Malaria Retinopathy Research Articles

Prothrombotic autoantibodies targeting platelet factor 4/polyanion are associated with pediatric cerebral malaria.

BACKGROUNDFeatures of consumptive coagulopathy and thromboinflammation are prominent in cerebral malaria (CM). We hypothesized that thrombogenic autoantibodies contribute to a procoagulant state in CM.METHODSPlasma from children with uncomplicated malaria (UM) (n = 124) and CM (n = 136) was analyzed by ELISA for a panel of 8 autoantibodies including anti-platelet factor 4/polyanion (anti-PF4/P), anti-phospholipid, anti-phosphatidylserine, anti-myeloperoxidase, anti-proteinase 3, anti-dsDNA, anti-β-2-glycoprotein I, and anti-cardiolipin. Plasma samples from individuals with nonmalarial coma (NMC) (n = 49) and healthy controls (HCs) (n = 56) were assayed for comparison. Associations with clinical and immune biomarkers were determined using univariate and logistic regression analyses.RESULTSMedian anti-PF4/P and anti-PS IgG levels were elevated in individuals with malaria infection relative to levels in HCs (P < 0.001) and patients with NMC (PF4/P: P < 0.001). Anti-PF4/P IgG levels were elevated in children with CM (median = 0.27, IQR: 0.19-0.41) compared with those with UM (median = 0.19, IQR: 0.14-0.22, P < 0.0001). Anti-PS IgG levels did not differ between patients with UM and those with CM (P = 0.39). When patients with CM were stratified by malaria retinopathy (Ret) status, the levels of anti-PF4/P IgG correlated negatively with the peripheral platelet count in patients with Ret+ CM (Spearman's rho [Rs] = 0.201, P = 0.04) and associated positively with mortality (OR = 15.2, 95% CI: 1.02-275, P = 0.048). Plasma from patients with CM induced greater platelet activation in an ex vivo assay relative to plasma from patients with UM (P = 0.02), and the observed platelet activation was associated with anti-PF4/P IgG levels (Rs= 0.293, P = 0.035).CONCLUSIONSThrombosis mediated by elevated anti-PF4/P autoantibodies may be one mechanism contributing to the clinical complications of CM.

PARACENTRAL ACUTE MIDDLE MACULOPATHY ASSOCIATED WITH SEVERE PLASMODIUM FALCIPARUM MALARIA.

To report a case of bilateral paracentral acute middle maculopathy (PAMM) lesions on spectral domain-optical coherence tomography (SD-OCT) secondary to severe Plasmodium falciparum malaria. Retrospective case report. SD-OCT, ultra-widefield fluorescein angiography, and OCT-angiography were performed and analysed. A 54-year-old healthy man presented with acute vision loss in both eyes few days after being diagnosed with severe Plasmodium falciparum malaria. Ophthalmoscopic examination was unremarkable but near-infrared reflectance imaging showed patchy hyporeflective areas located at the terminal tips of the venous branches. Corresponding SD-OCT demonstrated alternating bands of hyperreflectivity involving the inner nuclear layer and consistent with skip PAMM lesions. OCT-angiography illustrated corresponding flow signal loss at the level of the deep capillary plexus. Ultra-widefield fluorescein angiography showed peripheral retinal vein staining and capillary non-perfusion. PAMM may be an OCT manifestation of malaria retinopathy associated with severe Plasmodium falciparum infection.

Cerebrospinal fluid biomarkers provide evidence for kidney-brain axis involvement in cerebral malaria pathogenesis.

Cerebral malaria is one of the most severe manifestations of malaria and is a leading cause of acquired neurodisability in African children. Recent studies suggest acute kidney injury (AKI) is a risk factor for brain injury in cerebral malaria. The present study evaluates potential mechanisms of brain injury in cerebral malaria by evaluating changes in cerebrospinal fluid measures of brain injury with respect to severe malaria complications. Specifically, we attempt to delineate mechanisms of injury focusing on blood-brain-barrier integrity and acute metabolic changes that may underlie kidney-brain crosstalk in severe malaria. We evaluated 30 cerebrospinal fluid (CSF) markers of inflammation, oxidative stress, and brain injury in 168 Ugandan children aged 18 months to 12 years hospitalized with cerebral malaria. Eligible children were infected with Plasmodium falciparum and had unexplained coma. Acute kidney injury (AKI) on admission was defined using the Kidney Disease: Improving Global Outcomes criteria. We further evaluated blood-brain-barrier integrity and malaria retinopathy, and electrolyte and metabolic complications in serum. The mean age of children was 3.8 years (SD, 1.9) and 40.5% were female. The prevalence of AKI was 46.3% and multi-organ dysfunction was common with 76.2% of children having at least one organ system affected in addition to coma. AKI and elevated blood urea nitrogen, but not other measures of disease severity (severe coma, seizures, jaundice, acidosis), were associated with increases in CSF markers of impaired blood-brain-barrier function, neuronal injury (neuron-specific enolase, tau), excitatory neurotransmission (kynurenine), as well as altered nitric oxide bioavailability and oxidative stress (p < 0.05 after adjustment for multiple testing). Further evaluation of potential mechanisms suggested that AKI may mediate or be associated with CSF changes through blood-brain-barrier disruption (p = 0.0014), ischemic injury seen by indirect ophthalmoscopy (p < 0.05), altered osmolality (p = 0.0006) and through alterations in the amino acids transported into the brain. In children with cerebral malaria, there is evidence of kidney-brain injury with multiple potential pathways identified. These changes were specific to the kidney and not observed in the context of other clinical complications.

Malaria Retinopathy among Under-Five Children with Severe and Uncomplicated Malaria in a Tertiary Health Institution in Southwest Nigeria: A Comparative Study

Malaria Retinopathy among Under-Five Children with Severe and Uncomplicated Malaria in a Tertiary Health Institution in Southwest Nigeria: A Comparative Study

Elevated Cerebrospinal Fluid Tau Protein Concentrations on Admission Are Associated With Long-term Neurologic and Cognitive Impairment in Ugandan Children With Cerebral Malaria.

Elevated concentrations of cerebrospinal fluid (CSF) tau, a marker of axonal injury, have been associated with coma in severe malaria (cerebral malaria [CM]). However, it is unknown whether axonal injury is related to long-term neurologic deficits and cognitive impairment in children with CM. Admission CSF tau concentrations were measured in 145 Ugandan children with CM and compared to clinical and laboratory factors and acute and chronic neurologic and cognitive outcomes. Elevated CSF tau concentrations were associated with younger age, increased disease severity (lower glucose and hemoglobin concentrations, malaria retinopathy, acute kidney injury, and prolonged coma duration, all P < .05), and an increased CSF:plasma albumin ratio, a marker of blood-brain barrier breakdown (P < .001). Admission CSF tau concentrations were associated with the presence of neurologic deficits at hospital discharge, and at 6, 12, and 24 months postdischarge (all P ≤ .02). After adjustment for potential confounding factors, elevated log10-transformed CSF tau concentrations correlated with worse cognitive outcome z scores over 2-year follow-up for associative memory (β coefficient, -0.31 [95% confidence interval [CI], -.53 to -.10]) in children <5 years of age, and for overall cognition (-0.69 [95% CI, -1.19 to -.21]), attention (-0.78 [95% CI, -1.34 to -.23]), and working memory (-1.0 [95% CI, -1.68 to -.31]) in children ≥5 years of age (all P < .006). Acute axonal injury in children with CM is associated with long-term neurologic deficits and cognitive impairment. CSF tau concentrations at the time of the CM episode may identify children at high risk of long-term neurocognitive impairment.

A retinal model of cerebral malaria

Malaria is a causative factor in about 500.000 deaths each year world-wide. Cerebral malaria is a particularly severe complication of this disease and thus associated with an exceedingly high mortality. Malaria retinopathy is an ocular manifestation often associated with cerebral malaria, and presumably shares a substantial part of its pathophysiology. Here, we describe that indeed murine malaria retinopathy reproduced the main hallmarks of the corresponding human disease. In the living animal, we were able to follow the circulation and cellular localization of malaria parasites transgenically labelled with GFP via non-invasive in vivo retinal imaging. We found that malaria parasites cross the blood-retinal-barrier and infiltrate the neuroretina, concomitant with an extensive, irreversible, and long-lasting retinal neurodegeneration. Furthermore, anti-malarial treatment with dihydroartemisinin strongly diminished the load of circulating parasites but resolved the symptoms of the retinopathy only in part. In summary, we introduce here a novel preclinical model for human cerebral malaria that is much more directly accessible for studies into disease pathophysiology and development of novel treatment approaches. In vivo retinal imaging may furthermore serve as a valuable tool for the early diagnosis of the human disease.

Long-Term Neurological Deficits in Child Survivors of Plasmodium falciparum Cerebral Malaria in Sub-Saharan Africa

Cerebral malaria, characterized by multiple seizures, coma, and other neurological abnormalities, is a particularly devastating complication of Plasmodium falciparum malaria. Children in sub-Saharan Africa comprise the most susceptible group to cerebral malaria worldwide, with more than 575,000 cases each year. Long-term neurological deficits—including motor impairments, language regression, cognitive deficits, behavioural abnormalities, and epilepsy—occur in approximately 25% of child survivors of cerebral malaria, which is now recognized as the leading cause of childhood neurodisability in sub-Saharan Africa. These neurological sequelae generate a significant economic and social burden as child survivors’ impaired intellectual function impacts their prospects for education and future employment. While current understanding of risk factors, disease mechanisms, and treatments for these neurological deficits is lacking, recent studies have shown great promise in revolutionizing the way that cerebral malaria is diagnosed and treated. It is speculated that during an acute attack of cerebral malaria, an inflammatory response to malarial antigens in neural blood vessels triggers a cascade of events that ultimately results in cerebral tissue damage and hemorrhaging into the brain, causing long-term brain damage. Potential risk factors for neurological deficits include the duration of coma, the occurrence of multiple seizures, and high fever. Malaria retinopathy and angiopoietin are being investigated as potential biomarkers to improve the definitive diagnosis of cerebral malaria. New drug therapies to prevent long-term neurological deficits after cerebral malaria include erythropoietin and statins, and cognitive rehabilitation and speech therapy have been shown to be successful in rehabilitating survivors.

Plasmodium falciparum Histidine-Rich Protein-2 Plasma Concentrations Are Higher in Retinopathy-Negative Cerebral Malaria Than in Severe Malarial Anemia.

BackgroundMalaria retinopathy has been proposed as marker of “true” cerebral malaria (CM), ie, coma due to Plasmodium falciparum vs coma due to other causes, with incidental P falciparum parasitemia. Plasma P falciparum histidine-rich protein-2 (PfHRP2) concentrations distinguish retinopathy-positive (RP) from retinopathy-negative (RN) CM but have not been compared between RN CM and other forms of severe malaria or asymptomatic parasitemia (AP).MethodsWe compared plasma PfHRP2 concentrations in 260 children with CM (247 examined for retinopathy), 228 children with severe malarial anemia (SMA), and 30 community children with AP.Results Plasmodium falciparum HRP2 concentrations were higher in children with RP CM than RN CM (P = .006), with an area under the receiver operating characteristic curve of 0.61 (95% confidence interval, 0.53–0.68). Plasmodium falciparum HRP2 concentrations and sequestered parasite biomass were higher in RN CM than SMA (both P < .03) or AP (both P < .001).Conclusions Plasmodium falciparum HRP2 concentrations are higher in children with RN CM than in children with SMA or AP, suggesting that P falciparum is involved in disease pathogenesis in children with CM. Plasmodium falciparum HRP2 concentrations may provide a more feasible and consistent assessment of the contribution of P falciparum to severe disease than malaria retinopathy.

Assessing malaria retinopathy with PEEK (personal eye examination kit)

Assessing malaria retinopathy with PEEK (personal eye examination kit)

Comparison of the effectiveness of three retinal camera technologies for malarial retinopathy detection in Malawi.

The purpose of this study was to test the suitability of three available camera technologies (desktop, portable, and i-phone based) for imaging comatose children who presented with clinical symptoms of malaria. Ultimately, the results of the project would form the basis for a design of a future camera to screen for malaria retinopathy (MR) in a resource challenged environment. The desktop, portable, and i-phone based cameras were represented by the Topcon, Pictor Plus, and Peek cameras, respectively. These cameras were tested on N=23 children presenting with symptoms of cerebral malaria (CM) at a malaria clinic, Queen Elizabeth Teaching Hospital in Malawi, Africa. Each patient was dilated for binocular indirect ophthalmoscopy (BIO) exam by an ophthalmologist followed by imaging with all three cameras. Each of the cases was graded according to an internationally established protocol and compared to the BIO as the clinical ground truth. The reader used three principal retinal lesions as markers for MR: hemorrhages, retinal whitening, and vessel discoloration. The study found that the mid-priced Pictor Plus hand-held camera performed considerably better than the lower price mobile phone-based camera, and slightly the higher priced table top camera. When comparing the readings of digital images against the clinical reference standard (BIO), the Pictor Plus camera had sensitivity and specificity for MR of 100% and 87%, respectively. This compares to a sensitivity and specificity of 87% and 75% for the i-phone based camera and 100% and 75% for the desktop camera. The drawback of all the cameras were their limited field of view which did not allow complete view of the periphery where vessel discoloration occurs most frequently. The consequence was that vessel discoloration was not addressed in this study. None of the cameras offered real-time image quality assessment to ensure high quality images to afford the best possible opportunity for reading by a remotely located specialist.

Malaria retinopathy and cerebellitis in a 9-year-old boy in the United States

Malarial retinopathy is characterized by retinal whitening, vessel change, and hemorrhages usually associated with a white center. We present the case of a 9-year-old boy who presented with a systemic Plasmodium falciparum infection, hemorrhagic cerebellitis and malarial retinopathy characterized by "fire flare" hemorrhages (scleral icterus with subconjunctival hemorrhages), Roth spot-like hemorrhages, and subhyaloid hemorrhage. To our knowledge, this is the first reported case of hemorrhagic cerebellitis secondary to P. falciparum infection in the United States.

Demonstration of Retinal Micro-emboli in a Case of Malaria Retinopathy by Fundus Fluorescein Angiography.

Demonstration of Retinal Micro-emboli in a Case of Malaria Retinopathy by Fundus Fluorescein Angiography.

Value of Plasmodium falciparum Histidine-Rich Protein 2 Level and Malaria Retinopathy in Distinguishing Cerebral Malaria From Other Acute Encephalopathies in Kenyan Children

Background. The diagnosis of cerebral malaria is problematic in malaria-endemic areas because encephalopathy in patients with parasitemia may have another cause. Abnormal retinal findings are thought to increase the specificity of the diagnosis, and the level of histidine-rich protein 2 (HRP2) may reflect the parasite biomass.Methods. We examined the retina and measured plasma HRP2 levels in children with acute nontraumatic encephalopathy in Kenya. Logistic regression, with HRP2 level as an independent variable and World Health Organization–defined cerebral malaria and/or retinopathy as the outcome, was used to calculate malaria-attributable fractions (MAFs) and retinopathy-attributable fractions (RAFs).Results. Of 270 children, 140 (52%) had peripheral parasitemia, 80 (30%) had malaria retinopathy, and 164 (61%) had an HRP2 level of >0 U/mL. During 2006–2011, the incidence of HRP2 positivity among admitted children declined by 49 cases per 100 000 per year (a 78% reduction). An HRP2 level of >0 U/mL had a MAF of 93% for cerebral malaria, with a MAF of 97% observed for HRP2 levels of ≥10 U/mL (the level of the best combined sensitivity and specificity). HRP2 levels of >0 U/mL had a RAF of 77% for features of retinopathy combined, with the highest RAFs for macular whitening (99%), peripheral whitening (98%), and hemorrhages (90%).Conclusion. HRP2 has a high attributable fraction for features of malarial retinopathy, supporting its use in the diagnosis of cerebral malaria. HRP2 thresholds improve the specificity of the definition.

Seasonal Differences in Retinopathy-Negative versus Retinopathy-Positive Cerebral Malaria

Children with traditionally defined cerebral malaria (CM) can be subcategorized by the presence or absence of malaria retinopathy. We retrospectively reviewed the seasonal pattern of retinopathy status in patients admitted with CM in Blantyre, Malawi from 1997 to 2010. The proportion of children with CM who were retinopathy-positive was significantly greater during the peak seasonal rains when the community incidence of uncomplicated malaria is higher. This finding supports the hypothesis that retinopathy-negative and retinopathy-positive CM categories have different underlying etiologies.

Neurologic outcomes in retinopathy-negative cerebral malaria survivors

Patients surviving retinopathy-positive cerebral malaria (CM) are at high risk for the development of epilepsy, developmental disabilities, and behavioral abnormalities. We aimed to establish whether retinopathy-negative CM is also a risk factor for these outcomes. Between 2005 and 2007, survivors of CM and concurrently hospitalized controls in Blantyre, Malawi, were followed to assess the development of neurologic abnormalities. At discharge and every 3 months thereafter, incident cases of epilepsy and developmental disabilities were ascertained using screening questionnaires and confirmatory neurologic examinations. Incident cases of epilepsy and developmental disabilities were compared in retinopathy-negative CM survivors to controls and retinopathy-positive CM survivors. Thirty-five retinopathy-negative CM survivors were enrolled. Their neurologic outcomes were compared to 132 retinopathy-positive CM survivors and 272 controls. Compared to survivors of retinopathy-positive CM, children without malaria retinopathy have an equal odds of adverse neurologic outcome (odds ratio [OR] = 1.0, 95% confidence interval [CI] 0.4-2.2). Eleven of 35 survivors of retinopathy-negative CM had at least 1 adverse neurologic outcome compared to 2 of 272 controls (OR 61.9, 95% CI 13.0-295.5). In retinopathy-negative CM survivors, a Blantyre Coma Scale score ≤ 1 on admission was associated with an adverse outcome. Compared with controls, children surviving either retinopathy-negative or -positive CM are at similar high risk for adverse neurologic outcomes. Studies to evaluate preventive and therapeutic strategies in children with both retinopathy-negative and -positive CM are needed to improve mortality, morbidity, or both.

Transcriptional Profiling of Plasmodium falciparum Parasites from Patients with Severe Malaria Identifies Distinct Low vs. High Parasitemic Clusters

BackgroundIn the past decade, estimates of malaria infections have dropped from 500 million to 225 million per year; likewise, mortality rates have dropped from 3 million to 791,000 per year. However, approximately 90% of these deaths continue to occur in sub-Saharan Africa, and 85% involve children less than 5 years of age. Malaria mortality in children generally results from one or more of the following clinical syndromes: severe anemia, acidosis, and cerebral malaria. Although much is known about the clinical and pathological manifestations of CM, insights into the biology of the malaria parasite, specifically transcription during this manifestation of severe infection, are lacking.Methods and FindingsWe collected peripheral blood from children meeting the clinical case definition of cerebral malaria from a cohort in Malawi, examined the patients for the presence or absence of malaria retinopathy, and performed whole genome transcriptional profiling for Plasmodium falciparum using a custom designed Affymetrix array. We identified two distinct physiological states that showed highly significant association with the level of parasitemia. We compared both groups of Malawi expression profiles with our previously acquired ex vivo expression profiles of parasites derived from infected patients with mild disease; a large collection of in vitro Plasmodium falciparum life cycle gene expression profiles; and an extensively annotated compendium of expression data from Saccharomyces cerevisiae. The high parasitemia patient group demonstrated a unique biology with elevated expression of Hrd1, a member of endoplasmic reticulum-associated protein degradation system.ConclusionsThe presence of a unique high parasitemia state may be indicative of the parasite biology of the clinically recognized hyperparasitemic severe disease syndrome.

Accurate Diagnosis of Cerebral Malaria: A Role for Parasite Histidine-Rich Protein 2?

moderate transmission, plasma concentrations of pHRP2 appear to correspond well to body parasite biomass [5]. Elevated pHRP2 concentrations may, therefore, reflect a high level of sequestered parasites. In the current issue of the journal, Seydel and colleagues provide evidence that high pHRP2 concentrations are an excellent marker for biopsyor retinopathy-confirmed cerebral malaria [6]. The study design has several strengths that boost confidence in the accuracy of its findings, including the use of 3 study groups, which allowed for initial testing, establishment of an optimized pHRP2 cutoff level, and prospective assessment of the sensitivity and specificity of that cutoff level. The first study group consisted of children with WHO-defined cerebral malaria who died. The pHRP2 concentrations in children with autopsy-confirmed parasite sequestration were compared with the pHRP2 concentrations in those without sequestration. The pHRP2 concentrations distinguished almost perfectly between the 2 groups (area under receiver operating characteristic curve, 0.98). The second study group consisted of children from an earlier study who had WHOdefined cerebral malaria and who did (cases) or did not (controls) have malaria retinopathy. The pHRP2 concentrations in this group were used to identify a cutoff

Plasma Concentrations of Parasite Histidine-Rich Protein 2 Distinguish Between Retinopathy-Positive and Retinopathy-Negative Cerebral Malaria in Malawian Children

Brain histology and ophthalmoscopy suggest that approximately 25% of children with World Health Organization-defined cerebral malaria (CM) have a nonmalarial cause of death. Misclassification complicates clinical care, confounds studies of association, and may obfuscate successes in malaria control. Retinopathy predicts intracerebral parasite sequestration with >90% sensitivity and specificity, but detecting retinopathy requires well-trained personnel and expensive equipment. We investigated the utility of plasma concentrations of parasite histidine-rich protein 2 (pHRP2), a Plasmodium-specific protein, as a predictor of intracerebral parasite sequestration at autopsy and of malaria retinopathy on clinical examination in patients with clinically defined CM. In 64 autopsy cases, 47 of whom had histological evidence of sequestration, the sensitivity and specificity of a plasma pHRP2 level of >1700 ng/mL were 98% and 94%, respectively, and the area under the receiver operating characteristic (AUROC) curve was 0.98. In a separate, prospectively studied group of 101 children with clinically defined CM, of whom 71 had retinopathy, the same pHRP2 cutoff predicted retinopathy-positivity with a sensitivity of 90% and specificity of 87% (AUROC, 0.90). Elevated plasma pHRP2 concentrations can identify Malawian children with histologically confirmed or retinopathy-positive CM and is a more field-friendly approach to confirming the diagnosis than post mortem sampling or ophthalmoscopy.

Acute Brain MRI Findings in 120 Malawian Children with Cerebral Malaria: New Insights into an Ancient Disease

There have been few neuroimaging studies of pediatric CM, a common often fatal tropical condition. We undertook a prospective study of pediatric CM to better characterize the MRI features of this syndrome, comparing findings in children meeting a stringent definition of CM with those in a control group who were infected with malaria but who were likely to have a nonmalarial cause of coma. Consecutive children admitted with traditionally defined CM (parasitemia, coma, and no other coma etiology evident) were eligible for this study. The presence or absence of malaria retinopathy was determined. MRI findings in children with ret+ CM (patients) were compared with those with ret- CM (controls). Two radiologists blinded to retinopathy status jointly developed a scoring procedure for image interpretation and provided independent reviews. MRI findings were compared between patients with and without retinopathy, to assess the specificity of changes for patients with very strictly defined CM. Of 152 children with clinically defined CM, 120 were ret+, and 32 were ret-. Abnormalities much more common in the patients with ret+ CM were markedly increased brain volume; abnormal T2 signal intensity; and DWI abnormalities in the cortical, deep gray, and white matter structures. Focal abnormalities rarely respected arterial vascular distributions. Most of the findings in the more clinically heterogeneous ret- group were normal, and none of the abnormalities noted were more prevalent in controls. Distinctive MRI findings present in patients meeting a stringent definition of CM may offer insights into disease pathogenesis and treatment.

A better biomarker for cerebral malaria

A better biomarker for cerebral malaria