Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control
Abstract Background Understanding the clustering of infections for persistent malaria transmission is critical to determining how and where to target specific interventions. This study aimed to determine the density, blood meal sources and malaria transmission risk of anopheline vectors by targeting...
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| Format: | Article |
| Language: | English |
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BMC
2024-02-01
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| Series: | Parasites & Vectors |
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| Online Access: | https://doi.org/10.1186/s13071-023-06088-2 |
| _version_ | 1797275684959158272 |
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| author | Ashenafi Abossie Assalif Demissew Hallelujah Getachew Arega Tsegaye Teshome Degefa Kassahun Habtamu Daibin Zhong Xiaoming Wang Ming-Chieh Lee Guofa Zhou Christopher L. King James W. Kazura Guiyun Yan Delenasaw Yewhalaw |
| author_facet | Ashenafi Abossie Assalif Demissew Hallelujah Getachew Arega Tsegaye Teshome Degefa Kassahun Habtamu Daibin Zhong Xiaoming Wang Ming-Chieh Lee Guofa Zhou Christopher L. King James W. Kazura Guiyun Yan Delenasaw Yewhalaw |
| author_sort | Ashenafi Abossie |
| collection | DOAJ |
| description | Abstract Background Understanding the clustering of infections for persistent malaria transmission is critical to determining how and where to target specific interventions. This study aimed to determine the density, blood meal sources and malaria transmission risk of anopheline vectors by targeting malaria index cases, their neighboring households and control villages in Arjo-Didessa, southwestern Ethiopia. Methods An entomological study was conducted concurrently with a reactive case detection (RCD) study from November 2019 to October 2021 in Arjo Didessa and the surrounding vicinity, southwestern Ethiopia. Anopheline mosquitoes were collected indoors and outdoors in index case households and their surrounding households (neighboring households), as well as in control households, using pyrethrum spray cache (PSC) and U.S. Centers for Disease Control and Prevention (CDC) light traps. Adult mosquitoes were morphologically identified, and speciation in the Anopheles gambiae complex was done by PCR. Mosquito Plasmodium infections and host blood meal sources were detected by circumsporozoite protein enzyme-linked immunosorbent assay (CSP-ELISA) and cytochrome b-based blood meal PCR, respectively. Results Among the 770 anopheline mosquitoes collected, An. gambiae sensu lato (A. gambiae s.l.) was the predominant species, accounting for 87.1% (n = 671/770) of the catch, followed by the Anopheles coustani complex and Anopheles pharoensis, which accounted for 12.6% (n = 97/770) and 0.26% (n = 2/770) of the catch, respectively. From the sub-samples of An. gambiae s.l.analyzed with PCR, An. arabiensis and Anopheles amharicus were identified. The overall mean density of mosquitoes was 1.26 mosquitoes per trap per night using the CDC light traps. Outdoor mosquito density was significantly higher than indoor mosquito density in the index and neighboring households (P = 0.0001). The human blood index (HBI) and bovine blood index (BBI) of An. arabiensis were 20.8% (n = 34/168) and 24.0% (n = 41/168), respectively. The overall Plasmodium sporozoite infection rate of anophelines (An. arabiensis and An. coustani complex) was 4.4% (n = 34/770). Sporozoites were detected indoors and outdoors in captured anopheline mosquitoes. Of these CSP-positive species for Pv-210, Pv-247 and Pf, 41.1% (n = 14/34) were captured outdoors. A significantly higher proportion of sporozoite-infected mosquitoes were caught in index case households (5.6%, n = 8/141) compared to control households (1.1%, n = 2/181) (P = 0.02), and in neighboring households (5.3%, n = 24/448) compared to control households (P = 0.01). Conclusions The findings of this study indicated that malaria index cases and their neighboring households had higher outdoor mosquito densities and Plasmodium infection rates. The study also highlighted a relatively higher outdoor mosquito density, which could increase the potential risk of outdoor malaria transmission and may play a role in residual malaria transmission. Thus, it is important to strengthen the implementation of vector control interventions, such as targeted indoor residual spraying, long-lasting insecticidal nets and other supplementary vector control measures such as larval source management and community engagement approaches. Furthermore, in low transmission settings, such as the Arjo Didessa Sugarcane Plantation, providing health education to local communities, enhanced environmental management and entomological surveillance, along with case detection and management by targeting of malaria index cases and their immediate neighboring households, could be important measures to control residual malaria transmission and achieve the targeted elimination goals. Graphical Abstract |
| first_indexed | 2024-03-07T15:17:01Z |
| format | Article |
| id | doaj.art-6a5333a7da874caf859724d59354a3ac |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-03-07T15:17:01Z |
| publishDate | 2024-02-01 |
| publisher | BMC |
| record_format | Article |
| series | Parasites & Vectors |
| spelling | doaj.art-6a5333a7da874caf859724d59354a3ac2024-03-05T17:51:03ZengBMCParasites & Vectors1756-33052024-02-0117111410.1186/s13071-023-06088-2Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector controlAshenafi Abossie0Assalif Demissew1Hallelujah Getachew2Arega Tsegaye3Teshome Degefa4Kassahun Habtamu5Daibin Zhong6Xiaoming Wang7Ming-Chieh Lee8Guofa Zhou9Christopher L. King10James W. Kazura11Guiyun Yan12Delenasaw Yewhalaw13Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Arba Minch UniversityDepartment of Medical Laboratory Sciences, College of Medicine and Health Sciences, Ambo UniversitySchool of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma UniversitySchool of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma UniversitySchool of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma UniversityMenelik II College of Health SciencesProgram in Public Health, University of California at IrvineProgram in Public Health, University of California at IrvineProgram in Public Health, University of California at IrvineProgram in Public Health, University of California at IrvineCenter for Global Health & Diseases, School of Medicine, Case Western Reserve UniversityCenter for Global Health & Diseases, School of Medicine, Case Western Reserve UniversityProgram in Public Health, University of California at IrvineSchool of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma UniversityAbstract Background Understanding the clustering of infections for persistent malaria transmission is critical to determining how and where to target specific interventions. This study aimed to determine the density, blood meal sources and malaria transmission risk of anopheline vectors by targeting malaria index cases, their neighboring households and control villages in Arjo-Didessa, southwestern Ethiopia. Methods An entomological study was conducted concurrently with a reactive case detection (RCD) study from November 2019 to October 2021 in Arjo Didessa and the surrounding vicinity, southwestern Ethiopia. Anopheline mosquitoes were collected indoors and outdoors in index case households and their surrounding households (neighboring households), as well as in control households, using pyrethrum spray cache (PSC) and U.S. Centers for Disease Control and Prevention (CDC) light traps. Adult mosquitoes were morphologically identified, and speciation in the Anopheles gambiae complex was done by PCR. Mosquito Plasmodium infections and host blood meal sources were detected by circumsporozoite protein enzyme-linked immunosorbent assay (CSP-ELISA) and cytochrome b-based blood meal PCR, respectively. Results Among the 770 anopheline mosquitoes collected, An. gambiae sensu lato (A. gambiae s.l.) was the predominant species, accounting for 87.1% (n = 671/770) of the catch, followed by the Anopheles coustani complex and Anopheles pharoensis, which accounted for 12.6% (n = 97/770) and 0.26% (n = 2/770) of the catch, respectively. From the sub-samples of An. gambiae s.l.analyzed with PCR, An. arabiensis and Anopheles amharicus were identified. The overall mean density of mosquitoes was 1.26 mosquitoes per trap per night using the CDC light traps. Outdoor mosquito density was significantly higher than indoor mosquito density in the index and neighboring households (P = 0.0001). The human blood index (HBI) and bovine blood index (BBI) of An. arabiensis were 20.8% (n = 34/168) and 24.0% (n = 41/168), respectively. The overall Plasmodium sporozoite infection rate of anophelines (An. arabiensis and An. coustani complex) was 4.4% (n = 34/770). Sporozoites were detected indoors and outdoors in captured anopheline mosquitoes. Of these CSP-positive species for Pv-210, Pv-247 and Pf, 41.1% (n = 14/34) were captured outdoors. A significantly higher proportion of sporozoite-infected mosquitoes were caught in index case households (5.6%, n = 8/141) compared to control households (1.1%, n = 2/181) (P = 0.02), and in neighboring households (5.3%, n = 24/448) compared to control households (P = 0.01). Conclusions The findings of this study indicated that malaria index cases and their neighboring households had higher outdoor mosquito densities and Plasmodium infection rates. The study also highlighted a relatively higher outdoor mosquito density, which could increase the potential risk of outdoor malaria transmission and may play a role in residual malaria transmission. Thus, it is important to strengthen the implementation of vector control interventions, such as targeted indoor residual spraying, long-lasting insecticidal nets and other supplementary vector control measures such as larval source management and community engagement approaches. Furthermore, in low transmission settings, such as the Arjo Didessa Sugarcane Plantation, providing health education to local communities, enhanced environmental management and entomological surveillance, along with case detection and management by targeting of malaria index cases and their immediate neighboring households, could be important measures to control residual malaria transmission and achieve the targeted elimination goals. Graphical Abstracthttps://doi.org/10.1186/s13071-023-06088-2Index caseReactive case detectionSporozoite rateResidual malariaEthiopia |
| spellingShingle | Ashenafi Abossie Assalif Demissew Hallelujah Getachew Arega Tsegaye Teshome Degefa Kassahun Habtamu Daibin Zhong Xiaoming Wang Ming-Chieh Lee Guofa Zhou Christopher L. King James W. Kazura Guiyun Yan Delenasaw Yewhalaw Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control Parasites & Vectors Index case Reactive case detection Sporozoite rate Residual malaria Ethiopia |
| title | Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control |
| title_full | Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control |
| title_fullStr | Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control |
| title_full_unstemmed | Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control |
| title_short | Higher outdoor mosquito density and Plasmodium infection rates in and around malaria index case households in low transmission settings of Ethiopia: Implications for vector control |
| title_sort | higher outdoor mosquito density and plasmodium infection rates in and around malaria index case households in low transmission settings of ethiopia implications for vector control |
| topic | Index case Reactive case detection Sporozoite rate Residual malaria Ethiopia |
| url | https://doi.org/10.1186/s13071-023-06088-2 |
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