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The Cochrane Database of Systematic... Jul 2007Four types of malaria vaccine, SPf66 and MSP/RESA vaccines (against the asexual stages of the Plasmodium parasite) and CS-NANP and RTS,S vaccines (against the sporozoite... (Review)
Review
BACKGROUND
Four types of malaria vaccine, SPf66 and MSP/RESA vaccines (against the asexual stages of the Plasmodium parasite) and CS-NANP and RTS,S vaccines (against the sporozoite stages), have been tested in randomized controlled trials in endemic areas.
OBJECTIVES
To assess malaria vaccines against Plasmodium falciparum, P. vivax, P. malariae and P ovale in preventing infection, disease and death.
SEARCH STRATEGY
We searched the Cochrane Infectious Diseases Group Specialized Register (April 2004), CENTRAL (The Cochrane Library Issue 2, 2004), MEDLINE (1966 to April 2004), EMBASE (1980 to April 2004), Science Citation Index (1981 to April 2004), and reference lists of articles. We also contacted organizations and researchers in the field.
SELECTION CRITERIA
Randomized controlled trials comparing vaccines against Plasmodium falciparum, P. vivax, P. malariae or P. ovale with placebo or routine antimalarial control measures in people of any age receiving a challenge malaria infection.
DATA COLLECTION AND ANALYSIS
Two reviewers independently assessed trial quality and extracted data.
MAIN RESULTS
Eighteen efficacy trials involving 10,971 participants were included. There were ten trials of SPf66 vaccine, four trials of CS-NANP vaccines, two trials of RTS,S vaccine, and two of MSP/RESA vaccine. Results with SPf66 in reducing new malaria infections (P. falciparum) were heterogeneous: it was not effective in four African trials (Peto odds ratio (OR) 0.96, 95% confidence interval (CI) 0.81 to 1.14), but in five trials outside Africa the number of first attacks was reduced (Peto OR 0.77, 95% CI 0.67 to 0.88). Trials to date have not indicated any serious adverse events with SPf66 vaccine. In three trials of CS-NANP vaccines, there was no evidence for protection by these vaccines against P. falciparum malaria (Peto OR 1.12, 95% CI 0.64 to 1.93). In a small trial in non-immune adults in the USA, RTS,S gave strong protection against experimental infection with P. falciparum. In a trial in an endemic area of the Gambia in semi-immune people, there was a reduction in clinical malaria episodes in the second year of follow up, corresponding to a vaccine efficacy of 66% (CI 14% to 85%). In a trial in Papua New Guinea, MSP/RESA had no protective effect against episodes of clinical malaria. There was evidence of an effect on parasite density, but this differed according to whether the participants had been pretreated with sulfadoxine/pyrimethamine or not. The prevalence of infections with the parasite subtype of MSP2 in the vaccine was reduced compared with the other subtype (Peto OR 0.35, CI 0.23 to 0.53).
AUTHORS' CONCLUSIONS
There is no evidence for protection by SPf66 vaccines against P. falciparum in Africa. There is a modest reduction in attacks of P. falciparum malaria following vaccination with SPf66 in other regions. Further research with SPf66 vaccines in South America or with new formulations of SPf66 may be justified. There was not enough evidence to evaluate the use of CS-NANP vaccines. The RTS,S vaccine showed promising result, as did the MSP/RESA vaccine, but it should include the other main allelic form of MSP2. The MSP/RESA trial demonstrated that chemotherapy during a vaccine trial may reduce vaccine efficacy, and trials should consider very carefully whether this practice is justified.
Topics: Adult; Antigens, Protozoan; Humans; Malaria; Malaria Vaccines; Malaria, Falciparum; Protozoan Proteins; Randomized Controlled Trials as Topic; Recombinant Proteins; Vaccines, Synthetic
PubMed: 17636596
DOI: 10.1002/14651858.CD000129.pub2 -
The Cochrane Database of Systematic... Apr 2006A malaria vaccine is badly needed. SPf66 was one of the earliest vaccines developed. It is a synthetic peptide vaccine containing antigens from the blood stages of... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
A malaria vaccine is badly needed. SPf66 was one of the earliest vaccines developed. It is a synthetic peptide vaccine containing antigens from the blood stages of malaria linked together with an antigen from the sporozoite stage, and is targeted mainly against the blood (asexual) stages.
OBJECTIVES
To assess the effect of SPf66 malaria vaccines against Plasmodium falciparum, P. vivax, P. malariae, and P. ovale in preventing infection, disease, and death.
SEARCH STRATEGY
We searched the Cochrane Infectious Diseases Group Specialized Register (September 2005), CENTRAL (The Cochrane Library 2005, Issue 3), MEDLINE (1966 to September 2005), EMBASE (1980 to September 2005), LILACS (1982 to September 2005), Science Citation Index (1981 to September 2005), and reference lists of articles. We also contacted organizations and researchers in the field.
SELECTION CRITERIA
Randomized and quasi-randomized controlled trials comparing SPf66 vaccine with placebo or routine antimalarial control measures in people of any age receiving an artificial challenge or natural exposure to malaria infection (any species).
DATA COLLECTION AND ANALYSIS
Two people independently assessed trial quality and extracted data, including adverse events. Results were expressed as relative risks (RR) with 95% confidence intervals (CI).
MAIN RESULTS
Ten efficacy trials of SPf66 involving 9698 participants were included. Results with SPf66 in reducing new episodes of P. falciparum malaria were heterogeneous: it was not effective in four African trials (RR 0.98, 95% CI 0.90 to 1.07; 2371 participants) or in one Asian trial (RR 1.06, 95% CI 0.90 to 1.25; 1221 participants). In four trials in South America the number of first attacks with P. falciparum was reduced by 28% (RR 0.72, 95% CI 0.63 to 0.82; 3807 participants). It did not reduce episodes of P. vivax malaria or admission to hospital with severe malaria. Trials have not indicated any serious adverse events with SPf66 vaccine.
AUTHORS' CONCLUSIONS
There is no evidence for protection by SPf66 vaccines against P. falciparum in Africa. There is a modest reduction in attacks of P. falciparum malaria following vaccination with SPf66 in South America. There is no justification for further trials of SPf66 in its current formulation. Further research with SPf66 vaccines in South America or with new formulations of SPf66 may be justified.
Topics: Humans; Malaria; Malaria Vaccines; Protozoan Proteins; Randomized Controlled Trials as Topic; Recombinant Proteins; Vaccines, Synthetic
PubMed: 16625647
DOI: 10.1002/14651858.CD005966 -
Malaria Journal Feb 2017Transfusion-transmitted (TT) malaria is an alternative infection route that has gained little attention from authorities, despite representing a life-threatening... (Review)
Review
BACKGROUND
Transfusion-transmitted (TT) malaria is an alternative infection route that has gained little attention from authorities, despite representing a life-threatening condition. There has been no systematic review of this health problem in American countries. The aim of this study was to describe the clinical and epidemiological characteristics of TT malaria in the Americas and identify factors associated with lethality based on the studies published in the literature.
METHODS
Potentially relevant papers in all languages were retrieved from MEDLINE and LILACS. Additional articles were obtained from reviews and original papers. Publications on screening of candidate blood donors and on surveillance of TT malaria cases were included. Odds ratios with respective 95% confidence intervals (95% CI) were calculated. Epidemiological characteristics of blood donors of TT malaria cases, including a pooled positivity of different tests for malaria diagnosis, were retrieved.
RESULTS
A total of 63 publications regarding TT malaria from seven countries were included, from 1971 to 2016. A total of 422 cases of TT malaria were recorded. Most TT malaria cases were in females (62.0%) and 39.5% were in the ≥61 years-old age group. About half of all cases were from Mexico (50.7%), 40.3% from the United States of America (USA) and 6.6% from Brazil. Gyneco-obstetrical conditions (67.3%), surgical procedures (20.6%) and complications from neoplasias (6.1%) were the most common indications of transfusion. Packed red blood cells (RBCs) (50.7%) and whole blood (43.3%) were the blood products mostly associated with TT malaria. Cases were mostly caused by Plasmodium malariae (58.4%), followed by Plasmodium vivax (20.7%) and Plasmodium falciparum (17.9%). A total of 66.6% of cases were diagnosed by microscopy. Incubation period of 2-3 weeks was the most commonly observed (28.6%). Lethality was seen in 5.3% of cases and was associated with living in non-endemic countries, P. falciparum infection and concomitant neoplastic diseases.
CONCLUSION
There is an important research and knowledge gap regarding the TT malaria burden in Latin American countries where malaria remains endemic. No screening method that is practical, affordable and suitably sensitive is available at blood banks in Latin American countries, where infections with low parasitaemia contribute greatly to transmission. Lethality from TT malaria was not negligible. TT malaria needs to be acknowledged and addressed in areas moving toward elimination.
Topics: Brazil; Disease Transmission, Infectious; Humans; Malaria; Mexico; Plasmodium falciparum; Plasmodium malariae; Plasmodium vivax; Survival Analysis; Transfusion Reaction; United States
PubMed: 28202065
DOI: 10.1186/s12936-017-1726-y -
Malaria Journal Jan 2018Transfusion-transmitted malaria (TTM) is an accidental Plasmodium infection caused by whole blood or a blood component transfusion from a malaria infected donor to a...
BACKGROUND
Transfusion-transmitted malaria (TTM) is an accidental Plasmodium infection caused by whole blood or a blood component transfusion from a malaria infected donor to a recipient. Infected blood transfusions directly release malaria parasites in the recipient's bloodstream triggering the development of high risk complications, and potentially leading to a fatal outcome especially in individuals with no previous exposure to malaria or in immuno-compromised patients. A systematic review was conducted on TTM case reports in non-endemic areas to describe the epidemiological characteristics of blood donors and recipients.
METHODS
Relevant articles were retrieved from Pubmed, EMBASE, Scopus, and LILACS. From each selected study the following data were extracted: study area, gender and age of blood donor and recipient, blood component associated with TTM, Plasmodium species, malaria diagnostic method employed, blood donor screening method, incubation period between the infected transfusion and the onset of clinical symptoms in the recipient, time elapsed between the clinical symptoms and the diagnosis of malaria, infection outcome, country of origin of the blood donor and time of the last potential malaria exposure.
RESULTS
Plasmodium species were detected in 100 TTM case reports with a different frequency: 45% Plasmodium falciparum, 30% Plasmodium malariae, 16% Plasmodium vivax, 4% Plasmodium ovale, 2% Plasmodium knowlesi, 1% mixed infection P. falciparum/P. malariae. The majority of fatal outcomes (11/45) was caused by P. falciparum whilst the other fatalities occurred in individuals infected by P. malariae (2/30) and P. ovale (1/4). However, non P. falciparum fatalities were not attributed directly to malaria. The incubation time for all Plasmodium species TTM case reports was longer than what expected in natural infections. This difference was statistically significant for P. malariae (p = 0.006). A longer incubation time in the recipient together with a chronic infection at low parasite density of the donor makes P. malariae a subtle but not negligible risk for blood safety aside from P. falciparum.
CONCLUSIONS
TTM risk needs to be taken into account in order to enhance the safety of the blood supply chain from donors to recipients by means of appropriate diagnostic tools.
Topics: Blood Transfusion; Humans; Malaria; Plasmodium; Transfusion Reaction
PubMed: 29338786
DOI: 10.1186/s12936-018-2181-0 -
PloS One 2021In Sub-Saharan Africa (SSA), where malaria transmission is stable, malaria infection in pregnancy adversely affects pregnant women, fetuses, and newborns and is often... (Meta-Analysis)
Meta-Analysis
BACKGROUND
In Sub-Saharan Africa (SSA), where malaria transmission is stable, malaria infection in pregnancy adversely affects pregnant women, fetuses, and newborns and is often asymptomatic. So far, a plethora of primary studies have been carried out on asymptomatic malaria infection in pregnant women in SSA. Nevertheless, no meta-analysis estimated the burden of asymptomatic malaria infection in pregnant women in SSA, so this meta-analysis was carried out to bridge this gap.
METHODS
PubMed, Web of Science, Scopus, Embase, and ProQuest were systematically searched for relevant studies published until 4 August 2020, and also the expansion of the search was performed by October 24, 2020. We assessed heterogeneity among included studies using I-squared statistics (I2). Publication bias was assessed by visual inspection of the funnel plot and further quantitatively validated by Egger's and Begg's tests. The pooled prevalence and pooled odds ratio (OR) and their corresponding 95% Confidence Interval (CI) were estimated using the random-effects model in Stata 15 software.
RESULTS
For this meta-analysis, we included 35 eligible studies. The overall prevalence estimate of asymptomatic Plasmodium infection prevalence was 26.1%% (95%CI: 21-31.2%, I2 = 99.0%). According to species-specific pooled prevalence estimate, Plasmodium falciparum was dominant species (22.1%, 95%CI: 17.1-27.2%, I2 = 98.6%), followed by Plasmodium vivax, Plasmodium malariae and Plasmodium ovale, respectively, found to be 3% (95%CI: 0-5%, I2 = 88.3%), 0.8% (95%CI: 0.3-0.13%, I2 = 60.5%), and 0.2% (95%CI: -0.01-0.5%, I2 = 31.5%). Asymptomatic malaria-infected pregnant women were 2.28 times more likely anemic (OR = 2.28, 95%CI: 1.66-3.13, I2 = 56.3%) than in non-infected pregnant women. Asymptomatic malaria infection was 1.54 times higher (OR = 1.54, 95%CI: 1.28-1.85, I2 = 11.5%) in primigravida women compared to multigravida women.
CONCLUSION
In SSA, asymptomatic malaria infection in pregnant women is prevalent, and it is associated with an increased likelihood of anemia compared to non-infected pregnant women. Thus, screening of asymptomatic pregnant women for malaria and anemia should be included as part of antenatal care.
Topics: Africa South of the Sahara; Asymptomatic Infections; Coinfection; Female; Humans; Malaria; Plasmodium falciparum; Pregnancy; Pregnancy Complications, Parasitic; Prenatal Care; Prevalence
PubMed: 33793584
DOI: 10.1371/journal.pone.0248245 -
Malaria Journal Sep 2021Rapid accurate diagnosis followed by effective treatment is very important for malaria control. Light microscopy remains the "golden standard" method for malaria... (Meta-Analysis)
Meta-Analysis
Performance of rapid diagnostic tests, microscopy, loop-mediated isothermal amplification (LAMP) and PCR for malaria diagnosis in Ethiopia: a systematic review and meta-analysis.
BACKGROUND
Rapid accurate diagnosis followed by effective treatment is very important for malaria control. Light microscopy remains the "golden standard" method for malaria diagnosis. Diagnostic test method must have sufficient level of accuracy for detecting malaria parasites. Therefore, this study aimed to investigate the diagnostic accuracy of rapid diagnostic tests (RDTs), microscopy, loop-mediated isothermal amplification (LAMP) and/or polymerase chain reaction (PCR) for the malaria diagnosis in Ethiopia.
METHODS
Data bases such as PubMed, PubMed central, Science direct databases, Google scholar, and Scopus were searched from September to October, 2020 for studies assessing the diagnostic accuracy of RDTs, microscopy, LAMP and PCR methods for malaria diagnosis.
RESULTS
A total of 29 studies published between 2001 and 2020 were analysed using review manager, Midas (Stata) and Meta-disc. The sensitivity and specificity of studies comparing RDT with microscopy varies from 79%-100% to 80%-100%, respectively. The sensitivity of LAMP (731 tests) was 100% and its specificity was varies from 85 to 99% when compared with microscopy and PCR. Considerable heterogeneity was observed between studies included in this meta-analysis. Meta-regression showed that blinding status and target antigens were the major sources of heterogeneity (P < 0.05). RDT had an excellent diagnostic accuracy (Area under the ROC Curve = 0.99) when compared with microscopy. Its specificity was quite good (93%-100%) except for one outlier (28%), but lower "sensitivity" was observed when PCR is a reference test. This indicates RDT had a good diagnostic accuracy (AUC = 0.83). Microscopy showed a very good diagnostic accuracy when compared with PCR.
CONCLUSIONS
The present study showed that microscopy and RDTs had high efficiency for diagnosing febrile malaria patients. The diagnostic accuracy of RDT was excellent when compared with microscopy. This indicates RDTs have acceptable sensitivities and specificities to be used in resource poor settings as an alternative for microscopy. In this study, LAMP showed an excellent sensitivities and specificities. Furthermore, the need of minimum equipment and relatively short time for obtaining results can made LAMP one of the best alternatives especially for accurate diagnosis of asymptomatic malaria.
Topics: Diagnostic Tests, Routine; Ethiopia; Humans; Malaria; Microscopy; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Polymerase Chain Reaction
PubMed: 34579729
DOI: 10.1186/s12936-021-03923-8 -
Bulletin of the World Health... Sep 2012To synthesize findings from recent studies of strategies to deliver insecticide-treated nets (ITNs) at scale in malaria-endemic areas. (Review)
Review
OBJECTIVE
To synthesize findings from recent studies of strategies to deliver insecticide-treated nets (ITNs) at scale in malaria-endemic areas.
METHODS
Databases were searched for studies published between January 2000 and December 2010 in which: subjects resided in areas with endemicity for Plasmodium falciparum and Plasmodium vivax malaria; ITN delivery at scale was evaluated; ITN ownership among households, receipt by pregnant women and/or use among children aged < 5 years was evaluated; and the study design was an individual or cluster-randomized controlled design, nonrandomized, quasi-experimental, before-and-after, interrupted time series or cross-sectional without temporal or geographical controls. Papers describing qualitative studies, case studies, process evaluations and cost-effectiveness studies linked to an eligible paper were also included. Study quality was assessed using the Cochrane risk of bias checklist and GRADE criteria. Important influences on scaling up were identified and assessed across delivery strategies.
FINDINGS
A total of 32 papers describing 20 African studies were reviewed. Many delivery strategies involved health sectors and retail outlets (partial subsidy), antenatal care clinics (full subsidy) and campaigns (full subsidy). Strategies achieving high ownership among households and use among children < 5 delivered ITNs free through campaigns. Costs were largely comparable across strategies; ITNs were the main cost. Cost-effectiveness estimates were most sensitive to the assumed net lifespan and leakage. Common barriers to delivery included cost, stock-outs and poor logistics. Common facilitators were staff training and supervision, cooperation across departments or ministries and stakeholder involvement.
CONCLUSION
There is a broad taxonomy of strategies for delivering ITNs at scale.
Topics: Animals; Global Health; Humans; Insecticide-Treated Bednets; Insecticides; Malaria; Plasmodium malariae; Plasmodium vivax; Public Health; Social Marketing
PubMed: 22984312
DOI: 10.2471/BLT.11.094771 -
The Cochrane Database of Systematic... 2000Despite continued efforts to control the disease, malaria remains a major health problem in many regions of the world, especially sub-Saharan Africa, and new ways to... (Review)
Review
BACKGROUND
Despite continued efforts to control the disease, malaria remains a major health problem in many regions of the world, especially sub-Saharan Africa, and new ways to control or eradicate the disease are urgently needed. Two types of vaccine, SPf66 vaccine against the asexual stages, and NANP vaccines against the sporozoite stages of the Plasmodium parasite, have been tested in randomised clinical trials in endemic areas.
OBJECTIVES
To assess the effects of malaria vaccines.
SEARCH STRATEGY
The Cochrane Infectious Diseases Group trials register, the Cochrane Controlled Trials Register, Medline, Embase and reference lists of articles were searched. Organisations and researchers in the field were contacted.
SELECTION CRITERIA
Randomised trials comparing vaccines against Plasmodium falciparum, P. vivax, P. malariae or P. ovale, and placebo.
DATA COLLECTION AND ANALYSIS
Two independent reviewers assessed trial quality and conducted data extraction.
MAIN RESULTS
Thirteen efficacy trials involving about 7700 people were included. There were nine trials of the Spf66 vaccine and four trials of the NANP vaccines. There was large heterogeneity between trials when investigating the effect of SPf66 in reducing incidence of the first attack of P. falciparum malaria. When trials were subcategorised by location, there was no evidence for effect of SPf66 in reducing incidence of P. falciparum in four African trials conducted in children under 5 years of age (Peto odds ratio [OR] = 0.96, 95% confidence interval [CI] 0.81 to 1.14). In five trials outside Africa with participants aged 2 years to adult, there was a reduction in incidence by SPf66 vaccine (Peto OR = 0.77, 95% CI 0.67 to 0.88, fixed effects model). Significant heterogeneity remained between trials conducted outside Africa. Using a random effects model for these five trials, the OR was 0.74 (95% CI 0.54 to 1.01). In five trials, there was no evidence for effect of the SPf66 vaccine on the incidence of the first attack of P. vivax malaria (OR 1.01, 95% CI 0.87 to 1.17). Trials to date have not indicated any severe adverse effects of SPf66 vaccine. In three trials of NANP-based vaccines, there was no evidence for protection by these vaccines against P. falciparum malaria (OR 1.12, 95% CI 0.64 to 1.93).
REVIEWER'S CONCLUSIONS
There is no evidence for protection by SPf66 vaccines against P. falciparum in Africa. There is a modest reduction in attacks of P. falciparum malaria following vaccination with SPf66 in other regions. Further research with SPf66 vaccines in South America may be justified. Trials to date have not been of sufficient size to evaluate the effect of malaria vaccines on mortality or on severe malaria requiring admission to hospital. There was not enough evidence to evaluate the use of NANP vaccines.
Topics: Adult; Humans; Malaria; Malaria Vaccines; Malaria, Falciparum; Protozoan Proteins; Recombinant Proteins
PubMed: 10796492
DOI: 10.1002/14651858.CD000129 -
The Journal of Tropical Medicine and... Oct 1994The influence of infecting dose on severity of malaria is unknown. The medical literature contains descriptions and analyses of thousands of people, volunteers and... (Review)
Review
The influence of infecting dose on severity of malaria is unknown. The medical literature contains descriptions and analyses of thousands of people, volunteers and neurosyphilis patients, in whom malaria was induced artificially. In some studies it is possible to relate measures of dose to outcome. In this paper a systematic review of this literature is presented. Dose was inversely related to prepatent and incubation period, as expected. A few studies suggested a relation between dose and severity of disease but others did not. Difficulties in interpreting the studies are emphasized, and the findings are compared with those in experimental animals.
Topics: Animals; Birds; Culicidae; Humans; Insect Vectors; Macaca mulatta; Malaria; Malaria, Avian; Malaria, Falciparum; Malaria, Vivax; Mice; Plasmodium malariae; Rodentia; Severity of Illness Index; Time Factors
PubMed: 7932927
DOI: No ID Found