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Malaria is a significant health concern worldwide, particularly in Africa where its prevalence is still alarmingly high. Using artificial intelligence algorithms to diagnose cells with malaria provides great convenience for clinicians. In this paper, a densely connected convolutional dynamic learning network (DCDLN) is proposed for the diagnosis of malaria disease. Specifically, after data processing and partitioning of the dataset, the densely connected block is trained as a feature extractor. To classify the features extracted by the feature extractor, a classifier based on a dynamic learning network is proposed in this paper. Based on experimental results, the proposed DCDLN method demonstrates a diagnostic accuracy rate of 97.23%, surpassing the diagnostic performance than existing advanced methods on an open malaria cell dataset. This accurate diagnostic effect provides convincing evidence for clinicians to make a correct diagnosis. In addition, to validate the superiority and generalization capability of the DCDLN algorithm, we also applied the algorithm to the skin cancer and garbage classification datasets. DCDLN achieved good results on these datasets as well, demonstrating that the DCDLN algorithm possesses superiority and strong generalization performance. [ABSTRACT FROM AUTHOR]

Malaria is a tropical disease. However, due to travel, cases can be imported into countries with temperate climates. For instance there are 1300–1800 cases imported into the UK each year. Three-quarters of reported malaria cases are caused by Plasmodium falciparum , which is capable of causing severe or life-threatening disease. Roughly 10% of cases occur in children. Malaria in children often presents with misleading symptoms and the presentation of malaria can be delayed for many months. Therefore a travel history is important in all children presenting with fever. Awareness and early diagnosis using thick and thin blood films or rapid diagnostic tests is crucial in improving outcomes. Uncomplicated P. falciparum malaria should be treated with an artemisinin combination therapy (ACT), quinine with doxycycline or clindamycin, or atovaquone-proguanil. Severe or complicated malaria in children should be treated with intravenous artesunate or intravenous quinine if artesunate is not available. Children with severe malaria should be managed in a high-dependency or intensive care setting. Either an oral ACT or chloroquine can be used for the treatment of non-falciparum malaria. Dormant parasites (hypnozoites) may persist in the liver after treatment of P. vivax or P. ovale so primaquine may be required to prevent relapse. Prevention of malaria in children involves the use a combination of bite prevention strategies and chemoprophylaxis. Recent vaccine developments have seen WHO approving the malaria vaccine RTS,S/AS01 for prevention in children living in regions with high transmission in sub-Saharan countries. This short article gives practical advice to health care professionals caring for children who return from malaria endemic areas to countries where the condition is far less common. [ABSTRACT FROM AUTHOR]

• Plasmodium falciparum infection established from a retuning traveler from Kazakhstan. • Kazakhstan was declared malaria-free in 2012. • Patient had no travel history outside Europe, other than Kazakhstan. • Molecular tests done in Germany confirmed parasites belong to a NF54 type of African origin. • The possibility of airport malaria cannot be ruled out. Following a 2-week trip to Kazakhstan, a 42-year-old woman presented at the emergency department in Germany with fever, headache, nausea, and neurological symptoms. An infection with Plasmodium falciparum was rapidly diagnosed. The patient was immediately treated with intravenous artesunate and transferred to an intensive care unit. The initial parasite density was as high as 30% infected erythrocytes with 845,880 parasites/µL. Since Kazakhstan was declared malaria-free in 2012, molecular testing for Plasmodium has been initiated to identify a possible origin. Genotyping of the msp-1 gene and microsatellite markers showed that the parasites are of African origin, with two different alleles indicating a polyclonal infection. After a hospitalization of 10 days, the patient was discharged in good health. Overall, our results emphasize that malaria must be on the list of differential diagnoses for patients with fever of unknown origin, even if they come from countries where malaria does not commonly occur. [ABSTRACT FROM AUTHOR]

Malaria is an infectious disease caused by Plasmodium parasites that are mainly transmitted through the bites of infected female Anopheles mosquitoes. The average annual number of malaria cases was less than ten in Taiwan in the last five years. Most of the cases were caused by Plasmodium vivax and Plasmodium falciparum, and were primarily diagnosed in travelers who returned from Southeast Asia and Africa. Here, we report the first case of Plasmodium ovale infection within five years that was confirmed by peripheral blood smear examination and molecular identification in a 25-year-old Asian female patient who returned from Uganda. [ABSTRACT FROM AUTHOR]

Background: Our goal was to compare the strength of association and predictive ability of qualitative and quantitative electroencephalographic (EEG) factors with the outcomes of death and neurological disability in pediatric cerebral malaria (CM).Methods: We enrolled children with a clinical diagnosis of CM admitted to Queen Elizabeth Central Hospital (Blantyre, Malawi) between 2012 and 2017. A routine-length EEG was performed within four hours of admission. EEG data were independently interpreted using qualitative and quantitative methods by trained pediatric neurophysiologists. EEG interpreters were unaware of patient discharge outcome.Results: EEG tracings from 194 patients were reviewed. Multivariate modeling revealed several qualitative and quantitative EEG variables that were independently associated with outcomes. Quantitative methods modeled on mortality had better goodness of fit than qualitative ones. When modeled on neurological morbidity in survivors, goodness of fit was better for qualitative methods. When the probabilities of an adverse outcome were calculated using multivariate regression coefficients, only the model of quantitative EEG variables regressed on the neurological sequelae outcome showed clear separation between outcome groups.Conclusions: Multiple qualitative and quantitative EEG factors are associated with outcomes in pediatric CM. It may be possible to use quantitative EEG factors to create automated methods of study interpretation that have similar predictive abilities for outcomes as human-based interpreters, a rare resource in many malaria-endemic areas. Our results provide a proof-of-concept starting point for the development of quantitative EEG interpretation and prediction methodologies useful in resource-limited settings. [ABSTRACT FROM AUTHOR]

Malaria is a substantial febrile illness threat for children living in or travelling from endemic countries. It is a medical emergency but outcomes are better when there is prompt assessment, treatment and appropriate specialist input. It is one of the most common imported infections in the United Kingdom, and children are particularly vulnerable to deterioration if malaria is not suspected early and treated promptly. There were 1683 cases of imported malaria detected in the UK in 2018 and just over 1 in 10 cases were seen in children. In this short review we discuss the optimal assessment of the febrile child with suspected malaria and/or severe or complicated malaria and its treatment. [ABSTRACT FROM AUTHOR]

• Malaria classifiers are developed based on medical records of malaria patients. • Feature selection and machine learning techniques are used to build classifiers. • Eight significant features contribute most to malaria diagnosis. • The duration of fever is more significant than the temperature for malaria diagnosis. • Shivering, fever, and sweating are less significant symptoms in endemic regions. This study aims to identify significant symptoms and nonsymptom-related factors for malaria diagnosis in endemic regions of Indonesia. Medical records are collected from patients suffering from malaria and other febrile diseases from public hospitals in endemic regions of Indonesia. Interviews with eight Indonesian medical doctors are conducted. Feature selection and machine learning techniques are used to develop malaria classifiers for identifying significant symptoms and nonsymptom-related factors. Seven significant symptoms (duration of fever, headache, nausea and vomiting, heartburn, severe symptom, dizziness, and joint pain) and patients' history of malaria as a nonsymptom-related factor contribute most to malaria diagnosis. As a symptom, fever duration is more significant than temperature or fever for distinguishing malaria from other febrile diseases. Shivering, fever, and sweating (known to indicate malaria presence in Indonesia) are shown to be less significant than other symptoms in endemic regions. Three most suitable malaria classifiers have been developed to identify the significant features that can be used to predict malaria as distinct from other febrile diseases. With extensive experiments on the classifiers, the significant features identified can help medical doctors in the clinical diagnosis of malaria and raise public awareness of significant malaria symptoms at early stages. [ABSTRACT FROM AUTHOR]

Abstract A highly sensitive diagnostic system for determining low-density infections that are missed by conventional methods is necessary to detect the carriers of Plasmodium falciparum. A fluorescent blue-ray optical system with a polycarbonate scan disc was developed to detect P. falciparum -infected red blood cells (Pf -iRBCs), and nine samples could be analyzed simultaneously. The cultured P. falciparum strain 3D7 was used to examine the potential of the system for diagnosing malaria. After an RBC suspension had been applied to the disc, the cells were dispersed on the disc by rotation. During the 10 min standing period to allow the RBCs to settle on the disc surface, the cells were simultaneously stained with nuclear fluorescence staining dye Hoechst 34580, which was previously adsorbed on the disc surface. RBCs were arranged on the disc surface as a monolayer by removing excess cells through momentary rotation. Over 1.1 million RBCs remained on the disc for fluorescence analysis. A portable, battery-driven fluorescence image reader was employed to detect fluorescence-positive RBCs for approximately 40 min. A good correlation between examination of Giemsa-stained RBCs by light microscopy and the developed system was demonstrated in the parasitemia range of 0.0001–1.0% by linear regression analysis (R2 = 0.99993). The limit of detection of 0.00020% and good reproducibility for parasitemia determination were observed. The ability of the developed system to detect sub-microscopic low-density Pf -iRBCs and provide accurate quantitative evaluation with easy operation was demonstrated. Highlights • A fluorescent blue-ray optical system is developed for the detection of Plasmodium falciparum -infected red blood cells. • P. falciparum can be detected by the staining with nuclear staining dye Hoechst 34580. • Accurate, quantitative, and highly sensitive detection of Plasmodium falciparum can be performed. [ABSTRACT FROM AUTHOR]

Abstract Plasmodium ovale spp. are two of the six species of apicomplexan parasites belonging to the genus Plasmodium commonly causing disease in humans. A recent phylogeny study has identified both Plasmodium ovale species (P. ovale curtisi and P. ovale wallikeri) as two sympatric occurring species. The actual prevalence and clinical relevance of P. ovale spp. are likely underestimated due to low parasitemia and mixed infections, which pose a major challenge to microscopic diagnosis and are frequently undetectable using malaria Rapid Diagnostic Tests (RDTs). The aim of this work is to develop a HRM-based assay for simultaneous detection and differentiation of P. ovale wallikeri and P. ovale curtisi. Thirty three well-documented P. ovale spp. samples from previous studies were used for this study. The newly developed High Resolution Melting (HRM) assay targeting the apicoplast genome was highly specific to both P. ovale species. Adding a snapback tail at the 5' end of the forward primer for a nested HRM PCR, increased the melting temperature (Tm) difference between the two species. To our knowledge this study reports the first direct HRM assay developed on the apicoplast genome, specific for both P. ovale species. This method provides added value to the WHO open request of developing new practical malaria diagnostic methods for the malaria elimination program and could contribute to a quick and efficient diagnosis of low-level parasitemia, symptomatic or asymptomatic, as well as mixed or single P. ovale infections. [ABSTRACT FROM AUTHOR]

Highlights • The present study examined the significance of blood indices in adults with falciparum malaria with reference to clinical severity. • The results showed co-existence of hypoglycemia and thrombocytopenia. • Logistic regression analysis revealed low blood sugar as an independent predictive factor of thrombocytopenia. • Anemia in malaria was found to be the potential predictive factor of multi-organ dysfunction (MODS) with decrease in hemoglobin level increased the strength of association. • Thrombocytopenia can be a marker of MODS but its utility in prognostication could be modulated by hemoglobin and blood sugar level. Abstract The extent of abnormalities in blood indices and their subsequent effects on clinical severity in malaria differ among populations of different endemicity. However, these alterations have not been well investigated in Odisha, India and their prognostic implications in the context of multi-organ dysfunction (MODS) in severe malaria (SM) are not identified so far. The present study was carried out in 200 adult patients each from uncomplicated malaria and severe malaria groups to examine whether host haematological and biochemical parameters in Plasmodium falciparum infection can act as diagnostic marker for SM in adults patients of Odisha. The results showed thrombocytopenia as a potential risk factor for SM irrespective of disease features with least median platelet counts observed in patients with MODS (Platelet count: 144.5, P = < 0.0001) compared to mild malaria. Logistic regression analysis identified anemia (<10 mg/dl) as independent predictor of MODS (OR = 12.78, 95% CI = 4.93–33.2). The prognostic utility of thrombocytopenia (platelet count: ≤100,000/μl) as marker of MODS was largely modulated by hemoglobin and blood glucose level. Co-existence of hypoglycemia and thrombocytopenia was also observed. Our study revealed changes in blood indices such as low platelet, hemoglobin and blood glucose during falciparum infection in adults can be used as diagnostic criteria for predicting SM in combinations. The study also provides important clue for plausible hypoglycemia mediated platelet necrosis and clearance. Further studies in different endemic regions need to be conducted for validation of these findings and their implication as criteria for diagnosing SM in adults. [ABSTRACT FROM AUTHOR]

Highlights • An unsupervised method with crowdsourced data to detect forms in images is proposed. • The procedure consists of a clustering and a detection stage based on the EM algorithm. • The method accounts for outliers and is robust to unreliable annotators. • An online implementation of the method suited for streaming data is presented. • Experimental results with real data for Malaria diagnose support the approach. Abstract Crowdsourced data in science might be severely error-prone due to the inexperience of annotators participating in the project. In this work, we present a procedure to detect specific structures in an image given tags provided by multiple annotators and collected through a crowdsourcing methodology. The procedure consists of two stages based on the Expectation–Maximization (EM) algorithm, one for clustering and the other one for detection, and it gracefully combines data coming from annotators with unknown reliability in an unsupervised manner. An online implementation of the approach is also presented that is well suited to crowdsourced streaming data. Comprehensive experimental results with real data from the MalariaSpot project are also included. [ABSTRACT FROM AUTHOR]

Abstract Rapid diagnostic tests (RDT) are valuable tools that support prudent and timely use of antimalarial drugs, particularly if reliable microscopy is not available. However, the performance and reliability of these tests vary between and within geographical regions. The present study evaluated the performance of routine malaria RDT in Kenyan febrile patients in Busia County, Kenya. A cross sectional study design was employed to recruit febrile patients attending health facilities between August and November 2016. A total of 192 febrile patients who were slide positive and negative were evaluated for their infection status by nested PCR and RDTs (PfHRP2/pLDH). In addition, P. falciparum diversity of the histidine-rich proteins 2 and 3, that influences the RDT test results were determined. All individuals were P. falciparum positive. Among the investigated 192 febrile patients, 76 (40%) were positive by microscopy, 101 (53%) by RDTs and 80 (42%) were PCR positive. The performance of the CareStart™ HRP2/pLDH (pf) RDTs was better than microscopy (Sensitivity 94%; Specificity 75%) and Nucleic acid testing (sensitivity 95%, specificity 77%) with high negative predictive values, indicating the suitability of the RDT in routine practice. Specific pfhrp2/pfhrp3 deletions shown to associate with RDT false negativity was not observed. However, high genetic diversity among pfhrp2 gene was observed. Eleven new PfHRP2 and nine PfHRP3 repeats were observed. False positivity by microscopy and under reporting of infections may thus be a barrier in malaria control and elimination programs. The HRP2/pLDH(Pf) based RDT yet demonstrate to be an effective tool for malaria surveillance program. Highlights • PfHRP2 and PfHRP3 rich amino acid diversity among Kenyan Plasmodium falciparum isolates. • Comparative evaluation of PfHRP2/pLDH malaria RDT with microscopy and nested PCR methodologies. • No PfHRP2 deletions observed in Kenyan isolates known to associate with RDT Sensitivity. • PfHRP2/pLDH RDT still an effective tool for malaria surveillance program in Kenya. [ABSTRACT FROM AUTHOR]

Abstract An expatriate to Ivory Coast (supposedly allergic to artemether-lumefantrine) was diagnosed with severe malaria in Spain. Parasitemia increased from 2% up to 21% within 24 h under quinine (10 mg/kg) and clindamycin (450 mg/8 h) combination treatment. Molecular profiling of the patient revealed the presence of molecular markers of quinine and other antimalarials resistance. Additionally, multiple copies of pfpm2 gene were also noticed in the patient sample, despite the absence of piperaquine drug pressure in Ivory Coast. Parasitemia was cleared with artesunate (2.4 mg/kg) under a desensitization protocol. Nevertheless, detection of early treatment failure is needed mainly in cases of suspected antimalarial resistance. Graphical abstract Unlabelled Image Highlights • Diagnosis of imported malaria caused by Plasmodium falciparum in Spain. • Quinine resistant P. falciparum in Ivory Coast. • Molecular surveillance of antimalarial resistance markers. [ABSTRACT FROM AUTHOR]

Abstract Background Malaria is still a major public health problem in subtropical and tropical regions. The rapid and accurate diagnosis of malaria remains a challenge in most of the endemic areas. The primary objective of the present study was to evaluate the performance of multiplex/nested PCR in detecting Plasmodium falciparum at low parasite densities and mixed infection. Methods The study was performed in the Sistan-Baluchestan province of the southeastern Iran, from May 2015 to July 2016. A total of 105 patients suspected to malaria infection were enrolled in the study. The obtained DNA products, extracted from the thick/thin films, were analyzed by multiplex/nested PCR using genus-specific primers and compared with light microscopy. Results 43 samples were confirmed to be infected by microscopic examination. Among 43 microscopically diagnosed P. falciparum cases, 11.4% (12/105) were confirmed by multiplex/nested PCR, 36.2% (38/105) were confirmed as P. vivax , 1.9% (2/105) had mixed infections with P. falciparum and P. vivax. Among microscopy-negative samples, 10 samples turned malaria-positive in nPCR. In multiplex/nested PCR, the rate of mixed infections was 8.6% (9/105). When compared to LM, the sensitivity, specificity, positive predictive value and negative predictive value of multiplex/nested PCR were calculated to be 82.8, 91.5, 92.3 and 81.1%, respectively. Conclusion In this study, we showed that microscopic examination of blood smears does not reliably distinguish Plasmodium species in the case of mixed infections. Therefore, it seems that multiplex/nested PCR is a good candidate for examining the presence of malaria parasites in clinically suspected but microscopically negative cases. Highlights • 1-This research was done in order to Implementation of Malaria Elimination Program in Iran. • 2-The use of Multiplex/nested PCR test was able to detect all microscopy-positive samples as well as single or mixed infections and submicroscopic infections that were missed by Light Microscopy. • 3-DNA extraction was attempted from Giemsa-stained blood smears on glass slides from all patients with suspected malaria. [ABSTRACT FROM AUTHOR]

Abstract Malaria-infected individuals often harbor mixtures of genetically distinct parasite genotypes. We studied intra-host dynamics of parasite genotypes co-infecting asymptomatic adults in an area of intense malaria transmission in Chikhwawa, Malawi. Serial blood samples (5 ml) were collected over seven consecutive days from 25 adults with asymptomatic Plasmodium falciparum malaria and analyzed to determine whether a single peripheral blood sample accurately captures within-host parasite diversity. Blood samples from three of the participants were also analyzed by limiting dilution cloning and SNP genotyping of the parasite clones isolated to examine both the number and relatedness of co-infecting parasite haplotypes. We observed rapid turnover of co-infecting parasite genotypes in 88% of the individuals sampled (n = 22) such that the genetic composition of parasites infecting these individuals changed dramatically over the course of seven days of follow up. Nineteen of the 25 individuals sampled (76%) carried multiple parasite genotypes at baseline. Analysis of serial blood samples from three of the individuals revealed that they harbored 6, 12 and 17 distinct parasite haplotypes respectively. Approximately 70% of parasite haplotypes recovered from the three extensively sampled individuals were unrelated (proportion of shared alleles <83.3%) and were deemed to have primarily arisen from superinfection (inoculation of unrelated parasite haplotypes through multiple mosquito bites). The rest were related at the half-sib level or greater and were deemed to have been inoculated into individual human hosts via parasite co-transmission from single mosquito bites. These findings add further to the growing weight of evidence indicating that a single blood sample poorly captures within-host parasite diversity and underscore the importance of repeated blood sampling to accurately capture within-host parasite ecology. Our data also demonstrate a more pronounced role for parasite co-transmission in generating within-host parasite diversity in high transmission settings than previously assumed. Taken together, these findings have important implications for understanding the evolution of drug resistance, malaria transmission, parasite virulence, allocation of gametocyte sex ratios and acquisition of malaria immunity. • We examined if a single blood sample from a malaria-infected individual accurately captures within-host parasite diversity • We also examined patterns of kinship between co-infecting parasite haplotypes to infer malaria transmission dynamics • A single sample poorly captured within-host parasite diversity indicating the need for repeat sampling of infections • Single mosquito bites played a key role in generating within-host parasite diversity even in this high transmission area [ABSTRACT FROM AUTHOR]

Background: Submicroscopic malaria infections contribute to transmission in exposed populations but their extent is underestimated even by standard molecular diagnostics. Sophisticated sampling and ultra-sensitive molecular methods can maximise test sensitivity but are not feasible in routine surveillance. Here we investigate the gains achievable by using increasingly sensitive methods with the aim to understand what diagnostic sensitivity is necessary to guide malaria interventions.Methods: Venous blood samples were collected from participants in a cross-sectional survey in two coastal medium-endemic villages in Madang province, Papua New Guinea. Using ultra-sensitive quantitative PCR (us-qPCR) on concentrated high-volume blood samples (2 mL) as reference, we quantified the proportion of Plasmodium falciparum and Plasmodium vivax infections and gametocyte carriers detectable in fingerprick blood volumes (200 μL) by standard 18S rRNA qPCR, us-qPCR, rapid diagnostic test (RDT), and ultra-sensitive P falciparum RDT. We further compared the epidemiological patterns observed with each diagnostic approach in the study population.Findings: Venous blood samples were collected from 300 participants between Dec 5, 2016, and Feb 24, 2017 (ie, during peak rainy season). Standard qPCR identified 87 (54%) of 161 P falciparum infections and 73 (52%) of 141 P vivax infections detected by the reference method. us-qPCR identified an additional 11 (7%) P falciparum infections and 14 (10%) P vivax infections. 80 (86%) of 93 P falciparum gametocyte carriers and 75 (91%) of 82 P vivax gametocyte carriers were found among infections detectable by us-qPCR. Ultra-sensitive RDT missed half of P falciparum infections detected by standard qPCR, including high gametocytaemic infections. Epidemiological patterns corresponded well between standard qPCR and the reference method. As the prevalence of P vivax decreased with increasing age, the proportion of P vivax infections undetectable by standard qPCR increased.Interpretation: Almost all potentially transmitting parasite carriers were identified with us-qPCR on fingerprick blood volumes. Analysing larger blood volumes revealed a large pool of ultra-low-density P falciparum and P vivax infections, which are unlikely to be transmitted. Therefore, current RDTs cannot replace molecular diagnostics for identifying potential P falciparum transmitters.Funding: Swiss National Science Foundation. [ABSTRACT FROM AUTHOR]

This paper describes the development of an affinity sensor for the detection of Plasmodium falciparum parasite lactate dehydrogenase (pLDH) as one of the biomarkers used for malaria detection. The gold sensor was functionalised with anti-pLDH after cleaning the electrode surface to remove impurities (120 °C, 1 h). The sensor was then treated to block unreacted groups on the surface and minimise matrix interference, before applying it in a sandwich assay to detect pLDH in buffer samples using a dose concentration assay. The sensor was optimised to achieve the best detection sensitivity before using it for pLDH detection in serum samples. The developed sensor achieved a limit of detection (LOD) of 1.80 ng mL −1 and 0.70 ng mL −1 for the detection of pLDH in buffer and in serum samples respectively. The sensor sensitivity was enhanced further with the use of AuNP conjugated to the detection anti-pLDH-enzyme, achieving an LOD of 19 pg mL −1 in buffer and 23 pg mL −1 in serum samples. The performance of the sensor was compared to commercially available Plasmodium immunochromatographic (ICT) malaria kits. The developed sensor was able to detect pLDH in the Dd2 luc culture medium supernatant at 0.002% parasitaemia without the use of AuNP signal enhancement when compared to the OptiMAL-IT ICT kit (detect pLDH) and the BinaxNOW ICT kit (detection of both pLDH and Pf HRP 2) samples. Therefore, the sensor developed in this work is highly sensitive and can be used for pLDH detection for on-site diagnosis of malaria. A cheap and simple device as developed in this work is required to tackle malaria detection. [ABSTRACT FROM AUTHOR]

Abstract Many rapid diagnostic tests (RDT) used on suspected malaria cases are based on the detection of the protein encoded by the Plasmodium falciparum histidine-rich protein-2 (pfhrp2) gene, which shares a high sequence homology with pfhrp3 in the 3D7 reference genome. Parasite isolates showing pfhrp2 and pfhrp3 gene deletions have been emerging over the years, but a comprehensive genetic analysis of these variants is still lacking. With this purpose, genomic data from experimental P. falciparum genetic crosses between different laboratory lines (3D7, HB3, DD2, 7G8 and GB4) were first analysed (n = 98). The frequency of pfhrp2 deletions was consistent with a Mendelian prediction in HB3 × DD2 (56.7%; 95%CI = (39.5%–72.9%)). Moreover, the pfhrp2 and pfhrp3 deletions segregated independently of each other in the same genetic cross. Analysis of 3D7 × HB3 and 7G8 × GB4 estimated the probability of spontaneously generating a pfhrp2 deletion during sexual recombination to be up to 6.2%. Next, whole genome sequence data from 1970 P. falciparum isolates collected globally were analysed. Nine samples displayed depth of coverage consistent with pfhrp2 deletions (0.5%), but the corresponding split-read analysis could not confirm deletions in seven of these samples. Twenty-eight isolates had evidence of pfhrp3 deletions (1.4%), which are widespread in Southeast Asia. Finally, a meta-analysis of published data revealed a positive mean association between the frequencies of pfhrp2 and pfhrp3 deletions in Africa and South America. This result suggested a shared selective pressure acting on these genetic variants. In conclusion, evidence of genetic selection on both pfhrp2 and pfhrp3 deletions was presented, but experimental crosses do not provide evidence of a fitness cost of these variants. Further work is urgently needed to accurately determine the prevalence and the degree of association between these genetic variants, and the respective impact on diagnostic accuracy of many in-use RDT. Highlights • Deletions of pfhrp2 and pfhrp3 genes segregate independently of each other in the lab. • Genomic data from experimental crosses identified gene deletions masked in polyclonal infections. • Both pfhrp2 and pfhrp3 gene deletions are in low frequency worldwide. • Deletions of pfhrp3 gene are widespread in Southeast Asia. • These gene deletions are under selection globally. [ABSTRACT FROM AUTHOR]

Plasmodium falciparum malaria infections often comprise multiple distinct parasite clones. Few datasets have directly assessed infection complexity in humans and mosquitoes they infect. Examining parasites using molecular tools may provide insights into the selective transmissibility of isolates. Using capillary electrophoresis genotyping and next generation amplicon sequencing, we analysed complexity of parasite infections in human blood and in the midguts of mosquitoes that became infected in membrane feeding experiments using the same blood material in two West African settings. Median numbers of clones in humans and mosquitoes were higher in samples from Burkina Faso (4.5, interquartile range 2–8 for humans; and 2, interquartile range 1–3 for mosquitoes) than in The Gambia (2, interquartile range 1–3 and 1, interquartile range 1–3, for humans and mosquitoes, respectively). Whilst the median number of clones was commonly higher in human blood samples, not all transmitted alleles were detectable in the human peripheral blood. In both study sample sets, additional parasite alleles were identified in mosquitoes compared with the matched human samples (10–88.9% of all clones/feeding assay, n  = 73 feeding assays). The results are likely due to preferential amplification of the most abundant clones in peripheral blood but confirm the presence of low density clones that produce transmissible sexual stage parasites. [ABSTRACT FROM AUTHOR]

Peripheral blood smear analysis is a common practice to evaluate health status of a person. Many disorders such as malaria, anemia, leukemia, thrombocytopenia, sickle cell anemia etc., can be diagnosed by evaluating blood cells. Many groups have reported methods to automate blood smear analysis for detection of specific disorders for diagnostic purposes. In this paper, we have summarized the methods used to analyze peripheral blood smears using image processing techniques. We have categorized these methods into three groups based on approaches such as WBC analysis, RBC analysis and platelet analysis. We conclude that there is a need for a method of automation to match with human evaluation process and rule out any abnormality present in the blood smear. It is desirable for studies on automation of peripheral blood smear analysis to focus on development of robust method to handle illumination and color shade variations. Also, it is desirable to design a method which could collect all the abnormal regions from all views of a specimen to limit the manual evaluation to those regions making it more feasible for telemedicine applications. [ABSTRACT FROM AUTHOR]

DNA nanostructures can show dynamic responses to molecular triggers for a wide variety of applications. While DNA sequence signal triggers are now well-established, there is a critical need for a broader diversity of molecular triggers to drive dynamic responses in DNA nanostructures. DNA aptamers are ideal; they can both seamlessly integrate into DNA nanostructure scaffolds and transduce molecular recognition into functional responses. Here, we report construction and optimization of a DNA origami nanobox locked by a pair of DNA double strands where one strand is a DNA aptamer targeting the malaria biomarker protein Plasmodium falciparum lactate dehydrogenase. The protein acts as the key which enables box opening. We observe highly specific protein-mediated box opening by both transmission electron microscopy and fluorescence. Aptamer-enabled DNA boxes have significant potential for enabling direct responses to proteins and other biomolecules in nanoscale diagnostics, drug delivery and sensing devices. [ABSTRACT FROM AUTHOR]

Vector-borne diseases are a major concern for human health globally, especially malaria in densely populated, less developed, tropical regions of the world. Malaria causes loss of human life and economic harm, and may spread through travelers to new regions. Though there are sufficient therapeutics available for the effective treatment and cure of malaria, it infects millions of people and claims several thousand lives every year. Early diagnosis of the infection can potentially prevent the spread of disease, save lives, and mitigate the financial impact. Conventional analytical techniques are being widely employed for malaria diagnosis, but with low sensitivity and selectivity. Due to the poor-resource settings where malaria outbreaks often occur, most conventional diagnostic methods are not affordable and hence not effective in detection and controlling the spread of the infection. However, biosensors have improved the scope for affordable malaria diagnosis. Advances in biotechnology and nanotechnology have provided novel recognition materials and transducer elements, discoveries which allow the fabrication of affordable biosensor platforms with improved attributes. The present work covers the advancement in biosensors with an introduction to malaria, followed by conventional methods of malaria diagnosis, malaria markers, novel recognition elements and the biosensor principle. Finally, a proactive role and a perspective on developed biosensor platforms are discussed with potential biomedical applications. [ABSTRACT FROM AUTHOR]

There is a critical need for better biosensors for the detection and diagnosis of malaria. We previously developed a DNA aptamer that recognises the Plasmodium falciparum lactate dehydrogenase (PfLDH) enzyme with high sensitivity and specificity. The aptamer was integrated into an Aptamer-Tethered Enzyme Capture (APTEC) assay as a laboratory-based diagnostic approach. However, a portable equipment-free point-of-care aptamer-mediated biosensor could have a significant impact on malaria diagnosis in endemic regions. Here, we present a new concept for a malaria biosensor whereby aptamers are coated onto magnetic microbeads for magnet-guided capture, wash and detection of the biomarker. A biosensor incorporating three separate microfluidic chambers was designed to enable such magnet-guided equipment-free colorimetric detection of PfLDH. A series of microfluidic biosensor prototypes were optimised to lower rates of inter-chamber diffusion, increase sensitivity, and provide a method for point-of-care sample testing. The biosensor showed high sensitivity and specificity when detecting PfLDH using both in vitro cultured parasite samples and using clinical samples from malaria patients. The high performance of the biosensor provides a proof-of-principle for a portable biosensor that could be adaptable for a variety of aptamer-mediated diagnostic scenarios. [ABSTRACT FROM AUTHOR]

Malaria remains a major public health problem and a principal cause of morbidity and mortality in most developing countries. Although malaria still presents health problems, significant successes have been recorded in reducing deaths resulting from the disease. As malaria transmission continues to decline, control interventions will increasingly depend on the ability to define high-risk areas known as malaria hotspots. Therefore, there is urgent need to use geospatial tools such as geographic information system to detect spatial patterns of malaria and delineate disease hot spots for better planning and management. Thus, accurate mapping and prediction of seasonality of malaria hotspots is an important step towards developing strategies for effective malaria control. In this study, we modelled seasonal malaria hotspots as a function of habitat suitability of Anopheles arabiensis (A. Arabiensis) as a first step towards predicting likely seasonal malaria hotspots that could provide guidance in targeted malaria control. We used Geographical information system (GIS) and spatial statistic methods to identify seasonal hotspots of malaria cases at the country level. In order to achieve this, we first determined the spatial distribution of seasonal malaria hotspots using the Getis Ord G i * statistic based on confirmed positive malaria cases recorded at health facilities in Zimbabwe over four years (1996–1999). We then used MAXENT technique to model habitat suitability of A. arabiensis from presence data collected from 1990 to 2002 based on bioclimatic variables and altitude. Finally, we used autologistic regression to test the extent to which malaria hotspots can be predicted using A. arabiensis habitat suitability. Our results show that A. arabiensis habitat suitability consistently and significantly (p < 0.05) predicts malaria hotspots from 1996 to 1999. Overall, our results show that malaria hotspots can be predicted using A. arabiensis habitat suitability, suggesting the possibility of developing models for malaria early warning based on vector habitat suitability. [ABSTRACT FROM AUTHOR]

There is a critical need for better malaria rapid diagnostic tests to discriminate Plasmodium falciparum and Plasmodium vivax infection given the recent observation of HRP2 deletions in P. falciparum parasites. We previously identified a DNA aptamer, 2008s, that targets P. falciparum lactate dehydrogenase (PfLDH) and developed a sensitive aptamer-tethered enzyme capture (APTEC) assay. Here, we characterise two different LDH-binding DNA aptamers in their species-specific activities, then integrate within biochemical diagnostic assays and test in clinical samples. An enzyme-linked oligonucleotide assay demonstrated that aptamer pL1 bound with high affinity to both PfLDH and P. vivax lactate dehydrogenase (PvLDH), whereas aptamer 2008s was specific to PfLDH. An aptamer-tethered enzyme capture (APTEC) assay confirmed the specificity of 2008s in binding and capturing the enzyme activity of PfLDH which could be observed colorimetrically. In malaria patient samples, the 2008s APTEC assay was specific for P. falciparum blood samples and could discriminate against P. vivax blood samples. An aptamer for specific detection of falciparum malaria holds promise as a new strategy for species-specific malaria diagnosis rather than the conventional HRP2 immuno-assay. [ABSTRACT FROM AUTHOR]

Malaria infection poses a great threaten to public health even nowadays. The conventional diagnosis tools of malaria parasites and vectors require systematic training for the observers accompanied by the low throughput. In this study, a new detection system, i.e., multiplex microfluidic loop-mediated isothermal amplification (mμLAMP) array, was developed to provide a convenient, rapid and economical detection system for malaria diagnosis. A microfluidic-based detection chip was designed and developed, targeting the conserved gene of four Anopheles and two Plasmodium species responsible for most of the malaria cases occurred in China. The DNA preparation of Anopheles and Plasmodium samples was realized by using a newly-developed DNA extraction method. For this mμLAMP array system, the detection limit was determined to be 1 pg of targeting DNA with high sensitivity (>95%) and specificity (100%). Further, the accuracy of such mμLAMP analysis was evaluated by the analysis of 48 Anopheles mosquito samples, of which 30 were termed to be target Anopheles , displaying high consistency with that by morphological analysis. In conclusion, the mμLAMP detection system was proved to be a visible, sensitive, specific and high-throughput diagnostic tool. Considering the portable manipulation of such detection system, our studies shed light on its potential application of malaria surveillance on the spot. [ABSTRACT FROM AUTHOR]

In this study, we report the development of a paper-based platform with low amount of reagents for the detection of the histidine-rich protein 2 by an enzyme-based colorimetric assay aiming for the early diagnosis of Plasmodium falciparum malaria. A CO 2 laser cutter was used for the fabrication of the device in a simple layout suitable to perform the lateral flow assay, which consisted in a region for sample addition, a detection zone and an absorbent pad, all of which were linked by microfluidic channels. Investigations related to the performance of the sandwich immunoassay in the nitrocellulose membrane shown that the blocking and washing steps are essential to promote efficient antigen-antibody recognition and to generate reliable results, avoiding misinterpretations. Several parameters were also evaluated and the experimental conditions were optimized: concentration and incubation time with the capture antibody (50 μg mL −1 and 5 min, respectively); BSA solution at 1.5% (w/v) containing 0.1% (v/v) Tween 20 for blocking the nitrocellulose and 10 min as the incubation time; 10 mmol L −1 Tris-HCl buffer solution at pH 7.4 containing 0.15 mol L −1 NaCl and 0.1% (v/v) Tween 20 for washing the device before adding the ready to use TMB substrate at the detection zone. The system demonstrated a good sensitivity and detectability reaching a visual and calculated limit of detection of 5.0 ng mL −1 (65 parasites μL −1 ) and 4.5 ng mL −1 (59 parasites μL −1 ) respectively, a clinically relevant concentration that should be sufficient to identify the disease in the appearance of the first symptoms and with the advantage of not needing to use nanostructures or other strategy for signal amplification beyond the enzyme. [ABSTRACT FROM AUTHOR]

Malaria infection remains a significant risk for much of the population of tropical and subtropical areas, particularly in developing countries. Therefore, it is of high importance to develop sensitive, accurate and inexpensive malaria diagnosis tests. Here, we present a novel aptamer-based electrochemical biosensor (aptasensor) for malaria detection by impedance spectroscopy, through the specific recognition between a highly discriminatory DNA aptamer and its target Plasmodium falciparum lactate dehydrogenase (PfLDH). Interestingly, due to the isoelectric point (pI) of PfLDH, the aptasensor response showed an adjustable detection range based on the different protein net-charge at variable pH environments. The specific aptamer recognition allows sensitive protein detection with an expanded detection range and a low detection limit, as well as a high specificity for PfLDH compared to analogous proteins. The specific feasibility of the aptasensor is further demonstrated by detection of the target PfLDH in human serum. Furthermore, the aptasensor can be easily regenerated and thus applied for multiple usages. The robustness, sensitivity, and reusability of the presented aptasensor make it a promising candidate for point-of-care diagnostic systems. [ABSTRACT FROM AUTHOR]

The gold standard for malaria diagnosis is the microscopic examination of Giemsa stained thick blood smears though microscopy mostly may not detect the presence of Plasmodium species infections in asymptomatic samples. In the reported study, we used two diagnostic methods viz . the conventional microscopic examination and polymerase chain reaction (PCR) assay to analyse the asymptomatic malaria samples. PCR assay amplifying 18S small-subunit ribosomal RNA (SSU rRNA) gene of Plasmodium in 122 samples confirmed 68% of isolates as asymptomatic P . falciparum infections; with 87.9% mono-infections. We observed that the P . malariae positive samples were not diagnosed in microscopic examination of the blood smears but the PCR based diagnostic method revealed the presence of 12% P . malariae infections in asymptomatic samples from Yaoundé region of Cameroon where no official cases of P . malariae have been reported for over a decade. The sequence analysis further confirmed the presence of 12% P . malariae in malaria positive samples with three base pair deletions and five substitutions in the SSU rRNA gene. [ABSTRACT FROM AUTHOR]

Severe malaria is caused by the Apicomplexan parasite Plasmodium falciparum , and results in significant global morbidity and mortality, particularly among young children and pregnant women. P. falciparum exclusively infects human erythrocytes during clinical illness, and several natural erythrocyte polymorphisms are protective against severe malaria. Since erythrocytes are enucleated and lack DNA, genetic approaches to understand erythrocyte determinants of malaria infection have historically been limited. This review highlights recent advances in the use of hematopoietic stem cells to facilitate genetic screening for malaria host factors. While challenges still exist, this approach holds promise for gaining new insights into host–pathogen interactions in malaria. [ABSTRACT FROM AUTHOR]

Targeted intervention and resource allocation are essential for effective malaria control, particularly in remote areas, with predictive models providing important information for decision making. While a diversity of modeling technique have been used to create predictive models of malaria, no work has made use of Bayesian networks. Bayes nets are attractive due to their ability to represent uncertainty, model time lagged and nonlinear relations, and provide explanations. This paper explores the use of Bayesian networks to model malaria, demonstrating the approach by creating village level models with weekly temporal resolution for Tha Song Yang district in northern Thailand. The networks are learned using data on cases and environmental covariates. Three types of networks are explored: networks for numeric prediction, networks for outbreak prediction, and networks that incorporate spatial autocorrelation. Evaluation of the numeric prediction network shows that the Bayes net has prediction accuracy in terms of mean absolute error of about 1.4 cases for 1 week prediction and 1.7 cases for 6 week prediction. The network for outbreak prediction has an ROC AUC above 0.9 for all prediction horizons. Comparison of prediction accuracy of both Bayes nets against several traditional modeling approaches shows the Bayes nets to outperform the other models for longer time horizon prediction of high incidence transmission. To model spread of malaria over space, we elaborate the models with links between the village networks. This results in some very large models which would be far too laborious to build by hand. So we represent the models as collections of probability logic rules and automatically generate the networks. Evaluation of the models shows that the autocorrelation links significantly improve prediction accuracy for some villages in regions of high incidence. We conclude that spatiotemporal Bayesian networks are a highly promising modeling alternative for prediction of malaria and other vector-borne diseases. [ABSTRACT FROM AUTHOR]

Purpose To investigate the reliability of diffusion weighted image (DWI) measurements obtained on a 0.35 T MR scanner in Malawi for malaria research. Materials and methods The same healthy volunteers (n = 6) were scanned on a 0.35 T MR scanner in Malawi and a 3 T scanner in the US. Three subjects had two repeated DWI scans at 0.35 T. Due to scanner constraints, only three diffusion gradient directions for DWI on 0.35 T could be obtained. An apparent diffusion coefficient (ADC) map was reconstructed from the 0.35 T and the result was compared to standard DWI acquisition on the 3 T scanner. The mean ADC from 15 different regions and the voxel-wise coefficient of variation (CV) were calculated to investigate the intra-scanner and inter-scanner variability. Reproducibility was calculated using intra-class correlation coefficient (ICC). Results The 0.35 T intra-scanner ADC repeatability was high for all three subjects with repeated scans (ICC > 0.7). The intra-scanner correlation between repeated scans was also high (r > 0.67, p < 0.01). Comparing the ADC findings from the 0.35 T and 3 T MRs, the high inter-scanner correlation suggested that the 0.35 T ADC results were valid (ICC > 0.7, r > 0.5, p < 0.01). Voxel-wise CV revealed a few regions with larger variation (CV > 20%), which were primarily located in peripheral regions and the boundary of lateral ventricles, and likely due to partial volume effects in low field scans. Conclusion These findings support the validity of DWI obtained from low field MR scanners used in many low income countries. [ABSTRACT FROM AUTHOR]

Background and objective: In this note we propose a nonlinear programming approach for simultaneous fitting of quantile regression models for two or more quantiles. The approach is straightforward, flexible and practical. We apply this approach to a dataset of lactic acid values from a screening dataset in childhood malaria. Methods: We carry out the fitting of simultaneous quantile regression models using a specific definition of a quantile as an expectation via nonlinear programming methods given certain monotonicity constraints. Results: We illustrate through simulations and examples that are new approach to simultaneous quantile regression is practical and feasible. The approach is supplemented by providing a bootstrap framework for confidence interval estimation. Conclusions: Our nonlinear programming approach towards solving the simultaneous quantile regression fitting is shown to be a practical approach that should appeal to statistical practitioners. [ABSTRACT FROM AUTHOR]

The histidine-rich protein 2 of Plasmodium falciparum is the most common malaria antigen targeted by rapid diagnostic tests for the specific diagnosis of P. falciparum . Recently, pfhrp2 gene deletions have been documented in P. falciparum isolates from South America and some multiple endemic countries in Africa and Asia. Parasites with such gene deletions can produce false negative diagnostic results using HRP2-based rapid diagnostic kits. In the present work, the prevalence of P. falciparum parasites lacking pfhrp2 , pfhrp3 , which produces a second P. falciparum antigen that is recognized by PfHRP2 -based rapid diagnostic tests, and their flanking genes was evaluated in 135 P. falciparum isolates from Gash Barka region and in 9 isolates from Debub region, in Eritrea. In the analyzed samples, 56% (81/144) of isolates were pfhrp2 / pfhrp3 positive, while 9.7% (14/144) showed deletion of exon 2 of pfhrp2 gene and 43% (62/144) of isolates lacked the pfhrp3 gene. These results suggest that the pfhrp2 and pfhrp3 deletion phenomenon is present in a considerable proportion in the study areas, thus making the HRP2/3 based rapid diagnostic tests not completely reliable for malaria diagnosis in Eritrea. [ABSTRACT FROM AUTHOR]

What motivates community-based health workers to provide care in rural and remote areas, often on a voluntary or casual basis, is a key question for program managers and public health officials. This paper examines how a range of incentives offered as part of the Marasin Stoa Kipa program, a community-based malaria diagnosis and treatment program that has been implemented since 2007 within a major oil and gas development area in Papua New Guinea, are perceived and critiqued by community-based health workers. Nineteen interviews and seven focus group discussions with the workers who deliver services and members of the communities served by the program, conducted between November 4 and 25, 2015, reveal a pattern of mixed motivations and changes in motivation over time. This can be attributed partly to the unique social and economic circumstances in which the program is operating. Changes in the burden of disease as well as in global and national health services policy with implications for local level program operations also had an impact, as did the nature of relationships between program managers, community-based health workers, and program beneficiaries. Overall, the findings suggest that while financial and in-kind incentives can be a useful tool to motivate voluntary or minimally-compensated community-based health workers, they must be carefully structured to align with local social, economic, and epidemiological realities over the long-term. [ABSTRACT FROM AUTHOR]

Malaria is a precarious disease and a serious illness that can become life threatening very fast and can be incurable if not treated on time. According to the World Health Organization, Malaria causes 150–250 million infections and an estimated more than a million deaths each year. Microscopic image capture followed by visual observation as per the manual is the gold standard method for diagnosis of malaria. However, due to subjectivity and the complexity of manual assessment, microscopic diagnosis of malaria is tiring, time consuming and subject to human error. In this study, we have developed a novel automatic high performance method with minimal human dependence for detection and quantitation of malaria infected Red Blood Cells (RBC). The parasites detection test to identify malaria was computed using digital image processing techniques. This automated quantitation procedure was done in three parts: Segmentation, Identification and Detection. The methods used for the quantitation were Six Sigma threshold for segmenting Region of Interest followed by modified Hough transform to identify and count RBCs, and Kapur’s threshold method to detect malaria parasite infected RBCs. The developed package using Microsoft ® VB.NET 2008 framework is executed on various Giemsa stained thin blood smears digitally acquired using a charge coupled device attached to a microscope. Following analysis performed on seven sets of thin blood smear images, the values of Precision, Recall and F -measures obtained were 96%, 97% and 97% respectively. This is the first attempt to use a combination of Six Sigma threshold, Chess-Board distance, Hough transform and Kapur’s threshold to find the RBCs by deriving information from the image itself. Further, Kapur’s entropy measure was successfully applied to distinguish parasitized from un-infected cells. [ABSTRACT FROM AUTHOR]

The relationship between malaria infection and volatile compounds has been claimed mainly on the basis that they are believed to be an attractant for mosquitoes. However, since the association of emitted molecules with diseases has been observed for many pathologies, malaria-related volatile compounds are a potential diagnostic tool. The recent confirms of this hypothesis prompts the development of sensors for an effective exploitation of these potentialities. On these bases, we investigated the alteration of volatile compounds in a malaria murine model. For the scope, the total “volatilome” of Plasmodium berghei-infected mice was compared with that of non-infected animals. Gas chromatographic analysis of the sampled air reveals the existence of a pattern of compounds that, collectively considered, detects malaria infection. Finally, an array of porphyrins functionalized quartz microbalance gas sensors was applied to sort non-infected from infected mice. The application of a classification model to the sensor data provided more than 80% of correct identification with errors confined to mice with a low parasitemia level. Noteworthy, the sensor array was trained on data collected months before to run the tests. These results provide, although limited to a murine model, a first evidence of the potentialities of gas sensor technology for malaria diagnosis. [ABSTRACT FROM AUTHOR]

The magnitude of concurrent malaria infection and the impact it has on hematological abnormalities, such as anemia in people living with HIV/AIDS, is not well studied in Ethiopian set up. In this cross sectional study, therefore, we assessed the prevalence of concurrent malaria infection and anemia among highly active anti-retroviral therapy (HAART) naive people living with HIV/AIDS between October, 2012 to May, 2013 in Northern Ethiopia. After obtaining consent, socio demographic, clinical, immunological and behavioural data was obtained. The overall prevalence of concomitant malaria infection was 17.4%. Rural residents and low to middle income class clients were more frequently co-infected with malaria (p < 0.0001). Utilization of insecticide treated nets (p = 0.0002) and co-trimoxazole intake (p = 0.006) were protective factors against Plasmodium infection. The overall prevalence of anemia was also high (43%), being significantly higher (91.3%) in malaria positive people living with HIV/AIDS compared to malaria free HIV patients (32.8%) (p < 0.0001). Female gender (p = 0.011), history of opportunistic infections (P = 0.0027) and late HIV stages (III and IV) (p = 0.0001) were also significantly associated with anemia in HIV patients. In conclusion, concurrent malaria represents a common condition and there was a significant difference in the odds of anemia between malaria positive and negative people living with HIV/AIDS in Northern Ethiopia indicating a need for routine screening of people living with HIV/AIDS living in malaria endemic-areas and close monitoring of co-infected patients. Indeed utilization of ITNs, malaria prophylaxis and early HIV diagnosis are highly encouraged in people living with HIV/AIDS. [ABSTRACT FROM AUTHOR]

This paper investigates the feasibility of a cost effective high gradient magnetic separation based device for the detection and identification of malaria parasites in a blood sample. The design utilizes magnetic properties of hemozoin present in malaria-infected red blood cells (mRBCs) in order to separate and concentrate them inside a microfluidic channel slide for easier examination under the microscope. The design consists of a rectangular microfluidic channel with multiple magnetic wires positioned on top of and underneath it along the length of the channel at a small angle with respect to the channel axis. Strong magnetic field gradients, produced by the wires, exert sufficient magnetic forces on the mRBCs in order to separate and concentrate them in a specific region small enough to fit within the microscope field of view at magnifications typically required to identify the malaria parasite type. The feasibility of the device is studied using a model where the trajectories of the mRBCs inside the channel are determined using first-order ordinary differential equations (ODEs) solved numerically using a multistep ODE solver available within MATLAB. The mRBCs trajectories reveal that it is possible to separate and concentrate the mRBCs in less than 5 min, even in cases of very low parasitemia (1–10 parasites/µL of blood) using blood sample volumes of around 3 µL employed today. [ABSTRACT FROM AUTHOR]

We evaluated the diagnostic usefulness of the LH780 Coulter blood cell counter for detection and therapeutic monitoring of malaria including cross-reactivity with nucleated RBC (NRBC) samples. A total of 405 patients (43 patients with Plasmodium vivax malaria and the control group of 120 healthy subjects, 111 patients with fever, and 131 patients with NRBCs) were analyzed with routine CBC using the LH780. We analyzed the CBC results according to three selected parameters: an abnormal peak in the WBC histogram before 35 fL, the presence of red dots in the nonwhite cell zone of 2D WBC Diff Dataplot, and platelet-related flags suggesting platelet clumps or giant platelets. Of the 43 malaria samples collected at diagnosis, an abnormal peak (≥2.2 mm) was present in 93.0% (95% confidential interval (CI), 80.9–98.5%). Of all samples, 97.7% (95% CI, 87.7–99.9%) exhibited red dots, and platelet-related flags were observed in 81.4% (95% CI, 66.6–91.6%). The specificity of these three selected parameters was 83.1% (95% CI, 78.9–86.9%), 77.3% (95% CI, 72.7–81.6%), and 90.1% (95% CI, 86.5–92.9%), respectively. The abnormal peak (≥2.2 mm) showed moderate correlation with parasite level (r = 0.79). The three selected LH780 parameters were useful for identifying malaria in healthy subjects and febrile patients, but unsatisfactory for discriminating malaria in NRBC samples. The parameters showed a substantial proportion of false positives in the NRBC group, ranging from 26.7% to 49.6%. Therefore, microscopic confirmation will be necessary for application of these parameters for malaria screening and treatment monitoring. [ABSTRACT FROM AUTHOR]

Objectives: Currently louse-borne relapsing fever (LBRF) is primarily found in limited endemic foci in Ethiopia, Somalia and Sudan; no case of imported LBRF has been reported in Europe in the 9 years prior to 2015. The aim of our paper is to describe a new case of imported LBRF detected in Sicily, Italy, and to review all cases reported in migrants arrived in Europe in the last 10 years. Study design: Mini review of all published cases of louse-borne relapsing fever in Europe in the last 10 years. Methods: A computerized search without language restriction was conducted using PubMed combining the terms '(louse-borne relapsing fever or LBRF or recurrentis) and (refugee or Europe or migrant)' without limits. Furthermore, the 'Ahead-of-Print Articles' of the top 10 journals (ranked by Impact factor - Web of Science) of Infectious diseases and of Epidemiology were checked. Results: Our search identified 26 cases of LBRF between July and October 2015 in migrants recently arrived in Europe: 8 had been described in Italy; 1 in Switzerland; 2 in the Netherlands; 15 in Germany. We describe data regarding the clinical characteristics, diagnostic methods, therapy and outcome of these patients and of the new case. Conclusions: LBRF by Borrelia recurrentis should be considered among the clinical hypotheses in migrants presenting with fever, headache, chills, sweating, arthralgia, myalgia, dizziness, nausea and vomiting. [ABSTRACT FROM AUTHOR]

Abstract Recently, WHO published the first ever Essential Diagnostics List (EDL), which includes 113 tests, including tests for HIV, TB, malaria, hepatitis B and C, human papillomavirus (HPV) and syphilis. The EDL is a welcome first step in ensuring that diagnostics are a key part of all health systems. The impact of the list, however, will depend greatly on how countries adopt and implement the EDL. [ABSTRACT FROM AUTHOR]

Rapid, early, and accurate diagnosis of malaria is essential for effective disease management and surveillance, and can reduce morbidity and mortality associated with the disease. Although significant advances have been achieved for the diagnosis of malaria, these technologies are still far from ideal, being time consuming, complex and poorly sensitive as well as requiring separate assays for sample processing and detection. Therefore, the development of a fast and sensitive method that can integrate sample processing with detection of malarial infection is desirable. Here, we report a two-stage sample-to-answer system based on nucleic acid amplification approach for detection of malaria parasites. It combines the Dimethyl adipimidate (DMA)/Thin film Sample processing (DTS) technique as a first stage and the Mach-Zehnder Interferometer-Isothermal solid-phase DNA Amplification (MZI-IDA) sensing technique as a second stage. The system can extract DNA from malarial parasites using DTS technique in a closed system, not only reducing sample loss and contamination, but also facilitating the multiplexed malarial DNA detection using the fast and accurate MZI-IDA technique. Here, we demonstrated that this system can deliver results within 60 min (including sample processing, amplification and detection) with high sensitivity (<1 parasite μL −1 ) in a label-free and real-time manner. The developed system would be of great potential for better diagnosis of malaria in low-resource settings. [ABSTRACT FROM AUTHOR]

For the effective control of malaria, development of sensitive, accurate and rapid tool to diagnose and manage the disease is essential. In humans subjects, the severe form of malaria is caused by Plasmodium falciparum ( Pf ) and Plasmodium vivax ( Pv ) and there is need to identify these parasites in acute, chronic and latent (during and post-infection) stages of the disease. In this study, we report a species specific and sensitive diagnostic method for the detection of Pf and Pv in humans. First, we identified intra and intergenic multiloci short stretch of 152 (PfMLS152) and 110 (PvMLS110) nucleotides which is present up to 44 and 34 times in the genomes of Pf and Pv respectively. We developed the single-step amplification-based method using isolated DNA or from lysed red blood cells for the detection of the two malaria parasites. The limit of detection of real-time polymerase chain reaction based assays were 0.1copyof parasite/μl for PfMLS152 and PvMLS110 target sequences. Next, we have tested 250 clinically suspected cases of malaria to validate the method. Sensitivity and specificity for both targets were 100% compared to the quantitative buffy coat microscopy analysis and real-time PCR ( Pf -chloroquine resistance transporter (PfCRT) and Pv -lactate dehydrogenase (PvLDH)) based assays. The sensitivity of microscopy and real-time PCR (PfCRT and PvLDH primers) assays were 80.63%; 95%CI 75.22%–85.31%; p < 0.05 and 97.61%; 95%CI 94.50%–99.21%; p < 0.05 in detecting malaria infection respectively when compared to PfMLS152 and PvMLS110 targets to identify malaria infection in patients. These improved assays may have potential applications in evaluating malaria in asymptomatic patients, treatment, blood donors and in vaccine studies. [ABSTRACT FROM AUTHOR]

Surface enhanced Raman spectra (SERS) of normal red blood cells (RBCs) and Plasmodium falciparum infected RBCs (iRBCs) at different post invasion time were obtained based on silver nanorod array substrates. Distinct spectral differences were observed due to the cell membrane modification of RBCs during malaria infection. The SERS spectra of ring stage iRBCs had a characteristic Raman peak at Δ v = 1599 cm − 1 as compared to those of normal RBCs, while the trophozoite and schizoid stages had identical SERS spectra with a characteristic peak at Δ v = 723 cm − 1 , which is significantly different from ring stage iRBCs, consistent with ongoing modification of the iRBC membrane. Since ring stage iRBCs of P. falciparum are found circulating in blood, such a difference provides a new strategy for rapid malaria detection. The limit of detection as well as the ability to detect a mixed iRBC and RBC solution was also investigated. [ABSTRACT FROM AUTHOR]

One of the major obstacles to implement nucleic acid-based molecular diagnostics at the point-of-care (POC) and in resource-limited settings is the lack of sensitive and practical DNA detection methods that can be seamlessly integrated into portable platforms. Herein we present a sensitive yet simple DNA detection method using a surface-enhanced Raman scattering (SERS) nanoplatform: the ultrabright SERS nanorattle. The method, referred to as the nanorattle-based method, involves sandwich hybridization of magnetic beads that are loaded with capture probes, target sequences, and ultrabright SERS nanorattles that are loaded with reporter probes. Upon hybridization, a magnet was applied to concentrate the hybridization sandwiches at a detection spot for SERS measurements. The ultrabright SERS nanorattles, composed of a core and a shell with resonance Raman reporters loaded in the gap space between the core and the shell, serve as SERS tags for signal detection. Using this method, a specific DNA sequence of the malaria parasite Plasmodium falciparum could be detected with a detection limit of approximately 100 attomoles. Single nucleotide polymorphism (SNP) discrimination of wild type malaria DNA and mutant malaria DNA, which confers resistance to artemisinin drugs, was also demonstrated. These test models demonstrate the molecular diagnostic potential of the nanorattle-based method to both detect and genotype infectious pathogens. Furthermore, the method's simplicity makes it a suitable candidate for integration into portable platforms for POC and in resource-limited settings applications. [ABSTRACT FROM AUTHOR]

This prospective study assessed the incidence, clinical profile and outcome of malarial hepatopathy and its association with other complications in patients with malaria, proved by peripheral blood smear examination and rapid malaria test. Hyperbilirubinemia (Serum bilirubin >3 mg/dL) with >3-fold rise in serum aminotransferases in absence of a different explanation for such derangement was considered as malarial hepatopathy. Of 134 (falciparum-81, vivax-48 and mixed falciparum and vivax-5) malaria cases, hyperbilirubinemia occurred in 41.04%. Serum aspartate aminotransferase (AST) was raised >3-fold in 17.16% and serum alanine aminotransferase (ALT) in 4.47% cases. Malarial hepatopathy was observed in 4.47% (falciparum-5 and vivax malaria-1) cases, but had insignificant association with the type of malaria (p = 0.532). Serum bilirubin, AST and ALT levels were higher while age was lower in both overall (p < 0.05 each) and falciparum malaria cases with hepatopathy than without hepatopathy (p < 0.05 each). Malarial hepatopathy was associated with a higher incidence of cerebral malaria, shock, acute respiratory distress syndrome (ARDS) and acute kidney injury in both overall (p < 0.05 each) and falciparum malaria (p < 0.05 each) and hyponatremia and disseminated intravascular coagulation only in overall malaria (p < 0.05). Malarial hepatopathy had significant association with duration of hospitalization, parasite clearance time, fever clearance time and jaundice clearance time in overall (p < 0.05 each) and falciparum (p < 0.05 each) but not vivax malaria cases (p > 0.05 each). Mortality occurred in 1 (20%) case of falciparum-induced hepatopathy with an overall mortality of 16.66%. ARDS (p = 0.003) and shock (p = 0.026) were independently associated with malarial hepatopathy overall while only ARDS with falciparum-induced hepatopathy (p = 0.006). Thus, hepatocellular dysfunction is common in malaria but that qualifying as malarial hepatopathy is not common. Malarial hepatopathy is likely to occur in presence of other malarial complications. It is an epiphenomenon in severe malaria and indicative of severe disease. Establishing a particular association with malaria or mortality would require a larger case-control study of severe malaria. [ABSTRACT FROM AUTHOR]

Malaria remains common in sub-Saharan Africa, but it is frequently over-diagnosed and over-treated in hospitalized children. HIV is prevalent in many malaria endemic areas and may delay parasite clearance and increase mortality among children with malaria. This prospective cohort study enrolled children with suspected malaria between 3 months and 12 years of age hospitalized at two referral hospitals in Tanzania. Both a thick blood smear (BS) and a malaria rapid diagnostic test (mRDT) were performed. If discordant results were obtained, PCR was performed for Plasmodium falciparum . Malaria was confirmed if two out of three tests were positive. Malaria parasite densities were determined for two consecutive days after diagnosis and treatment of malaria. All participants were tested for HIV. Among 1492 hospitalized children, 400 (26.8%) were enrolled with suspected malaria infection. There were 196/400 (49.0%) males, and the median age was 18 [9–36] months. BS was positive in 95/400 (23.8%), and mRDT was positive in 70/400 (17.5%), with moderate agreement (Kappa = 0.598). Concordant results excluded malaria in 291/400 (72.8%) and confirmed malaria in 56/400 (14.0%). PCR performed on 53 discordant results confirmed malaria in 1/39 of the BS-positive/mRDT-negative cases, and 6/14 of the BS-negative/mRDT-positive cases. The prevalence of confirmed malaria was 63/400 (15.8%). In multivariable logistic regression, malaria was associated with HIV (OR 3.45 [1.65–7.20], p = 0.001). Current breastfeeding (OR 0.25 [0.11–0.56], p = 0.001) and higher hemoglobin (OR 0.70 [0.60–0.81], p < 0.001 per 1 g/dL) were associated with decreased odds of malaria. Malaria parasite clearance was delayed in HIV-infected participants (p < 0.001). Malaria is over-diagnosed even at referral centers in high transmission areas. Hospitalized HIV-infected children are more likely to have malaria and exhibit delayed clearance of parasites. Hospitals should consider using mRDTs as a first step for malaria testing among hospitalized children in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

An estimated 214 million cases of malaria were detected in 2015, which caused approximately 438 000 deaths. Around 90% of those cases occurred in Africa, where the lack of access to malaria diagnosis is largely due to shortage of expertise and equipment. Thus, the importance to develop new tools that facilitate the rapid and easy diagnosis of malaria for areas with limited access to healthcare services cannot be overstated. This paper presents an image processing and analysis methodology using supervised classification to assess the presence of P.falciparum trophozoites and white blood cells in Giemsa stained thick blood smears. The main differential factor is the usage of microscopic images exclusively acquired with low cost and accessible tools such as smartphones, using a dataset of 194 images manually annotated by an experienced parasilogist. Using a SVM classifier and a total of 314 image features extracted for each candidate, the automatic detection of trophozoites detection achieved a sensitivity of 80.5% and a specificity of 93.8%, while the white blood cells achieved 98.2% of sensitivity and 72.1% specificity. [ABSTRACT FROM AUTHOR]