The impact of malaria-protective red blood cell polymorphisms on parasite biomass in children with severe Plasmodium falciparum malaria.

Severe falciparum malaria is a major cause of preventable child mortality in sub-Saharan Africa. Plasma concentrations of P. falciparum Histidine-Rich Protein 2 (PfHRP2) have diagnostic and prognostic value in severe malaria. We investigate the potential use of plasma PfHRP2 and the sequestration index (the ratio of PfHRP2 to parasite density) as quantitative traits for case-only genetic association studies of severe malaria. Data from 2198 Kenyan children diagnosed with severe malaria, genotyped for 14 major candidate genes, show that polymorphisms in four major red cell genes that lead to hemoglobin S, O blood group, α-thalassemia, and the Dantu blood group, are associated with substantially lower admission plasma PfHRP2 concentrations, consistent with protective effects against extensive parasitized erythrocyte sequestration. In contrast the known protective ATP2B4 polymorphism is associated with higher plasma PfHRP2 concentrations, lower parasite densities and a higher sequestration index. We provide testable hypotheses for the mechanism of protection of ATP2B4.

Randomised controlled trial of oxygen therapy and high-flow nasal therapy in African children with pneumonia.

PURPOSE: The life-saving role of oxygen therapy in African children with severe pneumonia is not yet established. METHODS: The open-label fractional-factorial COAST trial randomised eligible Ugandan and Kenyan children aged > 28 days with severe pneumonia and severe hypoxaemia stratum (SpO2 < 80%) to high-flow nasal therapy (HFNT) or low-flow oxygen (LFO: standard care) and hypoxaemia stratum (SpO2 80-91%) to HFNT or LFO (liberal strategies) or permissive hypoxaemia (ratio 1:1:2). Children with cyanotic heart disease, chronic lung disease or > 3 h receipt of oxygen were excluded. The primary endpoint was 48 h mortality; secondary endpoints included mortality or neurocognitive sequelae at 28 days. RESULTS: The trial was stopped early after enrolling 1852/4200 children, including 388 in the severe hypoxaemia stratum (median 7 months; median SpO2 75%) randomised to HFNT (n = 194) or LFO (n = 194) and 1454 in the hypoxaemia stratum (median 9 months; median SpO2 88%) randomised to HFNT (n = 363) vs LFO (n = 364) vs permissive hypoxaemia (n = 727). Per-protocol 15% of patients in the permissive hypoxaemia group received oxygen (when SpO2 < 80%). In the severe hypoxaemia stratum, 48-h mortality was 9.3% for HFNT vs. 13.4% for LFO groups. In the hypoxaemia stratum, 48-h mortality was 1.1% for HFNT vs. 2.5% LFO and 1.4% for permissive hypoxaemia. In the hypoxaemia stratum, adjusted odds ratio for 48-h mortality in liberal vs permissive comparison was 1.16 (0.49-2.74; p = 0.73); HFNT vs LFO comparison was 0.60 (0.33-1.06; p = 0.08). Strata-specific 28 day mortality rates were, respectively: 18.6, 23.4 and 3.3, 4.1, 3.9%. Neurocognitive sequelae were rare. CONCLUSIONS: Respiratory support with HFNT showing potential benefit should prompt further trials.

Reliability and validity of the World Health Organization reading standards for paediatric chest radiographs used in the field in an impact study of Pneumococcal Conjugate Vaccine in Kilifi, Kenya.

BACKGROUND: Radiologically-confirmed pneumonia (RCP) is a specific end-point used in trials of Pneumococcal Conjugate Vaccine (PCV) to estimate vaccine efficacy. However, chest radiograph (CXR) interpretation varies within and between readers. We measured the repeatability and reliability of paediatric CXR interpretation using percent agreement and Cohen's Kappa and the validity of field readings against expert review in a study of the impact of PCV on pneumonia. METHODS: CXRs were obtained from 2716 children admitted between 2006 and 2014 to Kilifi County Hospital, Kilifi, Kenya, with clinically-defined severe or very-severe pneumonia. Five clinicians and radiologists attended a three-day training course on CXR interpretation using a WHO standard. All CXRs were read once by two local primary readers. Discordant readings and 13% of concordant readings were arbitrated by a panel of three expert radiologists. To assess repeatability, a 5% median random sample was presented twice. Sensitivity and specificity of the primary readers' interpretations was estimated against the 'gold-standard' of the arbitrators' results. RESULTS: Of 2716 CXRs, 2 were uninterpretable and 159 were evaluated twice. The percent agreement and Kappa for RCP were 89% and 0.68 and ranged between 84-97% and 0.19-0.68, respectively, for all pathological findings. Intra-observer repeatability was similar to inter-observer reliability. Sensitivities of the primary readers to detect RCP were 69% and 73%; specificities were 96% and 95%. CONCLUSION: Intra- and inter-observer agreements on interpretations of radiologically-confirmed pneumonia are fair to good. Reasonable sensitivity and high specificity make radiologically-confirmed pneumonia, determined in the field, a suitable measure of relative vaccine effectiveness.

Rapid intravenous rehydration of children with acute gastroenteritis and dehydration: a systematic review and meta-analysis.

BACKGROUND: The World Health Organization (WHO) recommends rapid intravenous rehydration, using fluid volumes of 70-100mls/kg over 3-6 h, with some of the initial volume given rapidly as initial fluid boluses to treat hypovolaemic shock for children with acute gastroenteritis (AGE) and severe dehydration. The evidence supporting the safety and efficacy of rapid versus slower rehydration remains uncertain. METHODS: We conducted a systematic review of randomised controlled trials (RCTs) on 11th of May 2017 comparing different rates of intravenous fluid therapy in children with AGE and moderate or severe dehydration, using standard search terms. Two authors independently assessed trial quality and extracted data. Non-RCTs and non-English articles were excluded. The primary endpoint was mortality and secondary endpoints included adverse events (safety) and treatment efficacy. MAIN RESULTS: Of the 1390 studies initially identified, 18 were assessed for eligibility. Of these, 3 studies (n = 464) fulfilled a priori criteria for inclusion; most studied children with moderate dehydration and none were conducted in resource-poor settings. Volumes and rates of fluid replacement varied from 20 to 60 ml/kg given over 1-2 h (fast) versus 2-4 h (slow). There was substantial heterogeneity in methodology between the studies with only one adjudicated to be of high quality. There were no deaths in any study. Safety endpoints only identified oedema (n = 6) and dysnatraemia (n = 2). Pooled analysis showed no significant difference between the rapid and slow intravenous rehydration groups for the proportion of treatment failures (N = 468): pooled RR 1.30 (95% CI: 0.87, 1.93) and the readmission rates (N = 439): pooled RR 1.39 (95% CI: 0.68, 2.85). CONCLUSIONS: Despite wide implementation of WHO Plan C guideline for severe AGE, we found no clinical evaluation in resource-limited settings, and only limited evaluation of the rate and volume of rehydration in other parts of the world. Recent concerns over aggressive fluid expansion warrants further research to inform guidelines on rates of intravenous rehydration therapy for severe AGE.

Rapid isolation of blood plasma using a cascaded inertial microfluidic device.

Blood, saliva, mucus, sweat, sputum, and other biological fluids are often hindered in their ability to be used in point-of-care (POC) diagnostics because their assays require some form of off-site sample pre-preparation to effectively separate biomarkers from larger components such as cells. The rapid isolation, identification, and quantification of proteins and other small molecules circulating in the blood plasma from larger interfering molecules are therefore particularly important factors for optical blood diagnostic tests, in particular, when using optical approaches that incur spectroscopic interference from hemoglobin-rich red blood cells (RBCs). In this work, a sequential spiral polydimethylsiloxane (PDMS) microfluidic device for rapid (∼1 min) on-chip blood cell separation is presented. The chip utilizes Dean-force induced migration via two 5-loop Archimedean spirals in series. The chip was characterized in its ability to filter solutions containing fluorescent beads and silver nanoparticles and further using blood solutions doped with a fluorescent protein. Through these experiments, both cellular and small molecule behaviors in the chip were assessed. The results exhibit an average RBC separation efficiency of ∼99% at a rate of 5.2 × 106 cells per second while retaining 95% of plasma components. This chip is uniquely suited for integration within a larger point-of-care diagnostic system for the testing of blood plasma, and the use of multiple filtering spirals allows for the tuning of filtering steps, making this device and the underlying technique applicable for a wide range of separation applications.

Four phases of intravenous fluid therapy: a conceptual model.

I.V. fluid therapy plays a fundamental role in the management of hospitalized patients. While the correct use of i.v. fluids can be lifesaving, recent literature demonstrates that fluid therapy is not without risks. Indeed, the use of certain types and volumes of fluid can increase the risk of harm, and even death, in some patient groups. Data from a recent audit show us that the inappropriate use of fluids may occur in up to 20% of patients receiving fluid therapy. The delegates of the 12th Acute Dialysis Quality Initiative (ADQI) Conference sought to obtain consensus on the use of i.v. fluids with the aim of producing guidance for their use. In this article, we review a recently proposed model for fluid therapy in severe sepsis and propose a framework by which it could be adopted for use in most situations where fluid management is required. Considering the dose-effect relationship and side-effects of fluids, fluid therapy should be regarded similar to other drug therapy with specific indications and tailored recommendations for the type and dose of fluid. By emphasizing the necessity to individualize fluid therapy, we hope to reduce the risk to our patients and improve their outcome.

Maternal perceptions of factors contributing to severe under-nutrition among children in a rural African setting.

INTRODUCTION: In developing countries, severe undernutrition in early childhood is associated with increased mortality and morbidity, and 10-40% of hospital admissions. The current study aimed to elicit maternal perceptions of factors that contribute to severe undernutrition among children in a rural Kenyan community in order to identify appropriate and acceptable targeted interventions. METHODS: The study consisted of 10 focus group discussions (FGDs) of between eight and ten mothers each, in a rural coastal community in Kenya. A grounded theory approach was used to analyse the FGD data. RESULTS: In all FGDs 'financial constraints' was the main reason given for severe undernutrition of children. The mothers reported the additional factors of inadequate food intake, ill health, inadequate care of children, heavy workload for mothers, inadequate control of family resources by women and a lack of resources for generating income for the family. The mothers also reported their local cultural belief that severe malnutrition was due to witchcraft and the violation of sexual taboos. CONCLUSIONS: The mothers in the study community recognised multiple aetiologies for severe undernutrition. A multidisciplinary approach is needed address the range of issues raised and so combat severe undernutrition. Suggested interventions include poverty alleviation, medical education and psychosocial strategies. The content and approach of any program must address the need for variability, determined by individual and local needs, concerns, attitudes and beliefs.

Characteristics and outcome of cardiopulmonary resuscitation in hospitalised African children.

OBJECTIVE: To review the characteristics and outcome of cardiopulmonary resuscitation in children at a rural hospital in Kenya. PATIENTS AND METHOD: All children aged 0-14 years who experienced > or =1 episode of respiratory or cardiopulmonary arrest during April 2002--2004 were prospectively identified. Demographic variables, cause of hospitalisation, type and duration of arrest, resuscitation measures taken and outcomes were determined. RESULTS: 114 children experienced at least one episode of respiratory arrest (RA) or cardiopulmonary arrest (CPA). Cardiopulmonary resuscitation (CPR) was performed on all children. "Do not resuscitate order" (DNR) was given in 15 patients after initial resuscitation. Eighty two patients (72%) had RA and 32 (28%) had CPA. 25/82 (30%) patients with RA survived initial CPR compared to 5/32 (16%) with CPA. Survival at discharge was 22% (18/82) in children who had RA while no one with CPA survived at discharge. The leading underlying diseases were severe malaria, septicaemia and severe malnutrition. Prolonged resuscitation beyond 15 min and receiving adrenaline [epinephrine] (at least one dose of 10 microg/kg IV) were predictive of poor final outcome. CONCLUSION: Cardiopulmonary arrest after admission has a very poor prognosis in our hospital. Infectious diseases are the main underlying causes of arrest. If a child fails to respond to the basic tenements of PALS within 15 min then it is unlikely that further efforts to sustain life will be fruitful in hospitals where ventilation facilities are not present.

The acceptability to women in Mombasa, Kenya, of the donation and transfusion of umbilical cord blood for severe anaemia in young children.

BACKGROUND AND OBJECTIVES: Severe anaemia, for which a blood transfusion can be life saving, is common in hospitalized children in sub-Saharan Africa but blood for transfusion is often in short supply. Umbilical cord blood is usually thrown away but could be a useful source of red cells for small volume transfusions in young children in this setting. The objective of this study was to evaluate the attitudes of women using the maternity services of the provincial hospital in Mombasa, Kenya, towards cord blood donation and transfusion, and essential aspects of this process including informed consent and the acceptability of screening for human immunodeficiency virus (HIV) infection. MATERIALS AND METHODS: A structured questionnaire was developed based on data provided by focus group discussions with women attending the hospital's maternity unit and administered to women who had recently delivered at the hospital. RESULTS: Of the 180 women who completed a questionnaire, the donation and transfusion of cord blood were acceptable to 81% and 78%, respectively. Ninety per cent of women who supported cord blood donation were willing to undergo further HIV testing at the time of delivery. Seventy-seven per cent of women wanted informed consent to be sought for cord blood donation and 66% of these felt they could make this decision alone. CONCLUSION: The donation of umbilical cord blood and its transfusion are acceptable to the majority of women delivering at Coast Provincial General Hospital, Mombasa. Findings from the study will benefit the planned cord blood donation programme at this facility.

Positive replication and linkage disequilibrium mapping of the chromosome 21q22.1 malaria susceptibility locus.

Four cytokine receptor genes are located on Chr21q22.11, encoding the alpha and beta subunits of the interferon-alpha receptor (IFNAR1 and IFNAR2), the beta subunit of the interleukin 10 receptor (IL10RB) and the second subunit of the interferon-gamma receptor (IFNGR2). We previously reported that two variants in IFNAR1 were associated with susceptibility to malaria in Gambians. We now present an extensive fine-scale mapping of the associated region utilizing 45 additional genetic markers obtained from public databases and by sequencing a 44 kb region in and around the IFNAR1 gene in 24 Gambian children (12 cases/12 controls). Within the IFNAR1 gene, a newly studied C --> G single-nucleotide polymorphism (IFNAR1 272354c-g) at position -576 relative to the transcription start was found to be more strongly associated with susceptibility to severe malaria. Association was observed in three populations: in Gambian (P=0.002), Kenyan (P=0.022) and Vietnamese (P=0.005) case-control studies. When all three studies were combined, using the Mantel-Haenszel test, the presence of IFNAR1 -576G was associated with a substantially elevated risk of severe malaria (N=2444, OR=1.38, 95% CI: 1.17-1.64; P=1.7 x 10(-4)). This study builds on previous work to further highlight the importance of the type-I interferon pathway in malaria susceptibility and illustrates the utility of typing SNPs within regions of high linkage disequilibrium in multiple populations to confirm initial positive associations.

Research priorities in the management of severe Plasmodium falciparum malaria in children.

Severe malaria is a common reason for admission to paediatric wards in hospitals across sub-Saharan Africa. Despite over 100 years of research, mortality remains high. Deaths are associated with severe metabolic acidosis, shock, severe anaemia, hypoglycaemia, impaired consciousness, raised intracranial pressure, and status epilepticus. Most inpatient deaths occur within 24 h of admission to hospital, before the beneficial effects of treatment with antimalarial drugs are achieved. This review covers the priority areas for research in the care of children with severe malaria, addressing each of the main risk factors associated with death, in a bid to reduce the inpatient mortality.

HLA class-I and class-II allele frequencies and two-locus haplotypes in Melanesians of Vanuatu and New Caledonia.

HLA class-I and class-II allele frequencies and two-locus haplotypes were examined in 367 unrelated Melanesians living on the islands of Vanuatu and New Caledonia. Diversity at all HLA class-I and class-II loci was relatively limited. In class-I loci, three HLA-A allelic groups (HLA-A*24, HLA-A*34 and HLA-A*11), seven HLA-B alleles or allelic groups (HLA-B*1506, HLA-B*5602, HLA-B*13, HLA-B*5601, HLA-B*4001, HLA-B*4002 and HLA-B*2704) and four HLA-C alleles or allelic groups (HLA-Cw*04, HLA-Cw*01, HLA-Cw*0702 and HLA-Cw*15) constituted more than 90% of the alleles observed. In the class-II loci, four HLA-DRB1 alleles (HLA-DRB1*15, HLA-DRB1*11, HLA-DRB1*04 and HLA-DRB1*16), three HLA-DRB3-5 alleles (HLA-DRB3*02, HLA-DRB4*01 and HLA-DRB5*01/02) and five HLA-DQB1 alleles (HLA-DQB1*0301, HLA-DQB1*04, HLA-DQB1*05, HLA-DQB1*0601 and HLA-DQB1*0602) constituted over 93, 97 and 98% of the alleles observed, respectively. Homozygosity showed significant departures from expected levels for neutrality based on allele frequency (i.e. excess diversity) at the HLA-B, HLA-Cw, HLA-DQB1 and HLA-DRB3/5 loci on some islands. The locus with the strongest departure from neutrality was HLA-DQB1, homozygosity being significantly lower than expected on all islands except New Caledonia. No consistent pattern was demonstrated for any HLA locus in relation to malaria endemicity.

Capillary refill: prognostic value in Kenyan children.

AIMS: To determine whether delayed capillary refill time (>3 seconds) is a useful prognostic indicator in Kenyan children admitted to hospital. METHODS: A total of 4160 children admitted to Kilifi District Hospital with malaria, malarial anaemia, acute respiratory tract infection (ARI), severe anaemia (haemoglobin <50 g/l), gastroenteritis, malnutrition, meningitis, or septicaemia were studied. RESULTS: Overall, delayed capillary refill time (dCRT), present in 346/4160 (8%) of the children, was significantly more common in fatal cases (44/189, 23%) than survivors (7.5%), and had useful prognostic value. In children admitted with malaria, gastroenteritis, or malnutrition, likelihood ratio tests suggested that dCRT was useful in identifying high risk groups for mortality, but its prognostic value in anaemia, ARI, and sepsis was unclear due to low case fatality or limited numbers. The severity features of impaired consciousness and deep breathing were significantly associated both with the presence of dCRT and fatal outcome. In children, with either of these severity features, a less stringent value of dCRT(>2 s) identified 50% of children with hypotension (systolic BP <2SD) and 40% of those requiring volume resuscitation (for metabolic acidosis). CONCLUSIONS: Although CRT is a simple bedside test, which may be used in resource poor settings as a guide to the circulatory status, dCRT should not be relied on in the absence of other features of severity. In non-severe disease, the additional presence of hypoxia, a moderately raised creatinine (>80 micromol/l), or a raised white cell count should prompt the need for fluid expansion.

Are bedside features of shock reproducible between different observers?

Shock is often under-reported in children attending hospitals in developing countries. Readily obtainable features of shock (capillary refill time, temperature gradient, pulse volume, and signs of dehydration) are widely used to help prioritise management in the emergency assessment of critically ill or injured children. However, data are lacking on their validity, including, importantly, reproducibility between observers. Agreement of these signs was examined in 100 consecutive children admitted to a paediatric ward on the coast of Kenya. After an initial training of clinical sign recognition, there was moderate agreement for most features of cardiovascular compromise (delayed capillary refill > or =4 s, kappa = 0.49; and weak pulse volume, kappa = 0.4) and only substantial agreement for temperature gradient (kappa = 0.62). For hydration status, only in the assessment of skin turgor was there a moderate level of agreement (kappa = 0.55). Capillary refill times and assessment of pulse volume recommended by the recent American consensus guidelines achieved only a "low" moderate to poor interrater agreement, questioning the reliability of such parameters.

Salicylate poisoning in children: report of three cases.

To raise clinicians' awareness of chronic (therapeutic) salicylate poisoning as a common cause of admission in paediatric patients presenting to hospital with respiratory distress (a clinical manifestation of metabolic acidosis) and a history of 'over the counter' treatment with salicylate (Aspirin). We present two complex cases and provide a review of the literature on pathogenesis, clinical presentation and management of salicylate poisoning. A complete history of the illness, including questions on drug use, is vital in assessing the cause of metabolic acidosis in children. Due to the limited options available in managing such patients in many developing countries, emphasis should be placed on prevention of poisoning by educating the community and health care providers.

Severe P. falciparum malaria in Kenyan children: evidence for hypovolaemia.

BACKGROUND: The role of volume resuscitation in severe Plasmodium falciparum malaria is controversial. AIM: To examine the role of hypovolaemia in severe childhood malaria. STUDY DESIGN: Retrospective review. METHODS: We studied 515 children admitted with severe malaria to a high-dependency unit (HDU) in Kilifi, Kenya. On admission to the HDU, children underwent a further assessment of vital signs and a standard clinical examination. RESULTS: Factors associated with a fatal outcome included deep breathing or acidosis (base excess below -8), hypotension (systolic blood pressure <80 mmHg), raised plasma creatinine (>80 micro mol/l), low oxygen saturation (<90%), dehydration and hypoglycaemia (<2.5 mmol/l). Shock was present in 212/372 (57%) children, of whom 37 (17.5%) died, and was absent in 160, of who only 7 (4.4%) died (chi(2) = 14.9; p = 0.001). DISCUSSION: Impaired tissue perfusion may play a role in the mortality of severe malaria. Moreover, volume resuscitation, an important life-saving intervention in children with hypovolaemia, should be considered in severe malaria with evidence of impaired tissue perfusion.

S17834, a new inhibitor of cell adhesion and atherosclerosis that targets nadph oxidase.

microdant stress is involved in the events that accompany endothelial cell expression of adhesion molecules and leukocyte adherence in many disease states, including atherosclerosis. A recently discovered benzo(b)pyran-4-one derivative, S17834 (10 to 50 micromol/L), reduced tumor necrosis factor-stimulated vascular cell adhesion molecule-1 (VCAM) mRNA accumulation and protein expression in human umbilical vein endothelial cells. Intercellular cell adhesion molecule-1 and E-selectin were also inhibited by S17834, but platelet endothelial cell adhesion molecule-1 was not. Adherence of U937 monocytic cells to the endothelial cells as well as to plastic plates coated with soluble VCAM, intercellular cell adhesion molecule-1, P-selectin, and E-selectin was also decreased. Consistent with an antioxidant mechanism of action, S17834 (10 to 50 micromol/L) inhibited tumor necrosis factor-stimulated release of superoxide from endothelial cells measured by cytochrome c reduction. S17834 had no effect on superoxide produced by xanthine oxidase, indicating that rather than by acting as a scavenger of superoxide anion, the drug acts by inhibiting the production of free radicals. Indeed, S17834 inhibited NADPH oxidase activity of endothelial cell membranes. The ability to inhibit superoxide anion production appears to be key in the effect of S17834 on superoxide anion production and VCAM expression, because these actions were mimicked by adenovirus-mediated overexpression of superoxide dismutase. Furthermore, these actions may be relevant in vivo, because S17834 reduced aortic superoxide anion levels by 40% and aortic atherosclerotic lesions by 60% in apolipoprotein E-deficient mice. These results indicate that S17834 inhibits adhesion molecule expression and adherence of leukocytes to endothelial cells as well as aortic atherogenesis and that perhaps these effects can be explained by its ability to inhibit endogenous superoxide anion production.

Genetic restriction of Plasmodium falciparum in an area of stable transmission: an example of island evolution?

To date, a high degree of polymorphism has been demonstrated at both the MSP1 and MSP2 loci in parasites from areas of stable malaria transmission. As a consequence, in such areas it is rare to find parasites of the same 2-locus genotype in more than 1 subject. We have studied MSP1 and MSP2 diversity in parasites collected from subjects with both symptomatic (n = 86) and asymptomatic (34) malaria living on the island of Santo, Vanuatu, an area of stable malaria transmission. Polymorphism at the MSP1 and MSP2 loci was considerably less than previously reported: only 5 MSP1 and 5 MSP2 alleles were detected and these showed no size variation within alleles. Santo is unique amongst the areas studied so far in that it is a small island at the limit of the malaria belt in the South Pacific. Thus, the evolution of the parasite population may have been affected by the small size and isolation of this island population. Moreover, limited parasite diversity may explain the unusually mild nature of Plasmodium falciparum disease on Santo. Islands have fascinated biologists for centuries and fuelled the advancement of evolutionary theory, since they are natural laboratories for the study of evolution. The simplicity of the Vanuatu P. falciparum population may facilitate the use and interpretation of sequence level analyses to address the mechanisms by which genetic diversity is generated and maintained in natural populations.