmodium infection by PCR. Risk of infection was associated with questionnaire-derived covariates and spatially stratified based on household GPS coordinates. Results The prevalence of PCR-detectable Plasmodium infection was 8.3% (349/4200) and was more than twice as high for Plasmodium vivax (6.4%, 268) than for Plasmodium falciparum (3.0%, 125, p < 0.001). 97.8% (262/268) of P. vivax and 92.8% (116/125, p < 0.05) of P. falciparum infections were neither accompanied by symptoms at the time of the interview nor detected by microscopy or RDT. Recent travels to forest sites (aOR 2.17, p < 0.01) and forest work (aOR 2.88, p < 0.001) were particularly strong risk factors and risk profiles for both species were similar. Large village-level differences in prevalence of Plasmodium infection were observed, ranging from 0.6% outside the forest to 40.4% inside. Residing in villages at the forest fringe or inside the forest compared to outside was associated with risk of infection (aOR 2.14 and 12.47, p < 0.001). Villages inside the forest formed spatial hotspots of infection despite adjustment for the other risk factors. Conclusions Persisting pockets of high malaria risk were detected in forested areas and in sub-populations engaging in forest-related activities. High levels of asymptomatic infections suggest the need of better case detection plans and the predominance of P. vivax the implementation of radical cure. In villages inside the forest, within-village exposure was indicated in addition to risk due to forest activities. Village-level stratification of targeted interventions based on forest proximity could render the elimination efforts more cost-effective and successful.http://link.springer.com/article/10.1186/s12936-020-03482-4ForestOccupational riskSpatialVivaxHotspotsCambodia |
| spellingShingle | Mirco Sandfort Amélie Vantaux Saorin Kim Thomas Obadia Anaïs Pepey Soazic Gardais Nimol Khim Dysoley Lek Michael White Leanne J. Robinson Benoit Witkowski Ivo Mueller Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia Malaria Journal Forest Occupational risk Spatial Vivax Hotspots Cambodia |
| title | Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia |
| title_full | Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia |
| title_fullStr | Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia |
| title_full_unstemmed | Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia |
| title_short | Forest malaria in Cambodia: the occupational and spatial clustering of Plasmodium vivax and Plasmodium falciparum infection risk in a cross-sectional survey in Mondulkiri province, Cambodia |
| title_sort | forest malaria in cambodia the occupational and spatial clustering of plasmodium vivax and plasmodium falciparum infection risk in a cross sectional survey in mondulkiri province cambodia |
| topic | Forest Occupational risk Spatial Vivax Hotspots Cambodia |
| url | http://link.springer.com/article/10.1186/s12936-020-03482-4 |
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