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Hailemeskel E, Tebeje SK, Ramjith J, Ashine T, Lanke K, Behaksra SW, Emiru T, Tsegaye T, Gashaw A, Kedir S, Chali W, Esayas E, Tafesse T, Abera H, Bulto MG, Shumie G, Petros B, Mamo H, Drakeley C, Gadisa E, Bousema T, Tadesse FG. Dynamics of asymptomatic Plasmodium falciparum and Plasmodium vivax infections and their infectiousness to mosquitoes in a low transmission setting of Ethiopia: a longitudinal observational study. Int J Infect Dis 2024; 143:107010. [PMID: 38490637 DOI: 10.1016/j.ijid.2024.107010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 03/11/2024] [Accepted: 03/11/2024] [Indexed: 03/17/2024] Open
Abstract
OBJECTIVE A 15-month longitudinal study was conducted to determine the duration and infectivity of asymptomatic qPCR-detected Plasmodium falciparum and Plasmodium vivax infections in Ethiopia. METHOD Total parasite and gametocyte kinetics were determined by molecular methods; infectivity to Anopheles arabiensis mosquitoes by repeated membrane feeding assays. Infectivity results were contrasted with passively recruited symptomatic malaria cases. RESULTS For P. falciparum and P. vivax infections detected at enrolment, median durations of infection were 37 days (95% confidence interval [CI], 15-93) and 60 days (95% CI, 18-213), respectively. P. falciparum and P. vivax parasite densities declined over the course of infections. From 47 feeding assays on 22 asymptomatic P. falciparum infections, 6.4% (3/47) were infectious and these infected 1.8% (29/1579) of mosquitoes. No transmission was observed in feeding assays on asymptomatic P. vivax mono-infections (0/56); one mixed-species infection was highly infectious. Among the symptomatic cases, 4.3% (2/47) of P. falciparum and 73.3% (53/86) of P. vivax patients were infectious to mosquitoes. CONCLUSION The majority of asymptomatic infections were of short duration and low parasite density. Only a minority of asymptomatic individuals were infectious to mosquitoes. This contrasts with earlier findings and is plausibly due to the low parasite densities in this population.
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Affiliation(s)
- Elifaged Hailemeskel
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia; Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands; Department of Biology, College of Natural and Computational Sciences, Wollo university, Dessie, Ethiopia; Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Surafel K Tebeje
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia; Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
| | - Jordache Ramjith
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - Kjerstin Lanke
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - Tadele Emiru
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Tizita Tsegaye
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Abrham Gashaw
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Soria Kedir
- Adama Regional Laboratory, Oromia Region Health Bureau, Adama, Ethiopia
| | - Wakweya Chali
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | | | - Haile Abera
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | - Girma Shumie
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Hassen Mamo
- Department of Microbial, Cellular and Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Chris Drakeley
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Teun Bousema
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
| | - Fitsum G Tadesse
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia; Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands; London School of Hygiene & Tropical Medicine, London, United Kingdom.
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Hailemeskel E, Tebeje SK, Behaksra SW, Shumie G, Shitaye G, Keffale M, Chali W, Gashaw A, Ashine T, Drakeley C, Bousema T, Gadisa E, Tadesse FG. The epidemiology and detectability of asymptomatic plasmodium vivax and plasmodium falciparum infections in low, moderate and high transmission settings in Ethiopia. Malar J 2021; 20:59. [PMID: 33482841 PMCID: PMC7821398 DOI: 10.1186/s12936-021-03587-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND As countries move to malaria elimination, detecting and targeting asymptomatic malaria infections might be needed. Here, the epidemiology and detectability of asymptomatic Plasmodium falciparum and Plasmodium vivax infections were investigated in different transmission settings in Ethiopia. METHOD A total of 1093 dried blood spot (DBS) samples were collected from afebrile and apparently healthy individuals across ten study sites in Ethiopia from 2016 to 2020. Of these, 862 were from community and 231 from school based cross-sectional surveys. Malaria infection status was determined by microscopy or rapid diagnostics tests (RDT) and 18S rRNA-based nested PCR (nPCR). The annual parasite index (API) was used to classify endemicity as low (API > 0 and < 5), moderate (API ≥ 5 and < 100) and high transmission (API ≥ 100) and detectability of infections was assessed in these settings. RESULTS In community surveys, the overall prevalence of asymptomatic Plasmodium infections by microscopy/RDT, nPCR and all methods combined was 12.2% (105/860), 21.6% (183/846) and 24.1% (208/862), respectively. The proportion of nPCR positive infections that was detectable by microscopy/RDT was 48.7% (73/150) for P. falciparum and 4.6% (2/44) for P. vivax. Compared to low transmission settings, the likelihood of detecting infections by microscopy/RDT was increased in moderate (Adjusted odds ratio [AOR]: 3.4; 95% confidence interval [95% CI] 1.6-7.2, P = 0.002) and high endemic settings (AOR = 5.1; 95% CI 2.6-9.9, P < 0.001). After adjustment for site and correlation between observations from the same survey, the likelihood of detecting asymptomatic infections by microscopy/RDT (AOR per year increase = 0.95, 95% CI 0.9-1.0, P = 0.013) declined with age. CONCLUSIONS Conventional diagnostics missed nearly half of the asymptomatic Plasmodium reservoir detected by nPCR. The detectability of infections was particularly low in older age groups and low transmission settings. These findings highlight the need for sensitive diagnostic tools to detect the entire parasite reservoir and potential infection transmitters.
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Affiliation(s)
- Elifaged Hailemeskel
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
- Department of Biomedical Sciences, College of Natural and Computational Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
- Department of Biology, College of Natural and Computational Sciences, Wollo University, PO Box, 1145, Dessie, Ethiopia
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Surafel K Tebeje
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Sinknesh W Behaksra
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Girma Shumie
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Getasew Shitaye
- Department of Biomedical Sciences, School of Medical Sciences, Bahir Dar University, Bahir Dar, Ethiopia
| | - Migbaru Keffale
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Wakweya Chali
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Abrham Gashaw
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Temesgen Ashine
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Endalamaw Gadisa
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Fitsum G Tadesse
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia.
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands.
- Institute of Biotechnology, Addis Ababa University, PO Box, 1176, Addis Ababa, Ethiopia.
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