Imported congenital malaria caused by Plasmodium ovale: A case report.

We describe a 5-week-old term infant with Plasmodium ovale severe congenital malaria in a non-endemic setting. She presented with diarrhea, poor feeding, lethargy, hepatosplenomegaly, and severe anemia. She was fortuitously diagnosed with malaria on routine blood smear, and successfully treated with intravenous artesunate. Subsequent history revealed maternal malaria diagnosis and treatment during pregnancy in Nigeria. This case underscores the importance of obtaining maternal exposure history and considering malaria testing in pregnant women and infants with unexplained illness. It also contributes to the limited literature on congenital malaria and severe malaria caused by P. ovale.

Children hospitalized with community-acquired pneumonia complicated by effusion: a single-centre retrospective cohort study.

OBJECTIVES: To describe children hospitalized with community-acquired pneumonia complicated by effusion (cCAP). DESIGN: Retrospective cohort study. SETTING: A Canadian children's hospital. PARTICIPANTS: Children without significant medical comorbidities aged < 18 years admitted from January 2015-December 2019 to either the Paediatric Medicine or Paediatric General Surgery services with any pneumonia discharge code who were documented to have an effusion/empyaema using ultrasound. OUTCOME MEASURES: Length of stay; admission to the paediatric intensive care unit; microbiologic diagnosis; antibiotic use. RESULTS: There were 109 children without significant medical comorbidities hospitalized for confirmed cCAP during the study period. Their median length of stay was 9 days (Q1-Q3 6-11 days) and 35/109 (32%) were admitted to the paediatric intensive care unit. Most (89/109, 74%) underwent procedural drainage. Length of stay was not associated with effusion size but was associated with time to drainage (0.60 days longer stay per day delay in drainage, 95%CI 0.19-1.0 days). Microbiologic diagnosis was more often made via molecular testing of pleural fluids (43/59, 73%) than via blood culture (12/109, 11%); the main aetiologic pathogens were S. pneumoniae (40/109, 37%), S. pyogenes (15/109, 14%), and S. aureus (7/109, 6%). Discharge on a narrow spectrum antibiotic (i.e. amoxicillin) was much more common when the cCAP pathogen was identified as compared to when it was not (68% vs. 24%, p < 0.001). CONCLUSIONS: Children with cCAP were commonly hospitalized for prolonged periods. Prompt procedural drainage was associated with shorter hospital stays. Pleural fluid testing often facilitated microbiologic diagnosis, which itself was associated with more appropriate antibiotic therapy.

Therapeutic Drug Monitoring of Moxifloxacin to Guide Treatment of Mycoplasma hominis Meningitis in an Extremely Preterm Infant.

Mycoplasma hominis (M hominis) is a rare cause of neonatal bacterial meningitis. Treatment can be challenging because of M hominis' intrinsic antibiotic resistance and the difficulty in accessing antimicrobial susceptibility testing. In this report, we describe an extremely preterm male infant with seizures who had a subsequent diagnosis of M hominis meningitis. Because of severity of illness, doxycycline (4 mg/kg IV every 24 hours) and moxifloxacin (5 mg/kg IV every 24 hours) were started empirically. Repeat cerebrospinal fluid cultures were negative and showed decreasing pleiocytosis. Given the concentration-dependent killing of moxifloxacin and concern for endovascular infection from a concomitant cerebral venous sinus thrombosis, serum concentrations of moxifloxacin were obtained to estimate pharmacokinetic and pharmacodynamic parameters. These were compared to the targets described in other case reports of M hominis meningitis. The maximum serum concentration (Cmax) was 2.5 mg/L, volume of distribution was 2.2 L/kg, clearance was 0.18 L/kg/hr, terminal half-life was 8.6 hours, and area-under-the-concentration-time curve (AUC) was 28.1 mg•hr/L. Using the range of minimum inhibitory concentrations (MICs) reported in the literature, the estimated Cmax/MIC for this patient was 21 to 158 (target Cmax/MIC: >10) and AUC/MIC was 234 to 1757 (target AUC/MIC: ≥100). Doxycycline and moxifloxacin were continued for 6 weeks. No adverse events to moxifloxacin or doxycycline were observed in the NICU. This report describes the successful treatment of M hominis neonatal meningitis and adds to the knowledge of pharmacokinetic and pharmacodynamic parameters of moxifloxacin in neonates. Additional data will help to confirm the role for routine therapeutic drug monitoring of moxifloxacin in neonates.

Clinical manifestations and health outcomes associated with Zika virus infections in adults: A systematic review.

BACKGROUND: Zika virus (ZIKV) has generated global interest in the last five years mostly due to its resurgence in the Americas between 2015 and 2016. It was previously thought to be a self-limiting infection causing febrile illness in less than one quarter of those infected. However, a rise in birth defects amongst children born to infected pregnant women, as well as increases in neurological manifestations in adults has been demonstrated. We systemically reviewed the literature to understand clinical manifestations and health outcomes in adults globally. METHODS: This review was registered prospectively with PROPSERO (CRD 42018096558). We systematically searched for studies in six databases from inception to the end of September 2020. There were no language restrictions. Critical appraisal was completed using the Joanna Briggs Institute Critical Appraisal Tools. FINDINGS: We identified 73 studies globally that reported clinical outcomes in ZIKV-infected adults, of which 55 studies were from the Americas. For further analysis, we considered studies that met 70% of critical appraisal criteria and described subjects with confirmed ZIKV. The most common symptoms included: exanthema (5,456/6,129; 89%), arthralgia (3,809/6,093; 63%), fever (3,787/6,124; 62%), conjunctivitis (2,738/3,283; 45%), myalgia (2,498/5,192; 48%), headache (2,165/4,722; 46%), and diarrhea (337/2,622; 13%). 36/14,335 (0.3%) of infected cases developed neurologic sequelae, of which 75% were Guillain-Barré Syndrome (GBS). Several subjects reported recovery from peak of neurological complications, though some endured chronic disability. Mortality was rare (0.1%) and hospitalization (11%) was often associated with co-morbidities or GBS. CONCLUSIONS: The ZIKV literature in adults was predominantly from the Americas. The most common systemic symptoms were exanthema, fever, arthralgia, and conjunctivitis; GBS was the most prevalent neurological complication. Future ZIKV studies are warranted with standardization of testing and case definitions, consistent co-infection testing, reporting of laboratory abnormalities, separation of adult and pediatric outcomes, and assessing for causation between ZIKV and neurological sequelae.

A common TLR1 polymorphism is associated with higher parasitaemia in a Southeast Asian population with Plasmodium falciparum malaria.

BACKGROUND: The factors leading to poor outcomes in malaria infection are incompletely understood. Common genetic variation exists in the human genes for Toll like receptors (TLRs) that alter host responses to pathogen-associated molecular patterns. Genetic variation in TLR1 and TLR6 could alter the risk of development of complicated malaria and ability of the host to control the parasite burden during acute Plasmodium falciparum infection. METHODS: Five single nucleotide polymorphisms in TLR1 and TLR6 in 432 patients with clinical P. falciparum monoinfection acquired on the Thai-Myanmar border were genotyped. Using logistic regression, associations with the development of complicated malaria and the percentage of infected erythrocytes (parasitaemia) on the day of presentation to clinical care (day zero) were tested. RESULTS: Genotypes carrying the T (major) allele of TLR1 rs5743551--an allele associated with improved outcomes in sepsis--were associated with higher parasitaemia measured on day zero (p = 0.03). DISCUSSION: Since malaria exerts strong genetic pressure on the human genome, protection from parasitaemia associated with TLR1 rs5743551 may account for the maintenance of an allele associated with poor outcomes in Caucasians with sepsis. CONCLUSION: These data suggest that genetic variation in TLR1 has effects on the host response to Plasmodium falciparum malaria in Asian populations. Genotypes from TLR6 showed no evidence of association with either complicated malaria or parasite burden.

Biomarkers of Host Response Predict Primary End-Point Radiological Pneumonia in Tanzanian Children with Clinical Pneumonia: A Prospective Cohort Study.

BACKGROUND: Diagnosing pediatric pneumonia is challenging in low-resource settings. The World Health Organization (WHO) has defined primary end-point radiological pneumonia for use in epidemiological and vaccine studies. However, radiography requires expertise and is often inaccessible. We hypothesized that plasma biomarkers of inflammation and endothelial activation may be useful surrogates for end-point pneumonia, and may provide insight into its biological significance. METHODS: We studied children with WHO-defined clinical pneumonia (n = 155) within a prospective cohort of 1,005 consecutive febrile children presenting to Tanzanian outpatient clinics. Based on x-ray findings, participants were categorized as primary end-point pneumonia (n = 30), other infiltrates (n = 31), or normal chest x-ray (n = 94). Plasma levels of 7 host response biomarkers at presentation were measured by ELISA. Associations between biomarker levels and radiological findings were assessed by Kruskal-Wallis test and multivariable logistic regression. Biomarker ability to predict radiological findings was evaluated using receiver operating characteristic curve analysis and Classification and Regression Tree analysis. RESULTS: Compared to children with normal x-ray, children with end-point pneumonia had significantly higher C-reactive protein, procalcitonin and Chitinase 3-like-1, while those with other infiltrates had elevated procalcitonin and von Willebrand Factor and decreased soluble Tie-2 and endoglin. Clinical variables were not predictive of radiological findings. Classification and Regression Tree analysis generated multi-marker models with improved performance over single markers for discriminating between groups. A model based on C-reactive protein and Chitinase 3-like-1 discriminated between end-point pneumonia and non-end-point pneumonia with 93.3% sensitivity (95% confidence interval 76.5-98.8), 80.8% specificity (72.6-87.1), positive likelihood ratio 4.9 (3.4-7.1), negative likelihood ratio 0.083 (0.022-0.32), and misclassification rate 0.20 (standard error 0.038). CONCLUSIONS: In Tanzanian children with WHO-defined clinical pneumonia, combinations of host biomarkers distinguished between end-point pneumonia, other infiltrates, and normal chest x-ray, whereas clinical variables did not. These findings generate pathophysiological hypotheses and may have potential research and clinical utility.

Chitinase 3-like 1 is induced by Plasmodium falciparum malaria and predicts outcome of cerebral malaria and severe malarial anaemia in a case-control study of African children.

BACKGROUND: Severe and fatal malaria are associated with dysregulated host inflammatory responses to infection. Chitinase 3-like 1 (CHI3L1) is a secreted glycoprotein implicated in regulating immune responses. Expression and function of CHI3L1 in malaria infection were investigated. METHODS: Plasma levels of CHI3L1 were quantified in a case-control study of Ugandan children presenting with Plasmodium falciparum malaria. CHI3L1 levels were compared in children with uncomplicated malaria (UM; n = 53), severe malarial anaemia (SMA; n = 59) and cerebral malaria (CM; n = 44) using the Kruskall Wallis-test, and evaluated for utility in predicting fatal (n = 23) versus non-fatal (n = 80) outcomes in severe disease using the Mann Whitney U test, receiver operating characteristic curves, and combinatorial analysis. Co-culture of P. falciparum with human peripheral blood mononuclear cells and the Plasmodium berghei ANKA experimental model of cerebral malaria were used to examine the role of CHI3L1 in severe malaria. RESULTS: In children presenting with falciparum malaria, CHI3L1 levels were increased in SMA and CM versus UM (p < 0.001). Among severe malaria cases, CHI3L1 levels at presentation predicted subsequent death (area under receiver operating characteristic curve 0.84 [95% CI 0.76-0.92]) and in combination with other host biomarkers, predicted mortality with high sensitivity (100% [85.7-100]) and specificity (81.3% [71.3-88.3]). Plasmodium falciparum stimulated CHI3L1 production by human peripheral blood mononuclear cells in vitro. CHI3L1 was increased in plasma and brain tissue in experimental cerebral malaria, but targeted Chi3l1 deletion did not alter cytokine production or survival in this model. CONCLUSIONS: These data suggest that plasma CHI3L1 measured at presentation correlates with malaria severity and predicts outcome in paediatric SMA and CM, but do not support a causal role for CHI3L1 in cerebral malaria pathobiology in the model tested.

Functional roles for C5a and C5aR but not C5L2 in the pathogenesis of human and experimental cerebral malaria.

The host immune response plays an important role in the onset and progression of cerebral malaria (CM). The complement system is an essential component of the innate immune response to malaria, and its activation generates the anaphylatoxin C5a. To test the hypothesis that C5a signaling contributes to the pathogenesis of CM, we investigated a causal role for the C5a receptors C5aR and C5L2 in a mouse model of experimental CM (ECM) induced by Plasmodium berghei ANKA infection, and using a case-control design, we examined levels of C5a in plasma samples from Ugandan children presenting with CM or uncomplicated malaria (UM). In the ECM model, C5aR(-/-) mice displayed significantly improved survival compared to their wild-type (WT) counterparts (P = 0.004), whereas C5L2(-/-) mice showed no difference in survival from WT mice. Improved survival in C5aR(-/-) mice was associated with reduced levels of the proinflammatory cytokines tumor necrosis factor (TNF) and gamma interferon (IFN-γ) and the chemokine, monocyte chemoattractant protein 1 (MCP-1) (CCL2). Furthermore, endothelial integrity was enhanced, as demonstrated by increased levels of angiopoietin-1, decreased levels of angiopoietin-2 and soluble ICAM-1, and decreased Evans blue extravasation into brain parenchyma. In the case-control study, the median levels of C5a at presentation were significantly higher in children with CM versus those in children with UM (43.7 versus 22.4 ng/ml; P < 0.001). These findings demonstrate that C5a is dysregulated in human CM and contributes to the pathogenesis of ECM via C5aR-dependent inflammation and endothelial dysfunction.

Angiopoietin-2 levels are associated with retinopathy and predict mortality in Malawian children with cerebral malaria: a retrospective case-control study*.

OBJECTIVE: To investigate the relationship among the angiopoietin-Tie-2 system, retinopathy, and mortality in children with cerebral malaria. DESIGN: A case-control study of retinopathy-positive vs. retinopathy-negative children with clinically defined cerebral malaria. SETTING: Queen Elizabeth Central Hospital in Blantyre, Malawi. SUBJECTS: One hundred fifty-five children presenting with severe malaria and meeting a strict definition of clinical cerebral malaria (Blantyre Coma Score ≤ 2, Plasmodium falciparum parasitemia, no other identifiable cause for coma) were included in the study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical and laboratory parameters were recorded at admission and funduscopic examinations were performed. Admission levels of angiopoietin-1, angiopoietin-2, and a soluble version of their cognate receptor were measured by enzyme-linked immunosorbent assay. We show that angiopoietin-1 levels are decreased and angiopoietin-2 and soluble Tie-2 levels are increased in children with cerebral malaria who had retinopathy compared with those who did not. Angiopoietin-2 and soluble Tie-2 were independent predictors of retinopathy (adjusted odds ratio [95% CI], angiopoietin-2, 4.3 [1.3-14.6], p = .019; soluble Tie-2, 9.7 [2.1-45.8], p = .004). Angiopoietin-2 and soluble Tie-2 were positively correlated with the number of hemorrhages, the severity or retinal whitening, and the extent of capillary whitening observed on funduscopic examination (p < .05 after adjustment for multiple comparisons). Angiopoietin-2 and soluble Tie-2 levels were elevated in children with cerebral malaria who subsequently died and angiopoetin-2 was an independent predictor of death (adjusted odds ratio: 3.9 [1.2-12.7], p = .024). When combined with clinical parameters, angiopoetin-2 improved prediction of mortality using logistic regression models and classification trees. CONCLUSIONS: These results provide insights into mechanisms of endothelial activation in cerebral malaria and indicate that the angiopoietin-Tie-2 axis is associated with retinopathy and mortality in pediatric cerebral malaria.

Taking the sting out of malaria.

The innate immune response to malaria is a major determinant of disease severity and outcome. In this issue of Immunity, Sharma et al. (2011) provide evidence of a unique DNA sensing pathway that may contribute to immunopathology in plasmodial infections.

Combinations of host biomarkers predict mortality among Ugandan children with severe malaria: a retrospective case-control study.

BACKGROUND: Severe malaria is a leading cause of childhood mortality in Africa. However, at presentation, it is difficult to predict which children with severe malaria are at greatest risk of death. Dysregulated host inflammatory responses and endothelial activation play central roles in severe malaria pathogenesis. We hypothesized that biomarkers of these processes would accurately predict outcome among children with severe malaria. METHODOLOGY/FINDINGS: Plasma was obtained from children with uncomplicated malaria (n = 53), cerebral malaria (n = 44) and severe malarial anemia (n = 59) at time of presentation to hospital in Kampala, Uganda. Levels of angiopoietin-2, von Willebrand Factor (vWF), vWF propeptide, soluble P-selectin, soluble intercellular adhesion molecule-1 (ICAM-1), soluble endoglin, soluble FMS-like tyrosine kinase-1 (Flt-1), soluble Tie-2, C-reactive protein, procalcitonin, 10 kDa interferon gamma-induced protein (IP-10), and soluble triggering receptor expressed on myeloid cells-1 (TREM-1) were determined by ELISA. Receiver operating characteristic (ROC) curve analysis was used to assess predictive accuracy of individual biomarkers. Six biomarkers (angiopoietin-2, soluble ICAM-1, soluble Flt-1, procalcitonin, IP-10, soluble TREM-1) discriminated well between children who survived severe malaria infection and those who subsequently died (area under ROC curve>0.7). Combinational approaches were applied in an attempt to improve accuracy. A biomarker score was developed based on dichotomization and summation of the six biomarkers, resulting in 95.7% (95% CI: 78.1-99.9) sensitivity and 88.8% (79.7-94.7) specificity for predicting death. Similar predictive accuracy was achieved with models comprised of 3 biomarkers. Classification tree analysis generated a 3-marker model with 100% sensitivity and 92.5% specificity (cross-validated misclassification rate: 15.4%, standard error 4.9%). CONCLUSIONS: We identified novel host biomarkers of pediatric severe and fatal malaria (soluble TREM-1 and soluble Flt-1) and generated simple biomarker combinations that accurately predicted death in an African pediatric population. While requiring validation in further studies, these results suggest the utility of combinatorial biomarker strategies as prognostic tests for severe malaria.

Caspase-12 dampens the immune response to malaria independently of the inflammasome by targeting NF-kappaB signaling.

Pathogen sensing by the inflammasome activates inflammatory caspases that mediate inflammation and cell death. Caspase-12 antagonizes the inflammasome and NF-κB and is associated with susceptibility to bacterial sepsis. A single-nucleotide polymorphism (T(125)C) in human Casp12 restricts its expression to Africa, Southeast Asia, and South America. Here, we investigated the role of caspase-12 in the control of parasite replication and pathogenesis in malaria and report that caspase-12 dampened parasite clearance in blood-stage malaria and modulated susceptibility to cerebral malaria. This response was independent of the caspase-1 inflammasome, as casp1(-/-) mice were indistinguishable from wild-type animals in response to malaria, but dependent on enhanced NF-κB activation. Mechanistically, caspase-12 competed with NEMO for association with IκB kinase-α/ß, effectively preventing the formation of the IκB kinase complex and inhibiting downstream transcriptional activation by NF-κB. Systemic inhibition of NF-κB or Ab neutralization of IFN-γ reversed the increased resistance of casp12(-/-) mice to blood-stage malaria infection.

CD36 and TLR interactions in inflammation and phagocytosis: implications for malaria.

CD36 participates in macrophage internalization of a variety of particles, and has been implicated in inflammatory responses to many of these ligands. To what extent CD36 cooperates with other receptors in mediating these processes remains unclear. Because CD36 has been shown to cooperate with TLR2, we investigated the roles and interactions of CD36 and TLRs in inflammation and phagocytosis. Using Ab-induced endocytosis of CD36 and phagocytosis of erythrocytes displaying Abs to CD36, we show that selective engagement and internalization of this receptor did not lead to proinflammatory cytokine production by primary human and murine macrophages. In addition, CD36-mediated phagocytosis of Plasmodium falciparum malaria-parasitized erythrocytes (PEs), which contain parasite components that activate TLRs, also failed to induce cytokine secretion from primary macrophages. Furthermore, we demonstrate that CD36-mediated internalization did not require TLR2 or the TLR-signaling molecule IRAK4. However, macrophage pretreatment with TLR agonists markedly stimulated particle uptake via CD36. Similarly, PE uptake was unaffected by TLR deficiency, but in wild-type cells was increased by pretreatment with purified P. falciparum glycosylphosphatidylinositols, which activate TLR2. Our findings indicate that CD36 must cooperate with other receptors such as TLRs to participate in cytokine responses. Although purified P. falciparum components activate TLRs, CD36-mediated internalization of intact PEs is not inflammatory. Further, CD36 mediates internalization of particles, including PEs, independently of TLR signaling, but can functionally cooperate with TLRs to enhance internalization.

Inflammatory pathways in malaria infection: TLRs share the stage with other components of innate immunity.

Severe forms of malaria infection claim over 1 million lives annually. One aspect of severe malaria pathogenesis is an excessive or dysregulated inflammatory response to infection. With the characterization of Toll-like receptors (TLRs), which initiate inflammation upon detection of microbial products, involvement of TLRs in the host response to malaria has undergone intense investigation. While TLRs appear to mediate inflammation in malaria infection and may contribute to development of severe malaria, it is unlikely that they operate in isolation from other components of innate immunity. Here, we highlight recent findings implicating other innate immune mechanisms in the host inflammatory response to malaria, propose how they may integrate and synergize with TLR pathways, and discuss opportunities and challenges associated with anti-inflammatory adjunctive therapy for the treatment of severe malaria.

Molecular diagnostic and surveillance tools for global malaria control.

Malaria is the most devastating parasitic infection in the world, annually causing over 1 million deaths and extensive morbidity. The global burden of malaria has increased over the last several decades, as have rates of imported malaria into non-endemic regions. Rapid and accurate diagnostics are a crucial component of malaria control strategies, and epidemiological surveillance is required to monitor trends in malaria prevalence and antimalarial drug resistance. Conventional malaria diagnostic and surveillance tools can be cumbersome and slow with limitations in both sensitivity and specificity. New molecular techniques have been developed in an attempt to overcome these restrictions. These molecular techniques are discussed with regard to their technical advantages and disadvantages, with an emphasis on the practicality of implementation in malaria-endemic and non-endemic regions.

Teichoic acid is an essential polymer in Bacillus subtilis that is functionally distinct from teichuronic acid.

Wall teichoic acids are anionic, phosphate-rich polymers linked to the peptidoglycan of gram-positive bacteria. In Bacillus subtilis, the predominant wall teichoic acid types are poly(glycerol phosphate) in strain 168 and poly(ribitol phosphate) in strain W23, and they are synthesized by the tag and tar gene products, respectively. Growing evidence suggests that wall teichoic acids are essential in B. subtilis; however, it is widely believed that teichoic acids are dispensable under phosphate-limiting conditions. In the work reported here, we carefully studied the dispensability of teichoic acid under phosphate-limiting conditions by constructing three new mutants. These strains, having precise deletions in tagB, tagF, and tarD, were dependent on xylose-inducible complementation from a distal locus (amyE) for growth. The tarD deletion interrupted poly(ribitol phosphate) synthesis in B. subtilis and represents a unique deletion of a tar gene. When teichoic acid biosynthetic proteins were depleted, the mutants showed a coccoid morphology and cell wall thickening. The new wall teichoic acid biogenesis mutants generated in this work and a previously reported tagD mutant were not viable under phosphate-limiting conditions in the absence of complementation. Cell wall analysis of B. subtilis grown under phosphate-limited conditions showed that teichoic acid contributed approximately one-third of the wall anionic content. These data suggest that wall teichoic acid has an essential function in B. subtilis that cannot be replaced by teichuronic acid.