Cerebral malaria in children

Neuregulin-1/ErbB4 signaling modulates Plasmodium falciparum HRP2-induced damage to brain cortical organoids

Human cerebral malaria (HCM) is a severe complication of Plasmodium falciparum (P.f.) infection that is characterized by capillary occlusions, rupture of the blood-brain barrier (BBB), perivascular cellular injury, and brain swelling. P.f.histidine-rich protein 2 (HRP2), a byproduct of parasitized red blood cell (pRBC) lysis, crosses the BBB when compromised to cause brain injury. We hypothesized that HRP2-induced neuronal damage can be attenuated by Neuregulin-1 (NRG1), an anti-inflammatory neuroprotective factor. Using brain cortical organoids, we determined that HRP2 upregulated cell death and inflammatory markers and disorganized brain organoid tissue. We identified toll-like receptors (TLR1 and 2) as potential mediators of HRP2-induced cellular damage and inflammation. Exogenous acute treatment of organoids with NRG1 attenuated HRP2 effects. The results indicate that HRP2 mediates malaria-associated HRP2-induced brain injury and inflammation and that NRG1 may be an effective therapy against HRP2 effects in the brain.

Plasma and Cerebrospinal Fluid Beta-Endorphin Levels Show a Strong Association in Children with Cerebral Malaria

BACKGROUND

Beta (β)-endorphins are endogenous neuropeptides found in the plasma and cerebrospinal fluid (CSF) of humans but there have been reports of the relationship between the plasma and CSF β-endorphin levels in different clinical conditions. However, the relationship between β-endorphin levels in the plasma and CSF of children with cerebral malaria (CM) has not been reported.

AIM

To determine the relationship between β-endorphin levels in the CSF and plasma of children with CM.

SETTINGS AND DESIGN

This cross-sectional study involved 40 children, aged between 6 months and 14 years, admitted with a diagnosis of CM at the Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife, Nigeria.

MATERIALS AND METHODS

One milliliter (mL) of venous blood and 1mL of CSF obtained from each subject at admission were used to determine the β-endorphin levels using enzyme-linked immunosorbent assay (ELISA) method.

STATISTICAL ANALYSIS

Bivariate linear regression was used to determine the association between plasma and CSF β-endorphin levels using the correlation coefficient (r), coefficient of determination (R 2), and P values.

RESULTS

The plasma β-endorphin levels significantly positively correlated with CSF β-endorphin (r = 0.568, P = 0.001) such that for every unit rise in plasma β-endorphin, CSF β-endorphin rose by 0.252 pmol/L (confidence interval: 0.132-0.371 pmol/L).

CONCLUSION

The finding of positive correlation between plasma and CSF β-endorphin levels in this study suggests a possible direct link between plasma and CSF in CM, probably from the disruption of the blood-brain barrier that has been reported in CM.

Infections in the immunocompromised child

Prevention and management of opportunistic infections in children is particularly relevant in an era demonstrating an increased prevalence of immunocompromising conditions. The presence of an unusual organism which results in serious infection in a child should therefore always raise the consideration of immune compromise. The more common opportunistic infections have become easier to recognize in recent times due to improved awareness and more refined diagnostic testing. Targeted treatment is usually followed by long-term prophylactic medication. The impact of these conditions on patient outcome is of clear significance and certainly warrants further discussion.

Cerebrospinal fluid and plasma β-endorphin levels in children with cerebral malaria

OBJECTIVES

Cerebral malaria (CM) is the most lethal form of malaria, yet its pathogenesis is not fully understood. Cytoadherence, sequestration, alterations in cytokine expression, inflammation, and microvascular obstruction are all hypothesized to be important in the aetio-pathogenesis of coma which characterizes cerebral malaria and the death which sometimes result. Beta (β)-endorphin has been postulated to be involved in the pathogenetic processes of inflammation and cytokine expression, although the exact role is unknown. The aim of this study was to determine the levels of β-endorphin in cerebrospinal fluid (CSF) and plasma of children with CM and compare the levels of β-endorphin in the plasma of children with CM with that of apparently healthy age- and sex-matched controls at Ile-Ife, Nigeria.

MATERIALS AND METHODS

Additional to the standard investigation for CM, CSF and venous blood samples were obtained from the subjects for the determination of β-endorphin levels.

RESULTS

Forty children with CM were studied along with forty age- and sex-matched controls. The mean CSF β-endorphin (± SD) level for the children with CM was 1.8 ± 0.9 pmol/L. The mean plasma β-endorphin levels at admission (3.1 ± 2.0 pmol/L) and discharge (4.1 ± 3.3 pmol/L) were higher in children with CM than in the control subjects (2.7 ± 0.7 pmol/L). However, only the mean plasma β-endorphin levels at discharge was significantly higher than that of controls (p = .012).

CONCLUSION

Children with CM had higher mean plasma β-endorphin levels compared to the controls and there was increased production of β-endorphins in children with CM during the course of the illness.

Immediate outcome and prognostic factors for cerebral malaria among children admitted to Mulago Hospital, Uganda

Despite treatment, cerebral malaria still has a high mortality. This study describes the clinical features, immediate outcome and prognostic factors for childhood cerebral malaria in Mulago Hospital, Kampala, Uganda. One hundred children who met the WHO criteria for cerebral malaria were prospectively recruited and followed up until discharge or death. Mortality was 7% and neurological sequelae occurred in 5% of survivors. Independent predictors of mortality were respiratory distress [adjusted OR 1.2 (95% CI 1.1-1.3)], circulatory failure [adjusted OR 2.1 (95% CI 1.8-2.4)], generalised hyporeflexia [adjusted OR 1.2 (95% CI 1.1-1.3)] and parasite density > or =500,000/microl [adjusted OR 1.02 (95% CI 1.01-1.2)]. Circulatory failure could be predicted by a combination of hypothermia, cold peripheries and dehydration. Death occurred within 12 hours of admission only in children with these predictors, and the risk of death increased with the number of risk factors. Multiple convulsions at admission predicted neurological sequelae [adjusted OR 12.8, 95% CI 3.0-211, p=0.014)]. Cerebral malaria mortality is predictable. Patients with respiratory distress, circulatory failure, generalised hyporeflexia and parasite density > or =500,000/microl need urgent treatment to prevent death. In primary health units, health workers may use a combination of cold peripheries, hypothermia and dehydration to predict circulatory failure.

Cerebellar atrophy in falciparum malaria

Severe neurological complications are associated with falciparum malaria. We describe the case of an eight-year-old male child with severe falciparum malaria with high-level parasitemia and severe thrombocytopenia. There were features of abnormal gait, speech difficulty and altered behavior pattern during the recovery phase. This occurred even after receiving antimalarial therapy. MRI showed bilateral cerebellar atrophy.

Atypical manifestations of malaria

Malaria remains a major cause of morbidity and mortality worldwide. The classic presentation of malaria with paroxysms of fever is seen only in 50%-70% of patients. Development of immunity, increasing resistance to antimalarial drugs, and indiscriminate use of antimalarial drugs have led to malaria presenting with unusual features. This review compiles a description of the various atypical manifestations of malaria.

The 'non-falciparum' malarias: the roles of epidemiology, parasite biology, clinical syndromes, complications and diagnostic rigour in guiding therapeutic strategies

Plasmodium vivax, P. ovale, P. malariae and P. falciparum routinely infect humans. The infections caused by these parasites are loosely referred to as vivax (or benign tertian), ovale, malariae (or quartan) and falciparum (or malignant tertian) malaria, respectively. Recently, P. knowlesi, a parasite of macaque monkeys in South-east Asia, has been identified as the cause of uncomplicated and severe human malaria in Malaysian Borneo. The prescription of appropriate therapies for reliably diagnosed malaria requires a grasp of the epidemiology of the 'non-falciparum' malarias, the biology of the parasites involved, the chemotherapeutic strategies that are available and the problems of emerging drug resistance and changing clinical syndromes. This review is intended to increase clinicians' understanding of how these factors relate to the selection of the antimalarial drugs to be given to a case of 'non-falciparum' malaria, with the aims of improving outcomes and preventing relapses and recrudescences.

Chapter 22: a history of child neurology and neurodisability

This chapter reviews the fascinating history of child neurology and neurodisability from amongst its earliest recorded origins, Mesopotamian tablets, through to magnetic resonance imaging. It is the first review of such breadth in this area since Levinson in 1948. As well as covering the traditionally covered areas namely cerebral palsy, epilepsy, and mental retardation, the chapter explores other areas of pediatric neurodisability that have, since Levinson, become mainstream practice and now fall within this area of specialty. These conditions include the autistic spectrum disorders and attention deficit disorder. The dramatic advances in neural imaging and genetics in helping to explain different pediatric neurological conditions are also discussed as well as concepts and understanding concerning recovery from brain damage. The changing epidemiology of neurodisability through effective advances in acute neonatal and pediatric medical care, screening programs and social interventions are also related. Lastly, the fundamental reappraisal of society's attitude toward the disabled following World War II is explored. The lives of the disabled began to be seen to have value, belatedly gaining legal protection against discrimination, gaining dignity, independence, and for the first time being listened to.

Risk factors for persisting neurological and cognitive impairments following cerebral malaria

BACKGROUND

Persisting neurological and cognitive impairments are common after cerebral malaria. Although risk factors for gross deficits on discharge have been described, few studies have examined those associated with persistent impairments.

METHODS

The risk factors for impairments following cerebral malaria were determined by examining hospital records of 143 children aged 6-9 years, previously admitted with cerebral malaria, who were assessed at least 20 months after discharge to detect motor, speech and language, and other cognitive (memory, attention, and non-verbal functioning) impairments.

RESULTS

The median age on admission was 30 months (IQR 19-42) and the median time from discharge to assessment was 64 months (IQR 40-78). Thirty four children (23.8%) were defined as having impairments: 14 (9.8%) in motor, 16 (11.2%) in speech and language, and 20 (14.0%) in other cognitive functions. Previous seizures (OR 5.6, 95% CI 2.0 to 16.0), deep coma on admission (OR 28.8, 95% CI 3.0 to 280), focal neurological signs observed during admission (OR 4.6, 95% CI 1.1 to 19.6), and neurological deficits on discharge (OR 4.5, 95% CI 1.4 to 13.8) were independently associated with persisting impairments. In addition, multiple seizures were associated with motor impairment, age <3 years, severe malnutrition, features of intracranial hypertension, and hypoglycaemia with language impairments, while prolonged coma, severe malnutrition, and hypoglycaemia were associated with impairments in other cognitive functions.

CONCLUSIONS

Risk factors for persisting neurological and cognitive impairments following cerebral malaria include multiple seizures, deep/prolonged coma, hypoglycaemia, and clinical features of intracranial hypertension. Although there are overlaps in impaired functions and risk factors, the differences in risk factors for specific functions may suggest separate mechanisms for neuronal damage. These factors could form the basis of future preventive strategies for persisting impairments.

Pediatric malaria in the developing world

Hundreds of millions of people suffer from malaria, and more than a million children die of malaria each year. Malaria typically presents with fever and headache, but the presentation often is nonspecific. The diagnosis should be based on blood tests, and thick and thin smears are the standard means of identifying parasites. In some areas, chloroquine still is effective as treatment, but other medications are needed in most parts of the world. Patients with severe disease (altered consciousness, marked anemia, and/or respiratory distress) should begin therapy parenterally. Control measures depend on the use of insecticide-treated bednets, early identification and treatment of symptomatic individuals, and intermittent preventive therapy. Progress continues toward the development of a useful vaccine.

Feasibility of LDF measurements of optic nerve head blood flow in children with cerebral malaria

The pathogenesis of cerebral malaria (CM), a significant cause of death in the tropics, is still not understood. Cerebral blood flow measurements would be important but are difficult under the conditions prevailing in CM clinics in the tropics. With the goal of using optic nerve head (ONH) blood flow (F(onh)) instead of cerebral blood flow to help outcome prediction, we have tested the feasibility of performing F(onh) measurements in comatose CM children, using a portable ocular laser Doppler flowmeter (LDF). Measurements were performed in one eye of each of 13 children (2.7 +/- 1.1 years) during a period of about 8 min. The Vel(onh) (the relative blood velocity), Vol(onh) (the relative blood volume), and F(onh) values were determined for each child from three to five measurements of 2 to 20 s. Average Vel(onh), Vol(onh), and F(onh) values were 0.49 +/- 0.08 kHz, 2.4 +/- 1.06 arbitrary units (a.u.), and 89 +/- 16.8 a.u., respectively. The average coefficients of variation of the flow parameters based on all segments in each child were 13 +/- 9% (range 1-29%) for Vel(onh), 27 +/- 13% (range 3-65%) for Vol(onh), and 23 +/- 12% (range 5-42%) for F(onh). This study demonstrates the feasibility of LDF measurements in CM children. The large range of these coefficients of variations could be due to the presence of fluctuations of ONH blood flow on a short time scale in these neurologically unstable children.

Cerebral malaria in rural India

OBJECTIVE

A cross-sectional hospital based study was carried out to investigate clinical features and outcome of cerebral malaria in a rural area.

METHODS

All children fulfilling inclusion criteria, were enrolled and were entered on specially designed proforma. Their peripheral smear (PS) were studied based on which the diagnosis was classified as definite cerebral malaria (DCM) and probable cerebral malaria (PCM).

RESULT

There were 2991 admissions in pediatric ward, of which 1394 (46.6%) were for fever. Of 781 (56.6%) cases with fever no cause was identified. Of the 56 cases positive for malarial parasite on PS 4.3% were Plasmodium vivax (PV) and 2.8% Plasmodium falciparum (PF). Fifteen patients fulfilled the criteria for study of which 7 were DCM and 8 belonged to PCM group. Twelve (80%) were in school-going age group and M : F ratio was 2 : 1. All patients presented with fever, and CNS involvement, 66.6% had convulsion, 7 developed coma, anaemia was seen in 60%, but only 20% required blood transfusion. Splenomegaly and hepatomegaly was seen in 53.3% and 47% cases respectively. Two patients died, one each in DCM and PCM. Cerebral malaria is a serious complication of severe falciparum malaria and is seen in approximately 32% of PF positive cases.

CONCLUSION

PCM is an entity which should be kept in mind when treating fever without definite focus in rural areas, because timely and specific therapy is lifesaving.

Central nervous system in cerebral malaria: 'Innocent bystander' or active participant in the induction of immunopathology?

Cerebral malaria (CM) is a major life-threatening complication of Plasmodium falciparum infection in humans, responsible for up to 2 million deaths annually. The mechanisms underlying the fatal cerebral complications are still not fully understood. Many theories exist on the aetiology of human CM. The sequestration hypo-thesis suggests that adherence of parasitized erythrocytes to the cerebral vasculature leads to obstruction of the microcirculation, anoxia or metabolic disturbances affecting brain function, resulting in coma. This mechanism alone seems insufficient to explain all the known features of CM. In this review we focus on another major school of thought, that CM is the result of an over-vigorous immune response originally evolved for the protection of the host. Evidence in support of this second hypothesis comes from studies in murine malaria models in which T cells, monocytes, adhesion molecules and cytokines, have been implicated in the development of the cerebral complications. Recent studies of human CM also indicate a role for the immune system in the neurological complications. However, it is likely that multiple mechanisms are involved in the induction of cerebral complications and both the presence of parasitized erythrocytes in the central nervous system (CNS) and immunopathological processes contribute to the pathogenesis of CM. Most studies examining immunopathological responses in CM have focused on reactions occurring primarily in the systemic circulation. However, these also do not fully account for the development of cerebral complications in CM. In this review we summarize results from human and mouse studies that demonstrate morphological and functional changes in the resident glial cells of the CNS. The degree of immune activation and degeneration of glial cells was shown to reflect the extent of neurological complications in murine cerebral malaria. From these results we highlight the need to consider the potentially important contribution within the CNS of glia and their secreted products, such as cytokines, in the development of human CM.

No evidence for cerebral hypoperfusion during cerebral malaria

OBJECTIVE

Among the mechanisms suggested for altered consciousness during cerebral malaria is the hypothesis of cerebral ischemia, which remains controversial, with little supportive O2 conflicting hemodynamic data. The purpose of this study was to test the hypothesis that cerebral ischemia is a main mechanism for altered consciousness during cerebral malaria.

SETTING

University hospital pediatric ward in a region with endemic cerebral malaria.

DESIGN

Prospective evaluation of cerebral hemodynamics and cerebral oxygenation during cerebral malaria compared with severe malaria anemia without altered consciousness.

PATIENTS

During a 2-wk period, we evaluated all patients who were admitted for cerebral malaria (n = 5). Age-matched patients admitted for severe malaria anemia without altered consciousness (n = 3) and outpatients (n = 3) were investigated for comparison.

INTERVENTIONS

All patients received the usual treatment according to their needs, which was determined by the physician in charge. Repeated neurologic evaluations were performed during the early management period in patients with cerebral malaria.

METHODS AND MAIN RESULTS

We repeatedly measured cerebral blood flow velocity (transcranial Doppler) and simultaneous systemic determinants of cerebral blood flow (arterial pressure, arterial oxygen saturation, PaCO2, rectal temperature, and hemoglobin concentration). The adequacy of cerebral blood flow to oxygen demands during cerebral malaria was assessed by continuous recording of jugular bulb venous oxygen saturation (using a fiberoptic device). Marked cerebral vasodilation was observed during cerebral malaria (systolic velocity, 1.45 +/- 0.09 m/s; diastolic velocity, 0.75 +/- 0.08 m/s; n = 4) and during severe malaria anemia (systolic velocity, 1.18 +/- 0.14 m/s; diastolic velocity, 0.55 +/- 0.05 m/s; n = 3) compared with control children (systolic velocity, 0.84 +/- 0.13 m/s; diastolic velocity, 0.35 +/- 0.06 m/s; n = 3; p < .05). During cerebral malaria, jugular bulb venous oxygen saturation remained stable, including during neurologic recovery, with initial values of 67.5 +/- 4.3%.

CONCLUSIONS

Because jugular bulb venous oxygen saturation remained within the normal range, cerebral hyperemia seems to be an adaptive response to altered systemic determinants, which argues against a hemodynamic mechanism for altered consciousness during cerebral malaria.

Malaria in travelers. Epidemiology, disease, and prevention

The combination of increases in international travel and escalating drug resistance has resulted in a growing number of travelers contracting malaria. Preventing malaria-associated morbidity and mortality will require improved health information for travelers about the risk of malaria and appropriate preventive measures, improved recognition of infection by physicians, rapid and accurate laboratory diagnosis, and prompt initiation of effective therapy.

Effect of iron chelation therapy on mortality in Zambian children with cerebral malaria

To examine the effect of iron chelation on mortality in cerebral malaria, we enrolled 352 children in a trial of deferoxamine in addition to standard quinine therapy at 2 centres in Zambia, one rural and one urban. Entrance criteria included age < 6 years, Plasmodium falciparum parasitaemia, normal cerebral spinal fluid, and unrousable coma. Deferoxamine (100 mg/kg/d infused for a total of 72 h) or placebo was added to a 7 d regimen of quinine that included a loading dose. Mortality overall was 18.3% (32/175) in the deferoxamine group and 10.7% (19/177) in the placebo group (adjusted odds ratio 1.8; 95% confidence interval 0.9-3.6; P = 0.074). At the rural study site, mortality was 15.4% (18/117) with deferoxamine compared to 12.7% (15/118) with placebo (P = 0.78, adjusted for covariates). At the urban site, mortality was 24.1% (14/58) with deferoxamine and 6.8% (4/59) with placebo (P = 0.061, adjusted for covariates). Among survivors, there was a non-significant trend to faster recovery from coma in the deferoxamine group (adjusted odds ratio 1.2; 95% confidence interval 0.97-1.6; P = 0.089). Hepatomegaly was significantly associated with higher mortality, while splenomegaly was associated with lower mortality. This study did not provide evidence for a beneficial effect on mortality in children with cerebral malaria when deferoxamine was added to quinine, given in a regimen that included a loading dose.

Malaria

The preeminent infectious threat to unwary tropical travelers, malaria is a preventable, mosquito-borne protozoan infection of red blood cells, which causes fever, anemia, respiratory failure, coma, and death. Malaria is a true medical emergency that requires rapid diagnosis and treatment. Unfortunately, in two thirds of tropical travelers who die of malaria, either treatment is delayed or the diagnosis is simply missed. Every tropical traveler with fever or unexplained, flu-like illness must be assumed to have life-threatening malaria and must have thick and thin blood smears immediately examined to confirm the diagnosis.

Redistribution and degeneration of retinal astrocytes in experimental murine cerebral malaria: relationship to disruption of the blood-retinal barrier

To determine whether astrocytes play a critical role in the pathogenesis of experimental murine cerebral malaria (EMCM), we examined changes in astrocyte morphology and distribution, using retinal wholemounts, in three models: a fatal cerebral malaria (CM) model, in which mice die showing cerebral symptoms; a "resolving" model, in which mice exhibit mild cerebral symptoms, but then recover; and a non-CM model, in which cerebral symptoms are not seen. In the fatal model, retinal astrocytes lost their even distribution from day 3 post-inoculation (p.i.) with malaria parasites, progressing to gliosis (day 5 p.i.), well before the onset of cerebral symptoms on day 6-7 p.i. At the terminal stage of the disease there was a loss of astrocyte processes contacting retinal vessels, often along vessel segments containing adherent monocytes. These features occurred in a mild form in the resolving model and were absent in the non-CM models. To investigate the mechanisms underlying these astrocytic changes, we carried out two experimental manipulations. Firstly, since dexamethasone ameliorates cerebral complications in the fatal CM model, the astrocytic response was monitored after dexamethasone treatment on days 0 and 1 p.i., or days 3 and 4 p.i. Second, to determine whether increased blood-retinal barrier (BRB) permeability initiates the astrocyte changes, breakdown of the BRB was induced experimentally by intra-carotid injection of arabinose and astrocyte morphology and distribution were examined 12, 24, and 48 h later. Retinal astrocytes in both the dexamethasone- and the arabinose-treated groups showed loss of even astrocyte distribution but no loss of astrocyte ensheathment of vessels. It is concluded that: i) astrocytes are involved in the pathogenesis of EMCM, since these changes are only prominent in the fatal model and occur substantially before the onset of cerebral symptoms; ii) the initial changes in astrocyte distribution may be a consequence of the increase in BRB permeability; and iii) the immune response triggered by the malaria parasite may be responsible for the loss of astrocyte ensheathment of vessel segments.

Chemotherapy and prevention of drug-resistant malaria

Drug-resistant falciparum and vivax malaria will continue to be an increasing problem. The incidence of drug-resistant malaria has been increasing at a rate that exceeds new drug development. Plasmodium falciparum has rapidly developed resistance to new synthetic antimalarials, including mefloquine and halofantrine. P. vivax malaria resistant to chloroquine and primaquine is now widespread in parts of Oceania; the optimal therapy for this infection is unknown. At present, a combination of qinghaosu derivatives and mefloquine appears to be the most active drug regimen against multidrug-resistant falciparum malaria from Southeast Asia. However, qinghaosu compounds are not yet licensed and widely available. The capacity of P. falciparum to rapidly develop drug resistance and the growing evidence that other plasmodia can evolve resistance suggests that within the next 10 years, we face the real prospect of untreatable malaria. Ultimately, control of malaria may require more creative approaches than additional inhibitory drugs. These might include: the identification of biochemical pathways unique to the parasite (such as drug efflux and heme polymerase), making it possible to design new classes of antimalarial agents that are selectively toxic to the parasite; methods to block parasite development in the mosquito vector; and multistage vaccines against both asexual and sexual stages in order to block both the pathophysiology and transmission of disease.

Predictors of severity of illness on presentation in children with cerebral malaria

The presenting features of 195 children with cerebral malaria were analysed to determine which correlated with severity of coma and anaemia. The children, who came from a single community in southern Zambia, were enrolled in an ongoing blinded drug trial in 1992 and 1993. Children with deep coma (scoring 0-2) had significantly longer duration of coma before presentation (P = 0.019) and were more likely to have been treated with chloroquine (P = 0.022) than children with light coma (scoring 3 or 4 on the Blantyre coma scale). Children with severe anaemia (haematocrit < 18%) were younger (P = 0.005), had been febrile longer (P = 0.005), had splenomegaly (P < 0.005) and hypoglycaemia (P < 0.008) more often and were more likely to have been treated with chloroquine (P < 0.005) than those without severe anaemia. The counts of asexual parasites in the peripheral blood were not significantly correlated with depth of coma or severity of anaemia. The observed widespread and uncontrolled use of chloroquine has probably led to the development of resistant malaria and of many severe complications despite early consultation. While early treatment of febrile illnesses in young children and immediate medical attention for altered consciousness must be emphasized in the community approach to severe malaria, our data indicate that effective public health measures will be difficult to develop in the face of a high prevalence of chloroquine resistance.

In-hospital morbidity and mortality due to malaria-associated severe anaemia in two areas of Malawi with different patterns of malaria infection

We examined the relative contribution of malaria-associated severe anaemia (parasitaemia and haematocrit < or = 15%) to malaria-related morbidity and mortality among children admitted at 2 hospitals in areas with different seasonal patterns of malaria infection in Malawi. The prevalence of malaria-associated severe anaemia was 8.5% among admissions at the hospital in an area with sustained, year-round infection (Mangochi District Hospital [MDH]), compared to 5.2% at the hospital in an area with a fluctuating pattern of infection (Queen Elizabeth Central Hospital [QECH]). Infants at MDH were nearly twice as likely to have malaria-associated severe anaemia as were those at QECH. Parasite density on admission was not related to the risk of severe anaemia at MDH, but it was at QECH. A similar proportion of all deaths was attributed to malaria at MDH (17.5%) and QECH (20.4%). However, malaria-associated severe anaemia accounted for 54% of malaria-related deaths at MDH compared to only 32% at QECH. Malaria-associated severe anaemia contributed significantly to morbidity and mortality at both sites, but its impact was more marked in the area with a sustained pattern of infection. These findings suggest that seasonal fluctuations in malaria infection may contribute to differences in patterns of malaria disease.

Severe childhood malaria in two areas of markedly different falciparum transmission in east Africa

Malaria remains a major public health challenge in sub-Saharan Africa, yet our knowledge of the epidemiology of malaria in terms of patterns of mortality and morbidity is limited. We have examined the presentation of severe, potentially life-threatening malaria to district hospitals in two very different transmission settings: Kilifi, Kenya with low seasonal transmission and Ifakara, Tanzania with high seasonal transmission. The minimum annual rates of severe disease in children below five years in both populations were similar (46 per 1000 children in Kilifi and 51 per 1000 children in Ifakara). However, there were important differences in the age and clinical patterns of severe disease; twice as many patients were under one year of age in Ifakara compared with Kilifi and there was a four fold higher rate of cerebral malaria and three fold lower rate of malaria anaemia among malaria patients at Kilifi compared with Ifakara. Reducing malaria transmission in Ifakara by 95%, for example with insecticide-treated bed nets, would result in a transmission setting comparable to that of Kilifi and although this reduction may yield early successes in reducing severe malaria morbidity and mortality in young, immunologically naive children, place these same children at increased risk at older ages of developing severe and potentially different manifestations of malaria infection hence producing no net cohort gain in survivorship from potentially fatal malaria.

Adhesion of parasitized red blood cells to cultured endothelial cells: a flow-based study of isolates from Gambian children with falciparum malaria

Adhesion of parasitized red blood cells to vascular endothelium is thought to play an important role in the development of the ischaemic complications associated with severe falciparum malaria. Using a novel, flow-based assay, we have investigated the adhesion of parasitized red blood cells to formalin-fixed human umbilical vein endothelial cells (HUVEC), for isolates obtained from 32 Gambian subjects with mild or severe falciparum malaria. Red cells infected with wild strains of Plasmodium falciparum were able to adhere to HUVEC under physiologically relevant flow conditions, but the level of adhesion was highly variable, ranging from 1 to 688 adherent cells per mm2 of HUVEC. Within isolates, some adherent parasitized cells remained stationary, whilst other formed less stable interactions and rolled slowly over the cell surface. There was no significant difference in adhesion of parasitized cells between isolates obtained from mild or severe cases of malaria, although a subset of isolates did show very high levels of adhesion. The results suggest that there is not a simple relationship between the adhesion of parasitized cells to cultured endothelial cells (presumably via the receptor ICAM-1) and the clinical severity of the disease, although variation in microvascular adhesion in vivo may still be a determinant of ischaemic complications.

Serum protein concentrations in Plasmodium falciparum malaria

In patients with uncomplicated Plasmodium falciparum infection cytokine-mediated serum protein levels of C-reactive protein (CRP), coeruloplasmin (COE), beta 2-microglobulin (B2M), alpha 1-acid glycoprotein (AAG), alpha 1-antitrypsin (AAT), haptoglobin (HPT), prealbumin (PRE), retinol binding protein (RBP), albumin (ALB) and transferrin (TRF) were measured in an endemic area of the Amazonian rain forest. Semi-immune (SI) and nonimmune (NI) patients were investigated. In both patient groups the serum concentrations of CRP, COE and B2M were elevated on admission. In addition AAG and AAT concentrations were increased in NI patients compared to control subjects. Significantly lower serum concentrations of HPT, PRE, RBP, ALB and TRF were seen in both patient groups during the acute phase of the disease, and were more pronounced in NI patients. After a 28-day follow-up, AAT and B2M were normal in SI patients but HPT, AAT and B2M were still significantly altered in NI patients.

Effect of iron chelation therapy on recovery from deep coma in children with cerebral malaria

BACKGROUND

Cerebral malaria is a severe complication of Plasmodium falciparum infection in children, with a mortality rate of 15 to 50 percent despite antimalarial therapy.

METHODS

To determine whether combining iron chelation with quinine therapy speeds the recovery of consciousness, we conducted a randomized, double-blind, placebo-controlled trial of the iron chelator deferoxamine in 83 Zambian children with cerebral malaria. To be enrolled, patients had to be less than six years old, have P. falciparum parasitemia, have normal cerebrospinal fluid without evidence of bacterial infection, and be in a coma from which they could not be aroused. Deferoxamine (100 mg per kilogram of body weight per day, infused intravenously for 72 hours) or placebo was added to standard therapy with quinine and sulfadoxine-pyrimethamine. The time to the recovery of full consciousness, time to parasite clearance, and mortality were examined with Cox proportional-hazards regression analysis.

RESULTS

The rate of recovery of full consciousness among the 42 patients given deferoxamine was 1.3 times that among the 41 given placebo (95 percent confidence interval, 0.7 to 2.3); the median time to recovery was 20.2 hours in the deferoxamine group and 43.1 hours in the placebo group (P = 0.38). Among 50 patients with deep coma, the rate of recovery of full consciousness was increased 2.2-fold with deferoxamine (95 percent confidence interval, 1.1 to 4.7), decreasing the median recovery time from 68.2 to 24.1 hours (P = 0.03). Among 69 patients for whom data on parasite clearance were available, the rate of clearance with deferoxamine was 2.0 times that with placebo (95 percent confidence interval, 1.2 to 3.6). Among all 83 patients, mortality was 17 percent in the deferoxamine group and 22 percent in the placebo group (P = 0.52).

CONCLUSIONS

Iron chelation therapy may hasten the clearance of parasitemia and enhance recovery from deep coma in cerebral malaria.

Prophylactic phenobarbitone in young children with severe falciparum malaria: pharmacokinetics and clinical effects

1. A method is described for the measurement of phenobarbitone (PB) by reversed phase high performance liquid chromatography (h.p.l.c.) from small samples of whole blood dried onto filter paper strips. 2. The disposition of PB given prophylactically to young children with severe malaria on parenteral quinine is contrasted with that in aparasitaemic Kenyan children on no antimalarial drugs. There were no differences in the disposition of PB between the two groups. 3. Peak blood PB concentrations were equal to or greater than 15 mg l-1 in 27% of the patients on quinine and 23% of those not on quinine; a concentration of 10 mg l-1 was achieved or exceeded by 100% and 92% of each group, respectively, and was maintained for 39 +/- 24 h (mean +/- s.d.), and 33 +/- 21 h, respectively. 4. In an open, dose-finding study, the progress of young children with cerebral malaria given prophylactic PB (10 mg kg-1), was contrasted with that of controls given no seizure prophylaxis. 5. The drug had no apparent effect on depth or duration of coma, but neither was the incidence of seizures reduced. 6. A controlled trial of prophylactic PB in young children with cerebral malaria is needed, but a larger dose than 10 mg kg-1 should be studied.