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Nchama VUNN, Said AH, Mtoro A, Bidjimi GO, Owono MA, Maye ERM, Mangue MEO, Okomo GNN, Pasialo BEN, Ondo DM, Lopez MSA, Mochomuemue FL, Obono MO, Besaha JCM, Chuquiyauri R, Jongo SA, Kamaka K, Kibondo UA, Athuman T, Falla CC, Eyono JNM, Smith JM, García GA, Raso J, Nyakarungu E, Mpina M, Schindler T, Daubenberger C, Lemiale L, Billingsley PF, Sim BKL, Richie TL, Church LWP, Olotu A, Tanner M, Hoffman SL, Abdulla S. Incidence of Plasmodium falciparum malaria infection in 6-month to 45-year-olds on selected areas of Bioko Island, Equatorial Guinea. Malar J 2021; 20:322. [PMID: 34284778 PMCID: PMC8290541 DOI: 10.1186/s12936-021-03850-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/11/2021] [Indexed: 11/10/2022] Open
Abstract
Background Extensive malaria control measures have been implemented on Bioko Island, Equatorial Guinea over the past 16 years, reducing parasite prevalence and malaria-related morbidity and mortality, but without achieving elimination. Malaria vaccines offer hope for reducing the burden to zero. Three phase 1/2 studies have been conducted successfully on Bioko Island to evaluate the safety and efficacy of whole Plasmodium falciparum (Pf) sporozoite (SPZ) malaria vaccines. A large, pivotal trial of the safety and efficacy of the radiation-attenuated Sanaria® PfSPZ Vaccine against P. falciparum is planned for 2022. This study assessed the incidence of malaria at the phase 3 study site and characterized the influence of socio-demographic factors on the burden of malaria to guide trial design. Methods A cohort of 240 randomly selected individuals aged 6 months to 45 years from selected areas of North Bioko Province, Bioko Island, was followed for 24 weeks after clearance of parasitaemia. Assessment of clinical presentation consistent with malaria and thick blood smears were performed every 2 weeks. Incidence of first and multiple malaria infections per person-time of follow-up was estimated, compared between age groups, and examined for associated socio-demographic risk factors. Results There were 58 malaria infection episodes observed during the follow up period, including 47 first and 11 repeat infections. The incidence of malaria was 0.25 [95% CI (0.19, 0.32)] and of first malaria was 0.23 [95% CI (0.17, 0.30)] per person per 24 weeks (0.22 in 6–59-month-olds, 0.26 in 5–17-year-olds, 0.20 in 18–45-year-olds). Incidence of first malaria with symptoms was 0.13 [95% CI (0.09, 0.19)] per person per 24 weeks (0.16 in 6–59-month-olds, 0.10 in 5–17-year-olds, 0.11 in 18–45-year-olds). Multivariate assessment showed that study area, gender, malaria positivity at screening, and household socioeconomic status independently predicted the observed incidence of malaria. Conclusion Despite intensive malaria control efforts on Bioko Island, local transmission remains and is spread evenly throughout age groups. These incidence rates indicate moderate malaria transmission which may be sufficient to support future larger trials of PfSPZ Vaccine. The long-term goal is to conduct mass vaccination programmes to halt transmission and eliminate P. falciparum malaria.
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Affiliation(s)
- Vicente Urbano Nsue Ndong Nchama
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Ali Hamad Said
- Medical Care Development International (MCDI), Silver Spring, USA. .,Ifakara Health Institute, Dar es Salaam, Tanzania.
| | - Ali Mtoro
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Gertrudis Owono Bidjimi
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Marta Alene Owono
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Escolastica Raquel Mansogo Maye
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Martin Eka Ondo Mangue
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Genaro Nsue Nguema Okomo
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Beltran Ekua Ntutumu Pasialo
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Dolores Mbang Ondo
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Maria-Silvia Angue Lopez
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Fortunata Lobede Mochomuemue
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Mariano Obiang Obono
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Juan Carlos Momo Besaha
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Raul Chuquiyauri
- Medical Care Development International (MCDI), Silver Spring, USA.,Sanaria Inc., Rockville, USA
| | | | - Kassim Kamaka
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | | | | | | | | | | | | | - José Raso
- Ministry of Health and Social Welfare, Equatorial Guinea (EGMOHSW), Malabo, Equatorial Guinea.,Medical Care Development International (MCDI), Silver Spring, USA
| | - Elizabeth Nyakarungu
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Maxmillian Mpina
- Ifakara Health Institute, Dar es Salaam, Tanzania.,Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Tobias Schindler
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Claudia Daubenberger
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | | | | | | | | | - Ally Olotu
- Medical Care Development International (MCDI), Silver Spring, USA.,Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland.,University of Basel, Basel, Switzerland
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