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Esayas E, Assefa M, Bennett A, Thomsen E, Gowelo S, Vajda E, Getachew A, Ashine T, Yeshaneh A, Kassa FA, Demisse M, Ntuku H, Dinka H, Golassa L, Lobo NF, Gadisa E. Bionomic characterization of Anopheles mosquitoes in the Ethiopian highlands and lowlands. Parasit Vectors 2024; 17:306. [PMID: 39014474 PMCID: PMC11251230 DOI: 10.1186/s13071-024-06378-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Accepted: 06/26/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND The protective effectiveness of vector control in malaria relies on how the implemented tools overlap with mosquito species-specific compositions and bionomic traits. In Ethiopia, targeted entomological data enabling strategic decision-making are lacking around high-risk migrant worker camps in the lowlands and resident communities in the highlands-resulting in suboptimal malaria control strategies for both populations. This study investigates spatial and temporal mosquito behavior, generating baseline evidence that will improve malaria control for both migrant workers in the lowlands and their home communities in the highlands. METHODS Hourly Centers for Disease Control and Prevention (CDC) light trap collections were performed indoors and outdoors during the peak (October to December 2022) and minor (March to May 2023) malaria transmission seasons. These seasons coincide with the post-long rain and post-short rain seasons, respectively. Eight resident households were sampled from each of four villages in the highlands and eight households/farm structures on and near farms in four villages in the lowlands. The sampling occurred between 18:00 and 06:00. Spatiotemporal vector behaviors and hourly indoor and outdoor mosquito capture rates, used as a proxy for human biting rates, were calculated for overall catches and for individual species. Adult mosquitoes were identified using morphological keys, and a subset of samples were confirmed to species by sequencing ribosomal DNA internal transcribed spacer region 2 (ITS2) and/or mitochondrial DNA cytochrome c oxidase subunit 1 (Cox1). RESULTS In the highlands, 4697 Anopheles mosquitoes belonging to 13 morphologically identified species were collected. The predominant species of Anopheles identified in the highlands was An. gambiae sensu lato (s.l.) (n = 1970, 41.9%), followed by An. demeilloni (n = 1133, 24.1%) and An. cinereus (n = 520, 11.0%). In the lowland villages, 3220 mosquitoes belonging to 18 morphological species were collected. Anopheles gambiae s.l. (n = 1190, 36.9%), An. pretoriensis (n = 899, 27.9%), and An. demeilloni (n = 564, 17.5%) were the predominant species. A total of 20 species were identified molecularly, of which three could not be identified to species through comparison with published sequences. In highland villages, the indoor Anopheles mosquito capture rate was much greater than the outdoor rate. This trend reversed in the lowlands, where the rate of outdoor captures was greater than the indoor rate. In both highlands and lowlands, Anopheles mosquitoes showed early biting activities in the evening, which peaked between 18:00 and 21:00, for both indoor and outdoor locations. CONCLUSIONS The high diversity of Anopheles vectors and their variable behaviors result in a dynamic and resilient transmission system impacting both exposure to infectious bites and intervention effectiveness. This creates gaps in protection allowing malaria transmission to persist. To achieve optimal control, one-size-fits-all strategies must be abandoned, and interventions should be tailored to the diverse spatiotemporal behaviors of different mosquito populations.
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Affiliation(s)
- Endashaw Esayas
- Malaria and Neglected Tropical Diseases Research Division, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
| | - Muluken Assefa
- Malaria and Neglected Tropical Diseases Research Division, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Adam Bennett
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Seattle, USA
| | - Edward Thomsen
- Malaria Elimination Initiative, University of California San Francisco, San Francisco, USA
| | - Steven Gowelo
- Malaria Elimination Initiative, University of California San Francisco, San Francisco, USA
| | - Elodie Vajda
- Malaria Elimination Initiative, University of California San Francisco, San Francisco, USA
| | - Asefaw Getachew
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Addis Ababa, Ethiopia
| | - Temesgen Ashine
- Malaria and Neglected Tropical Diseases Research Division, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Abebaw Yeshaneh
- West Gondar Zone Health Department, Amhara Regional Health Bureau, Metema, Ethiopia
| | - Fikregabrail Aberra Kassa
- Malaria and Neglected Tropical Diseases Research Division, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Mulugeta Demisse
- Malaria and Neglected Tropical Diseases Research Division, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Henry Ntuku
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Seattle, USA
| | - Hunduma Dinka
- Department of Applied Biology, School of Applied Natural Science, Adama Science and Technology University, Adama, Ethiopia
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Neil F Lobo
- Malaria Elimination Initiative, University of California San Francisco, San Francisco, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Endalamaw Gadisa
- Malaria and Neglected Tropical Diseases Research Division, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
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Abossie A, Demissew A, Getachew H, Tsegaye A, Degefa T, Habtamu K, Zhong D, Wang X, Lee MC, Zhou G, King CL, Kazura JW, Yan G, Yewhalaw D. 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. Parasit Vectors 2024; 17:53. [PMID: 38321572 PMCID: PMC10848356 DOI: 10.1186/s13071-023-06088-2] [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: 04/07/2023] [Accepted: 12/07/2023] [Indexed: 02/08/2024] Open
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.
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Affiliation(s)
- Ashenafi Abossie
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Arba Minch University, Arba Minch, Ethiopia.
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia.
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia.
| | - Assalif Demissew
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Ambo University, Ambo, Ethiopia
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Hallelujah Getachew
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Department of Medical Laboratory Technology, Arba Minch College of Health Sciences, Arba Minch, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Arega Tsegaye
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Department of Biology, College of Natural Science, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Teshome Degefa
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
| | - Kassahun Habtamu
- Menelik II College of Health Sciences, Addis Ababa, Ethiopia
- Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Daibin Zhong
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Xiaoming Wang
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Ming-Chieh Lee
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Guofa Zhou
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Christopher L King
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, 44106 OH, USA
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, 44106 OH, USA
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, Irvine, CA, 92697, USA
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
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Akirso A, Tamiru G, Eligo N, Lindtjørn B, Massebo F. High human blood meal index of mosquitoes in Arba Minch town, southwest Ethiopia: an implication for urban mosquito-borne disease transmission. Parasitol Res 2024; 123:102. [PMID: 38233721 PMCID: PMC10794327 DOI: 10.1007/s00436-024-08121-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 01/03/2024] [Indexed: 01/19/2024]
Abstract
Unplanned human population shifts in urban areas are expected to increase the prevalence of vector-borne diseases. This study aimed to investigate mosquito species composition, blood meal sources, and malaria vectors in an urban area. Indoor-resting adult mosquitoes were collected using Prokopack and host-seeking mosquitoes using Centers for Disease Control and Prevention light traps in Arba Minch town. Larval collection from artificial containers was done in those houses selected for adult mosquito collection. Anopheles adults collected and emerged from larvae were identified morphologically using a taxonomic key. ELISA was used to identify blood meal sources in freshly fed Anopheles and Culex mosquitoes, and CSP of Anopheles mosquitoes. A total of 16,756 female mosquitoes were collected. Of these, 93% (15,571) were Culex, 6% (1016) were Anopheles, and 1% (169) were Aedes mosquitoes. Out of the 130 adult mosquitoes that were raised from larvae collected from the containers, 20% were An. rhodesiensis, while the remaining 80% were Aedes mosquitoes. Out of 823 mosquitoes tested for blood meal origins, 86.3% (710/823) tested positive for human blood, 2.2% (18/823) tested positive for bovine blood, and 11.5% (95/823) were negative for human and bovine antibodies. Anopheles gambiae complex had a human blood meal index (HBI) of 50% (90/180; CI 42.3-57.5%) and a bovine blood meal index (BBI) of only 0.5% (95% CI 0.01-3.1%). Culex HBI was 96.7% (620/641), and its BBI index was 2.4% (15/641). While it was low (0.8%) in Culex, the proportion of An. gambiae complex with unidentified blood meal sources was 49.5% (95 CI% 41.9-56.9%). Among the 1016 Anopheles mosquitoes tested, a single An. gambiae complex (0.1%; 1/1016) was positive for P. vivax CSP. The high HBI indicates frequent contact between humans and vectors. To reduce human exposure, personal protection tools should be implemented.
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Affiliation(s)
- Adisu Akirso
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Girum Tamiru
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Nigatu Eligo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Bernt Lindtjørn
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Centre for International Health, University of Bergen, Bergen, Norway
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia.
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Eligo N, Wegayehu T, Pareyn M, Tamiru G, Lindtjørn B, Massebo F. Anopheles arabiensis continues to be the primary vector of Plasmodium falciparum after decades of malaria control in southwestern Ethiopia. Malar J 2024; 23:14. [PMID: 38195563 PMCID: PMC10777518 DOI: 10.1186/s12936-024-04840-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 01/04/2024] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND Investigating the species distribution and their role in malaria transmission is important as it varies from place to place and is highly needed to design interventions appropriate to the site. The current study aimed to investigate the Anopheles mosquito species distribution and their infection rate in southwestern Ethiopia. METHODS The study was conducted in 14 malaria-endemic kebeles (the smallest administrative unit), which were situated in eight different malaria-endemic districts and four zones in southwestern Ethiopia. Ten per cent of households in each village were visited to collect adult mosquitoes using Centers for Disease Control and Prevention (CDC) light traps. The larval and pupal collection was done from breeding sites within the villages, and reared to adults. Female mosquitoes were morphologically identified. The head and thorax of adult Anopheles mosquitoes were tested for circumsporozoite proteins (CSPs) using ELISA. At the same time, legs, wings, and abdomen were used to identify sibling species using PCR targeting the rDNA intergenic spacers region for species typing of the Anopheles funestus group and the internal transcribed spacer 2 region genes for Anopheles gambiae complex. RESULTS A total of 1445 Anopheles mosquitoes comprising eight species were collected. Of 813 An. gambiae complex tested by PCR, 785 (97%) were Anopheles arabiensis, and the remaining 28 (3%) were not amplified. There were 133 An. funestus group captured and tested to identify the species, of which 117 (88%) were positive for Anopheles parensis, and 15 (11%) were not amplified. A single specimen (1%) showed a band with a different base pair length from the known An. funestus group species. Sequencing revealed this was Anopheles sergentii. Among 1399 Anopheles tested for CSPs by ELISA, 5 (0.4%) An. arabiensis were positive for Plasmodium falciparum and a single (0.07%) was positive for Plasmodium vivax. CONCLUSIONS Anopheles arabiensis continues to play the principal role in malaria transmission despite implementing indoor-based interventions for decades. Sequencing results suggest that An. sergentii was amplified by the An. funestus group primer, producing PCR amplicon size of different length. Therefore, relying solely on amplifying a specific gene of interest in grouping species could be misleading, as different species may share the same gene.
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Affiliation(s)
- Nigatu Eligo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Teklu Wegayehu
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Myrthe Pareyn
- Clinical Sciences Department, Institute of Tropical Medicine, Antwerp, Belgium
| | - Girum Tamiru
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Bernt Lindtjørn
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Centre for International Health, University of Bergen, Bergen, Norway
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia.
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Elias S, Massebo F. Plasmodium falciparum remains the dominant parasite affecting children despite decades of implementing vector control in two villages of Wolaita Zone, Southwest Ethiopia. FRONTIERS IN EPIDEMIOLOGY 2024; 3:1305074. [PMID: 38455893 PMCID: PMC10911012 DOI: 10.3389/fepid.2023.1305074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 12/18/2023] [Indexed: 03/09/2024]
Abstract
Background Malaria is still a significant public health concern, and its prevention and control measures have different impacts in different areas. This study assesses the prevalence of malaria and the effectiveness of routine malaria control programmes such as indoor residual spray (IRS) in two Ethiopian villages. Methods The Kebeles (villages) were purposefully selected based on their malaria prevalence rates. A parasitology survey was conducted in Fango-Gelchecha pre- and post-IRS implementation, whereas in Shochora-Abela it was only conducted post-IRS implementation. The IRS was implemented as part of the routine malaria control programme in August 2017. Every fourth house from the village registration list was systematically selected, resulting in a sample of 300 households per village. A total of 3,075 individuals were enrolled for malaria testing using microscopy. Results After three to four months of application of IRS in August 2017, 59 malaria cases were confirmed, resulting in an overall prevalence of 1.9% (95% CI: 1.5-2.5). Of the positive cases, 18 cases (0.59%: 95% CI: 1.3-1.8) were from Shochora-Abela village, and 41 cases (1.33%: 95% CI: 1.1-1.3) were from Fango-Gelchecha. About age categories, the prevalence of malaria was 10.1% (95% CI: 5.9-15.9) among children under five, 4.7% (95% CI: 3.3-6.4) in children aged 5-14, and only 0.32% (95% CI: 0.13-0.67) in the age group 15 and above. Overall, P. falciparum was the dominant malaria parasite, accounting for 69.5% (95% CI: 56.1-80.8), while P. vivax malaria accounted for 30.5% (95% CI: 19.2-43.8). The malaria prevalence in Fango-Gelchecha village was 3.1% (95% CI: 2.3-4.0) before IRS and 2.6% (95% CI: 1.8-3.5) after IRS application. In the village of Shochora-Abela, the prevalence of malaria post-IRS was 1.2% (95% CI: 0.7-1.9), but the prevalence prior to IRS was not evaluated. Conclusions Plasmodium falciparum is the predominant parasite in the villages, mainly affecting children under five. Therefore, protecting young children should be the top priority for reducing infection burdens.
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Affiliation(s)
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
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Ayele S, Wegayehu T, Eligo N, Tamiru G, Lindtjørn B, Massebo F. Maize pollen diet enhances malaria mosquito longevity and infectivity to Plasmodium parasites in Ethiopia. Sci Rep 2023; 13:14490. [PMID: 37660195 PMCID: PMC10475124 DOI: 10.1038/s41598-023-41826-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 08/31/2023] [Indexed: 09/04/2023] Open
Abstract
Although larval diet quality may affect adult mosquito fitness, its impact on parasite development is scarce. Plant pollen from Zea mays, Typha latifolia, and Prosopis juliflora was ultraviolet-sterilized and examined for effects on larval development, pupation rate, adult mosquito longevity, survival and infectivity. The control larvae were fed Tetramin fish food as a comparator food. Four treatment and two control groups were used for each pollen diet, and each experimental tray had 25 larvae. Female An. arabiensis were starved overnight and exposed to infectious blood using a membrane-feeding system. The Kaplan-Meier curves and log-rank test were used for analysis. The Z. mays pollen diet increased malaria mosquito survival and pupation rate (91.3%) and adult emergence (85%). Zea mays and Tetramin fish food had comparable adulthood development times. Adults who emerged from larvae fed Z. mays pollen had the longest average wing length (3.72 mm) and were more permissive to P. vivax (45%) and P. falciparum (27.5%). They also survived longer after feeding on infectious blood and had the highest number of P. vivax oocysts. Zea mays pollen improved larval development, adult mosquito longevity, survival and infectivity to Plasmodium. Our findings suggest that malaria transmission in Z. mays growing villages should be monitored.
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Affiliation(s)
- Shilimat Ayele
- Department of Biology, Wachemo University, Hossana, Ethiopia
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Teklu Wegayehu
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Nigatu Eligo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Girum Tamiru
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Bernt Lindtjørn
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Centre for International Health, University of Bergen, Bergen, Norway
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia.
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Ayele T, Wondale B, Tamiru G, Eligo N, Lindtjørn B, Massebo F. Infectivity of symptomatic Plasmodium vivax cases to different generations of wild-caught and laboratory-adapted Anopheles arabiensis using a membrane feeding assay, Ethiopia. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2023; 4:100137. [PMID: 37637351 PMCID: PMC10457422 DOI: 10.1016/j.crpvbd.2023.100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 07/18/2023] [Accepted: 07/22/2023] [Indexed: 08/29/2023]
Abstract
When measuring human to mosquito transmission of Plasmodium spp., laboratory-adapted (colony) mosquitoes can be utilized. To connect transmission studies to the local epidemiology, it can be important to comprehend the relationship between infectivity in laboratory-adapted (colony) and wild-caught (wild) mosquitoes of the same species. Microscopically confirmed Plasmodium vivax cases were recruited from health facilities in Arba Minch town, and a nested polymerase chain reaction (nPCR) was used for subsequent confirmation. We performed paired membrane-feeding assays using colony An. arabiensis and three generations of wild origin An. arabiensis. Anopheles arabiensis aged 3-6 days were fed after being starved for 8-14 h. Microscopically, the oocyst development was evaluated at day 7 after feeding. Circumsporozoite proteins (CSPs) assay was carried out by enzyme-linked immunosorbent assay (ELISA). In 19 paired feeding experiments, the feeding efficiency was more than doubled in colony (median: 62.5%; interquartile range, IQR: 35-78%) than in wild mosquitoes (median: 28.5%; IQR: 17.5-40%; P < 0.001). Among the 19 P. vivax gametocyte-positive blood samples, 63.2% (n = 12) were infective to wild An. arabiensis and 73.7% (n = 14) were infective to colony An. arabiensis. The median infection rate was twice as high (26%) in the colony than in the wild (13%) An. arabiensis, although the difference was marginally insignificant (P = 0.06). Although the observed difference was not statistically significant (P = 0.19), the median number of oocysts per midgut was more than twice as high (17.8/midgut) in colony than in wild (7.2/midgut) An. arabiensis. The median feeding efficiency was 26.5% (IQR: 18-37%) in F1, 29.3% (IQR: 28-40%) in F2 and 31.2% (IQR: 30-37%) in F3 generations of wild An. arabiensis. Also, no significant difference was observed in oocyst infection rate and load between generations of wild An. arabiensis. CSP rate of P. vivax was 3.1% (3/97; 95% CI: 0.6-8.8%) in wild and 3.6% (3/84; 95% CI: 0.7-10.1%) in colony An. arabiensis. The results of the present study revealed that oocyst infection and load/midgut, and CSP rate were roughly comparable, indicating that colony mosquitoes can be employed for infectivity studies, while larger sample sizes may be necessary in future studies.
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Affiliation(s)
- Tenaye Ayele
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Department of Biology, Wolaita Sodo University, Sodo, Ethiopia
| | - Biniam Wondale
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Girum Tamiru
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Nigatu Eligo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Bernt Lindtjørn
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
- Centre for International Health, University of Bergen, Norway
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
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Assa A, Eligo N, Massebo F. Anopheles mosquito diversity, entomological indicators of malaria transmission and challenges of morphological identification in southwestern Ethiopia. Trop Med Health 2023; 51:38. [PMID: 37452392 PMCID: PMC10347854 DOI: 10.1186/s41182-023-00529-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023] Open
Abstract
BACKGROUND A number of Anopheles species play either a primary or secondary role in malaria transmission. This necessitates understanding the species composition, bionomics, and behaviors of malaria mosquitoes in a particular geographic area, which is relevant to design and implement tailored intervention tools. This study aimed to assess the species composition, sporozoite infection rate, and blood meal origins of malaria mosquitoes in two malaria-endemic villages of Boreda district in Gamo Zone, southwest Ethiopia. METHODS Thirty houses, 20 for Center for Disease Control and Prevention (CDC) light traps and 10 for Pyrethrum Spray Catches (PSC) were randomly selected for bimonthly mosquito collection from October 2019 to February 2020. An enzyme-linked immunosorbent assay (ELISA) was carried out to detect the blood meal origins and circumsporozoite proteins (CSPs). The entomological inoculation rate (EIR) was calculated by multiplying the sporozoite and human biting rates from PSCs. Anopheles gambiae complex and An. funestus group samples were further identified to species by the polymerase chain reaction (PCR). Anopheles species with some morphological similarity with An. gambiae complex or An. funestus group were tested using the primers of the two species complexes. RESULTS A total of 14 Anopheles species were documented, of which An. demeilloni was found to be the dominant species. An. arabiensis was found to be positive for P. falciparum CSP with the overall CSP rate of 0.53% (1/190: 95% CI 0.01-2.9). The overall estimated P. falciparum EIR of An. arabiensis from PSC was 1.5 infectious bites/person/5 months. Of the 145 freshly fed Anopheles mosquitoes tested for blood meal sources, 57.9% (84/145) had bovine blood meal, 15.2% (22/145) had human blood meal origin alone, and 16.5% (24/145) had a mixed blood meal origin of human and bovine. Anopheles demeilloni were more likely to feed on blood meals of bovine origin (102/126 = 80.9%), while An. arabiensis were more likely to have blood meals of human origin. Eleven samples (2.6%; 11/420) were morphologically categorized as An. demeilloni, but it has been identified as An. leesoni (the only An. funestus group identified in the area) by PCR, though it requires additional verification by sequencing, because different species genes may have amplified for these species specific primers. Similarly, a small number of An. arabiensis were morphologically identified as An. salbaii, An. maculipalpis and An. fuscivenosus. CONCLUSIONS AND RECOMMENDATIONS In spite of the wide variety of Anopheles mosquito species, An. arabiensis dominates indoor malaria transmission, necessitating additional interventions targeting this species. In addition, increasing entomological knowledge may make morphological identification less difficult.
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Affiliation(s)
- Adilo Assa
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Nigatu Eligo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
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Tomas T, Eligo N, Tamiru G, Massebo F. Outdoor and early hour human biting activities of malaria mosquitoes and the suitability of clay pot for outdoor resting mosquito collection in malaria endemic villages of southern Rift Valley, Ethiopia. Parasite Epidemiol Control 2022; 19:e00278. [PMID: 36345433 PMCID: PMC9636569 DOI: 10.1016/j.parepi.2022.e00278] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 08/21/2022] [Accepted: 10/26/2022] [Indexed: 11/07/2022] Open
Abstract
Background Sampling adult Anopheles mosquitoes is important for assessing vector density, estimating the sporozoite infection rate, and quantifying the impact of vector control interventions. The objective of this study was to assess the Anopheles mosquito species composition, and their outdoor and indoor biting activities, and to evaluate the suitability of clay pots for indoor and outdoor resting mosquito collections. Methods Two malaria-endemic villages in the Gamo zone were purposely selected. Forty clay pots were deployed for outdoor resting mosquitoes sampling and another forty for indoor resting sampling. Twenty pit shelters were constructed for outdoor resting mosquito collection. The human landing catch (HLC) technique was employed to collect indoor and outdoor host-seeking mosquitoes in two households in each village. Morphological identification of the Anopheles mosquito was done using an identification key. Enzyme-linked immunosorbent assay technique was used for blood meal origin and circumsporozoite proteins (CSP) test. Speciation of An. gambiae complex was done using polymerase chain reaction. A Chi-square test was used to compare the effectiveness of clay pot and pit shelters for outdoor resting sampling. Results A total of 904 female Anopheles mosquitoes comprising An. gambiae complex, An. pharoensis, An. tenebrosus, An. dencalicus and An. demelloni were sampled. The majority (64%) of them were sampled by the HLC technique. There was a slight difference between the outdoor clay pot (19%) and pit shelter (17%) collection. No Anopheles mosquitoes were collected indoor using clay pots. All mosquitoes were tested for CSPs, but none of them were found to be positive. Anopheles mosquitoes were tending to bite humans outdoor than indoors, and their peak biting hours was 10–11 pm. The human blood meal index of Anopheles mosquitoes was 0.07 from pit shelters and it was 0.04 from clay pots. The bovine blood meal index was 0.45 for mosquitoes from both pit shelters and clay pot collections. Conclusion Anopheles arabiensis was the predominant species and it was tending to bite cattle more than humans. Clay pot could be suitable for outdoor resting mosquito collection, but not for indoor resting species.
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Debash H, Bisetegn H, Ebrahim H, Feleke DG, Gedefie A, Tilahun M, Shibabaw A, Ebrahim E, Fiseha M, Abeje G. Prevalence and associated risk factors of malaria among febrile under-five children visiting health facilities in Ziquala district, Northeast Ethiopia: A multicenter cross-sectional study. PLoS One 2022; 17:e0276899. [PMID: 36301956 PMCID: PMC9612493 DOI: 10.1371/journal.pone.0276899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/16/2022] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Malaria is among the leading causes of mortality and morbidity among under five children in developing countries. Ethiopia has set targets for controlling and eliminating malaria through at-risk group interventions. However, the disease remains a serious public health concern in endemic areas like in Wollo, Northeast Ethiopia. Therefore, this study aimed to determine malaria prevalence, risk factors and parasite density among under five children in Ziquala district. METHOD A facility-based cross-sectional study was conducted in Ziquala hospital, and Tsitsika, Mishra and Hamusit health centers in Ziquala district, Northeast Ethiopia, from January 2022 to April 2022. The study enrolled a total of 633 under five children using a systematic sampling technique. A capillary blood sample was collected from each child to prepared thin and thick blood smears. Smears were then stained with 10% Giemsa and examined under light microscope. A pretested structured questionnaire was used to collect on socio-demographic data, parental/caregiver knowledge, and malaria determining factors. Bivariable and multivariable logistic regression analysis was done to identify factors associated with malaria. RESULT The overall prevalence of malaria among children visiting Ziquala district health institutions was 24.6% (156/633). Plasmodium falciparum, P. vivax, and mixed infection (both species) accounted for 57.1%, 38.5%, and 4.5% of the cases, respectively. Regarding to parasite load, moderate parasitemia was the most common, followed by low and high parasitemia with the proportion of 53.8%, 31.4% and 14.7% parasite density, respectively. Malaria infection was linked to irregular utilization of insecticide-treated bed nets (AOR = 5.042; 95% CI: 2.321-10.949), staying outside at night (AOR = 2.109; 95% CI: 1.066-4.173), and parents not receiving malaria health education in the past six months (AOR = 4.858; 95% CI: 2.371-9.956). CONCLUSION Malaria was prevalent among children under the age of five enrolled in the study. The local government should focus on regular insecticide treated net utilization, reducing the risk of mosquito bites while sleeping outdoors at night and increasing public understanding of malaria prevention and control through health education would also help to minimize the burden of malaria.
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Affiliation(s)
- Habtu Debash
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Habtye Bisetegn
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Hussen Ebrahim
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Daniel Getacher Feleke
- Department of Microbiology, Immunology and Parasitology, College of Medicine and Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Alemu Gedefie
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Mihret Tilahun
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Agumas Shibabaw
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Endris Ebrahim
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Mesfin Fiseha
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Wollo University, Dessie, Ethiopia
| | - Getu Abeje
- Department of Medical Laboratory Science, College of Medicine and Health Sciences, Samara University, Samara, Ethiopia
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Jimoh RG, Abisoye OA, Uthman MMB. Ensemble Feed-Forward Neural Network and Support Vector Machine for Prediction of Multiclass Malaria Infection. JOURNAL OF INFORMATION AND COMMUNICATION TECHNOLOGY 2021. [DOI: 10.32890/jict2022.21.1.6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Globally, recent research are focused on developing appropriate and robust algorithms to provide a robust healthcare system that is versatile and accurate. Existing malaria models are plagued with low rate of convergence, overfitting, limited generalization due to restriction to binary cases prediction, and proneness to local minimum errors in finding reliable testing output due to complexity of features in the feature space, which is a black box in nature. This study adopted a stacking method of heterogeneous ensemble learning of ArtificialNeural Network (ANN) and Support Vector Machine (SVM) algorithms to predict multiclass, symptomatic, and climatic malaria infection. ANN produced 48.33 percent accuracy, 60.61 percent sensitivity, and 45.58 percent specificity. SVM with Gaussian kernel function gave better performance results of 85.60 percent accuracy, 84.06 percent sensitivity, and 86.09 percent specificity. Consequently, to improve prediction performance, a stacking method was introduced to ensemble SVM with ANN. The proposed ensemble malaria model was tuned on different thresholds at a threshold value of 0.60, the ensemble model gave an optimum accuracy of 99.86 percent, sensitivity 100 percent, specificity 98.68 percent, and mean square error 0.14. The ensemble model experimental results indicated that stacked multiple classifiers produced better results than a single model. This research demonstrated the efficiency of heterogeneous stacking ensemble model on effects of climatic variations on multiclass malaria infection classification. Furthermore, the model reduced complexity, overfitting, low rate of convergence, and proneness to local minimum error problems of multiclass malaria infection in comparison to previous related models.
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Affiliation(s)
- Rasheed Gbenga Jimoh
- Department of Computer Science, Faculty of Communication and Information Science, University of Ilorin
| | | | - Muhammed Mubashir Babatunde Uthman
- Department of Epidemiology and Community Health, Faculty of Clinical Sciences, College of Health Sciences, University of Ilorin, Nigeria
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Ketema T, Bacha K, Getahun K, del Portillo HA, Bassat Q. Plasmodium vivax epidemiology in Ethiopia 2000-2020: A systematic review and meta-analysis. PLoS Negl Trop Dis 2021; 15:e0009781. [PMID: 34525091 PMCID: PMC8476039 DOI: 10.1371/journal.pntd.0009781] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 09/27/2021] [Accepted: 09/01/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Ethiopia is one of the scarce African countries where Plasmodium vivax and P. falciparum co-exist. There has been no attempt to derive a robust prevalence estimate of P. vivax in the country although a clear understanding of the epidemiology of this parasite is essential for informed decisions. This systematic review and meta-analysis, therefore, is aimed to synthesize the available evidences on the distribution of P. vivax infection by different locations/regions, study years, eco-epidemiological zones, and study settings in Ethiopia. METHODS This study was conducted in accordance with Preferred Reposting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Studies conducted and published over the last two decades (2000 to 2020) that reported an estimate of P. vivax prevalence in Ethiopia were included. The Cochrane Q (χ2) and the I2 tests were used to assess heterogeneity, and the funnel plot and Egger's test were used to examine publication bias. A p-value of the χ2 test <0.05 and an I2 value >75% were considered presence of considerable heterogeneity. Random effect models were used to obtain pooled estimate of P. vivax infection prevalence. This study is registered with PROSPERO (International Prospective Register of Systematic Reviews): ID CRD42020201761. RESULTS We screened 4,932 records and included 79 studies that enrolled 1,676,659 confirmed malaria cases, from which 548,214 (32.69%) were P. vivax infections and 1,116,581 (66.59%) were due to P. falciparum. The rest were due to mixed infections. The pooled estimate of P. vivax prevalence rate was 8.93% (95% CI: 7.98-9.88%) with significant heterogeneity (I2 = 100%, p<0.0001). Regional differences showed significant effects (p<0.0001, and I2 = 99.4%) on the pooled prevalence of P. vivax, while study years (before and after the scaling up of interventional activities) did not show significant differences (p = 0.9, I2 = 0%). Eco-epidemiological zones considered in the analysis did show a significant statistical effect (p<0.001, I2 = 78.5%) on the overall pooled estimate prevalence. Also, the study setting showed significant differences (p = 0.001, and I2 = 90.3%) on the overall prevalence, where significant reduction of P. vivax prevalence (4.67%, 95%CI: 1.41-7.93%, p<0.0001) was observed in studies conducted at the community level. The studies included in the review demonstrated lack of publication bias qualitatively (symmetrical funnel plot) and quantitatively [Egger's test (coefficient) = -2.97, 95% CI: -15.06-9.13, p = 0.62]. CONCLUSION The estimated prevalence of P. vivax malaria in Ethiopia was 8.93% with P. vivax prevailing in the central west region of Ethiopia, but steadily extending to the western part of the country. Its distribution across the nation varies according to geographical location, study setting and study years.
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Affiliation(s)
- Tsige Ketema
- Jimma University, College of Natural Sciences, Department of Biology, Jimma, Ethiopia
- ISGlobal, Institute for Global Health, Hospital Clinic-Universitat de Barcelona, Barcelona, Spain
- * E-mail:
| | - Ketema Bacha
- Jimma University, College of Natural Sciences, Department of Biology, Jimma, Ethiopia
| | - Kefelegn Getahun
- Jimma University, College of Social Sciences and Humanity, Department of Geography and Environmental Studies, Jimma, Ethiopia
| | - Hernando A. del Portillo
- ISGlobal, Institute for Global Health, Hospital Clinic-Universitat de Barcelona, Barcelona, Spain
- IGTP, Germans Trias i Pujol Health Research Institute, Badalona, Spain
- ICREA, Catalan Institution for Research and Advanced Studies, Barcelona, Spain
| | - Quique Bassat
- ISGlobal, Institute for Global Health, Hospital Clinic-Universitat de Barcelona, Barcelona, Spain
- ICREA, Catalan Institution for Research and Advanced Studies, Barcelona, Spain
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McMahon A, Mihretie A, Ahmed AA, Lake M, Awoke W, Wimberly MC. Remote sensing of environmental risk factors for malaria in different geographic contexts. Int J Health Geogr 2021; 20:28. [PMID: 34120599 PMCID: PMC8201719 DOI: 10.1186/s12942-021-00282-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/03/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Despite global intervention efforts, malaria remains a major public health concern in many parts of the world. Understanding geographic variation in malaria patterns and their environmental determinants can support targeting of malaria control and development of elimination strategies. METHODS We used remotely sensed environmental data to analyze the influences of environmental risk factors on malaria cases caused by Plasmodium falciparum and Plasmodium vivax from 2014 to 2017 in two geographic settings in Ethiopia. Geospatial datasets were derived from multiple sources and characterized climate, vegetation, land use, topography, and surface water. All data were summarized annually at the sub-district (kebele) level for each of the two study areas. We analyzed the associations between environmental data and malaria cases with Boosted Regression Tree (BRT) models. RESULTS We found considerable spatial variation in malaria occurrence. Spectral indices related to land cover greenness (NDVI) and moisture (NDWI) showed negative associations with malaria, as the highest malaria rates were found in landscapes with low vegetation cover and moisture during the months that follow the rainy season. Climatic factors, including precipitation and land surface temperature, had positive associations with malaria. Settlement structure also played an important role, with different effects in the two study areas. Variables related to surface water, such as irrigated agriculture, wetlands, seasonally flooded waterbodies, and height above nearest drainage did not have strong influences on malaria. CONCLUSION We found different relationships between malaria and environmental conditions in two geographically distinctive areas. These results emphasize that studies of malaria-environmental relationships and predictive models of malaria occurrence should be context specific to account for such differences.
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Affiliation(s)
- Andrea McMahon
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, OK USA
| | - Abere Mihretie
- Health, Development, and Anti-Malaria Association, Addis Ababa, Ethiopia
| | - Adem Agmas Ahmed
- Malaria Control and Elimination Partnership in Africa, Bahir Dar, Ethiopia
| | | | - Worku Awoke
- School of Public Health, Bahir Dar University, Bahir Dar, Ethiopia
| | - Michael Charles Wimberly
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, OK USA
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Olbamo T, Esayas E, Gebre T, Massebo F. An evaluation of repellency and feeding inhibition of ethno-medicinal plants against major malaria vectors in southern Ethiopia. Parasit Vectors 2021; 14:190. [PMID: 33827658 PMCID: PMC8025576 DOI: 10.1186/s13071-021-04694-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/19/2021] [Indexed: 11/21/2022] Open
Abstract
Background Plant-based mosquito control methods may use as a supplementary malaria vector control strategy. This study aimed to evaluate the effect of smoking ethno-medicinal plants on indoor density and feeding activity of malaria vectors at early hours of the night and its residual effect after midnight in southern Ethiopia. Methods Both field and tent trials were conducted to evaluate the impact of smoking Juniperus procera leaves, Eucalyptus globulus seeds and Olea europaea leaves in Kolla Shara Village from July 2016 to February 2017. For the field trial, five grass-thatched traditional huts (three for ethno-medicinal plants and two as control [only charcoal smoking and non-charcoal smoking]) were used. Indoor host-seeking mosquitoes were collected by CDC light traps. A Latin square design was employed to minimize the bias due to the variation in house location and different sampling nights. For the tent experiment, 25 3–5-day-old starved wild female Anopheles mosquitoes reared from the larvae were released into the tents where a calf was tethered at the mid-point of each tent. Results A total of 614 Anopheles mosquitoes belonging to 5 species were collected from 5 huts, of which 93.4% was An. arabiensis; O. europaea, E. globulus and J. procera reduced the indoor density of An. arabiensis, with the mean percentage drop of 80%, 73% and 70%, respectively. In the tent trial, smoking of these plants had significant knockdown effects and inhibited feeding on the calves (F = 383.5, DF = 3, P < 0.01). The mean knockdown effect due to O. europaea was relatively high (17.7 ± 0.54; 95% CI 16.8–18.6), while it was only 0.9 ± 0.1 (95% CI 0.29–1.52) in the control tents. All the test plants used in the tent trial caused significantly inhibited feeding activity of An. arabiensis on the host (F = 383.5, DF = 3, P < 0.01). About 94.5%, 89.5% and 86% of mosquitoes were unfed because of the smoking effect of O. europaea, E. globulus and J. procera, respectively, whereas only 19.5% were unfed in the control tent. Conclusions Smoking ethno-medicinal plant materials reduced indoor density of malaria vectors and inhibited feeding on calves inside the tents. Thus, plant-based mosquito control methods may play a vital role in reducing mosquito bites in the early hours of the night and thereby reduce residual malaria transmission. ![]()
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Affiliation(s)
- Tekle Olbamo
- Department of Animal Science, Jinka University, Jinka, Ethiopia.,Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Endashaw Esayas
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia. .,Malaria and Neglected Tropical Diseases Research Directorate, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
| | - Tizazu Gebre
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
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15
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Eba K, Habtewold T, Yewhalaw D, Christophides GK, Duchateau L. Anopheles arabiensis hotspots along intermittent rivers drive malaria dynamics in semi-arid areas of Central Ethiopia. Malar J 2021; 20:154. [PMID: 33731115 PMCID: PMC7971958 DOI: 10.1186/s12936-021-03697-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/11/2021] [Indexed: 11/30/2022] Open
Abstract
Background Understanding malaria vector’s population dynamics and their spatial distribution is important to define when and where the largest infection risks occur and implement appropriate control strategies. In this study, the seasonal spatio-temporal dynamics of the malaria vector population and transmission intensity along intermittent rivers in a semi-arid area of central Ethiopia were investigated. Methods Mosquitoes were collected monthly from five clusters, 2 close to a river and 3 away from a river, using pyrethrum spray catches from November 2014 to July 2016. Mosquito abundance was analysed by the mixed Poisson regression model. The human blood index and sporozoite rate was compared between seasons by a logistic regression model. Results A total of 2784 adult female Anopheles gambiae sensu lato (s.l.) were collected during the data collection period. All tested mosquitoes (n = 696) were identified as Anopheles arabiensis by polymerase chain reaction. The average daily household count was significantly higher (P = 0.037) in the clusters close to the river at 5.35 (95% CI 2.41–11.85) compared to the clusters away from the river at 0.033 (95% CI 0.02–0.05). Comparing the effect of vicinity of the river by season, a significant effect of closeness to the river was found during the dry season (P = 0.027) and transition from dry to wet season (P = 0.032). Overall, An. arabiensis had higher bovine blood index (62.8%) as compared to human blood index (23.8%), ovine blood index (9.2%) and canine blood index (0.1%). The overall sporozoite rate was 3.9% and 0% for clusters close to and away from the river, respectively. The overall Plasmodium falciparum and Plasmodium vivax entomologic inoculation rates for An. arabiensis in clusters close to the river were 0.8 and 2.2 infective bites per person/year, respectively. Conclusion Mosquito abundance and malaria transmission intensity in clusters close to the river were higher which could be attributed to the riverine breeding sites. Thus, vector control interventions including targeted larval source management should be implemented to reduce the risk of malaria infection in the area. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03697-z.
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Affiliation(s)
- Kasahun Eba
- Biometrics Research Centre, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.,Department of Environmental Health Science and Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Tibebu Habtewold
- Department of Life Sciences, Imperial College London, London, UK
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Jimma University, P.O.Box 378, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center, Jimma University, P.O.Box 378, Jimma, Ethiopia
| | | | - Luc Duchateau
- Biometrics Research Centre, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
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Esayas E, Tufa A, Massebo F, Ahemed A, Ibrahim I, Dillu D, Bogale EA, Yared S, Deribe K. Malaria epidemiology and stratification of incidence in the malaria elimination setting in Harari Region, Eastern Ethiopia. Infect Dis Poverty 2020; 9:160. [PMID: 33222698 PMCID: PMC7682082 DOI: 10.1186/s40249-020-00773-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/02/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Ethiopia has shown notable progress in reducing the burden of malaria over the past two decades. Because of this progress, the country has shifted efforts from control to elimination of malaria. This study was conducted to analyse the malaria epidemiology and stratification of incidence in the malaria elimination setting in eastern Ethiopia. METHODS A retrospective study was conducted to analyse the epidemiology of malaria by reviewing the district health office data from 2013 to 2019 in Harari Region. In addition, three years of sub-district level malaria data were used to stratify the malaria transmission intensity. Malaria interventions (Long-lasting insecticidal nets [LLIN] and indoor residual spraying [IRS]) employed were reviewed to analyse the intervention coverage at the Regional level. Descriptive statistics were used to show the malaria transmission in terms of years, season and species of the malaria parasite. Incidence rate per 1000 population and death rate per 1 000 000 population at risk were computed using the total population of each year. RESULTS In the Harari Region, malaria incidence showed a more pronounced declining trend from 2017 to 2019. Plasmodium falciparum, P. vivax and mixed infections accounted for 69.2%, 30.6% and 0.2% of the cases, respectively. There was an increment in malaria intervention coverage and improved malaria diagnosis. In the year 2019 the coverage of LLIN and IRS in the Region were 93.4% and 85.1% respectively. The annual malaria incidence rate dropped from 42.9 cases per 1000 population in 2013 to 6.7 cases per 1000 population in 2019. Malaria-related deaths decreased from 4.7 deaths per 1 000 000 people annually in 2013 to zero, and there have been no deaths reported since 2015. The malaria risk appears to be heterogeneous and varies between districts. A higher number of malaria cases were recorded in Erer and Jenella districts, which constitute 62% of the cases in the Region. According to the sub-district level malaria stratification, there was shrinkage in the malaria transmission map and about 70% of the sub-districts have achieved elimination targets. CONCLUSIONS In the Harari Region, malaria morbidity and mortality have been significantly declined. Thus, if this achievement is sustained and scaling-up of the existing malaria prevention and control strategies by focusing on those populations living in the higher malaria transmission districts and sub-districts, planning of malaria elimination from the study area might be feasible.
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Affiliation(s)
- Endashaw Esayas
- Harari Regional Health Bureau, Malaria Control and Elimination Program, Harar, Ethiopia.
- Malaria and Neglected Tropical Diseases Research Directorate, Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
| | - Asefa Tufa
- Harari Regional Health Bureau, Malaria Control and Elimination Program, Harar, Ethiopia
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Abdulhamid Ahemed
- Harari Regional Health Bureau, Malaria Control and Elimination Program, Harar, Ethiopia
| | - Ibssa Ibrahim
- Harari Regional Health Bureau, Malaria Control and Elimination Program, Harar, Ethiopia
| | - Dereje Dillu
- Federal Ministry of Health, Addis Ababa, Ethiopia
| | - Eyuel Asemahegn Bogale
- Malaria and Neglected Tropical Diseases Research Directorate, Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | - Kebede Deribe
- Global Health and Infection Department, Brighton and Sussex Medical School, Brighton, 19PX, BN, UK
- School of Public Health, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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Sriporn K, Tsai CF, Tsai CE, Wang P. Analyzing Malaria Disease Using Effective Deep Learning Approach. Diagnostics (Basel) 2020; 10:diagnostics10100744. [PMID: 32987888 PMCID: PMC7601431 DOI: 10.3390/diagnostics10100744] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/23/2020] [Accepted: 09/23/2020] [Indexed: 11/16/2022] Open
Abstract
Medical tools used to bolster decision-making by medical specialists who offer malaria treatment include image processing equipment and a computer-aided diagnostic system. Malaria images can be employed to identify and detect malaria using these methods, in order to monitor the symptoms of malaria patients, although there may be atypical cases that need more time for an assessment. This research used 7000 images of Xception, Inception-V3, ResNet-50, NasNetMobile, VGG-16 and AlexNet models for verification and analysis. These are prevalent models that classify the image precision and use a rotational method to improve the performance of validation and the training dataset with convolutional neural network models. Xception, using the state of the art activation function (Mish) and optimizer (Nadam), improved the effectiveness, as found by the outcomes of the convolutional neural model evaluation of these models for classifying the malaria disease from thin blood smear images. In terms of the performance, recall, accuracy, precision, and F1 measure, a combined score of 99.28% was achieved. Consequently, 10% of all non-dataset training and testing images were evaluated utilizing this pattern. Notable aspects for the improvement of a computer-aided diagnostic to produce an optimum malaria detection approach have been found, supported by a 98.86% accuracy level.
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Affiliation(s)
- Krit Sriporn
- Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Neipu, Pingtung 91201, Taiwan;
- Department of Information Technology, Suratthani Rajabhat University, Suratthani 84100, Thailand
| | - Cheng-Fa Tsai
- Department of Management Information Systems, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Correspondence: ; Tel.: +886-08-770-3202 (ext. 7906)
| | - Chia-En Tsai
- Department of Biochemistry and Molecular Biology, National Cheng Kung University, Tainan 70101, Taiwan;
| | - Paohsi Wang
- Department of Food and Beverage Management, Cheng Shiu University, Kaohsiung 83347, Taiwan;
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