scholarly journals Incidence of Plasmodium falciparum malaria infection in 6-month to 45-year-olds on selected areas of Bioko Island, Equatorial Guinea

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Vicente Urbano Nsue Ndong Nchama ◽  
Ali Hamad Said ◽  
Ali Mtoro ◽  
Gertrudis Owono Bidjimi ◽  
Marta Alene Owono ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Control ◽  
Malaria Infection ◽  
Age Groups ◽  
Control Measures ◽  
Equatorial Guinea ◽  
Safety And Efficacy ◽  
Bioko Island ◽  
Malaria Vaccines

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.

Incidence of Plasmodium Falciparum Malaria Infection in 6-month- to 45-year-olds on Bioko Island, Equatorial Guinea.

2021 ◽  
Author(s):  
Vicente Urbano Nsue Ndong Nchama ◽  
Ali Hamad Said ◽  
Ali Mtoro ◽  
Gertrudis Owono Bidjimi ◽  
Marta Alene Owono Eyang ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Control ◽  
Malaria Infection ◽  
Age Groups ◽  
Control Measures ◽  
Equatorial Guinea ◽  
Safety And Efficacy ◽  
Bioko Island ◽  
Malaria Vaccines

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 Pf 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 North Bioko Province, Bioko Island, was followed for 24 weeks after clearance of parasitemia. Assessment of clinical presentation consistent with malaria and thick blood smears were performed every two 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: 58 malaria infection episodes (malaria) were 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 fairly evenly throughout age groups. These incidence rates are sufficient to support the planned future trial of PfSPZ Vaccine. The long-term goal is to conduct mass vaccination programs to halt transmission and eliminate Pf malaria.

scholarly journals REDUCTION IN INFECTION WITH PLASMODIUM FALCIPARUM ONE YEAR AFTER THE INTRODUCTION OF MALARIA CONTROL INTERVENTIONS ON BIOKO ISLAND, EQUATORIAL GUINEA

2006 ◽  
Vol 74 (6) ◽  
pp. 972-978 ◽  
Author(s):  
IMMO KLEINSCHMIDT ◽  
JAISHREE RAMAN ◽  
BRIAN SHARP ◽  
LUIS E. BENAVENTE ◽  
JOSEPH CARTER ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Control ◽  
Equatorial Guinea ◽  
Bioko Island ◽  
One Year

scholarly journals Risk of Plasmodium falciparum infection in south-west Burkina Faso - potential impact of expanding eligibility for seasonal malaria chemoprevention

2021 ◽  
Author(s):  
Anne L Wilson ◽  
Steve W Lindsay ◽  
Alfred Tiono ◽  
Jean Baptiste Yaro ◽  
Hilary Ranson ◽  
...  
Keyword(s):  
Risk Factors ◽  
Plasmodium Falciparum ◽  
Burkina Faso ◽  
Malaria Transmission ◽  
Malaria Control ◽  
Control Measures ◽  
Sub Saharan Africa ◽  
South West ◽  
Seasonal Malaria Chemoprevention ◽  
The Impact

Abstract Background Burkina Faso has one of the highest malaria burdens in sub-Saharan Africa despite the mass deployment of insecticide-treated nets (ITNs) and use of seasonal malaria chemoprevention (SMC) in children aged up to 5 years. Identification of risk factors for Plasmodium falciparum infection in rural Burkina Faso could help to identify and target malaria control measures. Methods A cross-sectional survey of 1,199 children and adults was conducted during the peak malaria transmission season in south-west Burkina Faso in 2017. Logistic regression was used to identify risk factors for microscopically confirmed P. falciparum infection. A malaria transmission dynamic model was used to determine the impact on malaria cases averted of administering SMC to children aged 5–15 year old. Results P. falciparum prevalence was 32.8% in the study population. Children aged 5 to < 10 years old were at 3.74 times the odds (95% CI = 2.68–5.22, p < 0.001) and children aged 10 to 15 years old at 3.14 times the odds (95% CI = 1.20–8.21, p = 0.02) of P. falciparum infection compared to children aged less than 5 years old. Administration of SMC to children aged up to 10 years is predicted to avert an additional 57 malaria cases per 1000 population per year (9.4% reduction) and administration to children aged up to 15 years would avert an additional 89 malaria cases per 1000 population per year (14.6% reduction) in the Cascades Region, assuming coverage of pyrethroid-piperonyl butoxide ITNs. Conclusion Malaria infections were high in all age strata, although highest in children aged 5 to 15 years, despite roll out of core malaria control interventions. Given the burden of infection in school-age children, extension of the eligibility criteria for SMC could help reduce the burden of malaria in Burkina Faso and other countries in the region.

scholarly journals Reduced Prevalence of Malaria Infection in Children Living in Houses with Window Screening or Closed Eaves on Bioko Island, Equatorial Guinea

PLoS ONE ◽  
2013 ◽  
Vol 8 (11) ◽  
pp. e80626 ◽  
Author(s):  
John Bradley ◽  
Andrea M. Rehman ◽  
Christopher Schwabe ◽  
Daniel Vargas ◽  
Feliciano Monti ◽  
...  
Keyword(s):  
Malaria Infection ◽  
Equatorial Guinea ◽  
Bioko Island ◽  
Window Screening

scholarly journals Clustering of asymptomatic Plasmodium falciparum infection and the effectiveness of targeted malaria control measures

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Jeffrey G. Shaffer ◽  
Mahamoudou B. Touré ◽  
Nafomon Sogoba ◽  
Seydou O. Doumbia ◽  
Jules F. Gomis ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Control ◽  
Falciparum Infection ◽  
Control Measures ◽  
Plasmodium Falciparum Infection

scholarly journals Population Genetic Analysis of the Plasmodium Falciparum Erythrocyte Binding Antigen-175 (EBA-175) Gene in Equatorial Guinea

2021 ◽  
Author(s):  
Pei-Kui Yang ◽  
Xue-Yan Liang ◽  
Min Lin ◽  
Jiang-Tao Chen ◽  
Hui-Ying Huang ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Plasmodium Falciparum ◽  
Natural Selection ◽  
Malaria Vaccine ◽  
Blood Stage ◽  
Equatorial Guinea ◽  
Bioko Island ◽  
Erythrocyte Binding ◽  
Region Ii ◽  
Blood Stage Malaria

Abstract Background: Plasmodium falciparum erythrocyte binding antigen-175 (PfEBA-175) is a candidate antigen for a blood-stage malaria vaccine, while various polymorphisms in the PfEBA-175 gene among global P. falciparum populations have prevented the development of effective vaccines based on this gene. At the same time, the dimorphism of the F- and C-fragments associated with high endemic of severe malaria has been described. This study aimed to investigate the dimorphism of PfEBA-175 on both the Bioko island and continent of Equatorial Guinea, as well as the genetic polymorphism and natural selection of global PfEBA-175.Methods: A total of 218 blood samples were collected from patients with P. falciparum malaria on Bioko Island and Bata district in 2018 and 2019. The allelic dimorphism of PfEBA-175 region II was investigated by nested polymerase chain reaction and sequencing. Polymorphic characteristics and the effect of natural selection were analyzed using MEGA 7.0, DnaSP 6.0 and PopART programs. Genetic diversity in 312 global PfEBA-175 region II sequences was also analyzed. Protein function prediction of new amino acid mutation sites was performed using PolyPhen-2 and Foldx program.Results: Allelic dimorphism of PfEBA-175 was identified in the study area, and the frequency of the F-fragment was higher than that of the C-fragment in both Bioko Island and Bata district populations. Additionally, single infections (87.80%) were more frequent than mixed infections (12.20%). A total of 49 monoclonal PfEBA-175 region II sequences of Bioko Island and Bata district were sequenced successfully. PfEBA-175 of Bioko Island and Bata district isolates showed a high degree of genetic variability and heterogeneity, with π values of 0.00407 & 0.00411 and Hd values of 0.958 & 0.976 for nucleotide diversity, respectively. The values of Tajima's D of PfEBA-175 on Bata district and Bioko Island were 0.56395 and -0.27018, respectively. Globally, PfEBA-175 isolates from Asia were more diverse than those from Africa and South America, and genetic differentiation quantified by the fixation index between Asian and South American countries populations was significant (Fst>0.15, P<0.05). A total of 312 global isolates clustered in 92 haplotypes, and only one cluster contained isolates from three continents. The mutations A34T, K109E, D278Y, K301N, L305V and D329N were predicted as probably damaging by PolyPhen-2. Among them, mutations A34T, K301N and L305V led to significant increases in the free energy difference (ΔΔG>1), indicating destabilization of the protein structure.Conclusions: This study proved the dimorphism of PfEBA-175, and also demonstrated that the F-fragment was remarkably predominant in the study area. The distribution patterns and genetic diversity of PfEBA-175 in Equatorial Guinea isolates were similar to those of isolates worldwide. High levels of recombination events were observed in PfEBA-175 isolates globally, suggesting that natural selection and intragenic recombination might be the main drivers of genetic diversity in global PfEBA-175. These results have important reference value for the development of blood-stage malaria vaccine based on this antigen.

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