Plasmodium knowlesi infection is associated with elevated circulating biomarkers of brain injury and endothelial activation

Introduction

Malaria remains a major public health concern with substantial morbidity and mortality worldwide. In Malaysia, the emergence of Plasmodium knowlesi has led to a surge in zoonotic malaria cases and deaths in recent years. Signs of cerebral involvement have been observed in a non-comatose, fatal case of severe knowlesi infection, but the potential impact of this malaria species on the brain remains underexplored. To address this gap, we investigated circulating levels of brain injury, inflammation, and vascular biomarkers in a cohort of knowlesi-infected patients and controls.

Methods

Archived plasma samples from 19 patients with confirmed symptomatic knowlesi infection and 19 healthy, age-matched controls from Peninsular Malaysia were analysed. A total of 52 plasma biomarkers of brain injury, inflammation, and vascular activation were measured using Luminex and SIMOA assays. Wilcoxon tests were used to examine group differences, and biomarker profiles were explored through hierarchical clustering heatmap analysis.

Results

Bonferroni-corrected analyses revealed significantly elevated brain injury biomarker levels in knowlesi-infected patients, including S100B (p<0.0001), Tau (p=0.0007), UCH-L1 (p<0.0001), αSyn (p<0.0001), Park7 (p=0.0006), NRGN (p=0.0022), and TDP-43 (p=0.005). Compared to controls, levels were lower in the infected group for BDNF (p<0.0001), CaBD (p<0.0001), CNTN1 (p<0.0001), NCAM-1 (p<0.0001), GFAP (p=0.0013), and KLK6 (p=0.0126). Hierarchical clustering revealed distinct group profiles for circulating levels of brain injury and vascular activation biomarkers.

Conclusions

Our findings highlight for the first time the impact of Plasmodium knowlesi infection on the brain, with distinct alterations in cerebral injury and endothelial activation biomarker profiles compared to healthy controls. Further studies are warranted to investigate the pathophysiology and clinical significance of these altered surrogate markers, through both neuroimaging and long-term neurocognitive assessments.

Vivax malaria: a possible stumbling block for malaria elimination in India

Plasmodium vivax is geographically the most widely dispersed human malaria parasite species. It has shown resilience and a great deal of adaptability. Genomic studies suggest that P. vivax originated from Asia or Africa and moved to the rest of the world. Although P. vivax is evolutionarily an older species than Plasmodium falciparum, its biology, transmission, pathology, and control still require better elucidation. P. vivax poses problems for malaria elimination because of the ability of a single primary infection to produce multiple relapses over months and years. P. vivax malaria elimination program needs early diagnosis, and prompt and complete radical treatment, which is challenging, to simultaneously exterminate the circulating parasites and dormant hypnozoites lodged in the hepatocytes of the host liver. As prompt surveillance and effective treatments are rolled out, preventing primaquine toxicity in the patients having glucose-6-phosphate dehydrogenase (G6PD) deficiency should be a priority for the vivax elimination program. This review sheds light on the burden of P. vivax, changing epidemiological patterns, the hurdles in elimination efforts, and the essential tools needed not just in India but globally. These tools encompass innovative treatments for eliminating dormant parasites, coping with evolving drug resistance, and the development of potential vaccines against the parasite.

Plasmodium vivax transcriptomics: What is new?

Malaria is the leading human parasitosis and is transmitted through the bite of anopheline mosquitoes infected with parasites of the genus Plasmodium spp. Among the seven species that cause malaria in humans, Plasmodium vivax is the most prevalent species in Latin America. In recent years, there have been an increasing number of reports of clinical complications caused by P. vivax infections, which were previously neglected and underestimated. P. vivax biology remains with large gaps. The emergence of next-generation sequencing technology has ensured a breakthrough in species knowledge. Coupled with this, the deposition of the P. vivax Sal-1 reference genome allowed an increase in transcriptomics projects by accessing messenger RNA. Thus, the regulation of differential gene expression according to the parasite life stage was verified, and several expressed genes were linked to different biological functions. Today, with the progress associated with RNA sequencing technologies, it is possible to detect nuances and obtain robust results. Discoveries provided by transcriptomic studies allow us to understand topics such as RNA expression and regulation and proteins and metabolic pathways involved during different stages of the parasite life cycle. The information obtained enables a better comprehension of immune system evasion mechanisms; invasion and adhesion strategies used by the parasite; as well as new vaccine targets, potential molecular markers, and others therapeutic targets. In this review, we provide new insights into P. vivax biology by summarizing recent findings in transcriptomic studies.

Plasmodium vivax vaccine: What is the best way to go?

Malaria is one of the most devastating human infectious diseases caused by Plasmodium spp. parasites. A search for an effective and safe vaccine is the main challenge for its eradication. Plasmodium vivax is the second most prevalent Plasmodium species and the most geographically distributed parasite and has been neglected for decades. This has a massive gap in knowledge and consequently in the development of vaccines. The most significant difficulties in obtaining a vaccine against P. vivax are the high genetic diversity and the extremely complex life cycle. Due to its complexity, studies have evaluated P. vivax antigens from different stages as potential targets for an effective vaccine. Therefore, the main vaccine candidates are grouped into preerythrocytic stage vaccines, blood-stage vaccines, and transmission-blocking vaccines. This review aims to support future investigations by presenting the main findings of vivax malaria vaccines to date. There are only a few P. vivax vaccines in clinical trials, and thus far, the best protective efficacy was a vaccine formulated with synthetic peptide from a circumsporozoite protein and Montanide ISA-51 as an adjuvant with 54.5% efficacy in a phase IIa study. In addition, the majority of P. vivax antigen candidates are polymorphic, induce strain-specific and heterogeneous immunity and provide only partial protection. Nevertheless, immunization with recombinant proteins and multiantigen vaccines have shown promising results and have emerged as excellent strategies. However, more studies are necessary to assess the ideal vaccine combination and test it in clinical trials. Developing a safe and effective vaccine against vivax malaria is essential for controlling and eliminating the disease. Therefore, it is necessary to determine what is already known to propose and identify new candidates.

Impact of Plasmodium vivax malaria on executive and cognitive functions in elderlies in the Brazilian Amazon

The exact path leading to cognitive impairment that goes beyond malaria is unclear, but it appears to be the result of interactive factors. Time of exposure to disease and recurrences are potentially major determinant variables. Cognitive impairment is described mainly in children, rarely in adults. The disease in high endemic areas usually does not affect elderlies, because of acquired immunity over time. However, this population is relatively more frequently sick in lower endemic areas, such as in the Amazon. This study assessed the effect of Plasmodium vivax malaria on the executive and cognitive functions of elderlies, in the Brazilian Amazon. A cohort study was conducted to evaluate executive and cognitive functions one week (T0), two months (T2) and eight months (T8) after the malaria episode. Mini-Mental State Examination (MMSE), Beck Depression Inventory II (BDI-II), Clock Drawing Test (CDT), Wechsler adult intelligence scale (WAIS-III), and Wisconsin Card Sorting Test (WCST) were used to assess executive and cognitive functions. One hundred-forty elderlies were enrolled (70 with P. vivax malaria and 70 without malaria). P. vivax malaria was associated with impairment of the executive and cognitive functions in elderlies for up to 8 months after acute P. vivax malaria. Prior history of malaria, recurrences and higher parasitemia were independently associated with various surrogates of executive and cognitive impairment. With the increase in life expectancy, elderlies living in malaria endemic areas will deserve more attention from health authorities, to guarantee improvement of their quality of life in the tropics.

Cerebral Malaria: Current Clinical and Immunological Aspects

This review focuses on current clinical and immunological aspects of cerebral malaria induced by Plasmodium falciparum infection. Albeit many issues concerning the inflammatory responses remain unresolved and need further investigations, current knowledge of the underlying molecular mechanisms is highlighted. Furthermore, and in the light of significant limitations in preventative diagnosis and treatment of cerebral malaria, this review mainly discusses our understanding of immune mechanisms in the light of the most recent research findings. Remarkably, the newly proposed CD8+ T cell-driven pathophysiological aspects within the central nervous system are summarized, giving first rational insights into encouraging studies with immune-modulating adjunctive therapies that protect from symptomatic cerebral participation of Plasmodium falciparum infection.

Extracellular vesicles in malaria: an agglomeration of two decades of research

Malaria is a complex parasitic disease, caused by Plasmodium spp. More than a century after the discovery of malaria parasites, this disease continues to pose a global public health problem and the pathogenesis of the severe forms of malaria remains incompletely understood. Extracellular vesicles (EVs), including exosomes and microvesicles, have been increasingly researched in the field of malaria in a bid to fill these knowledge gaps. EVs released from Plasmodium-infected red blood cells and other host cells during malaria infection are now believed to play key roles in disease pathogenesis and are suggested as vital components of the biology of Plasmodium spp. Malaria-derived EVs have been identified as potential disease biomarkers and therapeutic tools. In this review, key findings of malaria EV studies over the last 20 years are summarized and critically analysed. Outstanding areas of research into EV biology are identified. Unexplored EV research foci for the future that will contribute to consolidating the potential for EVs as agents in malaria prevention and control are proposed.

Identification of immunodominant epitopes in allelic variants VK210 and VK247 of Plasmodium Vivax Circumsporozoite immunogen

Plasmodium vivax-induced malaria is among the leading causes of morbidity and mortality in sub-tropical and tropical regions and infect 2.85 billion people globally. The continual rise and propagation of resistance against anti-malarial drugs is a prerequisite to develop a potent vaccine candidate for Plasmodium vivax (P. vivax). Circumsporozoite protein (CSP) is an important immunogen of malaria parasite that has the conserved CSP structure as an immune dominant B-cell epitope. In current study, we focused on designing multi-epitope vaccines (MEVs) using various immunoinformatics tools against Pakistani based allelic variants VK210 and VK247 of P. vivax CSP (PvCSP) gene. Antigenicity, allergic potential and physicochemical parameters of both PvCSP variants were assessed for the designed MEVs and they were within acceptable range suitable for post experimental investigations. The three-dimensional structures of both MEVs have been predicted ab initio, optimized, and validated by using different online servers. The both MEVs candidates were stable and free from aggregation-prone regions. The stability of both MEVs had been improved by a disulfide engineering approach. To estimate the binding energy and stability of the MEVs, molecular docking simulation and binding free energy calculations with TLR-4 immune receptor have been conducted. The docking score of PvCSP210 and PvCSP247 for TLR-4 was -6.34 kJ/mol and - 2.3 kJ/mol, respectively. For PvCSP210-TLR4 system, mean RMSD was 4.96 Å while PvCSP247-TLR4 system, average RMSD was 4.49 Å. The binding free energy of PvCSP210-TLR4 complex and PvCSP247-TLR4 complex was -50.49/-117.15 kcal/mol (MMGBSA/MMPSA) and -52.94/-96.26 kcal/mol (MMGBSA/MMPSA), respectively. The expression of both MEVs produced in Escherichia coli K12 expression system by in silico cloning was significant. Immune simulation revealed that the proposed MEVs induce strong humoral and cellular immunological responses, in addition to significant production of interleukins and cytokines. In conclusions, we believed that the MEVs proposed in current research, using combine approach of immunoinformatics, structural biology and biophysical approaches, could induce protective and effective immune responses against P. vivax and the experimental validation of our findings could contribute to the development of potential malaria vaccine.

Studies on Activities and Chemical Characterization of Medicinal Plants in Search for New Antimalarials: A Ten Year Review on Ethnopharmacology

Malaria is an endemic disease that affected 229 million people and caused 409 thousand deaths, in 2019. Disease control is based on early diagnosis and specific treatment with antimalarial drugs since no effective vaccines are commercially available to prevent the disease. Drug chemotherapy has a strong historical link to the use of traditional plant infusions and other natural products in various cultures. The research based on such knowledge has yielded two drugs in medicine: the alkaloid quinine from Cinchona species, native in the Amazon highland rain forest in South America, and artemisinin from Artemisia annua, a species from the millenary Chinese medicine. The artemisinin-based combination therapies (ACTs), proven to be highly effective against malaria parasites, and considered as “the last bullet to fight drug-resistant malaria parasites,” have limited use now due to the emergence of multidrug resistance. In addition, the limited number of therapeutic options makes urgent the development of new antimalarial drugs. This review focuses on the antimalarial activities of 90 plant species obtained from a search using Pubmed database with keywords “antimalarials,” “plants” and “natural products.” We selected only papers published in the last 10 years (2011–2020), with a further analysis of those which were tested experimentally in malaria infected mice. Most plant species studied were from the African continent, followed by Asia and South America; their antimalarial activities were evaluated against asexual blood parasites, and only one species was evaluated for transmission blocking activity. Only a few compounds isolated from these plants were active and had their mechanisms of action delineated, thereby limiting the contribution of these medicinal plants as sources of novel antimalarial pharmacophores, which are highly necessary for the development of effective drugs. Nevertheless, the search for bioactive compounds remains as a promising strategy for the development of new antimalarials and the validation of traditional treatments against malaria. One species native in South America, Ampelozyzyphus amazonicus, and is largely used against human malaria in Brazil has a prophylactic effect, interfering with the viability of sporozoites in in vitro and in vivo experiments.

Parasite-Host Interaction and Pathophysiology Studies of the Human Relapsing Malarias Plasmodium vivax and Plasmodium ovale Infections in Non-Human Primates

Malaria remains a serious health concern across the globe. Historically neglected, non-Falciparum human malarias were put back on the agenda by a paradigm shift in the fight against malaria from malaria control to malaria eradication. Here, we review the modeling of the relapsing parasites Plasmodium vivax (P. vivax) and Plasmodium ovale (P. ovale) in non-human primates with a specific focus on the contribution of these models to our current understanding of the factors that govern parasite-host interactions in P. vivax and P. ovale parasite biology and pathophysiology.

Neurological complications in patients with Plasmodium vivax malaria from Karachi, Pakistan

BACKGROUND

Malaria remains an endemic disease in Pakistan with an estimated healthcare burden of 1.6 million cases annually, with Plasmodium vivax accounting for 67% of reported cases. P. vivax is the most common species causing malaria outside of Africa, with approximately 13.8 million reported cases worldwide.

METHOD

We report a series of P. vivax cases with cerebral involvement that presented at Aga Khan University Hospital, Karachi, Pakistan.

RESULTS

The majority of the patients presented with high-grade fever accompanied by projectile vomiting and abnormal behaviour, seizures, shock and unconsciousness. Seven of 801 patients with P. vivax monoinfection presented or developed cerebral complications. P. vivax infections were diagnosed based on peripheral smears and rapid diagnostic testing.

CONCLUSION

P. vivax infection can lead to severe complications, although not with the frequency of Plasmodium falciparum infection. Current cases highlight an increasing trend of cerebral complications caused by P. vivax.

Plasmodium vivax Biology: Insights Provided by Genomics, Transcriptomics and Proteomics

During the last decade, the vast omics field has revolutionized biological research, especially the genomics, transcriptomics and proteomics branches, as technological tools become available to the field researcher and allow difficult question-driven studies to be addressed. Parasitology has greatly benefited from next generation sequencing (NGS) projects, which have resulted in a broadened comprehension of basic parasite molecular biology, ecology and epidemiology. Malariology is one example where application of this technology has greatly contributed to a better understanding of Plasmodium spp. biology and host-parasite interactions. Among the several parasite species that cause human malaria, the neglected Plasmodium vivax presents great research challenges, as in vitro culturing is not yet feasible and functional assays are heavily limited. Therefore, there are gaps in our P. vivax biology knowledge that affect decisions for control policies aiming to eradicate vivax malaria in the near future. In this review, we provide a snapshot of key discoveries already achieved in P. vivax sequencing projects, focusing on developments, hurdles, and limitations currently faced by the research community, as well as perspectives on future vivax malaria research.

Naturally Acquired Human Antibodies Against Reticulocyte-Binding Domains of Plasmodium vivax Proteins, PvRBP2c and PvRBP1a, Exhibit Binding-Inhibitory Activity

Background

Crucial gaps in our understanding of Plasmodium vivax reticulocyte invasion and protective immunity have hampered development of vivax vaccines. P. vivax exclusively invades reticulocytes that is mediated by the P. vivax reticulocyte-binding proteins (PvRBPs) specifically PvRBP2c and PvRBP1a. Vivax infections in Duffy-null individuals have suggested the evolution of alternate invasion pathways that may be mediated by the PvRBPs. Thus, PvRBPs appear as potential targets for efficacious P. vivax neutralization. However, there are limited data validating their vaccine efficacy. In the absence of vivax invasion assays, binding-inhibitory activity of antibodies has been reported to be associated with protection and a measure of vaccine potential.

Methods

-based analysis was performed of the PvRBP reticulocyte-binding properties and binding-inhibitory activity of specific anti-PvRBP2c/PvRBP1a human antibodies.

Results

PvRBP2c and PvRBP1a displayed a distinct reticulocyte-binding specificity, and their specific reticulocyte-binding domains were mapped within their N-terminal regions. Importantly, naturally acquired antibodies against the reticulocyte-binding domains efficaciously blocked reticulocyte binding of native PvRBPs, suggesting that the human immune system produced functional binding-inhibitory antibodies through exposure to vivax malaria.

Conclusions

Reticulocyte-binding domains of PvRBP2c/PvRBP1a are targets of naturally acquired binding-inhibitory antibodies, substantiating their promise as candidate antigens against which vaccine-inducible immunity could potentially be boosted through natural infections.

Severe Plasmodium vivax infection in Korea

Background

Although severe malaria by Plasmodium vivax has been increasingly reported, there are marked variations in the type and rate of the complications by geographic area. This is possibly because of the presence of concurrent falciparum malaria or bacteraemia, and of differences in underlying immune status among the infected subjects. Furthermore, published studies on P. vivax in temperate regions are limited. The present study investigated severe vivax malaria in Korea, where only vivax malaria occurs. Hence, other compounding factors are rare. Additionally, most of the patients are possibly non-immune to this malarial disease.

Methods

Adults with vivax malaria observed in one 860-bed university hospital from January 2006 to December 2012 were retrospectively evaluated. Seventeen patients who had travelled overseas within 6 months before the presentation of malaria were excluded. Severe vivax malaria was diagnosed according to World Health Organization criteria. Other complications were also investigated.

Results

Two-hundred and ten patients were enrolled, of which 88 (41.9%) were treated as inpatients and the remainder as outpatients. Eleven patients were treated in an intensive care unit; among them, five patients received mechanical ventilation, and one needed extracorporeal membrane oxygenation therapy (ECMO) additionally. Severe vivax malaria was identified in 44 patients (21.0%), and the most common severe complication was pulmonary manifestation (40/188, 21.9%), which was followed by cerebral malaria (5/210, 2.4%), shock (4/210, 1.9%), spontaneous bleeding (3/210, 1.4%), metabolic acidosis (3/210, 3.5%) and acute kidney injury (2/210, 1.0%). Unusual complications, such as splenic infarction (ten patients) and retinal haemorrhage (two patients) were sometimes observed. There were no deaths, but the case involving ECMO was potentially fatal.

Conclusions

Plasmodium vivax infection can be severe to be fatal and is frequently associated with various complications in non-immune adults. The frequency of each complication seems to differ from other countries. Hence, further investigation is needed to elucidate the causes and mechanisms responsible for these differences.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1684-4) contains supplementary material, which is available to authorized users.

Role of Plasmodium vivax Dihydropteroate Synthase Polymorphisms in Sulfa Drug Resistance

Dihydropteroate synthase (DHPS) is a known sulfa drug target in malaria treatment, existing as a bifunctional enzyme together with hydroxymethyldihydropterin pyrophosphokinase (HPPK). Polymorphisms in key residues of Plasmodium falciparum DHPS (PfDHPS) have been characterized and linked to sulfa drug resistance in malaria. Genetic sequencing of P. vivax dhps (Pvdhps) from clinical isolates has shown several polymorphisms at the positions equivalent to those in the Pfdhps genes conferring sulfa drug resistance, suggesting a mechanism for sulfa drug resistance in P. vivax similar to that seen in P. falciparum To characterize the role of polymorphisms in the PvDHPS in sulfa drug resistance, various mutants of recombinant PvHPPK-DHPS enzymes were expressed and characterized. Moreover, due to the lack of a continuous in vitro culture system for P. vivax parasites, a surrogate P. berghei model expressing Pvhppk-dhps genes was established to demonstrate the relationship between sequence polymorphisms and sulfa drug susceptibility and to test the activities of PvDHPS inhibitors on the transgenic parasites. Both enzyme activity and transgenic parasite growth were sensitive to sulfadoxine to different degrees, depending on the number of mutations that accumulated in DHPS. Ki values and 50% effective doses were higher for mutant PvDHPS enzymes than the wild-type enzymes. Altogether, the study provides the first evidence of sulfa drug resistance at the molecular level in P. vivax Furthermore, the enzyme inhibition assay and the in vivo screening system can be useful tools for screening new compounds for their activities against PvDHPS.

Role of Serum Lactate and Malarial Retinopathy in Prognosis and Outcome of Falciparum and Vivax Cerebral Malaria: A Prospective Cohort Study in Adult Assamese Tribes

Introduction:

There is no comprehensive data or studies relating to clinical presentation and prognosis of cerebral malaria (CM) in the tribal settlements of Assam. High rates of transmission and deaths from complicated malaria guided us to conduct a prospective observational cohort study to evaluate the factors associated with poor outcome and prognosis in patients of CM.

Materials and Methods:

We admitted 112 patients to the Bandarpara and Damodarpur Tribal Health Centers (THCs) between 2011 and 2013 with a strict diagnosis of CM. We assessed the role of clinical, fundoscopy and laboratory findings (mainly lactic acid) in the immediate outcome in terms of death and recovery, duration of hospitalization, neurocognitive impairment, cranial nerve palsies and focal neurological deficit.

Results:

The case fatality rate of CM was 33.03% and the prevalence of residual neurological sequelae at discharge was 16.07%. These are significantly higher than the previous studies. The mortality rate and neurological complications rate in patients with retinal whitening was 38.46% and 23.07%, with vessel changes was 25% and 18.75%, with retinal hemorrhage was 55.55% and 11.11% and with hyperlactatemia was 53.85% and 18.46%, respectively. Three patients of papilledema alone died.

Conclusion:

Our study suggests a strong correlation between hyperlactatemia, retinal changes (whitening, vessel changes and hemorrhage) and depth and duration of coma with longer duration of hospitalization, increased mortality, neurological sequelae and death. Plasmodium vivax mono-infection as a cause of CM has been confirmed. Prognostic evaluation of CM is useful for judicious allocation of resources in the THC.

Severe Malaria Associated with Plasmodium falciparum and P. vivax among Children in Pawe Hospital, Northwest Ethiopia

Despite rigorous effort made to control malaria for more than a century, it is still among the main public health problems in least developed regions of the world. Majority of deaths associated with malaria occur in sub-Sahara Africa among biologically risked groups. Thus, this study was designed to assess the incidence of severe malaria syndromes among children in Pawe Hospital, Northwest Ethiopia. Children seeking medication for malaria infection in Pawe Hospital during the study period were recruited. Sociodemographic characteristics, physical, hematological, and clinical features of complicated malaria were assessed following standard parasitological and clinical procedures. A total of 263 children were found malaria positive. Among these, 200 were infected with Plasmodium falciparum. Most of the severe malaria symptoms were observed among children infected with P. falciparum and P. vivax. The study showed that significant number of the children developed severe life threatening malaria complications. This calls for prompt early diagnosis and effective treatment of patients to reduce mortality and complications associated with malaria in the study site.

Cerebral malaria in a man with Plasmodium vivax mono-infection: a case report

Cerebral malaria (CM) is a diffuse encephalopathy associated with coma and seizures commonly caused by Plasmodium falciparum (P. falciparum) in children with severe malaria. We present a case of a 19-year-old man with CM due to Plasmodium vivax (P. vivax) infection. Cerebrospinal fluid (CSF) was negative for Japanese B encephalitis, enterovirus, herpes simplex 1 and 2, varicella and mumps viruses as determined by real-time polymerase chain reaction (PCR). P. falciparum and P. vivax species were analysed by microscopy, immunochromatography and PCR assays and confirmed mono-infection of P. vivax in the patient's blood, and P. falciparum infection was established to be negative. The patient was discharged after intensive supportive care and antimalarial treatment (intravenous artesunate and oral doxycycline). We conclude that P. vivax infection is associated with CM, a life-threatening complication rarely seen in coastal districts of Karnataka. In endemic areas, the possibility of CM should be considered even with P. vivax infection.

Investigating the Pathogenesis of Severe Malaria: A Multidisciplinary and Cross-Geographical Approach

More than a century after the discovery of Plasmodium spp. parasites, the pathogenesis of severe malaria is still not well understood. The majority of malaria cases are caused by Plasmodium falciparum and Plasmodium vivax, which differ in virulence, red blood cell tropism, cytoadhesion of infected erythrocytes, and dormant liver hypnozoite stages. Cerebral malaria coma is one of the most severe manifestations of P. falciparum infection. Insights into its complex pathophysiology are emerging through a combination of autopsy, neuroimaging, parasite binding, and endothelial characterizations. Nevertheless, important questions remain regarding why some patients develop life-threatening conditions while the majority of P. falciparum-infected individuals do not, and why clinical presentations differ between children and adults. For P. vivax, there is renewed recognition of severe malaria, but an understanding of the factors influencing disease severity is limited and remains an important research topic. Shedding light on the underlying disease mechanisms will be necessary to implement effective diagnostic tools for identifying and classifying severe malaria syndromes and developing new therapeutic approaches for severe disease. This review highlights progress and outstanding questions in severe malaria pathophysiology and summarizes key areas of pathogenesis research within the International Centers of Excellence for Malaria Research program.

Resistance to antimalarial drugs: An endless world war against Plasmodium that we risk losing

The objective of this review was to describe the 'state of the art' of Plasmodium falciparum resistance to the main antimalarial drugs. A brief note on Plasmodium vivax is also included. Resistance of P. falciparum to the various antimalarials has a long history of hits and misses. During the last 60 years, the pace at which this parasite has developed resistance to antimalarial drugs has exceeded the pace at which new drugs have been developed. In the last decade, the introduction of artemisinin-based combination therapies (ACTs) as a first-line drug treatment for non-complicated P. falciparum malaria had led to extraordinary results in disease control, especially in sub-Saharan Africa. However, the emergence and spread of resistance to artemisinin in Southeast Asia jeopardise these results. In conclusion, the possible spread of artemisinin resistance in Africa should be considered as an epochal disaster.

Angiopoietin-2 and angiopoietin-2/angiopoietin-1 ratio as indicators of potential severity of Plasmodium vivax malaria in patients with thrombocytopenia

Introduction

Angiogenic factors such as angiopoietin 1 (Ang-1) and angiopoietin 2 (Ang-2) are biomarkers produced during activation and dysfunction of the vascular endothelium in several infectious diseases. The aim of this study was to determine the serum levels of Ang-1 and Ang-2 and to establish their relationship with the main indicators of worst-case prognosis in patients with P. vivax malaria.

Methods

This is a retrospective case-control study nested within a cohort of symptomatic malaria patients. A potentially severe case was defined as a patient that presented at least one of the main indicators of the worst-case prognosis for falciparum malaria, as established by the World Health Organization. Ang-2 and Ang-1 and the Ang-2/Ang-1 ratio were used to analyze the role of angiopoietins as biomarkers in signaling potentially severe vivax malaria. ROC curves were generated to identify a cut-off point discriminating between the angiopoietin concentrations that were most strongly associated with potential infection severity.

Results

The serum levels of Ang-2 and the Ang-2/Ang-1 ratio were higher in the case group. In contrast, the serum levels of Ang-1 were lower in the cases than in the control patients. The blood count for platelets showed a positive correlation with Ang-1 and a negative correlation with Ang-2 and with the Ang-2/Ang-1 ratio. The area under the ROC curve (AUC) for serum angiopoietins, as an indicator of worst-case prognosis in a potentially severe P. vivax malarial infection, was larger in the subgroup of patients with platelet counts <75,000/µL.

Conclusion

This study showed that patients with predictors of worst-case prognoses for P. vivax malaria have lower Ang-1 and higher Ang-2 serum levels (and higher values for the Ang-2/Ang-1 ratio) than controls. Elevated serum levels of Ang-2 and high values for the Ang-2/Ang-1 ratio may potentially be used as predictors of worst-case prognoses for P. vivax malaria, especially in patients with thrombocytopenia.

Is Plasmodium vivax malaria a severe malaria?: a systematic review and meta-analysis

Background

Plasmodium vivax is one of the major species of malaria infecting humans. Although emphasis on P. falciparum is appropriate, the burden of vivax malaria should be given due attention. This study aimed to synthesize the evidence on severe malaria in P. vivax infection compared with that in P. falciparum infection.

Methods/Principal Findings

We searched relevant studies in electronic databases. The main outcomes required for inclusion in the review were mortality, severe malaria (SM) and severe anaemia (SA). The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Overall, 26 studies were included. The main meta-analysis was restricted to the high quality studies. Eight studies (n = 27490) compared the incidence of SM between P. vivax infection and P. falciparum mono-infection; a comparable incidence was found in infants (OR: 0.45, 95% CI:0.04–5.68, I²:98%), under 5 year age group (OR: 2.06, 95% CI: 0.83–5.1, I²:83%), the 5–15 year-age group (OR: 0.6, 95% CI: 0.31–1.16, I²:81%) and adults (OR: 0.83, 95% CI: 0.67–1.03, I²:25%). Six studies reported the incidences of SA in P. vivax infection and P. falciparum mono-infection; a comparable incidence of SA was found among infants (OR: 3.47, 95%:0.64–18.94, I²: 92%), the 5–15 year-age group (OR:0.71, 95% CI: 0.06–8.57, I²:82%). This was significantly lower in adults (OR:0.75, 95% CI: 0.62–0.92, I²:0%). Five studies (n = 71079) compared the mortality rate between vivax malaria and falciparum malaria. A lower rate of mortality was found in infants with vivax malaria (OR:0.61, 95% CI:0.5–0.76, I²:0%), while this was comparable in the 5–15 year- age group (OR: 0.43, 95% CI:0.06–2.91, I²:84%) and the children of unspecified-age group (OR: 0.77, 95% CI:0.59–1.01, I²:0%).

Conclusion

Overall, the present analysis identified that the incidence of SM in patients infected with P. vivax was considerable, indicating that P. vivax is a major cause of SM. Awareness of the clinical manifestations of vivax malaria should prompt early detection. Subsequent treatment and monitoring of complications can be life-saving.

Until recently, vivax malaria has received less attention than falciparum malaria and was deemed neglected. There has been a surge in studies that documented the contribution of Plasmodium vivax to severe malaria in some endemic countries such as Thailand, Brazil, Indonesia, Papua New Guinea and India. We aimed to synthesize the evidence on severe malaria in P. vivax infection compared with that in P. falciparum infection. We searched relevant studies in electronic databases. The combined results of the eight relatively high quality studies showed a comparable incidence between vivax malaria and falciparum malaria in infants, under 5 year age group, the 5–15 year age group and adults. The combined results of the six relatively high quality studies revealed a comparable incidence of severe anaemia between P. vivax infection and P. falciparum mono-infection in both the infants and the 5–15 year age group. Considering that severe malaria and deaths attributable to P. vivax is not a rare event, raised clinical awareness of the manifestations of vivax malaria in patients of any age should prompt early detection of malaria. It is likely that early detection, appropriate treatment commenced in a timely manner and close monitoring of any complications could be life-saving and contribute to the attainment of the global vision of no malaria deaths.

Slow clearance of Plasmodium vivax with chloroquine amongst children younger than six months of age in the Brazilian Amazon

Plasmodium vivax is the most widespread parasite causing malaria, being especially prevalent in the Americas and Southeast Asia. Children are one of the most affected populations, especially in highly endemic areas. However, there are few studies evaluating the therapeutic response of infants with vivax malaria. This study retrospectively evaluated the parasitaemia clearance in children diagnosed with vivax malaria during the first five days of exclusive treatment with chloroquine (CQ). Infants aged less than six months old had a significantly slower parasitaemia clearance time compared to the group of infants and children between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon test; p = 0.004). The impaired clearance of parasitaemia in younger children with vivax malaria is shown for the first time in Latin America. It is speculated that CQ pharmacokinetics in young children with vivax malaria is distinct, but this specific population may also allow the detection of CQ-resistant parasites during follow-up, due to the lack of previous immunity.

Thrombocytopenia in Plasmodium vivax Malaria: How Significant?

Introduction. Thrombocytopenia is frequently noticed with P. falciparum malaria but is less reported and studied with P. vivax. Materials and Methods. The study was conducted in the Department of Medicine, SBKS MI & RC, Pipariya. We included patients who were diagnosed with vivax malaria. The data regarding their clinical and hematological profile was collected and analysed. Result. A total of 66 patients were included. 42 (63%) had platelet count <100000/mm(3). Mean platelet count was 1,18,650, range being 8000/mm(3)-6,10,000/mm(3). Amongst those with thrombocytopenia, 16 (38.09%) had anemia, 14 (33.33%) had serum creatinine >1.2 gm/dL, 15 (35.71%) had jaundice (s. bilirubin > 1.2), 2 (4.76%) had altered sensorium, 6 (14.28%) had ARDS, 2 needed ventilator support, and 1 expired. Amongst those with normal platelet count, 5 (20.83%) had anemia and 1 had jaundice whereas none had elevated s. creatinine, altered sensorium, or lung involvement. Conclusion. Thrombocytopenia is now being seen more commonly with vivax malaria. Patients with platelet count <1 lac/cumm have more severe disease.

Imported malaria at Buraidah Central Hospital, Qassim, Saudi Arabia: a retrospective analysis

BACKGROUND

Malaria is a major threat to global health and it is a widespread throughout tropical and subtropical countries with an increasing risk to travellers.

METHODS

A retrospective analysis was conducted to investigate the epidemiology of imported malaria at Buraidah in Qassim region, Saudi Arabia during the period of January 2010 through April 2013.

RESULTS

There were 46 imported malaria cases. These cases were Plasmodium vivax (89.1%), Plasmodium falciparum (0.02%) and were mixed in 4 cases. Their age range between 14 and 54 and the mean was 29.7 years. Around three quarter (71.2%) of the patients were males. Most of the patients were Indian (54.3%) and Pakistani (23.9%). Over half (54.3%) of the patients had severe malaria, mainly severe anaemia, jaundice and hypotension. There was no mortality among the patients.

CONCLUSIONS

Most of the detected malaria cases in this setting were among expatriates, particularly from the Indian subcontinent, while the predominant species was P. vivax. More than 50% of the cases presented with severe malaria.

Plasmodium vivax cerebral malaria complicated with venous sinus thrombosis in Colombia

Complicated malaria is usually due to Plasmodium falciparum. Nevertheless, Plasmodium vivax is infrequently related with life-threatening complications. Few cases have been reported of severe Plasmodium vivax infection, and most of them from Southeast Asia and India. We report the first case of cerebral malaria due to Plasmodium vivax in Latin America, complicated with sagittal sinus thrombosis and confirmed by a molecular method.

Primaquine for preventing relapse in people with Plasmodium vivax malaria treated with chloroquine

BACKGROUND

Plasmodium vivax infections are an important contributor to the malaria burden worldwide. The World Health Organization recommends a 14-day course of primaquine (0.25 mg/kg/day, giving an adult dose of 15 mg/day) to eradicate the liver stage of the parasite and prevent relapse of the disease. Many people find a 14-day primaquine regimen difficult to complete, and there is a potential risk of haemolytic anaemia in people with glucose-6-phosphate-dehydrogenase enzyme (G6PD) deficiency. This review evaluates primaquine in P. vivax, particularly alternatives to the standard 14-day course.

OBJECTIVES

To compare alternative primaquine regimens to the recommended 14-day regimen for preventing relapses (radical cure) in people with P. vivax malaria treated for blood stage infection with chloroquine. We also summarize trials comparing primaquine to no primaquine that led to the recommendation for the 14-day regimen.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group's Specialized Register, CENTRAL (The Cochrane Library), MEDLINE, EMBASE and LILACS up to 8 October 2013. We checked conference proceedings, trial registries and reference lists and contacted researchers and pharmaceutical companies for eligible studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and quasi-RCTs comparing various primaquine dosing regimens with the standard primaquine regimen (15 mg/day for 14 days), or with no primaquine, in people with vivax malaria treated for blood stage infection with chloroquine.

DATA COLLECTION AND ANALYSIS

We independently assessed trial eligibility, trial quality, and extracted data. We calculated risk ratios (RR) with 95% confidence intervals (CI) for dichotomous data, and used the random-effects model in meta-analyses if there was significant heterogeneity. We assessed the overall quality of the evidence using the GRADE approach.

MAIN RESULTS

We included 15 trials (two cluster-RCTs) of 4377 adult and child participants. Most trials excluded people with G6PD deficiency. Trials compared various regimens of primaquine with the standard primaquine regimen, or with placebo or no treatment. All trials treated blood stage infection with chloroquine. Alternative primaquine regimens compared to 14-day primaquineRelapse rates were higher over six months with the five-day primaquine regimen than the standard 14-day regimen (RR 10.05, 95% CI 2.82 to 35.86; two trials, 186 participants, moderate quality evidence). Similarly, relapse over six months was higher with three days of primaquine than the standard 14-day regimen (RR 3.18, 95% CI 2.1 to 4.81; two trials, 262 participants, moderate quality evidence; six months follow-up); and with primaquine for seven days followed up over two months, compared to 14-day primaquine (RR 2.24, 95% CI 1.24 to 4.03; one trial, 126 participants, low quality evidence).Relapse with once-weekly supervised primaquine for eight weeks was little different over nine months follow-up compared to 14-day self-administered primaquine in one small study (RR 2.97, 95% CI 0.34 to 25.87; one trial, 129 participants, very low quality evidence). Primaquine regimens compared to no primaquineThe number of people that relapsed was similar between people given five days of primaquine or given placebo or no primaquine (four trials, 2213 participants, high quality evidence; follow-up six to 15 months); but lower with 14 days of primaquine (RR 0.6; 95% CI 0.48 to 0.75; ten trials, 1740 participants, high quality evidence; follow-up seven weeks to 15 months).No serious adverse events were reported. Treatment-limiting adverse events were rare and non-serious adverse events were mild and transient. Trial authors reported that people tolerated the drugs.We did not find trials comparing higher dose primaquine regimens (0.5 mg/kg/day or more) for five days or more with the 14-day regimen.

AUTHORS' CONCLUSIONS

The analysis confirms the current World Health Organization recommendation for 14-day primaquine (15 mg/day) to prevent relapse of vivax malaria. Shorter primaquine regimens at the same daily dose are associated with higher relapse rates. The comparative effects with weekly primaquine are promising, but require further trials to establish equivalence or non-inferiority compared to the 14-day regimen in high malaria transmission settings.

A new hypothesis on the manifestation of cerebral malaria: the secret is in the liver

Despite the abundance of information on cerebral malaria (CM), the pathogenesis of this disease is not completely understood. At present, two nonexclusive dominant hypotheses exist to explain how the neurological syndrome manifests: the sequestration (or mechanical) hypothesis and the inflammatory hypothesis. The sequestration hypothesis states that sequestration of Plasmodium falciparum-parasitized red blood cells (pRBCs) to brain capillary endothelia causes obstruction of capillary blood flow followed by brain tissue anoxia and coma. The inflammatory hypothesis postulates that P. falciparum infection releases toxic molecules in the circulation, inducing an imbalanced systemic inflammatory response that leads to coagulopathy, brain endothelial cell dysfunction, accumulation of leukocytes in the brain microcirculation, blood brain barrier (BBB) leakage, cerebral vasoconstriction, edema, and coma. However, both hypotheses, even when considered together, are not sufficient to fully explain the pathogenesis of CM. Here, we propose that the development of acute liver failure (ALF) together with BBB breakdown are the necessary and sufficient conditions for the genesis of CM. ALF is characterized by coagulopathy and hepatic encephalopathy (HE) in a patient without pre-existing liver disease. Signs of hepatic dysfunction have been shown to occur in 2.5-40% of CM patients. In addition, recent studies with murine models demonstrated that mice presenting experimental cerebral malaria (ECM) had hepatic damage and brain metabolic changes characteristic of HE. However, the occurrence of CM in patients with mild or without apparent hepatocellular liver damage and the presence of liver damage in non-CM murine models indicate that the development of ALF during malaria infection is not the single factor responsible for neuropathology. To solve this problem, we also propose that BBB breakdown contributes to the pathogenesis of CM and synergizes with hepatic failure to cause neurological signs and symptoms. BBB dysfunction would thus occur in CM by a mechanism similar to the one occurring in sepsis and is in agreement with the inflammatory hypothesis. Nevertheless, differently from in the inflammatory hypothesis, BBB leakage would facilitate the penetration of ammonia and other toxins into the brain parenchyma, but would not be sufficient to cause CM when occurring alone. We believe our hypothesis better explains the pathogenesis of CM, does not have problems to deal with the exception data not explained by the previous hypotheses, and reveals new targets for adjunctive therapy.

Plasmodium vivax associated severe malaria complications among children in some malaria endemic areas of Ethiopia

BACKGROUND

Although, Plasmodium vivax is a rare parasite in most parts of Africa, it has significant public health importance in Ethiopia. In some parts of the country, it is responsible for majority of malaria associated morbidity. Recently severe life threatening malaria syndromes, frequently associated to P. falciparum, has been reported from P. vivax mono-infections. This prompted designing of the current study to assess prevalence of severe malaria complications related to P. vivax malaria in Ethiopia.

METHODS

The study was conducted in two study sites, namely Kersa and Halaba Kulito districts, located in southwest and southern parts of Ethiopia, respectively. Children, aged ≤ 10 years, who visited the two health centers during the study period, were recruited to the study. Clinical and demographic characteristics such as age, sex, temperature, diarrhea, persistent vomiting, confusion, respiratory distress, hepatomegaly, splenomegaly, hemoglobinuria, and epitaxis were assessed for a total of 139 children diagnosed to have P. vivax mono-infection. Parasitological data were collected following standard procedures. Hemoglobin and glucose level were measured using portable hemocue instrument.

RESULTS

Median age of children was 4.25 ± 2.95 years. Geometric mean parasite count and mean hemoglobin level were 4254.89 parasite/μl and 11.55 g/dl, respectively. Higher prevalence rate of malaria and severe malaria complications were observed among children enrolled in Halaba district (P < 0.001). However, severe parasitemia was higher (72.4%) among children who visited Serbo health center (Kersa district). Male children had significantly higher risk of malaria infection (OR = 1.9, 95% CI, 1.08 to 3.34), while female had higher risk to anemia (OR = 1.91, 95% CI, 1.08 - 3.34). The observed number of anemic children was 43%, of which most of them were found in age range from 0-3 years. Furthermore, P. vivax malaria was a risk factor for incidence of anemia (P < 0.05) in the two sites.

CONCLUSION

P. vivax associated severe malaria complications observed in this study was lower than those reported from other countries. However, incidence of severe malaria complications in one of the sites, Halaba district, where there is highest treatment failure to first line drug, could have significant impact on national malaria prevention and control activities.

Plasmodium vivax: clinical spectrum, risk factors and pathogenesis

Vivax malaria was historically described as 'benign tertian malaria' because individual clinical episodes were less likely to cause severe illness than Plasmodium falciparum. Despite this, Plasmodium vivax was, and remains, responsible for major morbidity and significant mortality in vivax-endemic areas. Single infections causing febrile illness in otherwise healthy individuals rarely progress to severe disease. Nevertheless, in the presence of co-morbidities, P. vivax can cause severe illness and fatal outcomes. Recurrent or chronic infections in endemic areas can cause severe anaemia and malnutrition, particularly in early childhood. Other severe manifestations include acute lung injury, acute kidney injury and uncommonly, coma. Multiorgan failure and shock are described but further studies are needed to investigate the role of bacterial and other co-infections in these syndromes. In pregnancy, P. vivax infection can cause maternal anaemia, miscarriage, low birth weight and congenital malaria. Compared to P. falciparum, P. vivax has a greater capacity to elicit an inflammatory response, resulting in a lower pyrogenic threshold. Conversely, cytoadherence of P. vivax to endothelial cells is less frequent and parasite sequestration is not thought to be a significant cause of severe illness in vivax malaria. With a predilection for young red cells, P. vivax does not result in the high parasite biomass associated with severe disease in P. falciparum, but a four to fivefold greater removal of uninfected red cells from the circulation relative to P. falciparum is associated with a similar risk of severe anaemia. Mechanisms underlying the pathogenesis of severe vivax syndromes remain incompletely understood.

Pediatric cerebral malaria: a scourge of Africa

Cerebral malaria, defined as an otherwise unexplained coma in a patient with Plasmodium falciparum parasitemia, affects up to 1 million people per year, the vast majority of them being children living in sub-Saharan Africa. Despite optimal treatment, this condition kills 15% of those affected and leaves 30% of survivors with neurologic sequelae. The clinical diagnosis is hampered by its poor specificity, but the presence or absence of a malarial retinopathy in cerebral malaria has proven to be important in the differentiation of underlying coma etiology. Both antimalarials and intense supportive care are necessary for optimal treatment. As of yet, clinical trials of adjunctive therapies have not improved the high rates of mortality and morbidity. Survivors are at high risk of neurologic sequelae including epilepsy, neurodisabilities and cognitive–behavioral problems. The neuroanatomic and functional bases of these sequelae are being elucidated. Although adjunctive therapy trials continue, the best hope for African children may lie in disease prevention. Strategies include bednets, chemoprophylaxis and vaccine development.

Erythrocyte Binding Activity Displayed by a Selective Group of Plasmodium vivax Tryptophan Rich Antigens Is Inhibited by Patients' Antibodies

Plasmodium vivax is a very common but non-cultivable malaria parasite affecting large human population in tropical world. To develop therapeutic reagents for this malaria, the parasite molecules involved in host-parasite interaction need to be investigated as they form effective vaccine or drug targets. We have investigated here the erythrocyte binding activity of a group of 15 different Plasmodium vivax tryptophan rich antigens (PvTRAgs). Only six of them, named PvTRAg, PvTRAg38, PvTRAg33.5, PvTRAg35.2 PvTRAg69.4 and PvATRAg74, showed binding to host erythrocytes. That the PvTRAgs binding to host erythrocytes was specific was evident from the competitive inhibition and saturation kinetics results. The erythrocyte receptors for these six PvTRAgs were resistant to trypsin and neuraminidase. These receptors were also chymotrypsin resistant except the receptors for PvTRAg38 and PvATRAg74 which were partially sensitive to this enzyme. The cross-competition studies showed that the chymotrypsin resistant RBC receptor for each of these two proteins was different. Altogether, there seems to be three RBC receptors for these six PvTRAgs and each PvTRAg has two RBC receptors. Both RBC receptors for PvTRAg, PvTRAg69.4, PvTRAg33.5, and PvTRAg35.2 were common to all these four proteins. These four PvTRAgs also shared one of their RBC receptors with PvTRAg38 as well as with PvATRAg74. The erythrocyte binding activity of these six PvTRAgs was inhibited by the respective rabbit polyclonal antibodies as well as by the natural antibodies produced by the P. vivax exposed individuals. It is concluded that only selective few PvTRAgs show erythrocyte binding activity involving different receptor molecules which can be blocked by the natural antibodies. Further studies on these receptor and ligands may lead to the development of therapeutic reagents for P. vivax malaria.

Parasitoses of the human central nervous system

Cerebral involvement in parasitoses is an important clinical manifestation of most of the human parasitoses. Parasites that have been described to affect the central nervous system (CNS), either as the dominant or as a collateral feature, include cestodes (Taenia solium (neurocysticerciasis), Echinococcus granulosus (cerebral cystic echinococcosis), E. multilocularis (cerebral alveolar echinococcosis), Spirometra mansoni (neurosparganosis)), nematodes (Toxocara canis and T. cati (neurotoxocariasis), Trichinella spiralis (neurotrichinelliasis), Angiostrongylus cantonensis and A. costaricensis (neuroangiostrongyliasis), Gnathostoma spinigerum (gnathostomiasis)), trematodes (Schistosoma mansoni (cerebral bilharziosis), Paragonimus westermani (neuroparagonimiasis)), or protozoa (Toxoplasma gondii (neurotoxoplasmosis), Acanthamoeba spp. or Balamuthia mandrillaris (granulomatous amoebic encephalitis), Naegleria (primary amoebic meningo-encephalitis), Entamoeba histolytica (brain abscess), Plasmodium falciparum (cerebral malaria), Trypanosoma brucei gambiense/rhodesiense (sleeping sickness) or Trypanosoma cruzi (cerebral Chagas disease)). Adults or larvae of helminths or protozoa enter the CNS and cause meningitis, encephalitis, ventriculitis, myelitis, ischaemic stroke, bleeding, venous thrombosis or cerebral abscess, clinically manifesting as headache, epilepsy, weakness, cognitive decline, impaired consciousness, confusion, coma or focal neurological deficits. Diagnosis of cerebral parasitoses is dependent on the causative agent. Available diagnostic tools include clinical presentation, blood tests (eosinophilia, plasmodia in blood smear, antibodies against the parasite), cerebrospinal fluid (CSF) investigations, imaging findings and occasionally cerebral biopsy. Treatment relies on drugs and sometimes surgery. Outcome of cerebral parasitoses is highly variable, depending on the effect of drugs, whether they are self-limiting (e.g. Angiostrongylus costaricensis) or whether they remain undetected or asymptomatic, like 25% of neurocysticerciasis cases.

Severe Plasmodium vivax malaria among sudanese children at New Halfa Hospital, Eastern Sudan

BACKGROUND

There are few published reports on severe Plasmodium vivax malaria in Africa.

METHODS

Clinical pattern/manifestations of severe P. vivax were described in children admitted at New Halfa Hospital in Sudan between September 2009-December 2011.

RESULTS

Eighteen children were admitted at the hospital during the study period with different manifestations of severe P. vivax malaria namely: severe anaemia (6, 33.3%), jaundice (5, 27.8%), thrombocytopenia (4, 22.2%), hypotension (3, 16.7%), cerebral malaria (2, 11.1%), epistaxis (2, 11.1%), renal impairment (1, 5.5%), hypogylcaemia and more than one manifestation (5, 27.8%).

CONCLUSION

Severe P. vivax malaria is an existing entity in eastern Sudan. Further studies are required to understand emergence of severe P. vivax malaria.

Postmortem characterization of patients with clinical diagnosis of Plasmodium vivax malaria: to what extent does this parasite kill?

BACKGROUND

Severe disease attributable to Plasmodium vivax infection is already well described worldwide; however, autopsies in these patients are scarce.

METHODS

From 1996 to 2010, 19 patient deaths with a clinical diagnosis of P. vivax infection occurred in a tertiary care center in the Brazilian Amazon. Seventeen of these 19 deaths were fully autopsied. Clinical charts, macroscopic autopsy reports, and stored paraffinized tissue blocks were retrieved. Nested polymerase chain reaction was performed in paraffinized samples of spleen and lung to confirm P. vivax monoinfection. Immunohistofluorescence was used to detect P. vivax parasitized red blood cells (RBCs).

RESULTS

Of 17 autopsies, 13 revealed that death could be attributed to P. vivax infection; in the remaining 4, acute diseases other than malaria were found to be the cause of death. The primary complication in patients in which malaria contributed to death was acute respiratory distress syndrome (ARDS) and pulmonary edema associated with the accumulation of neutrophils in the interalveolar space (6 cases). Spleen rupture (3 cases) and multiorgan dysfunction syndrome (3 cases) were the second most common complications. One child evolving with coma was also characterized, but no parasite was detected in the brain tissue. In one patient who developed ARDS and presented negative peripheral parasitemia by the time of death, scattered parasitized red blood cells were seen inside pulmonary capillaries, suggesting some sequestration in the lung.

CONCLUSIONS

In 13 of 17 deceased patients, P. vivax infection was the plausible cause of death. However, more studies are needed to understand pathogenesis related to severe disease.

Renal cortical necrosis and acute kidney injury associated with Plasmodium vivax: a neglected human malaria parasite

Plasmodium vivax is causing increasingly more cases of severe malaria worldwide. There is an urgent need to reexamine the clinical spectrum and burden of P. vivax so that adequate control measures can be implemented against this emerging but neglected disease. Herein, we report a case of renal acute cortical necrosis and acute kidney injury (AKI) associated with P. vivax monoinfection. Her initial serum creatinine was 7.3 mg/dL on admission. Modification of Diet in Renal Disease (MDRD) Study glomerular filtration rate (GFR) value was 7 mL/min/1.73 m(2) (normal kidney function-GFR above 90 mL/min/1.73 m(2) and no proteinuria). On follow-up, 5 months later, her SCr. was 2.43 mg/dl with no proteinuria. MDRD GFR value was 24 mL/min/1.73 m(2) suggesting severe chronic kidney disease (CKD; GFR less than 60 or kidney damage for at least 3 months), stage 4. Our case report highlights the fact that P. vivax malaria is benign by name but not always by nature. AKI associated with P. vivax malaria can lead to CKD. Further studies are needed to determine why P. vivax infections are becoming more severe.

Malaria evolution in South Asia: knowledge for control and elimination

The study of malaria parasites on the Indian subcontinent should help us understand unexpected disease outbreaks and unpredictable disease presentations from Plasmodium falciparum and Plasmodium vivax infections. The Malaria Evolution in South Asia (MESA) research program is one of ten International Centers of Excellence for Malaria Research (ICEMR) sponsored by the US National Institutes of Health. In this second of two reviews, we describe why population structures of Plasmodia in India will be characterized and how we will determine their consequences on disease presentation, outcome and patterns. Specific projects will determine if genetic diversity, possibly driven by parasites with higher genetic plasticity, plays a role in changing epidemiology, pathogenesis, vector competence of parasite populations and whether innate human genetic traits protect Indians from malaria today. Deep local clinical knowledge of malaria in India will be supplemented by basic scientists who bring new research tools. Such tools will include whole genome sequencing and analysis methods; in vitro assays to measure genome plasticity, RBC cytoadhesion, invasion, and deformability; mosquito infectivity assays to evaluate changing parasite-vector compatibilities; and host genetics to understand protective traits in Indian populations. The MESA-ICEMR study sites span diagonally across India and include a mixture of very urban and rural hospitals, each with very different disease patterns and patient populations. Research partnerships include government-associated research institutes, private medical schools, city and state government hospitals, and hospitals with industry ties. Between 2012 and 2017, in addition to developing clinical research and basic science infrastructure at new clinical sites, our training workshops will engage new scientists and clinicians throughout South Asia in the malaria research field.