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The Lancet. Planetary Health Mar 2022Rice fields in Africa are major breeding sites for malaria vectors. However, when reviewed in the 1990s, in settings where transmission was relatively intense, there was... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Rice fields in Africa are major breeding sites for malaria vectors. However, when reviewed in the 1990s, in settings where transmission was relatively intense, there was no tendency for malaria indices to be higher in villages with irrigated rice fields than in those without. Subsequently, intervention coverage in sub-Saharan Africa has been massively scaled up and malaria infection prevalence has halved. We re-examined this rice-malaria relationship to assess whether, with lower malaria transmission, malaria risk is greater in rice-growing than in non-rice-growing areas.
METHODS
For this systematic review and meta-analysis, we searched EMBASE, Global Health, PubMed, Scopus, and Web of Science to identify observational studies published between Jan 1, 1900, and Sept 18, 2020. Studies were considered eligible if they were observational studies (cross-sectional, case-control, or cohort) comparing epidemiological or entomological outcomes of interest between people living in rice-growing and non-rice-growing rural communities in sub-Saharan Africa. Studies with pregnant women, displaced people, and military personnel as participants were excluded because they were considered not representative of a typical community. Data were extracted with use of a standardised data extraction form. The primary outcomes were parasite prevalence (P falciparum parasite rate age-standardised to 2-10-year-olds, calculated from total numbers of participants and number of infections [confirmed by microscopy or rapid diagnostic test] in each group) and clinical malaria incidence (number of diagnoses [fever with Plasmodium parasitaemia confirmed by microscopy or rapid diagnostic test] per 1000 person-days in each group). We did random-effects meta-analyses to estimate the pooled risk ratio (RR) for malaria parasite prevalence and incidence rate ratio (IRR) for clinical malaria in rice-growing versus non-rice-growing villages. RRs were compared in studies conducted before and after 2003 (chosen to mark the start of the mass scale-up of antimalaria interventions). This study is registered with PROSPERO (CRD42020204936).
FINDINGS
Of the 2913 unique studies identified and screened, 53 studies (including 113 160 participants across 14 African countries) were eligible for inclusion. In studies done before 2003, malaria parasite prevalence was not significantly different in rice-growing versus non-rice-growing villages (pooled RR 0·82 [95% CI 0·63-1·06]; 16 studies, 99 574 participants); however, in post-2003 studies, prevalence was significantly higher in rice-growing versus non-rice growing villages (1·73 [1·01-2·96]; seven studies, 14 002 participants). Clinical malaria incidence was not associated with residence in rice-growing versus non-rice-growing areas (IRR 0·75 [95% CI 0·47-1·18], four studies, 77 890). Potential limitations of this study include its basis on observational studies (with evidence quality rated as very low according to the GRADE approach), as well as its omission for the effects of seasonality and type of rice being cultivated. Risk of bias and inconsistencies was relatively serious, with I greater than 90% indicating considerable heterogeneity.
INTERPRETATION
Irrigated rice-growing communities in sub-Saharan Africa are exposed to greater malaria risk, as well as more mosquitoes. As increasing rice production and eliminating malaria are two major development goals in Africa, there is an urgent need to improve methods for growing rice without producing mosquitoes.
FUNDING
Wellcome Trust Our Planet Our Health programme, CGIAR Agriculture for Nutrition and Health.
Topics: Africa South of the Sahara; Animals; Cross-Sectional Studies; Female; Humans; Malaria; Observational Studies as Topic; Oryza; Pregnancy; Prevalence
PubMed: 35278391
DOI: 10.1016/S2542-5196(21)00349-1 -
Nutrients Aug 2023Vitamin E has an antioxidant property and is associated with protection against malaria. The current study used systematic review and meta-analysis approaches examining... (Meta-Analysis)
Meta-Analysis Review
Vitamin E has an antioxidant property and is associated with protection against malaria. The current study used systematic review and meta-analysis approaches examining the variance in blood levels of vitamin E in malaria patients as compared with uninfected individuals. The protocol for the systematic review was registered with PROSPERO (CRD4202341481). Searches for pertinent studies were carried out on Embase, MEDLINE, Ovid, PubMed, Scopus, ProQuest, and Google Scholar. The combined effect estimate (Cohen's d) of the difference in vitamin E levels in malaria patients as compared with uninfected individuals was estimated using the random effects model. The searches yielded 2009 records, and 23 studies were included in the systematic review. The majority of the studies (80%) found that vitamin E levels were significantly lower in malaria patients than those who were not infected. Overall, the results revealed a significant reduction in blood levels of vitamin E in malaria patients when compared with uninfected individuals ( < 0.01, Cohen's d: -2.74, 95% CI: -3.72-(-1.76), I: 98.69%, 21 studies). There was a significant reduction in blood levels of vitamin E in patients suffering from severe malaria, in comparison with those experiencing less severe forms of the disease ( < 0.01, Cohen's d: -0.56, 95% CI: -0.85-(-0.26), I: 0%, 2 studies), but no variation in blood levels of vitamin E among patients suffering from either or malaria ( = 0.13, Cohen's d: -1.15, 95% CI: -2.62-0.33, I: 93.22%, 3 studies). In summary, the present study strongly suggests that vitamin E levels are significantly reduced in malaria patients, with a more pronounced decrease observed in cases of severe malaria. However, the type of malaria parasite, specifically or , did not appear to influence the levels of vitamin E. This study highlights the potential role of vitamin E in the pathogenesis of malaria and suggests that improved vitamin E status might be beneficial for improving disease outcomes.
Topics: Humans; Vitamin E; Malaria; Malaria, Vivax; Antioxidants
PubMed: 37571409
DOI: 10.3390/nu15153472 -
Malaria Journal Mar 2024Anopheles vagus (subgenus Cellia) has been identified as a vector for malaria, filariasis, and Japanese encephalitis in Asia. Sporozoites of Plasmodium falciparum and... (Review)
Review
BACKGROUND
Anopheles vagus (subgenus Cellia) has been identified as a vector for malaria, filariasis, and Japanese encephalitis in Asia. Sporozoites of Plasmodium falciparum and Plasmodium vivax have been found in this zoophilic mosquito in Asia and Indonesia. This study systematically reviews publications regarding An. vagus species, variation, bio-ecology, and malaria transmission in various localities in Asia, especially Indonesia, to determine whether the current data support An. vagus as a species complex.
METHODS
The databases Pubmed, Scopus, Europe PMC, and Proquest were searched to identify information regarding the morphology, karyotypes, polytene chromosome, cross-mating, ecology, and molecular identification of An. vagus was then evaluated to determine whether there were possible species complexes.
RESULTS
Of the 1326 articles identified, 15 studies were considered for synthesis. The Anopheles spp. samples for this study came from Asia. Eleven studies used morphology to identify An. vagus, with singular studies using each of karyotype identification, chromosomal polytene identification, and cross-breeding experiments. Ten studies used molecular techniques to identify Anopheles spp., including An. vagus. Most studies discovered morphological variations of An. vagus either in the same or different areas and ecological settings. In this review, the members of An. vagus sensu lato grouped based on morphology (An. vagus, An. vagus vagus, An. vagus limosus, and An. limosus), karyotyping (form A and B), and molecular (An. vagus genotype A and B, An. vagus AN4 and AN5). Genetic analysis revealed a high conservation of the ITS2 fragment among members except for the An. vagus genotype B, which was, in fact, Anopheles sundaicus. This review also identified that An. vagus limosus and An. vagus vagus were nearly identical to the ITS2 sequence.
CONCLUSION
Literature review studies revealed that An. vagus is conspecific despite the distinct morphological characteristic of An. vagus and An. limosus. Further information using another barcoding tool, such as mitochondrial COI and ND6 and experimental cross-mating between the An. vagus and An. limosus may provide additional evidence for the status of An. vagus as a species complex.
Topics: Animals; Phylogeny; Anopheles; Genotype; Mosquito Vectors; Malaria
PubMed: 38539155
DOI: 10.1186/s12936-024-04888-0 -
BMC Medicine Jan 2020In endemic areas, pregnant women are highly susceptible to Plasmodium falciparum malaria characterized by the accumulation of parasitized red blood cells (pRBC) in the...
BACKGROUND
In endemic areas, pregnant women are highly susceptible to Plasmodium falciparum malaria characterized by the accumulation of parasitized red blood cells (pRBC) in the placenta. In subsequent pregnancies, women develop protective immunity to pregnancy-associated malaria and this has been hypothesized to be due to the acquisition of antibodies to the parasite variant surface antigen VAR2CSA. In this systematic review we provide the first synthesis of the association between antibodies to pregnancy-specific P. falciparum antigens and pregnancy and birth outcomes.
METHODS
We conducted a systematic review and meta-analysis of population-based studies (published up to 07 June 2019) of pregnant women living in P. falciparum endemic areas that examined antibody responses to pregnancy-specific P. falciparum antigens and outcomes including placental malaria, low birthweight, preterm birth, peripheral parasitaemia, maternal anaemia, and severe malaria.
RESULTS
We searched 6 databases and identified 33 studies (30 from Africa) that met predetermined inclusion and quality criteria: 16 studies contributed estimates in a format enabling inclusion in meta-analysis and 17 were included in narrative form only. Estimates were mostly from cross-sectional data (10 studies) and were heterogeneous in terms of magnitude and direction of effect. Included studies varied in terms of antigens tested, methodology used to measure antibody responses, and epidemiological setting. Antibody responses to pregnancy-specific pRBC and VAR2CSA antigens, measured at delivery, were associated with placental malaria (9 studies) and may therefore represent markers of infection, rather than correlates of protection. Antibody responses to pregnancy-specific pRBC, but not recombinant VAR2CSA antigens, were associated with trends towards protection from low birthweight (5 studies).
CONCLUSIONS
Whilst antibody responses to several antigens were positively associated with the presence of placental and peripheral infections, this review did not identify evidence that any specific antibody response is associated with protection from pregnancy-associated malaria across multiple populations. Further prospective cohort studies using standardized laboratory methods to examine responses to a broad range of antigens in different epidemiological settings and throughout the gestational period, will be necessary to identify and prioritize pregnancy-specific P. falciparum antigens to advance the development of vaccines and serosurveillance tools targeting pregnant women.
Topics: Africa; Cross-Sectional Studies; Erythrocytes; Female; Humans; Infant, Low Birth Weight; Malaria, Falciparum; Placenta; Plasmodium falciparum; Pregnancy; Pregnancy Complications, Parasitic; Pregnancy Outcome
PubMed: 31941488
DOI: 10.1186/s12916-019-1467-6 -
Annals of Parasitology 2020Asymptomatic Plasmodium falciparum infection during pregnancy is a major cause of foetal and maternal morbidity and mortality. The current study estimated the prevalence... (Meta-Analysis)
Meta-Analysis
Asymptomatic Plasmodium falciparum infection during pregnancy is a major cause of foetal and maternal morbidity and mortality. The current study estimated the prevalence of asymptomatic P. falciparum infection among pregnant women in Nigeria. We systematically searched the PubMed, Web of Science, Google Scholar and AJOL databases for studies that estimated the prevalence of asymptomatic P. falciparum infection in pregnant women up to December, 2019, and identified additional studies from reference lists. Twenty-seven studies which fulfilled eligibility criteria were included in final systematic review and meta-analysis. The prevalence of asymptomatic P. falciparum infection of individual study varied from 2.1% to 95.4%. Most surveys were performed in the southern parts of Nigeria. We observed a high degree of heterogeneity in most pooled estimates (I2 > 75%; p < 0.01). The pooled estimate of asymptomatic P. falciparum infection prevalence across studies for the entire period was 34.3% (95% CI: 24.0-46.3), ranging from 34.7% (95% CI: 22.8-48.9) in primigravida to 28.5% (95% CI: 15.8-45.8%) in the first trimester. Studies conducted from 2000-2009 (51.3%; 95% CI: 29.1-73.0), southern Nigeria (41.8%; 95% CI: 28.2-56.7), rural areas (52.1%; 95% CI: 19.4-83.0), and median sample size ≥ 246 (41.5; 95% CI: 25.9-58.9), had the highest pooled prevalence. Asymptomatic P. falciparum infection is considered high in pregnant women in Nigeria. This results, therefore, emphasize the need to actively diagnose and treat asymptomatic malaria infection during all antenatal care visits.
Topics: Female; Humans; Malaria, Falciparum; Nigeria; Plasmodium falciparum; Pregnancy; Pregnancy Complications, Parasitic; Prevalence
PubMed: 33126296
DOI: 10.17420/ap6603.266 -
Nutrients Oct 2023Despite several studies examining the relationship between calcium levels and malaria, inconsistencies and varied results remain in the literature. This study aimed to... (Meta-Analysis)
Meta-Analysis
Despite several studies examining the relationship between calcium levels and malaria, inconsistencies and varied results remain in the literature. This study aimed to synthesize the evidence on the association between blood calcium levels and malaria severity. A systematic literature search was conducted in the Embase, Scopus, PubMed, Ovid, and Google Scholar databases. The studies that investigated calcium levels in participants with malaria were reviewed and included for synthesis. The quality of included studies was assessed based on a standardized checklist by the Joanna Briggs Institute (JBI) critical appraisal checklists. The thematic synthesis had been used for qualitative synthesis. For the quantitative synthesis, the meta-analysis was performed to estimate the pooled effect sizes for differences in calcium levels between groups of participants using a random effect model using Hedge's g as a measure of effect size. Out of the 4574 identified records, 14 studies were reviewed. The thematic synthesis across these studies noted a consistent theme: reduced calcium levels in malaria patients compared to uninfected controls. However, the meta-analysis encompassing three specific analyses-comparing calcium levels between malaria patients and controls, severe and non-severe malaria cases, and fatal cases versus survivors-showed no significant difference in calcium levels. The statistics were as follows: (1) = 0.15, Hedge's g: -1.00, 95% CI: -2.37-0.38, : 98.97, 9 studies; (2) = 0.35, Hedge's g: -0.33, 95% CI: -1.02-0.36, : 81.61, 3 studies; and (3) = 0.71, Hedge's g: -0.14, 95% CI: -0.91-0.62, : 87.05, 3 studies. Subgroup analyses indicated that regional disparities, especially between Africa and Asia, and participant age groups may influence these outcomes. While a trend of decreased calcium levels in malaria patients was observed, the meta-analytical results suggest regional and age-related variations. Further investigations should emphasize these differences to better guide clinical management, prognostic applications, and the crafting of policies concerning malaria's metabolic effects.
Topics: Humans; Malaria, Vivax; Plasmodium falciparum; Calcium; Malaria; Africa
PubMed: 37960176
DOI: 10.3390/nu15214522 -
International Journal of Environmental... Jan 2021Coinfection of malaria and intestinal helminths affects one third of the global population, largely among communities with severe poverty. The spread of these parasitic... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Coinfection of malaria and intestinal helminths affects one third of the global population, largely among communities with severe poverty. The spread of these parasitic infections overlays in several epidemiological locations and the host shows different outcomes. This systematic review and meta-analysis determine the pooled prevalence of malaria and intestinal helminthiases coinfections among malaria suspected patients in Ethiopia.
METHODS
Primary studies published in English language were retrieved using appropriate search terms on Google Scholar, PubMed/MEDLINE, CINHAL, Scopus, and Embase. The Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) was used for critical appraisal of studies. A pooled statistical meta-analysis was conducted using STATA Version 14.0 software. The heterogeneity and publication bias were assessed using the I2 statistics and Egger's test, respectively. Duval and Tweedie's nonparametric trim and fill analysis using the random-effect analysis. The Random effects model was used to estimate the summary prevalence of comorbidity of malaria and soil transmitted helminthiases and the corresponding 95% confidence intervals (CI). The review protocol has registered in PROSPERO number CRD42019144803.
RESULTS
We identified ten studies ( = 6633 participants) in this study. The overall pooled result showed 13% of the ambulatory patients infected by malaria and intestinal helminths concurrently in Ethiopia. The pooled prevalence of and , and mixed infections were 12, 30, and 6%, respectively. The most common intestinal helminth parasites detected were , , and .
CONCLUSIONS
The comorbidity of malaria and intestinal helminths causes lower hemoglobin level leading to maternal anemia, preterm delivery, and still birth in pregnant women and lactating mother. School-aged children and neonates coinfected by plasmodium species and soil transmitted helminths develop cognitive impairment, protein energy malnutrition, low birth weight, small for gestational age, and gross motor delay. The Ministry of Health of Ethiopia and its international partners working on malaria elimination programs should give more emphasis to the effect of the interface of malaria and soil transmitted helminths, which calls for an integrated disease control and prevention.
Topics: Animals; Child; Comorbidity; Ethiopia; Female; Health Facilities; Helminths; Humans; Infant, Newborn; Lactation; Malaria; Outpatients; Pregnancy; Prevalence
PubMed: 33498343
DOI: 10.3390/ijerph18030862 -
BMC Infectious Diseases Jun 2020Cerebral malaria is the most severe form of infection with Plasmodium falciparum characterized by a highly inflammatory response. This systematic review aimed to...
BACKGROUND
Cerebral malaria is the most severe form of infection with Plasmodium falciparum characterized by a highly inflammatory response. This systematic review aimed to investigate the association between TNF-α levels and cerebral malaria.
METHODS
This review followed the Preferred Reporting of Systematic Review and Meta-analyses (PRISMA) guidelines. The search was performed at PubMed, LILACS, Scopus, Web of Science, The Cochrane Library, OpenGrey and Google Scholar. We have included studies of P. falciparum-infected humans with or without cerebral malaria and TNF-α dosage level. All studies were evaluated using a risk of bias tool and the GRADE approach.
RESULTS
Our results have identified 2338 studies, and 8 articles were eligible according to this systematic review inclusion criteria. Among the eight articles, five have evaluated TNF- α plasma dosage, while two have evaluated at the blood and one at the brain (post-Morten). Among them, only five studies showed higher TNF-α levels in the cerebral malaria group compared to the severe malaria group. Methodological problems were identified regarding sample size, randomization and blindness, but no risk of bias was detected.
CONCLUSION
Although the results suggested that that TNF-α level is associated with cerebral malaria, the evidence is inconsistent and imprecise. More observational studies evaluating the average TNF-alpha are needed.
Topics: Adolescent; Adult; Aged; Child; Child, Preschool; Female; Humans; Malaria, Cerebral; Malaria, Falciparum; Male; Middle Aged; Plasmodium falciparum; Tumor Necrosis Factor-alpha; Young Adult
PubMed: 32576141
DOI: 10.1186/s12879-020-05107-2 -
PloS One 2022The artemisinin derivatives are the preferred antimalaria drugs for treating severe Plasmodium falciparum malaria. However, their clinical effectiveness compared to each... (Meta-Analysis)
Meta-Analysis
Comparative efficacy and safety of the artemisinin derivatives compared to quinine for treating severe malaria in children and adults: A systematic update of literature and network meta-analysis.
BACKGROUND
The artemisinin derivatives are the preferred antimalaria drugs for treating severe Plasmodium falciparum malaria. However, their clinical effectiveness compared to each other is unknown. Our objective, therefore, was to evaluate the efficacy and safety of the artemisinin derivatives and quinine for treating severe P. falciparum malaria in children and adults using a network meta-analysis.
METHODS AND FINDINGS
Review protocol was registered with PROSPERO, CRD42020218190. We updated the search strategies of three Cochrane systematic reviews which included published and unpublished randomised control trials (RCTs) that have compared specific artemisinin derivatives to quinine in treating severe malaria. Search included CENTRAL, MEDLINE, Embase, LILACS, ISI Web of Science and trial registries up to February 2021. We screened studies, extracted data, assessed risk of bias, and quality of evidence in duplicate. Separate network meta-analyses in the frequentist framework, using a random effects model, with quinine as reference, were conducted for adults and children, and rankings were produced using p-scores to assess mortality, parasite clearance, coma recovery, fever clearance, neurological sequela and adverse events. Searches identified 818 citations, 33 RCTs were eligible. We pooled 7795 children and 3182 adults. The networks involved artesunate, artemether, rectal artemisinin, arteether and quinine. Compared to quinine, artesunate reduced mortality in children (risk ratio (RR), 0.76; 95%CI [0.65 to 0.89], moderate quality), adults (RR, 0.55; 95%CI [0.40 to 0.75], moderate quality) and in cerebral malaria (RR, 0.72; 95%CI [0.55 to 0.94], moderate quality). Compared to rectal artemisinin and intramuscular arteether, the efficacy and safety of parenteral artesunate, and intramuscular artemether in treating severe malaria are not clear. Rankings showed that none of the artemisinin drugs were consistently superior in all the outcomes assessed. Indirect evidence produced were of very low ratings due to suspected publication bias and imprecision.
CONCLUSIONS
Artesunate reduces mortality compared to quinine for both adults and children in Asia and Africa including cerebral malaria. The artemisinin derivatives remain the best treatment for severe malaria but their comparative clinical effectiveness is yet to be fully explored.
Topics: Adult; Antimalarials; Artemether; Artemisinins; Artesunate; Child; Humans; Malaria, Cerebral; Malaria, Falciparum; Network Meta-Analysis; Quinine
PubMed: 35857773
DOI: 10.1371/journal.pone.0269391 -
Malaria Journal Apr 2021The emergence of artemisinin resistance in Southeast Asia and Plasmodium falciparum kelch13 propeller gene mutations in sub-Saharan African pose the greatest threat to... (Meta-Analysis)
Meta-Analysis
Efficacy and safety of dihydroartemisinin-piperaquine versus artemether-lumefantrine for treatment of uncomplicated Plasmodium falciparum malaria in Ugandan children: a systematic review and meta-analysis of randomized control trials.
BACKGROUND
The emergence of artemisinin resistance in Southeast Asia and Plasmodium falciparum kelch13 propeller gene mutations in sub-Saharan African pose the greatest threat to global efforts to control malaria. This is a critical concern in Uganda, where artemisinin-based combination therapy (ACT) is the first-line treatment for uncomplicated falciparum. The objective of this study was to compare the efficacy and safety of dihydroartemisinin-piperaquine (DHA-PQ) and artemether-lumefantrine (AL) for the treatment of uncomplicated falciparum malaria in Ugandan children.
METHODS
A search of PubMed and the Cochrane Central Register of Controlled Trials for retrieving randomized controlled trials comparing the efficacy and safety of DHA-PQ and AL for treatment of uncomplicated falciparum malaria in Ugandan children was done. The search was performed up to 31 August 2020. The data extracted from eligible studies and pooled as risk ratio (RR) with a 95% confidence interval (CI), using Rev Man Software (5.4). The protocol was registered in PROSPERO, ID: CRD42020182354.
RESULTS
Eleven trials were included in this review and two of them only included under safety outcome. Total 3798 participants were enrolled. The PCR unadjusted treatment failure was significantly lower with DHA-PQ at day 28 (RR 0.30, 95% CI 0.19-0.49; participants = 7863; studies = 5; I = 93%, low quality evidence) and at day 42 (RR 0.53, 95% CI 0.38-0.76; participants = 1618; studies = 4; I = 79%, moderate quality of evidence). The PCR adjusted treatment failure at day 42 was significantly lower with DHA-PQ treatment group (RR 0.45, 95% CI 0.28 to 0.72; participants = 1370; studies = 5, high quality of evidence), and it was below 5% in both arms at day 28 (moderate quality of evidence). AL showed a longer prophylactic effect on new infections which may last for up to 63 days (PCR-adjusted treatment failure: RR 2.04, 95% CI 1.13-3.70; participants = 1311; studies = 2, moderate quality of evidence). Compared to AL, DHA-PQ was associated with a slightly higher frequency of cough (RR 1.07, 95% CI 1.01 to 1.13; 2575 participants; six studies; high quality of evidence). In both treatment groups, the risk of recurrent parasitaemia due to possible recrudescence was less than 5% at day 28. The appearance of gametocyte between 29 and 42 days was also significantly lower in DHA-PQ than AL (RR 0.26, 95% CI 0.12 to 0.56; participants = 623; studies = 2; I = 0%).
CONCLUSION
Compared to AL, DHA-PQ appeared to reduce treatment failure and gametocyte carriage in Ugandan children. This may trigger DHA-PQ to become the first-line treatment option. Both treatments were safe and well-tolerated.
Topics: Antimalarials; Artemether, Lumefantrine Drug Combination; Artemisinins; Child; Child, Preschool; Drug Combinations; Humans; Infant; Malaria, Falciparum; Quinolines; Randomized Controlled Trials as Topic; Uganda
PubMed: 33794897
DOI: 10.1186/s12936-021-03711-4