scholarly journals Longitudinal study on Plasmodium falciparum gametocyte carriage following artemether-lumefantrine administration in a cohort of children aged 12-47 months living in Western Kenya, a high transmission area

2014 ◽  
Vol 13 (1) ◽  
pp. 265 ◽  
Author(s):  
Ben Andagalu ◽  
Joan Mativo ◽  
Edwin Kamau ◽  
Bernhards Ogutu
1996 ◽  
Vol 54 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Pierre Daubersies ◽  
Sebastien Magne ◽  
Thierry Fandeur ◽  
Odile Mercereau-Puijalon ◽  
Selma Sallenave-Sales ◽  
...  

2020 ◽  
Author(s):  
Christine Wanjala ◽  
Elke Bergmann-Leitner ◽  
Hoseah M Akala ◽  
Geoffrey Odhiambo ◽  
Bernhards R Ogutu ◽  
...  

Abstract BACKGROUND Naturally acquired immunity which is characterized by protection against overt clinical disease and high parasitemia is acquired with age and transmission intensity. The role of naturally acquired immunity on the efficacy of antimalarial drugs including artemisinin combination therapies (ACTs), the first-line treatments for uncomplicated Plasmodium falciparum has been demonstrated. This study investigated the role of naturally acquired immunity in the response to malaria ACT drug treatment in symptomatic patients living in a malaria high-transmission area of Western Kenya. METHODS This study used samples obtained from a therapeutic efficacy study conducted in western Kenya, an areas of high transmission which assessed ACTs. Sera samples from malaria immune (n = 105) and naïve participants (n = 6) were assessed for in vitro growth inhibitory activity against 3 D7 P. falciparum using a fluorescent-based Growth Inhibition Assay (GIA). Participants’ age and parasite clearance parameters were used in the analysis. RESULTS The key observations of the study are: (1) Sera with intact complement displayed higher GIA activity at lower serum dilutions; (2) there was significant relationship between GIA activity, parasite clearance rate, and slope half-life; (3) Age was a confounding factor when comparing the GIA activity with parasite clearance kinetics. CONCLUSION Taken together, this study demonstrates for the first time there is synergy of complement, pre-existing immunity, and drug treatment in younger patients with symptomatic malaria in a high-transmission area.


2020 ◽  
Vol 103 (1) ◽  
pp. 369-377 ◽  
Author(s):  
Meghna R. Desai ◽  
Aaron M. Samuels ◽  
Wycliffe Odongo ◽  
John Williamson ◽  
Nobert Awino Odero ◽  
...  

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246773
Author(s):  
Akua Kyerewaa Botwe ◽  
Seth Owusu-Agyei ◽  
Muhammad Asghar ◽  
Ulf Hammar ◽  
Felix Boakye Oppong ◽  
...  

PLoS ONE ◽  
2020 ◽  
Vol 15 (10) ◽  
pp. e0240814
Author(s):  
Akua Kyerewaa Botwe ◽  
Seth Owusu-Agyei ◽  
Muhammad Asghar ◽  
Ulf Hammar ◽  
Felix Boakye Oppong ◽  
...  

2019 ◽  
Author(s):  
Christine Wanjala ◽  
Elke Bergmann-Leitner ◽  
Hoseah M Akala ◽  
Geoffrey Odhiambo ◽  
Bernhards R Ogutu ◽  
...  

Abstract BACKGROUND: Naturally acquired immunity which is characterized by protection against overt clinical disease and high parasitemia is acquired with age and transmission intensity. The role of naturally acquired immunity on the efficacy of antimalarial drugs including artemisinin combination therapies (ACTs), the first-line treatments for uncomplicated Plasmodium falciparum has been demonstrated. This study investigated the role of naturally acquired immunity in the response to malaria ACT drug treatment in symptomatic patients living in a malaria high-transmission area of Western Kenya.METHODS: This study used samples obtained from a therapeutic efficacy study conducted in western Kenya, an areas of high transmission which assessed ACTs. Sera samples from malaria immune (n = 105) and naïve participants (n = 6) were assessed for in vitro growth inhibitory activity against 3D7 P. falciparum using a fluorescent-based Growth Inhibition Assay (GIA). Participants’ age and parasite clearance parameters were used in the analysis.RESULTS: The key observations of the study are: (1) Sera with intact complement displayed higher GIA activity at lower serum dilutions; (2) there was significant relationship between GIA activity, parasite clearance rate, and slope half-life; (3) Age was a confounding factor when comparing the GIA activity with parasite clearance kinetics.CONCLUSION: Taken together, this study demonstrates for the first time there is synergy of complement, pre-existing immunity, and drug treatment in younger patients with symptomatic malaria in a high-transmission area.


Author(s):  
Aaron M Samuels ◽  
Nobert Awino Odero ◽  
Wycliffe Odongo ◽  
Kephas Otieno ◽  
Vincent Were ◽  
...  

Abstract Background Global gains toward malaria elimination have been heterogeneous and have recently stalled. Interventions targeting afebrile malaria infections may be needed to address residual transmission. We studied the efficacy of repeated rounds of community-based mass testing and treatment (MTaT) on malaria infection prevalence in western Kenya. Methods Twenty clusters were randomly assigned to 3 rounds of MTaT per year for 2 years or control (standard of care for testing and treatment at public health facilities along with government-sponsored mass long-lasting insecticidal net [LLIN] distributions). During rounds, community health volunteers visited all households in intervention clusters and tested all consenting individuals with a rapid diagnostic test. Those positive were treated with dihydroartemisinin-piperaquine. Cross-sectional community infection prevalence surveys were performed in both study arms at baseline and each year after 3 rounds of MTaT. The primary outcome was the effect size of MTaT on parasite prevalence by microscopy between arms by year, adjusted for age, reported LLIN use, enhanced vegetative index, and socioeconomic status. Results Demographic and behavioral characteristics, including LLIN usage, were similar between arms at each survey. MTaT coverage across the 3 annual rounds ranged between 75.0% and 77.5% in year 1, and between 81.9% and 94.3% in year 2. The adjusted effect size of MTaT on the prevalence of parasitemia between arms was 0.93 (95% confidence interval [CI], .79–1.08) and 0.92 (95% CI, .76–1.10) after year 1 and year 2, respectively. Conclusions MTaT performed 3 times per year over 2 years did not reduce malaria parasite prevalence in this high-transmission area. Clinical Trials Registration NCT02987270.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kelsey M. Sumner ◽  
Elizabeth Freedman ◽  
Lucy Abel ◽  
Andrew Obala ◽  
Brian W. Pence ◽  
...  

AbstractMalaria control may be enhanced by targeting reservoirs of Plasmodium falciparum transmission. One putative reservoir is asymptomatic malaria infections and the scale of their contribution to transmission in natural settings is not known. We assess the contribution of asymptomatic malaria to onward transmission using a 14-month longitudinal cohort of 239 participants in a high transmission site in Western Kenya. We identify P. falciparum in asymptomatically- and symptomatically-infected participants and naturally-fed mosquitoes from their households, genotype all parasites using deep sequencing of the parasite genes pfama1 and pfcsp, and use haplotypes to infer participant-to-mosquito transmission through a probabilistic model. In 1,242 infections (1,039 in people and 203 in mosquitoes), we observe 229 (pfcsp) and 348 (pfama1) unique parasite haplotypes. Using these to link human and mosquito infections, compared with symptomatic infections, asymptomatic infections more than double the odds of transmission to a mosquito among people with both infection types (Odds Ratio: 2.56; 95% Confidence Interval (CI): 1.36–4.81) and among all participants (OR 2.66; 95% CI: 2.05–3.47). Overall, 94.6% (95% CI: 93.1–95.8%) of mosquito infections likely resulted from asymptomatic infections. In high transmission areas, asymptomatic infections are the major contributor to mosquito infections and may be targeted as a component of transmission reduction.


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