scholarly journals Acquired Immunity to Malaria

2009 ◽  
Vol 22 (1) ◽  
pp. 13-36 ◽  
Author(s):  
Denise L. Doolan ◽  
Carlota Dobaño ◽  
J. Kevin Baird
Keyword(s):  
Plasmodium Falciparum ◽  
High Risk ◽  
Immune Status ◽  
Severe Disease ◽  
Sub Saharan Africa ◽  
Acquired Immunity ◽  
Sub Saharan ◽  
High Risk Infants ◽  
Induced Immunity ◽  
Infants And Young Children

SUMMARY Naturally acquired immunity to falciparum malaria protects millions of people routinely exposed to Plasmodium falciparum infection from severe disease and death. There is no clear concept about how this protection works. There is no general agreement about the rate of onset of acquired immunity or what constitutes the key determinants of protection; much less is there a consensus regarding the mechanism(s) of protection. This review summarizes what is understood about naturally acquired and experimentally induced immunity against malaria with the help of evolving insights provided by biotechnology and places these insights in the context of historical, clinical, and epidemiological observations. We advocate that naturally acquired immunity should be appreciated as being virtually 100% effective against severe disease and death among heavily exposed adults. Even the immunity that occurs in exposed infants may exceed 90% effectiveness. The induction of an adult-like immune status among high-risk infants in sub-Saharan Africa would greatly diminish disease and death caused by P. falciparum. The mechanism of naturally acquired immunity that occurs among adults living in areas of hyper- to holoendemicity should be understood with a view toward duplicating such protection in infants and young children in areas of endemicity.

scholarly journals Modeling the temporal dynamics of cervicovaginal microbiota identifies targets that may promote reproductive health

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Alexander Munoz ◽  
Matthew R. Hayward ◽  
Seth M. Bloom ◽  
Muntsa Rocafort ◽  
Sinaye Ngcapu ◽  
...  
Keyword(s):  
High Risk ◽  
Bacterial Communities ◽  
High Probability ◽  
Temporal Dynamics ◽  
Transition Probabilities ◽  
Low Risk ◽  
Sub Saharan Africa ◽  
Reproductive Outcomes ◽  
Bacterial Composition ◽  
Sub Saharan

Abstract Background Cervicovaginal bacterial communities composed of diverse anaerobes with low Lactobacillus abundance are associated with poor reproductive outcomes such as preterm birth, infertility, cervicitis, and risk of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). Women in sub-Saharan Africa have a higher prevalence of these high-risk bacterial communities when compared to Western populations. However, the transition of cervicovaginal communities between high- and low-risk community states over time is not well described in African populations. Results We profiled the bacterial composition of 316 cervicovaginal swabs collected at 3-month intervals from 88 healthy young Black South African women with a median follow-up of 9 months per participant and developed a Markov-based model of transition dynamics that accurately predicted bacterial composition within a broader cross-sectional cohort. We found that Lactobacillus iners-dominant, but not Lactobacillus crispatus-dominant, communities have a high probability of transitioning to high-risk states. Simulating clinical interventions by manipulating the underlying transition probabilities, our model predicts that the population prevalence of low-risk microbial communities could most effectively be increased by manipulating the movement between L. iners- and L. crispatus-dominant communities. Conclusions The Markov model we present here indicates that L. iners-dominant communities have a high probability of transitioning to higher-risk states. We additionally identify transitions to target to increase the prevalence of L. crispatus-dominant communities. These findings may help guide future intervention strategies targeted at reducing bacteria-associated adverse reproductive outcomes among women living in sub-Saharan Africa.

scholarly journals Kelch 13-propeller polymorphisms in Plasmodium falciparum from Jazan region, southwest Saudi Arabia

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Ommer Mohammed Dafalla ◽  
Mohammed Alzahrani ◽  
Ahmed Sahli ◽  
Mohammed Abdulla Al Helal ◽  
Mohammad Mohammad Alhazmi ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Saudi Arabia ◽  
Parasite Clearance ◽  
Sub Saharan Africa ◽  
Local Alignment ◽  
Nucleotide Polymorphisms ◽  
Gene Encoding ◽  
Synonymous Mutations ◽  
Search Tool ◽  
Sub Saharan

Abstract Background Artemisinin-based combination therapy (ACT) is recommended at the initial phase for treatment of Plasmodium falciparum, to reduce morbidity and mortality in all countries where malaria is endemic. Polymorphism in portions of P. falciparum gene encoding kelch (K13)-propeller domains is associated with delayed parasite clearance after ACT. Of about 124 different non-synonymous mutations, 46 have been identified in Southeast Asia (SEA), 62 in sub-Saharan Africa (SSA) and 16 in both the regions. This is the first study designed to analyse the prevalence of polymorphism in the P. falciparum k13-propeller domain in the Jazan region of southwest Saudi Arabia, where malaria is endemic. Methods One-hundred and forty P. falciparum samples were collected from Jazan region of southwest Saudi Arabia at three different times: 20 samples in 2011, 40 samples in 2016 and 80 samples in 2020 after the implementation of ACT. Plasmodium falciparum kelch13 (k13) gene DNA was extracted, amplified, sequenced, and analysed using a basic local alignment search tool (BLAST). Results This study obtained 51 non-synonymous (NS) mutations in three time groups, divided as follows: 6 single nucleotide polymorphisms (SNPs) ‘11.8%’ in samples collected in 2011 only, 3 (5.9%) in 2011and 2016, 5 (9.8%) in 2011 and 2020, 5 (9.8%) in 2016 only, 8 (15.7%) in 2016 and 2020, 14 (27.5%) in 2020 and 10 (19.6%) in all the groups. The BLAST revealed that the 2011 isolates were genetically closer to African isolates (53.3%) than Asian ones (46.7%). Interestingly, this proportion changed completely in 2020, to become closer to Asian isolates (81.6%) than to African ones (18.4%). Conclusions Despite the diversity of the identified mutations in the k13-propeller gene, these data did not report widespread artemisinin-resistant polymorphisms in the Jazan region where these samples were collected. Such a process would be expected to increase frequencies of mutations associated with the resistance of ACT.

scholarly journals TNFα*2 marks high risk of severe disease during Plasmodium falciparum malaria and other infections in Sri Lankans

1999 ◽  
Vol 115 (2) ◽  
pp. 350-355 ◽  
Author(s):  
J. WATTAVIDANAGE ◽  
R. CARTER ◽  
K. L. R. L. PERERA ◽  
A. MUNASINGHA ◽  
S. BANDARA ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
High Risk ◽  
Falciparum Malaria ◽  
Severe Disease ◽  
Plasmodium Falciparum Malaria

scholarly journals High residual prevalence of vaccine-serotypeStreptococcus pneumoniaecarriage after introduction of a pneumococcal conjugate vaccine in Malawi: a prospective serial cross-sectional study

2018 ◽  
Author(s):  
Todd D. Swarthout ◽  
Claudio Fronterre ◽  
José Lourenço ◽  
Uri Obolski ◽  
Andrea Gori ◽  
...  
Keyword(s):  
Cross Sectional Study ◽  
Sub Saharan Africa ◽  
Relative Reduction ◽  
Cross Sectional ◽  
Rigorous Evaluation ◽  
Pneumococcal Carriage ◽  
Sub Saharan ◽  
Induced Immunity ◽  
Indirect Protection ◽  
Carriage Prevalence

ABSTRACTBackgroundThere are concerns that pneumococcal conjugate vaccines (PCV) in sub-Saharan Africa sub-optimally interrupt vaccine-serotype (VT) carriage and transmission, thus limiting vaccine-induced direct and indirect protection. We assessed carriage in vaccinated children and unvaccinated populations targeted for indirect protection, between 4 and 7 years after Malawi’s November 2011 introduction of PCV13 using a 3+0 schedule.MethodsWe conducted sequential prospective nasopharyngeal carriage surveys between 2015 and 2018 among healthy PCV-vaccinated and PCV-unvaccinated children, and HIV-infected adults. VT and NVT carriage risk by age was analysed by non-linear regression.ResultsAmong PCV-vaccinated children, there was a 24% relative reduction in carriage, from a mean 21.1% to 16.1%; 45% reduction among older PCV-unvaccinated children, from 27.5% to 15.2%; 41.4% reduction among adults, from 15.2% to 8.9%. Using carriage data from children 3.6 to 10 years of age, VT carriage probability declined with age, with a similar prevalence half-life among PCV-vaccinated (3.34 years) and PCV-unvaccinated (3.26 years) children.ConclusionCompared to high-income settings, the 3+0 schedule in Malawi has led to a sub-optimal reduction in pneumococcal carriage prevalence. This is likely due to recolonisation of vaccinated children with waning vaccine-induced immunity, resulting in insufficient indirect protection of unvaccinated populations. Rigorous evaluation of strategies to augment vaccine-induced control of carriage, including alternative schedules and catch-up campaigns is required.

scholarly journals Modified EPOCH for high‐risk non‐Hodgkin lymphoma in sub‐Saharan Africa

2019 ◽  
Vol 9 (1) ◽  
pp. 77-83 ◽  
Author(s):  
Takondwa Zuze ◽  
Grace K. Ellis ◽  
Edwards Kasonkanji ◽  
Bongani Kaimila ◽  
Richard Nyasosela ◽  
...  
Keyword(s):  
High Risk ◽  
Hodgkin Lymphoma ◽  
Sub Saharan Africa ◽  
Non Hodgkin Lymphoma ◽  
Sub Saharan

scholarly journals Time to scale up PrEP beyond the highest-risk populations? Modelling insights from high-risk women in sub-Saharan Africa

2020 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Hannah Grant ◽  
Gabriela B. Gomez ◽  
Katharine Kripke ◽  
Ruanne V. Barnabas ◽  
Charlotte Watts ◽  
...  
Keyword(s):  
High Risk ◽  
Scale Up ◽  
Sub Saharan Africa ◽  
High Risk Women ◽  
Sub Saharan
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