Meta-Analysis of Human Antibodies Against Plasmodium falciparum Variable Surface and Merozoite Stage Antigens

Concerted efforts to fight malaria have caused significant reductions in global malaria cases and mortality. Sustaining this will be critical to avoid rebound and outbreaks of seasonal malaria. Identifying predictive attributes that define clinical malaria will be key to guide development of second-generation tools to fight malaria. Broadly reactive antibodies against variable surface antigens that are expressed on the surface of infected erythrocytes and merozoites stage antigens are targets of naturally acquired immunity and prime candidates for anti-malaria therapeutics and vaccines. However, predicting the relationship between the antigen-specific antibodies and protection from clinical malaria remains unresolved. Here, we used new datasets and multiple approaches combined with re-analysis of our previous data to assess the multi-dimensional and complex relationship between antibody responses and clinical malaria outcomes. We observed 22 antigens (17 PfEMP1 domains, 3 RIFIN family members, merozoite surface protein 3 (PF3D7_1035400), and merozoites-associated armadillo repeats protein (PF3D7_1035900) that were selected across three different clinical malaria definitions (1,000/2,500/5,000 parasites/µl plus fever). In addition, Principal Components Analysis (PCA) indicated that the first three components (Dim1, Dim2 and Dim3 with eigenvalues of 306, 48, and 29, respectively) accounted for 66.1% of the total variations seen. Specifically, the Dim1, Dim2 and Dim3 explained 52.8%, 8.2% and 5% of variability, respectively. We further observed a significant relationship between the first component scores and age with antibodies to PfEMP1 domains being the key contributing variables. This is consistent with a recent proposal suggesting that there is an ordered acquisition of antibodies targeting PfEMP1 proteins. Thus, although limited, and further work on the significance of the selected antigens will be required, these approaches may provide insights for identification of drivers of naturally acquired protective immunity as well as guide development of additional tools for malaria elimination and eradication.

Clinical Characteristics, Complications and Predictors of Outcome of Hospitalized Adult Sudanese Patients with COVID-19 and Malaria Co-Infection in Sudan: A Multi-Center Retrospective Cross-sectional Study

Malaria and coronavirus disease 2019 (COVID‐19) share several characteristics that could lead to cross‐infection, particularly in malaria‐endemic areas. Early COVID‐19 symptoms might be misdiagnosed for malaria in clinical settings. Also, both diseases can cause fatal complications. So, laboratory testing for both diseases was recommended by the World Health Organization. To study the clinical characteristics and outcomes of Adult Sudanese patients with COVID‐19 and malaria coinfection. This retrospective cross‐sectional study was conducted from January 2021 to October 2021 in Wad Medani. Total coverage of all Sudanese patients above 18 years old with a confirmed diagnosis of coinfection with COVID‐19 and malaria was included, and data were collected using a data collection sheet. Data were analyzed using R software version 4.0.2. Data were described and presented as mean, standard deviation, and number (percentage). To find associated factors with in‐hospital outcome, χ² test, fisher exact test, and independent t test or Wilcoxon rank‐sum test were used. In this study, 156 participants were diagnosed with COVID‐19 and malaria coinfection. Most of them were between 60 and 70 years (30.8%), the majority were males (59%). Shortness of breath (76.3%) and acute respiratory distress syndrome (35.3%) were the most common symptom and complications among coinfected patients, respectively. Ground glass opacity (n = 47/49, 95.9%) is the most common result for computed tomography scan. Atrial fibrillation was the most common abnormal electrocardiogram finding (n = 6/62, 9.7%). Overall mortality among all participants was (63/156, 40.4%). High mortality rate was found among the coinfected patients. More attention is needed towards fighting COVID‐19 and malaria coinfection. There may be a link between malaria and COVID‐19.

Seeking diagnostic and prognostic biomarkers for childhood bacterial pneumonia in sub-Saharan Africa: study protocol for an observational study

INTRODUCTION

Clinically diagnosed pneumonia in children is a leading cause of paediatric hospitalisation and mortality. The aetiology is usually bacterial or viral, but malaria can cause a syndrome indistinguishable from clinical pneumonia. There is no method with high sensitivity to detect a bacterial infection in these patients and, as result, antibiotics are frequently overprescribed. Conversely, unrecognised concomitant bacterial infection in patients with malarial infections occur with omission of antibiotic therapy from patients with bacterial infections. Previously, we identified two combinations of blood proteins with 96% sensitivity and 86% specificity for detecting bacterial disease. The current project aimed to validate and improve these combinations by evaluating additional biomarkers in paediatric patients with clinical pneumonia. Our goal was to describe combinations of a limited number of proteins with high sensitivity and specificity for bacterial infection to be incorporated in future point-of-care tests. Furthermore, we seek to explore signatures to prognosticate clinical pneumonia.

METHODS AND ANALYSIS

Patients (n=900) aged 2-59 months presenting with clinical pneumonia at two Gambian hospitals will be enrolled and classified according to criteria for definitive bacterial aetiology (based on microbiological tests and chest radiographs). We will measure proteins at admission using Luminex-based immunoassays in 90 children with definitive and 160 with probable bacterial aetiology, and 160 children classified according to the prognosis of their disease. Previously identified diagnostic signatures will be assessed through accuracy measures. Moreover, we will seek new diagnostic and prognostic signatures through machine learning methods, including support vector machine, penalised regression and classification trees.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Gambia Government/Medical Research Council Unit The Gambia Joint Ethics Committee (protocol 1616) and the institutional review board of Boston University Medical Centre (STUDY00000958). Study results will be disseminated to the staff of the study hospitals, in scientific seminars and meetings, and in publications.

TRIAL REGISTRATION NUMBER

H-38462.

Plasmodium vivax and Neisseria meningitidis co-infection in a newborn

Invasive infections due to Neisseria meningitidis in Colombia are unusual in newborns, in contrast to infections due to Plasmodium vivax which is one of the main pathogens related to the presentation of fever in this age group, especially in the indigenous population. We report a case of co-infection of these two microorganisms in a child.

Epilepsy and Malaria in Children Aged 1 to 15 Years in Parakou in 2018: Case-Control Study

Objective:

To study the link between malaria and epilepsy in children in Parakou district.

Methods:

This case-control study included children 1-15 years of age with epilepsy. Each case of epilepsy was matched to 2 controls for age, sex and neighborhood of residence. The exposure variables were a history of malaria (number and type), family history of epilepsy and other past medical history. The odds ratios (OR) and their confidence interval were used to estimate association.

Results:

A total of 123 children including 41 children with epilepsy and 82 controls were included. The overall average number of malaria episodes per year in both groups combined was 1.8 ± 0.9 episodes. In the multivariate analysis, cerebral malaria (OR: 50.35 [5.28-480.30]), family history of epilepsy (OR: 12.17 [2.15-69.01]) and number of malaria episodes (OR: 13.27 [4.53-98.48]) were associated.

Conclusion:

This study supports the association between cerebral malaria and the onset of epilepsy.

Diagnosing Malaria: Methods, Tools, and Field Applicability

Diagnosing malaria is a key component of effective case management and monitoring of antimalarial programs worldwide. This chapter features the different diagnostic approaches currently in use or under testing for use in case management and/or epidemiological studies of malaria. Emphasis is laid on the basic principles of each diagnostic approach as well as their operational limits under different malaria endemicity settings. The discussed methods are defined as "conventional" or "unconventional" depending on their widespread use in malaria case management. The chapter therefore provides a practical guide to students, health practitioners, and field researchers involved in the fight against malaria through community-based interventions.

Extent of inappropriate prescription of artemisinin and anti-malarial injections to febrile outpatients, a cross-sectional analytic survey in the Greater Accra region, Ghana

Background

Febrile children seen in malaria hypo-endemic settings, such as the Greater Accra region (GAR) of Ghana are more likely to be suffering from a non-malarial febrile illness compared to those seen in hyper-endemic settings. The need for prescribers to rely on malaria test results to guide treatment practices in the GAR is even greater. This study was designed to investigate the factors associated with inappropriate artemisinin-based combination therapy (ACT) prescription.

Methods

A survey was conducted in six health facilities in the region in 2015. Treatment practices for febrile outpatient department (OPD) patients were obtained from their records. Prescribers were interviewed and availability of malaria commodities were assessed. The primary outcome was the proportion of patients prescribed ACT inappropriately. Independent variables included patient age and access to care, prescriber factors (professional category, work experience, access to guidelines, exposure to training). Data were analysed using Stata at 95% CI (α-value of 0.05). Frequencies and means were used to describe the characteristics of patients and prescribers. To identify the predictors of inappropriate ACT prescription, regression analyses were performed accounting for clustering.

Results

Overall, 2519 febrile OPD records were analysed; 45.6% (n = 1149) were younger than 5 years. Only 40.0% of patients were tested. The proportion of patients who were prescribed ACT inappropriately was 76.4% (n = 791 of 1036). Of these 791 patients, 141 (17.8%) were prescribed anti-malarial injections. Patients seen in facilities with rapid diagnostic tests (RDT) in stock were less likely to be prescribed ACT inappropriately, (AOR: 0.04, 95% CI 0.01–0.14, p < 0.001) compared to those seen in facilities with RDT stock-outs. Prescribers who had been trained on malaria case management within the past year were 4 times more likely to prescribe ACT inappropriately compared to those who had not been trained (AOR: 4.1; 95% CI (1.5–11.6); p < 0.01). Patients seen by prescribers who had been supervised were 8 times more likely to be  prescribed ACT inappropriately.

Conclusion

Inappropriate ACT prescription to OPD febrile cases was high. Training and supervision of health workers appears not to be yielding the desired outcomes. Further research is needed to understand this observation.

Determinants of health workers intention to use malaria rapid diagnostic test in Kintampo North Municipality, Ghana - a cross-sectional study

BACKGROUND

Resistance to antimalarial drugs resulting from overuse of the medication remains a threat to malaria control and elimination in endemic settings including Ghana. Reliance on clinical signs alone results in patients being diagnosed with malaria falsely. The World Health Organization and local guidelines recommend test-based diagnosis with malaria rapid diagnostic test (mRDT) or microscopy before prescription of antimalarial drugs. Despite the scale-up of mRDT through the procurement of mRDT kits and training of health workers on mRDT-led diagnosis of malaria, its use remains low with about 85% health workers reporting satisfaction with the presumptive diagnosis.

METHODS

A quantitative cross-sectional study was conducted to investigate the determinants of intention to use mRDT among health workers in Kintampo North Municipality, Ghana. A total of 110 health workers were surveyed from February to April 2017. Intention to use mRDT was measured as the primary outcome with a 5-item scale questionnaire based on the Technology Acceptance Model (TAM). We then tested its association with hypothesized determinants: coherence, cognitive participation, collective action, and reflexive action informed by the Normalization Process Theory (NPT) as well as health workers' background characteristics using linear regression modeling.

RESULTS

The mean intention to use mRDT score was 82% (SD: 12.6). The regression model showed health workers intention to use mRDT was positively associated with coherence (β = 0.40, 95% CI 0.16-0.65) and cognitive participation (β = 0.36, 95% CI 0.15-0.58). Intention to use mRDT score was 6.85 units higher among health workers with three or more years of experience compared to those with less than 3 years of experience (β = 6.85 95% CI 0.59-13.12). However, intention to use mRDT score was inversely related to reflexive monitoring and collective action but not significant.

CONCLUSION

The study identified that intention to use mRDT was positively influenced by health workers having a proper understanding of the aims and expected benefits (coherence) of the intervention and the availability of experienced staff and intervention champions (cognitive participation) to promote mRDT use among health workers.

Detachment of retinal pigment epithelium in retinopathy due to malaria

CASE REPORT

A 45-year-old man was diagnosed with malaria with neurological involvement. Two months later he referred metamorphopsia in the left eye. Malarial retinopathy was observed in the fundus examination. The Optic Coherence Tomography (OCT) of the macula showed parafoveal pigment epithelium detachment (DEP). Specific anti-malarial treatment was initiated, with the disappearance of the retinopathy being observed.

DISCUSSION

Plasmodium falciparum is responsible for the retinopathy in neurological malaria. A funduscopic examination and macular OCT should be performed in these patients, as it is associated with a higher mortality when there is a retinal involvement.

Changes in Malaria Epidemiology in Africa and New Challenges for Elimination

Although the burden of Plasmodium falciparum malaria is gradually declining in many parts of Africa, it is characterized by spatial and temporal variability that presents new and evolving challenges for malaria control programs. Reductions in the malaria burden need to be sustained in the face of changing epidemiology whilst simultaneously tackling significant pockets of sustained or increasing transmission. Large-scale, robust surveillance mechanisms that measure rather than estimate the actual burden of malaria over time from large areas of the continent where such data are lacking need to be prioritized. We review these fascinating developments, caution against complacency, and make the case that improving the extent and quality of malaria surveillance is vital for Africa as she marches on towards elimination.

Febrile illness diagnostics and the malaria-industrial complex: a socio-environmental perspective

BACKGROUND

Global prioritization of single-disease eradication programs over improvements to basic diagnostic capacity in the Global South have left the world unprepared for epidemics of chikungunya, Ebola, Zika, and whatever lies on the horizon. The medical establishment is slowly realizing that in many parts of sub-Saharan Africa (SSA), particularly urban areas, up to a third of patients suffering from acute fever do not receive a correct diagnosis of their infection.

MAIN BODY

Malaria is the most common diagnosis for febrile patients in low-resource health care settings, and malaria misdiagnosis has soared due to the institutionalization of malaria as the primary febrile illness of SSA by international development organizations and national malaria control programs. This has inadvertently created a "malaria-industrial complex" and historically obstructed our complete understanding of the continent's complex communicable disease epidemiology, which is currently dominated by a mélange of undiagnosed febrile illnesses. We synthesize interdisciplinary literature from Ghana to highlight the complexity of communicable disease care in SSA from biomedical, social, and environmental perspectives, and suggest a way forward.

CONCLUSION

A socio-environmental approach to acute febrile illness etiology, diagnostics, and management would lead to substantial health gains in Africa, including more efficient malaria control. Such an approach would also improve global preparedness for future epidemics of emerging pathogens such as chikungunya, Ebola, and Zika, all of which originated in SSA with limited baseline understanding of their epidemiology despite clinical recognition of these viruses for many decades. Impending ACT resistance, new vaccine delays, and climate change all beckon our attention to proper diagnosis of fevers in order to maximize limited health care resources.

Ocular parasitoses: A comprehensive review

Parasitic infections of the eyes are a major cause of ocular diseases across the globe. The causative agents range from simple organisms such as unicellular protozoans to complex metazoan helminths. The disease spectrum varies depending on the geographic location, prevailing hygiene, living and eating habits of the inhabitants, and the type of animals that surround them. They cause enormous ocular morbidity and mortality not because they are untreatable, but largely due to late or misdiagnosis, often from unfamiliarity with the diseases produced. We provide an up-to-date comprehensive overview of the ophthalmic parasitoses. Each section describes the causative agent, mode of transmission, geographic distribution, ocular pathologies, and their management for common parasites with brief mention of the ones that are rare.

Responses to Bacteria, Virus, and Malaria Distinguish the Etiology of Pediatric Clinical Pneumonia

RATIONALE

Plasma-detectable biomarkers that rapidly and accurately diagnose bacterial infections in children with suspected pneumonia could reduce the morbidity of respiratory disease and decrease the unnecessary use of antibiotic therapy.

OBJECTIVES

Using 56 markers measured in a multiplexed immunoassay, we sought to identify proteins and protein combinations that could discriminate bacterial from viral or malarial diagnoses.

METHODS

We selected 80 patients with clinically diagnosed pneumonia (as defined by the World Health Organization) who also met criteria for bacterial, viral, or malarial infection based on clinical, radiographic, and laboratory results. Ten healthy community control subjects were enrolled to assess marker reliability. Patients were subdivided into two sets: one for identifying potential markers and another for validating them.

MEASUREMENTS AND MAIN RESULTS

Three proteins (haptoglobin, tumor necrosis factor receptor 2 or IL-10, and tissue inhibitor of metalloproteinases 1) were identified that, when combined through a classification tree signature, accurately classified patients into bacterial, malarial, and viral etiologies and misclassified only one patient with bacterial pneumonia from the validation set. The overall sensitivity and specificity of this signature for the bacterial diagnosis were 96 and 86%, respectively. Alternative combinations of markers with comparable accuracy were selected by support vector machine and regression models and included haptoglobin, IL-10, and creatine kinase-MB.

CONCLUSIONS

Combinations of plasma proteins accurately identified children with a respiratory syndrome who were likely to have bacterial infections and who would benefit from antibiotic therapy. When used in conjunction with malaria diagnostic tests, they may improve diagnostic specificity and simplify treatment decisions for clinicians.

Challenges with implementing malaria rapid diagnostic tests at primary care facilities in a Ghanaian district: a qualitative study

Background

Rapid diagnostic Tests (RDTs) for malaria enable diagnostic testing at primary care facilities in resource-limited settings, where weak infrastructure limits the use of microscopy. In 2010, Ghana adopted a test-before-treat guideline for malaria, with RDT use promoted to facilitate diagnosis. Yet healthcare practitioners still treat febrile patients without testing, or despite negative malaria test results. Few studies have explored RDT implementation beyond the notions of provider or patient acceptability. The aim of this study was to identify the factors directly influencing malaria RDT implementation at primary care facilities in a Ghanaian district.

Methods

Qualitative interviews, focus groups and direct observations were conducted with 50 providers at six purposively selected primary care facilities in the Atwima–Nwabiagya district. Data were analysed thematically.

Results

RDT implementation was hampered by: (1) healthcare delivery constraints (weak supply chain, limited quality assurance and control, inadequate guideline emphasis, staffing limitations); (2) provider perceptions (entrenched case-management paradigms, limited preparedness for change); (3) social dynamics of care delivery (expected norms of provider-patient interaction, test affordability); and (4) limited provider engagement in policy processes leading to fragmented implementation of health sector reform.

Conclusion

Limited health system capacity, socio-economic, political, and historical factors hampered malaria RDT implementation at primary care facilities in the study district. For effective RDT implementation providers must be: (1) adequately enabled through efficient allocation and management of essential healthcare commodities; (2) appropriately empowered with the requisite knowledge and skill through ongoing, effective professional development; and (3) actively engaged in policy dialogue to demystify socio-political misconceptions that hinder health sector reform policies from improving care delivery. Clear, consistent guideline emphasis, with complementary action to address deep-rooted provider concerns will build their confidence in, and promote uptake of recommended policies, practices, and technology for diagnosing malaria.

Community Knowledge and Perceived Effectiveness of Interventions to Reduce Malaria: Implications for Sustained Use of Malaria Interventions in Rufiji District, Southeastern Tanzania

Insecticides treated-nets (ITNs) and artemether-lumefantrine (ALu), crucial for malaria elimination, depend on perceived effectiveness in reducing malarial fevers. We examined community knowledge and perceived effectiveness of ITNs and ALu for reducing malaria in Rufiji district. Heads of households were interviewed on causes of fever in underfives, fever history, and antimalarial use during the last 2 weeks, perceived effectiveness of, and willingness to continue using ALu and ITNs. A total of 1,885 respondents were interviewed, a majority (88.2%) females. Illnesses with fever (malaria-76.1% and respiratory conditions-58.9%) were major health problems. There was a very high recognition of fever as malaria symptom (95.1%). There were mixed perceptions on effectiveness of ALu and ITNs: ALu (52.8%) and on ITNs as highly effective (48.1%). Both ALu and ITNs were judged partially effective. Reorientation of social marketing to increase demand for ALu and ITNs for malaria control consolidation is crucial.

Malaria Diagnosis Across the International Centers of Excellence for Malaria Research: Platforms, Performance, and Standardization

Diagnosis is “the act of identifying a disease, illness, or problem by examining someone or something.” When an individual with acute fever presents for clinical attention, accurate diagnosis leading to specific, prompt treatment often saves lives. As applied to malaria, not only individual patient diagnosis is important but also assessing population-level malaria prevalence using appropriate diagnostic methods is essential for public health purposes. Similarly, identifying (diagnosing) fake antimalarial medications prevents the use of counterfeit drugs that can have disastrous effects. Therefore, accurate diagnosis in broad areas related to malaria is fundamental to improving health-care delivery, informing funding agencies of current malaria situations, and aiding in the prioritization of regional and national control efforts. The International Centers of Excellence for Malaria Research (ICEMR), supported by the U.S. National Institute of Allergy and Infectious Diseases, has collaborated on global efforts to improve malaria diagnostics by working to harmonize and systematize procedures across different regions where endemicity and financial resources vary. In this article, the different diagnostic methods used across each ICEMR are reviewed and challenges are discussed.

Etiology of Severe Febrile Illness in Low- and Middle-Income Countries: A Systematic Review

Background

With apparent declines in malaria worldwide during the last decade and more widespread use of malaria rapid diagnostic tests, healthcare workers in low-resource areas face a growing proportion of febrile patients without malaria. We sought to describe current knowledge and identify information gaps of the etiology severe febrile illness in low-and middle-income countries.

Methods and Findings

We conducted a systematic review of studies conducted in low-and-middle income countries 1980–2013 that prospectively assessed consecutive febrile patients admitted to hospital using rigorous laboratory-based case definitions. We found 45 eligible studies describing 54,578 patients; 9,771 (17.9%) had a positive result for ≥1 pathogen meeting diagnostic criteria. There were no eligible studies identified from Southern and Middle Africa, Eastern Asia, Oceania, Latin American and Caribbean regions, and the European region. The median (range) number of diagnostic tests meeting our confirmed laboratory case definitions was 2 (1 to 11) per study. Of diagnostic tests, 5,052 (10.3%) of 49,143 had confirmed bacterial or fungal bloodstream infection; 709 (3.8%) of 18,142 had bacterial zoonosis; 3,488 (28.5%) of 12,245 had malaria; and 1,804 (17.4%) of 10,389 had a viral infection.

Conclusions

We demonstrate a wide range of pathogens associated with severe febrile illness and highlight the substantial information gaps regarding the geographic distribution and role of common pathogens. High quality severe febrile illness etiology research that is comprehensive with respect to pathogens and geographically representative is needed.

Acute respiratory infection and bacteraemia as causes of non-malarial febrile illness in African children: a narrative review

The replacement of "presumptive treatment for malaria" by "test before treat" strategies for the management of febrile illness is raising awareness of the importance of knowing more about the causes of illness in children who are suspected to have malaria but return a negative parasitological test. The most common cause of non-malarial febrile illness (NMFI) in African children is respiratory tract infection. Whilst the bacterial causes of NMFI are well known, the increasing use of sensitive techniques such as polymerase chain reaction (PCR) tests is revealing large numbers of viruses that are potential respiratory pathogens. However, many of these organisms are commonly present in the respiratory tract of healthy children so causality and risk factors for pneumonia remain poorly understood. Infection with a combination of viral and bacterial pathogens is increasingly recognised as important in the pathogenesis of pneumonia. Similarly, blood stream infections with organisms typically grown by aerobic culture are well known but a growing number of organisms that can be identified only by PCR, viral culture, or serology are now recognised to be common pathogens in African children. The high mortality of hospitalised children on the first or second day of admission suggests that, unless results are rapidly available, diagnostic tests to identify specific causes of illness will still be of limited use in guiding the potentially life saving decisions relating to initial treatment of children admitted to district hospitals in Africa with severe febrile illness and a negative test for malaria. Malaria control and the introduction of vaccines against Haemophilus influenzae type b and pneumococcal disease are contributing to improved child survival in Africa. However, increased parasitological testing for malaria is associated with increased use of antibiotics to which resistance is already high.

Management of severe paediatric malaria in resource-limited settings

Over 90% of the world's severe and fatal Plasmodium falciparum malaria is estimated to affect young children in sub-Sahara Africa, where it remains a common cause of hospital admission and inpatient mortality. Few children will ever be managed on high dependency or intensive care units and, therefore, rely on simple supportive treatments and parenteral anti-malarials. There has been some progress on defining best practice for antimalarial treatment with the publication of the AQUAMAT trial in 2010, involving 5,425 children at 11 centres across 9 African countries, showing that in artesunate-treated children, the relative risk of death was 22.5% (95% confidence interval (CI) 8.1 to 36.9) lower than in those receiving quinine. Human trials of supportive therapies carried out on the basis of pathophysiology studies, have so far made little progress on reducing mortality; despite appearing to reduce morbidity endpoints, more often than not they have led to an excess of adverse outcomes. This review highlights the spectrum of complications in African children with severe malaria, the therapeutic challenges of managing these in resource-poor settings and examines in-depth the results from clinical trials with a view to identifying the treatment priorities and a future research agenda.

Distribution of Plasmodium falciparum gametocytes and malaria-attributable fraction of fever episodes along an altitudinal transect in Western Cameroon

BACKGROUND

Highland areas are hypoendemic zones of malaria and are therefore prone to epidemics, due to lack of protective immunity. So far, Cameroon has not succeeded in implementing a convenient and effective method to detect, prevent and forecast malaria epidemic in these peculiar zones. This monitoring and evaluation study aims to assess the operational feasibility of using the human malaria infectious reservoir (HMIR) and the malaria-attributable fraction of fever episodes (MAFE) as indicators, in designing a malaria epidemic early warning system (MEWS).

METHODS

Longitudinal parasitological surveys were conducted in sentinel health centres installed in three localities, located along an altitudinal transect in Western Cameroon: Santchou (750 m), Dschang (1,400 m) and Djuttitsa (1,965 m). The syndromes of outpatients with malaria-like complaints were recorded and their blood samples examined. The HMIR and the MAFE were estimated and their spatial-temporal variations described.

RESULTS

The prevalence of asexual Plasmodium infection in outpatients decreased with increasing altitude; meanwhile the HMIR remained fairly constant, indicating that scarcity of malaria disease in highlands is likely due to absence of vectors and not parasites. In lowland, children carried the heaviest malaria burden in the form of febrile episodes, and asexual parasites decreased with age, after an initial peak in the 0-5 year's age group; however, they were similar for all age groups in highland. The HMIR did not show any variation with age in the plain; but some discrepancies were observed in the highland with extreme age groups, and migration of populations between lowland and highland was suspected to be the cause. Plasmodium infection was perennial in the lowland and seasonal uphill, with malaria disease occurring here mostly during the short dry season. The MAFE was high and did not change with altitude.

CONCLUSION

It is obvious that a malaria outbreak will cause the sudden rise of HMIR and MAFE in highland, prior to the malaria season; the discrepancy with lowland would then help detecting an incipient malaria epidemic. It is recommended that in designing the MEWS, the National Malaria Control Programme should include these parameters and put special emphasis on: altitude, age groups and seasons.

The relationship between Plasmodium infection, anaemia and nutritional status in asymptomatic children aged under five years living in stable transmission zones in Kinshasa, Democratic Republic of Congo

BACKGROUND

Malaria is preventable and treatable when recommended interventions are properly implemented. Thus, diagnosis and treatment focus on symptomatic individuals while asymptomatic Plasmodium infection (PI) plays a role in the sustainability of the transmission and may also have an impact on the morbidity of the disease in terms of anaemia, nutritional status and even cognitive development of children. The objective of this study was to assess PI prevalence and its relationship with known morbidity factors in a vulnerable but asymptomatic stratum of the population.

METHODS

A simple random sample, household survey in asymptomatic children under the age of five was conducted from April to September 2012 in two health areas of the health zone of Mont Ngafula 1, Kinshasa, Democratic Republic of Congo.

RESULTS

The PI prevalence were 30.9% (95% CI: 26.5-35.9) and 14.3% (95% CI: 10.5-18.1) in Cité Pumbu and Kindele health areas, respectively, (OR: 2.7; p <0.001). All were Plasmodium falciparum infected and 4% were co-infected with Plasmodium malariae. In Cité Pumbu and Kindele, the prevalence of anaemia (haemoglobin <11 g/dL) was 61.6% (95% CI: 56.6-66.5) and 39.3% (95% CI: 34.0-44.6), respectively, (OR: 2.5; p <0.001). The health area of Cité Pumbu had 32% (95% CI: 27.5-37.0) of chronic malnutrition (HAZ score ≤ -2SD) compared to 5.1% (95% CI: 2.8-7.6) in Kindele. PI was predictor factor for anaemia (aOR: 3.5, p =0.01) and within infected children, there was an inverse relationship between parasite density and haemoglobin level (β = -5*10(-5), p <0.001). Age older than 12 months (aOR: 3.8, p = 0.01), presence of anaemia (aOR: 3.4, p =0.001), chronic malnutrition (aOR: 1.8, p = 0.01), having a single parent/guardian (aOR: 1.6, p =0.04), and the non-use of insecticide-treated nets (aOR: 1.7, p = 0.04) were all predictors for PI in the overall population.

CONCLUSION

PI in asymptomatic children was correlated with anaemia and chronic malnutrition and was thus a harmful condition in the study population. Malaria control initiatives should not only focus on treatment of symptomatic infections but also take into consideration asymptomatic but infected children.

To report a case of unilateral proliferative retinopathy following noncerebral malaria with Plasmodium falciparum in Southern India

The retinopathy in association with malaria fever described so far includes retinal hemorrhages, vessel changes, retinal discoloration/whitening and papilledema. Malaria retinopathy has been mostly described in severe cases, associated with Plasmodium falciparum, correlating the patho-physiology of retinal and cerebral manifestations. We report an unusual case of proliferative retinopathy as a manifestation of malaria fever, caused by P. falciparum with no cerebral involvement. The patient had features of unilateral retinal vascular occlusion with proliferative changes and vitreous hemorrhage. To the best of our knowledge, such a case has never been reported so far in the literature. This report highlights the possible occurrence of severe proliferative changes associated with malaria fever, which if diagnosed early can prevent possible blindness.

Genetic Diversity and Allelic Frequency of Glutamate-Rich Protein (GLURP) in Plasmodium falciparum Isolates from Sub-Saharan Africa

Glutamate-rich protein is a Plasmodium falciparum (Pf) antigen found in all stages of the parasite and has been reported to induce clinical immunity. The R0 and R2 regions have been found to exhibit a high degree of conservation, therefore serving as a good vaccine design material. We assayed the genetic diversity of Pf glurp genes in the R0 and R2 regions, as well as evaluated the role of seasonality on allelic frequency. A total of 402 genomic DNA samples, extracted from filter paper blood samples, were screened by nested polymerase chain reaction (PCR) analysis of Pf glurp R0 and R2 regions, in addition to fragment analysis of the polymorphic regions to identify allelic diversity of the parasite population. We found an extensive heterogeneity in the R2 region in general, and this heterogeneity is seasonally dependent, indicative of region plasticity. The R0 region displayed genetic conservation, as expected. We conclude that positive genotyping results with glurp R0 region should be seen as indicative of an active Pf infection, requiring adequate treatment. In addition, we advocate extending the possibility that an R0 region genotypic positivity could serve as diagnostic tool, thereby reducing cases of untreated or poorly treated infection, contributory to recrudescence or treatment failure.

Maladjusted host immune responses induce experimental cerebral malaria-like pathology in a murine Borrelia and Plasmodium co-infection model

In the Plasmodium infected host, a balance between pro- and anti-inflammatory responses is required to clear the parasites without inducing major host pathology. Clinical reports suggest that bacterial infection in conjunction with malaria aggravates disease and raises both mortality and morbidity in these patients. In this study, we investigated the immune responses in BALB/c mice, co-infected with Plasmodium berghei NK65 parasites and the relapsing fever bacterium Borrelia duttonii. In contrast to single infections, we identified in the co-infected mice a reduction of L-Arginine levels in the serum. It indicated diminished bioavailability of NO, which argued for a dysfunctional endothelium. Consistent with this, we observed increased sequestration of CD8+ cells in the brain as well over expression of ICAM-1 and VCAM by brain endothelial cells. Co-infected mice further showed an increased inflammatory response through IL-1β and TNF-α, as well as inability to down regulate the same through IL-10. In addition we found loss of synchronicity of pro- and anti-inflammatory signals seen in dendritic cells and macrophages, as well as increased numbers of regulatory T-cells. Our study shows that a situation mimicking experimental cerebral malaria (ECM) is induced in co-infected mice due to loss of timing and control over regulatory mechanisms in antigen presenting cells.

Deconstructing "malaria": West Africa as the next front for dengue fever surveillance and control

Presumptive treatment of febrile illness patients for malaria remains the norm in endemic areas of West Africa, and "malaria" remains the top source of health facility outpatient visits in many West African nations. Many other febrile illnesses, including bacterial, viral, and fungal infections, share a similar symptomatology as malaria and are routinely misdiagnosed as such; yet growing evidence suggests that much of the burden of febrile illness is often not attributable to malaria. Dengue fever is one of several viral diseases with symptoms similar to malaria, and the combination of rapid globalization, the long-standing presence of Aedes mosquitoes, case reports from travelers, and recent seroprevalence surveys all implicate West Africa as an emerging front for dengue surveillance and control. This paper integrates recent vector ecology, public health, and clinical medicine literature about dengue in West Africa across community, regional, and global geographic scales. We present a holistic argument for greater attention to dengue fever surveillance in West Africa and renew the call for improving differential diagnosis of febrile illness patients in the region.

Rapid diagnostic tests versus clinical diagnosis for managing people with fever in malaria endemic settings

BACKGROUND

In 2010, the World Health Organization recommended that all patients with suspected malaria are tested for malaria before treatment. In rural African settings light microscopy is often unavailable. Diagnosis has relied on detecting fever, and most people were given antimalarial drugs presumptively. Rapid diagnostic tests (RDTs) provide a point-of-care test that may improve management, particularly of people for whom the RDT excludes the diagnosis of malaria.

OBJECTIVES

To evaluate whether introducing RDTs into algorithms for diagnosing and treating people with fever improves health outcomes, reduces antimalarial prescribing, and is safe, compared to algorithms using clinical diagnosis.

SEARCH METHODS

We searched the Cochrane Infectious Disease Group Specialized Register; CENTRAL (The Cochrane Library); MEDLINE; EMBASE; CINAHL; LILACS; and the metaRegister of Controlled Trials for eligible trials up to 10 January 2014. We contacted researchers in the field and reviewed the reference lists of all included trials to identify any additional trials.

SELECTION CRITERIA

Individual or cluster randomized trials (RCTs) comparing RDT-supported algorithms and algorithms using clinical diagnosis alone for diagnosing and treating people with fever living in malaria-endemic settings.

DATA COLLECTION AND ANALYSIS

Two authors independently applied the inclusion criteria and extracted data. We combined data from individually and cluster RCTs using the generic inverse variance method. We presented all outcomes as risk ratios (RR) with 95% confidence intervals (CIs), and assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

We included seven trials, enrolling 17,505 people with fever or reported history of fever in this review; two individually randomized trials and five cluster randomized trials. All trials were conducted in rural African settings.In most trials the health workers diagnosing and treating malaria were nurses or clinical officers with less than one week of training in RDT supported diagnosis. Health worker prescribing adherence to RDT results was highly variable: the number of participants with a negative RDT result who received antimalarials ranged from 0% to 81%.Overall, RDT supported diagnosis had little or no effect on the number of participants remaining unwell at four to seven days after treatment (6990 participants, five trials, low quality evidence); but using RDTs reduced prescribing of antimalarials by up to three-quarters (17,287 participants, seven trials, moderate quality evidence). As would be expected, the reduction in antimalarial prescriptions was highest where health workers adherence to the RDT result was high, and where the true prevalence of malaria was lower.Using RDTs to support diagnosis did not have a consistent effect on the prescription of antibiotics, with some trials showing higher antibiotic prescribing and some showing lower prescribing in the RDT group (13,573 participants, five trials, very low quality evidence).One trial reported malaria microscopy on all enrolled patients in an area of moderate endemicity, so we could compare the number of patients in the RDT and clinical diagnosis groups that actually had microscopy confirmed malaria infection but did not receive antimalarials. No difference was detected between the two diagnostic strategies (1280 participants, one trial, low quality evidence).

AUTHORS' CONCLUSIONS

Algorithms incorporating RDTs can substantially reduce antimalarial prescribing if health workers adhere to the test results. Introducing RDTs has not been shown to improve health outcomes for patients, but adherence to the test result does not seem to result in worse clinical outcomes than presumptive treatment.Concentrating on improving the care of RDT negative patients could improve health outcomes in febrile children.

Emergency care research funding in the global health context: trends, priorities, and future directions

Over the past few decades there has been a steady growth in funding for global health, yet generally little is known about funding for global health research. As part of the 2013 Academic Emergency Medicine consensus conference, a session was convened to discuss emergency care research funding in the global health context. Overall, the authors found a lack of evidence available to determine funding priorities or quantify current funding for acute care research in global health. This article summarizes the initial preparatory research and reports on the results of the consensus conference focused on identifying challenges and strategies to improve funding for global emergency care research. The consensus conference meeting led to the creation of near- and long-term goals to strengthen global emergency care research funding and the development of important research questions. The research questions represent a consensus view of important outstanding questions that will assist emergency care researchers to better understand the current funding landscape and bring evidence to the debate on funding priorities of global health and emergency care. The four key areas of focus for researchers are: 1) quantifying funding for global health and emergency care research, 2) understanding current research funding priorities, 3) identifying barriers to emergency care research funding, and 4) using existing data to quantify the need for emergency services and acute care research. This research agenda will enable emergency health care scientists to use evidence when advocating for more funding for emergency care research.

Management of severe malaria in the intensive care unit

Severe malaria is a medical emergency requiring early intervention to prevent death. This article highlights key aspects of the management of severe malaria syndromes in the intensive care unit, with a focus on individual case management of imported malaria. Key differences in the presentation, management, and outcomes of severe malaria by endemicity and by age group are emphasized. In all groups with severe malaria, intravenous artesunate is the antimalarial agent of choice. This article discusses specific antimalarial therapies, optimal supportive management strategies, differences from strategies for bacterial sepsis, and trials of adjunctive therapy for severe malaria in humans.

High seroprevalence for typhus group rickettsiae, southwestern Tanzania

Rickettsioses caused by typhus group rickettsiae have been reported in various African regions. We conducted a cross-sectional survey of 1,227 participants from 9 different sites in the Mbeya region, Tanzania; overall seroprevalence of typhus group rickettsiae was 9.3%. Risk factors identified in multivariable analysis included low vegetation density and highway proximity.

Scaling-up attention to nonmalaria acute undifferentiated fever

Studies have reported that only a small fraction of fever cases in malaria-endemic areas are actually caused by malaria. Much greater emphasis is now needed to step up attention to the appropriate management of nonmalarial acute undifferentiated febrile illness. There is an overlap at the start of clinical manifestations of different febrile illnesses which makes it difficult to adhere to the clinical guidelines. The development of rigorous guidelines based on high quality research and a consensus from the core group of content experts are needed. An innovative financing mechanism for universal access to such appropriate management should also be considered.

High seroprevalence of Rift Valley FEVER AND EVIDENCE FOR ENDEMIC circulation in Mbeya region, Tanzania, in a cross-sectional study

Background

The Rift Valley fever virus (RVFV) is an arthropod-borne phlebovirus. RVFV mostly causes outbreaks among domestic ruminants with a major economic impact. Human infections are associated with these events, with a fatality rate of 0.5–2%. Since the virus is able to use many mosquito species of temperate climates as vectors, it has a high potential to spread to outside Africa.

Methodology/Principal Findings

We conducted a stratified, cross-sectional sero-prevalence survey in 1228 participants from Mbeya region, southwestern Tanzania. Samples were selected from 17,872 persons who took part in a cohort study in 2007 and 2008. RVFV IgG status was determined by indirect immunofluorescence. Possible risk factors were analyzed using uni- and multi-variable Poisson regression models. We found a unique local maximum of RVFV IgG prevalence of 29.3% in a study site close to Lake Malawi (N = 150). The overall seroprevalence was 5.2%. Seropositivity was significantly associated with higher age, lower socio-economic status, ownership of cattle and decreased with distance to Lake Malawi. A high vegetation density, higher minimum and lower maximum temperatures were found to be associated with RVFV IgG positivity. Altitude of residence, especially on a small scale in the high-prevalence area was strongly correlated (PR 0.87 per meter, 95% CI = 0.80–0.94). Abundant surface water collections are present in the lower areas of the high-prevalence site. RVF has not been diagnosed clinically, nor an outbreak detected in the high-prevalence area.

Conclusions

RVFV is probably circulating endemically in the region. The presence of cattle, dense vegetation and temperate conditions favour mosquito propagation and virus replication in the vector and seem to play major roles in virus transmission and circulation. The environmental risk-factors that we identified could serve to more exactly determine areas at risk for RVFV endemicity.

We describe a high seropositivity rate for Rift Valley fever virus, in up to 29.3% of tested individuals from the shore of Lake Malawi in southwestern Tanzania, and much lower rates from areas distant to the lake. Rift Valley fever disease or outbreaks have not been observed there in the past, which suggests that the virus is circulating under locally favorable conditions and is either a non-pathogenic strain, or that occasional occurrence of disease is missed. We were able to identify a low socio-economic status and cattle ownership as possible socio-economic risk factors for an individual to be seropositive. Environmental risk factors associated with seropositivity include dense vegetation, and ambient land surface temperatures which may be important for breeding success of the mosquitoes which transmit Rift Valley fever, and for efficient multiplication of the virus in the mosquito. Low elevation of the home, and proximity to Lake Malawi probably lead to abundant surface water collections, which serve as breeding places for mosquitoes. These findings will inform patient care in the areas close to Lake Malawi, and may help to design models which predict low-level virus circulation.

Reducing malaria misdiagnosis: the importance of correctly interpreting Paracheck Pf® "faint test bands" in a low transmission area of Tanzania

Background

Although malaria rapid diagnostic tests (RDTs) have been extensively evaluated since their introduction in the early 1990's, sensitivity and specificity vary widely limiting successful integration into clinical practice. This paper reviews specific issues surrounding RDT use in field settings and presents results of research investigating how to interpret "faint test bands" on ParaCheck Pf^® in areas of low transmission in order to reduce malaria misdiagnosis.

Methods

A multi-phase cross-sectional study was conducted at a remote hospital in the northern Tanzanian highlands. Capillary blood samples were taken from consenting participants (n = 319) for blood smear and ParaCheck Pf^® testing. Primary outcome variables were sensitivity, specificity and proportion misdiagnosed by ParaCheck Pf^® and local microscopy. ParaCheck Pf^® "faint bands" were classified as both true positives or true negatives during evaluation to determine appropriate clinical interpretation. Multivariate logistic regression adjusted for age and gender was conducted to determine odds of misdiagnosis for local microscopy and ParaCheck Pf^®.

Results

Overall, 23.71% of all ParaCheck Pf^® tests resulted in a "faint band" and 94.20% corresponded with true negatives. When ParaCheck Pf^® "faint bands" were classified as positive, specificity was 75.5% (95% CI = 70.3% - 80.6%) as compared to 98.9% (95% CI = 97.0% - 99.8%) when classified as negative. The odds of misdiagnosis by local microscopy for those > 5 years as compared to those ≤ 5 years are 0.370 (95% CI = 0.1733 - 0.7915, p = 0.010). In contrast, even when ParaCheck Pf^® faint bands are considered positive, the odds of misdiagnosis by ParaCheck Pf^® for those > 5 years as compared to those ≤ 5 years are 0.837 (95% CI = 0.459 - 1.547, p = 0.5383).

Conclusions

We provide compelling evidence that in areas of low transmission, "faint bands" should be considered a negative test when used to inform clinical decision-making. Correct interpretation of RDT test bands in a clinical setting plays a central role in successful malaria surveillance, appropriate patient management and most importantly reducing misdiagnosis.

Effect of supplementation with zinc and other micronutrients on malaria in Tanzanian children: a randomised trial

BACKGROUND

It is uncertain to what extent oral supplementation with zinc can reduce episodes of malaria in endemic areas. Protection may depend on other nutrients. We measured the effect of supplementation with zinc and other nutrients on malaria rates.

METHODS AND FINDINGS

In a 2×2 factorial trial, 612 rural Tanzanian children aged 6-60 months in an area with intense malaria transmission and with height-for-age z-score≤-1.5 SD were randomized to receive daily oral supplementation with either zinc alone (10 mg), multi-nutrients without zinc, multi-nutrients with zinc, or placebo. Intervention group was indicated by colour code, but neither participants, researchers, nor field staff knew who received what intervention. Those with Plasmodium infection at baseline were treated with artemether-lumefantrine. The primary outcome, an episode of malaria, was assessed among children reported sick at a primary care clinic, and pre-defined as current Plasmodium infection with an inflammatory response, shown by axillary temperature ≥37.5°C or whole blood C-reactive protein concentration ≥ 8 mg/L. Nutritional indicators were assessed at baseline and at 251 days (median; 95% reference range: 191-296 days). In the primary intention-to-treat analysis, we adjusted for pre-specified baseline factors, using Cox regression models that accounted for multiple episodes per child. 592 children completed the study. The primary analysis included 1,572 malaria episodes during 526 child-years of observation (median follow-up: 331 days). Malaria incidence in groups receiving zinc, multi-nutrients without zinc, multi-nutrients with zinc and placebo was 2.89/child-year, 2.95/child-year, 3.26/child-year, and 2.87/child-year, respectively. There was no evidence that multi-nutrients influenced the effect of zinc (or vice versa). Neither zinc nor multi-nutrients influenced malaria rates (marginal analysis; adjusted HR, 95% CI: 1.04, 0.93-1.18 and 1.10, 0.97-1.24 respectively). The prevalence of zinc deficiency (plasma zinc concentration <9.9 µmol/L) was high at baseline (67% overall; 60% in those without inflammation) and strongly reduced by zinc supplementation.

CONCLUSIONS

We found no evidence from this trial that zinc supplementation protected against malaria.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00623857

Antibodies to Plasmodium falciparum antigens and the risk of clinical malaria in endemic populations

As the research for the development of a malaria vaccine becomes increasingly important, a thorough understanding of the protection afforded by antibodies against parasite antigens is essential. The factors affecting the protective ability of antibodies elicited by highly immunogenic malaria parasite antigens and their interaction have been investigated in a study of Ugandan children by Greenhouse and colleagues. Their interesting finding of the effect of prior exposure on the protection provided against symptomatic malaria and the importance of the results in the immuno-epidemiological studies are discussed in this article.

Effect of α(+)-thalassaemia on episodes of fever due to malaria and other causes: a community-based cohort study in Tanzania

Background

It is controversial to what degree α⁺-thalassaemia protects against episodes of uncomplicated malaria and febrile disease due to infections other than Plasmodium.

Methods

In Tanzania, in children aged 6-60 months and height-for-age z-score < -1.5 SD (n = 612), rates of fevers due to malaria and other causes were compared between those with heterozygous or homozygotes α⁺-thalassaemia and those with a normal genotype, using Cox regression models that accounted for multiple events per child.

Results

The overall incidence of malaria was 3.0/child-year (1, 572/526 child-years); no differences were found in malaria rates between genotypes (hazard ratios, 95% CI: 0.93, 0.82-1.06 and 0.91, 0.73-1.14 for heterozygotes and homozygotes respectively, adjusted for baseline factors that were predictive for outcome). However, this association strongly depended on age: among children aged 6-17 months, those with α⁺-thalassaemia experienced episodes more frequently than those with a normal genotype (1.30, 1.02-1.65 and 1.15, 0.80-1.65 for heterozygotes and homozygotes respectively), whereas among their peers aged 18-60 months, α⁺-thalassaemia protected against malaria (0.80, 0.68-0.95 and 0.78, 0.60-1.03; p-value for interaction 0.001 and 0.10 for hetero- and homozygotes respectively). No effect was observed on non-malarial febrile episodes.

Conclusions

In this population, the association between α⁺-thalassaemia and malaria depends on age. Our data suggest that protection by α⁺-thalassaemia is conferred by more efficient acquisition of malaria-specific immunity.

Erythropoietin levels are not independently associated with malaria-attributable severe disease in Mozambican children

Background

Severe malaria is difficult to differentiate from other forms of malaria or other infections with similar symptoms. Any parameter associated to malaria-attributable severe disease could help to improve severe malaria diagnosis.

Methodology

This study assessed the relation between erythropoietin (EPO) and malaria-attributable severe disease in an area of Mozambique with moderate malaria transmission. 211 children <5 years, recruited at Manhiça District Hospital or in the surrounding villages, were included in one of the following groups: severe malaria (SM, n = 44), hospital malaria without severity (HM, n = 49), uncomplicated malaria (UM, n = 47), invasive bacterial infection without malaria parasites (IBI, n = 39) and healthy community controls (C, n = 32). Malaria was diagnosed by microscopy and IBI by blood/cerebrospinal fluid culture.

Principal Findings

Mean EPO concentration in the control group was 20.95 U/l (SD = 2.96 U/l). Values in this group were lower when compared to each of the clinical groups (p = 0.026 C versus UM, p<0.001 C vs HM, p<0.001 C vs SM and p<0.001 C vs IBI). In the 3 malaria groups, values increased with severity [mean = 40.82 U/l (SD = 4.07 U/l), 125.91 U/l (SD = 4.99U/l) and 320.87 U/l (SD = 5.91U/l) for UM, HM and SM, respectively, p<0.001]. The IBI group [mean = 101.75 U/l (SD = 4.12 U/l)] presented lower values than the SM one (p = 0.002). In spite of the differences, values overlapped between study groups and EPO levels were only associated to hemoglobin. Hemoglobin means of the clinical groups were 93.98 g/dl (SD = 14.77 g/dl) for UM, 75.96 g/dl (SD = 16.48 g/dl) for HM, 64.34 g/dl (SD = 22.99 g/dl) for SM and 75.67 g/dl (SD = 16.58 g/dl) for IBI.

Conclusions

Although EPO levels increase according to malaria severity and are higher in severe malaria than in bacteremia, the utility of EPO to distinguish malaria-attributable severe disease is limited due to the overlap of values between the study groups and the main role of hemoglobin in the expression of EPO.

Continuing intense malaria transmission in northern Uganda

Recent reports of reductions in malaria transmission in several African countries have resulted in optimism that malaria can be eliminated in parts of Africa where it is currently endemic. It is not known whether these trends are global or whether they are also present in areas where political instability has hindered effective malaria control. We determined malaria parasite carriage and age-dependent antibody responses to Plasmodium falciparum antigens in cross-sectional surveys in Apac, northern Uganda that was affected by political unrest. Under-five parasite prevalence was 55.8% (115/206) by microscopy and 71.9% (41/57) by polymerase chain reaction. Plasmodium ovale alone, or as a co-infection, was detected in 8.6% (12/139) and Plasmodium malariae in 4.3% (6/139) of the infections. Age seroprevalence curves gave no indication of recent changes in malaria transmission intensity. Malaria control remains a tremendous challenge in areas that have not benefited from large-scale interventions, illustrated here by the district of Apac.

Acute seizures attributable to falciparum malaria in an endemic area on the Kenyan coast

Falciparum malaria is an important cause of acute symptomatic seizures in children admitted to hospitals in sub-Saharan Africa, and these seizures are associated with neurological disabilities and epilepsy. However, it is difficult to determine the proportion of seizures attributable to malaria in endemic areas since a significant proportion of asymptomatic children have malaria parasitaemia. We studied children aged 0–13 years who had been admitted with a history of seizures to a rural Kenyan hospital between 2002 and 2008. We examined the changes in the incidence of seizures with the reduction of malaria. Logistic regression was used to model malaria-attributable fractions for seizures (the proportion of seizures caused by malaria) to determine if the observed decrease in acute symptomatic seizures was a measure of seizures that are attributable to malaria. The overall incidence of acute symptomatic seizures over the period was 651/100 000/year (95% confidence interval 632–670) and it was 400/100 000/year (95% confidence interval 385–415) for acute complex symptomatic seizures (convulsive status epilepticus, repetitive or focal) and 163/100 000/year (95% confidence interval 154–173) for febrile seizures. From 2002 to 2008, the incidence of all acute symptomatic seizures decreased by 809/100 000/year (69.2%) with 93.1% of this decrease in malaria-associated seizures. The decrease in the incidence of acute complex symptomatic seizures during the period was 111/100 000/year (57.2%) for convulsive status epilepticus, 440/100 000/year (73.7%) for repetitive seizures and 153/100 000/year (80.5%) for focal seizures. The adjusted malaria-attributable fractions for seizures with parasitaemia were 92.9% (95% confidence interval 90.4–95.1%) for all acute symptomatic seizures, 92.9% (95% confidence interval 89.4–95.5%) for convulsive status epilepticus, 93.6% (95% confidence interval 90.9–95.9%) for repetitive seizures and 91.8% (95% confidence interval 85.6–95.5%) for focal seizures. The adjusted malaria-attributable fractions for seizures in children above 6 months of age decreased with age. The observed decrease in all acute symptomatic seizures (809/100 000/year) was similar to the predicted decline (794/100 000/year) estimated by malaria-attributable fractions at the beginning of the study. In endemic areas, falciparum malaria is the most common cause of seizures and the risk for seizures in malaria decreases with age. The reduction in malaria has decreased the burden of seizures that are attributable to malaria and this could lead to reduced neurological disabilities and epilepsy in the area.

Estimating the global clinical burden of Plasmodium falciparum malaria in 2007

BACKGROUND

The epidemiology of malaria makes surveillance-based methods of estimating its disease burden problematic. Cartographic approaches have provided alternative malaria burden estimates, but there remains widespread misunderstanding about their derivation and fidelity. The aims of this study are to present a new cartographic technique and its application for deriving global clinical burden estimates of Plasmodium falciparum malaria for 2007, and to compare these estimates and their likely precision with those derived under existing surveillance-based approaches.

METHODS AND FINDINGS

In seven of the 87 countries endemic for P. falciparum malaria, the health reporting infrastructure was deemed sufficiently rigorous for case reports to be used verbatim. In the remaining countries, the mapped extent of unstable and stable P. falciparum malaria transmission was first determined. Estimates of the plausible incidence range of clinical cases were then calculated within the spatial limits of unstable transmission. A modelled relationship between clinical incidence and prevalence was used, together with new maps of P. falciparum malaria endemicity, to estimate incidence in areas of stable transmission, and geostatistical joint simulation was used to quantify uncertainty in these estimates at national, regional, and global scales. Combining these estimates for all areas of transmission risk resulted in 451 million (95% credible interval 349-552 million) clinical cases of P. falciparum malaria in 2007. Almost all of this burden of morbidity occurred in areas of stable transmission. More than half of all estimated P. falciparum clinical cases and associated uncertainty occurred in India, Nigeria, the Democratic Republic of the Congo (DRC), and Myanmar (Burma), where 1.405 billion people are at risk. Recent surveillance-based methods of burden estimation were then reviewed and discrepancies in national estimates explored. When these cartographically derived national estimates were ranked according to their relative uncertainty and replaced by surveillance-based estimates in the least certain half, 98% of the global clinical burden continued to be estimated by cartographic techniques.

CONCLUSIONS AND SIGNIFICANCE

Cartographic approaches to burden estimation provide a globally consistent measure of malaria morbidity of known fidelity, and they represent the only plausible method in those malaria-endemic countries with nonfunctional national surveillance. Unacceptable uncertainty in the clinical burden of malaria in only four countries confounds our ability to evaluate needs and monitor progress toward international targets for malaria control at the global scale. National prevalence surveys in each nation would reduce this uncertainty profoundly. Opportunities for further reducing uncertainty in clinical burden estimates by hybridizing alternative burden estimation procedures are also evaluated.

Parasite threshold associated with clinical malaria in areas of different transmission intensities in north eastern Tanzania

Background

In Sub-Sahara Africa, malaria due to Plasmodium falciparum is the main cause of ill health. Evaluation of malaria interventions, such as drugs and vaccines depends on clinical definition of the disease, which is still a challenge due to lack of distinct malaria specific clinical features. Parasite threshold is used in definition of clinical malaria in evaluation of interventions. This however, is likely to be influenced by other factors such as transmission intensity as well as individual level of immunity against malaria.

Methods

This paper describes step function and dose response model with threshold parameter as a tool for estimation of parasite threshold for onset of malaria fever in highlands (low transmission) and lowlands (high transmission intensity) strata. These models were fitted using logistic regression stratified by strata and age groups (0-1, 2-3, 4-5, 6-9, and 10-19 years). Dose response model was further extended to fit all age groups combined in each stratum. Sub-sampling bootstrap was used to compute confidence intervals. Cross-sectional and passive case detection data from Korogwe district, north eastern Tanzania were used.

Results

Dose response model was better in the estimation of parasite thresholds. Parasite thresholds (scale = log parasite/μL) were high in lowlands than in highlands. In the lowlands, children in age group 4-5 years had the highest parasite threshold (8.73) while individuals aged 10-19 years had the lowest (6.81). In the highlands, children aged 0-1 years had the highest threshold (7.12) and those aged 10-19 years had the lowest (4.62). Regression analysis with all ages combined showed similar pattern of thresholds in both strata, whereby, in the lowlands the threshold was highest in age group 2-5 years and lowest in older individuals, while in the highlands was highest in age group 0-1 and decreased with increased age. The sensitivity of parasite threshold by age group ranged from 64%-74% in the lowlands and 67%-97% in the highlands; while specificity ranged between 67%-90% in the lowlands and 37%-73% in the highlands.

Conclusion

Dose response model with threshold parameter can be used to estimate parasite threshold associated with malaria fever onset. Parasite threshold were lower in older individuals and in low malaria transmission area.