Bacteremia in Malawian children with severe malaria: prevalence, etiology, HIV coinfection, and outcome

Community-acquired bloodstream infections in Africa: a systematic review and meta-analysis

Data on the prevalence and causes of community-acquired bloodstream infections in Africa are scarce. We searched three databases for studies that prospectively studied patients admitted to hospital with at least a blood culture, and found 22 eligible studies describing 58 296 patients, of whom 2051 (13.5%) of 15 166 adults and 3527 (8.2%) of 43 130 children had bloodstream infections. 1643 (29.1%) non-malaria bloodstream infections were due to Salmonella enterica (58.4% of these non-typhoidal Salmonella), the most prevalent isolate overall and in adults, and 1031 (18.3% overall) were due to Streptococcus pneumoniae, the most common isolate in children. Other common isolates included Staphylococcus aureus (531 infections; 9.5%) and Escherichia coli (412; 7.3%). Mycobacterium tuberculosis complex accounted for 166 (30.7%) of 539 isolates in seven studies that used mycobacterial culture techniques. HIV infection was associated with any bloodstream infection, particularly with S enterica and M tuberculosis complex bacteraemia. Where recorded, patients with bloodstream infections had an in-hospital case fatality of 18.1%. Our results show that bloodstream infections are common and associated with high mortality. Improved clinical microbiology services and reassessment of empirical treatment guidelines that account for the epidemiology of bloodstream infections might contribute to better outcomes.

Microbiologic and clinical features of Salmonella species isolated from bacteremic children in eastern Democratic Republic of Congo

BACKGROUND

The morbidity of Salmonella bloodstream infections is unacceptably high in Africa. In 2000, the WHO Global Salmonella-Surveillance (GSS) program was founded to reduce the health burden of foodborne diseases. The incorporation, in 2002, of the Democratic Republic of Congo (DRC) in this program allowed the improvement of laboratory capacities. In this retrospective study, we describe the first signs of impact the GSS program has had in DRC in the management of bacteremia.

METHODS

Between 2002 and 2006, we evaluated, in one pediatric hospital, the microbiologic and clinical features of Salmonella isolated from children suspected of having bacteremia. A random selection of isolates was typed by pulsed field gel electrophoresis (PFGE).

RESULTS

Among the 1528 children included in the study, 26.8% were bacteremic. Salmonella accounted for 59% of all bloodstream infections. Salmonella typhimurium (60.5%) and Salmonella enteritidis (22.3%) were the most common Salmonella serotypes. In total, 92.4% were resistant to at least 3 antimicrobials with the following proportion of strains resistant to: ampicillin (86%), chloramphenicol (92%), trimethoprim/sulfamethoxazole (95%), and tetracycline (34%). In 2002, 32.1% of children received an appropriate empiric antimicrobial treatment. In 2006, with the restoration of the confidence in the results provided by the laboratory, we observed an increase of the proportion of patients appropriately (82.9%) treated with antimicrobials (P < 0.01) without any decrease in the overall mortality rates associated with salmonellae bacteremia.

CONCLUSIONS

Our findings indicate the benefit to strengthen laboratory capacities in Africa, allowing the development of management guidelines of bloodstream infection.

Taming the elephant: Salmonella biology, pathogenesis, and prevention

Salmonella infections continue to cause substantial morbidity and mortality throughout the world. However, recent discoveries and new paradigms promise to lead to novel strategies to diagnose, treat, and prevent Salmonella infections. This review provides an update of the Salmonella field based on oral presentations given at the recent 3rd ASM Conference on Salmonella: Biology, Pathogenesis and Prevention.

Malaria in children

The past decade has seen an unprecedented surge in political commitment and international funding for malaria control. Coverage with existing control methods (ie, vector control and artemisinin-based combination therapy) is increasing, and, in some Asian and African countries, childhood morbidity and mortality from malaria caused by Plasmodium falciparum are starting to decline. Consequently, there is now renewed interest in the possibility of malaria elimination. But the ability of the parasite to develop resistance to antimalarial drugs and increasing insecticide resistance of the vector threaten to reduce and even reverse current gains. Plasmodium vivax, with its dormant liver stage, will be particularly difficult to eliminate, and access to effective and affordable treatment at community level is a key challenge. New drugs and insecticides are needed urgently, while use of an effective vaccine as part of national malaria control programmes remains an elusive goal. This Seminar, which is aimed at clinicians who manage children with malaria, especially in resource-poor settings, discusses present knowledge and controversies in relation to the epidemiology, pathophysiology, diagnosis, treatment, and prevention of malaria in children.

WHO guidelines for antimicrobial treatment in children admitted to hospital in an area of intense Plasmodium falciparum transmission: prospective study

OBJECTIVES

To assess the performance of WHO's "Guidelines for care at the first-referral level in developing countries" in an area of intense malaria transmission and identify bacterial infections in children with and without malaria.

DESIGN

Prospective study.

SETTING

District hospital in Muheza, northeast Tanzania.

PARTICIPANTS

Children aged 2 months to 13 years admitted to hospital for febrile illness.

MAIN OUTCOME MEASURES

Sensitivity and specificity of WHO guidelines in diagnosing invasive bacterial disease; susceptibility of isolated organisms to recommended antimicrobials.

RESULTS

Over one year, 3639 children were enrolled and 184 (5.1%) died; 2195 (60.3%) were blood slide positive for Plasmodium falciparum, 341 (9.4%) had invasive bacterial disease, and 142 (3.9%) were seropositive for HIV. The prevalence of invasive bacterial disease was lower in slide positive children (100/2195, 4.6%) than in slide negative children (241/1444, 16.7%). Non-typhi Salmonella was the most frequently isolated organism (52/100 (52%) of organisms in slide positive children and 108/241 (45%) in slide negative children). Mortality among children with invasive bacterial disease was significantly higher (58/341, 17%) than in children without invasive bacterial disease (126/3298, 3.8%) (P<0.001), and this was true regardless of the presence of P falciparum parasitaemia. The sensitivity and specificity of WHO criteria in identifying invasive bacterial disease in slide positive children were 60.0% (95% confidence interval 58.0% to 62.1%) and 53.5% (51.4% to 55.6%), compared with 70.5% (68.2% to 72.9%) and 48.1% (45.6% to 50.7%) in slide negative children. In children with WHO criteria for invasive bacterial disease, only 99/211(47%) of isolated organisms were susceptible to the first recommended antimicrobial agent.

CONCLUSIONS

In an area exposed to high transmission of malaria, current WHO guidelines failed to identify almost a third of children with invasive bacterial disease, and more than half of the organisms isolated were not susceptible to currently recommended antimicrobials. Improved diagnosis and treatment of invasive bacterial disease are needed to reduce childhood mortality.

Task shifting routine inpatient pediatric HIV testing improves program outcomes in urban Malawi: a retrospective observational study

BACKGROUND

This study evaluated two models of routine HIV testing of hospitalized children in a high HIV-prevalence resource-constrained African setting. Both models incorporated "task shifting," or the allocation of tasks to the least-costly, capable health worker.

METHODS AND FINDINGS

Two models were piloted for three months each within the pediatric department of a referral hospital in Lilongwe, Malawi between January 1 and June 30, 2008. Model 1 utilized lay counselors for HIV testing instead of nurses and clinicians. Model 2 further shifted program flow and advocacy responsibilities from counselors to volunteer parents of HIV-infected children, called "patient escorts." A retrospective review of data from 6318 hospitalized children offered HIV testing between January-December 2008 was conducted. The pilot quarters of Model 1 and Model 2 were compared, with Model 2 selected to continue after the pilot period. There was a 2-fold increase in patients offered HIV testing with Model 2 compared with Model 1 (43.1% vs 19.9%, p<0.001). Furthermore, patients in Model 2 were younger (17.3 vs 26.7 months, p<0.001) and tested sooner after admission (1.77 vs 2.44 days, p<0.001). There were no differences in test acceptance or enrollment rates into HIV care, and the program trends continued 6 months after the pilot period. Overall, 10244 HIV antibody tests (4779 maternal; 5465 child) and 453 DNA-PCR tests were completed, with 97.8% accepting testing. 19.6% of all mothers (n = 1112) and 8.5% of all children (n = 525) were HIV-infected. Furthermore, 6.5% of children were HIV-exposed (n = 405). Cumulatively, 72.9% (n = 678) of eligible children were evaluated in the hospital by a HIV-trained clinician, and 68.3% (n = 387) successfully enrolled into outpatient HIV care.

CONCLUSIONS/SIGNIFICANCE

The strategy presented here, task shifting from lay counselors alone to lay counselors and patient escorts, greatly improved program outcomes while only marginally increasing operational costs. The wider implementation of this strategy could accelerate pediatric HIV care access in high-prevalence settings.

Importance of antibody and complement for oxidative burst and killing of invasive nontyphoidal Salmonella by blood cells in Africans

Bacteremia caused by nontyphoidal strains of Salmonella is endemic among African children. Case-fatality rates are high and antibiotic resistance increasing, but no vaccine is currently available. T cells are important for clearance of Salmonella infection within macrophages, but in Africa, invasive Salmonella disease usually manifests in the blood and affects children between 4 months and 2 y of age, when anti-Salmonella antibody is absent. We have previously found a role for complement-fixing bactericidal antibody in protecting these children. Here we show that opsonic activity of antibody and complement is required for oxidative burst and killing of Salmonella by blood cells in Africans. Induction of neutrophil oxidative burst correlated with anti-Salmonella IgG and IgM titers and C3 deposition on bacteria and was significantly lower in African children younger than 2 y compared with older children. Preopsonizing Salmonella with immune serum overcame this deficit, indicating a requirement for antibody and/or complement. Using different opsonization procedures, both antibody and complement were found to be necessary for optimal oxidative burst, phagocytosis and killing of nontyphoidal Salmonella by peripheral blood cells in Africans. Although most strains of African nontyphoidal Salmonella can be killed with antibody and complement alone, phagocytes in the presence of specific antibody and complement can kill strains resistant to killing by immune serum. These findings increase the likelihood that an antibody-inducing vaccine will protect against invasive nontyphoidal Salmonella disease in African children.

Invasive salmonellosis among children admitted to a rural Tanzanian hospital and a comparison with previous studies

Background

The importance of invasive salmonellosis in African children is well recognized but there is inadequate information on these infections. We conducted a fever surveillance study in a Tanzanian rural hospital to estimate the case fraction of invasive salmonellosis among pediatric admissions, examine associations with common co-morbidities and describe its clinical features. We compared our main findings with those from previous studies among children in sub-Saharan Africa.

Methodology/Principal Findings

From 1 March 2008 to 28 Feb 2009, 1,502 children were enrolled into the study. We collected clinical information and blood for point of care tests, culture, and diagnosis of malaria and HIV. We analyzed the clinical features on admission and outcome by laboratory-confirmed diagnosis. Pathogenic bacteria were isolated from the blood of 156 (10%) children, of which 14 (9%) were S. typhi, 45 (29%) were NTS and 97 (62%) were other pathogenic bacteria. Invasive salmonellosis accounted for 59/156 (38%) bacteremic children. Children with typhoid fever were significantly older and presented with a longer duration of fever. NTS infections were significantly associated with prior antimalarial treatment, malarial complications and with a high risk for death.

Conclusions/Significance

Invasive salmonellosis, particularly NTS infection, is an important cause of febrile disease among hospitalized children in our rural Tanzanian setting. Previous studies showed considerable variation in the case fraction of S. typhi and NTS infections. Certain suggestive clinical features (such as older age and long duration of fever for typhoid whereas concomitant malaria, anemia, jaundice and hypoglycemia for NTS infection) may be used to distinguish invasive salmonellosis from other severe febrile illness.

Impact of infection with human immunodeficiency virus-1 (HIV) on the risk of cancer among children in Malawi - preliminary findings

BACKGROUND

The impact of infection with HIV on the risk of cancer in children is uncertain, particularly for those living in sub-Saharan Africa. In an ongoing study in a paediatric oncology centre in Malawi, children (aged

METHODS

Only children with a cancer diagnosis were included. Odds ratios (OR) for being HIV positive were estimated for each cancer type (with adjustment for age (<5 years, >/= 5 years) and sex) using children with other cancers and non-malignant conditions as a comparison group (excluding the known HIV-associated cancers, Kaposi sarcoma and lymphomas, as well as children with other haematological malignancies or with confirmed non-cancer diagnoses).

RESULTS

Of the 586 children recruited, 541 (92%) met the inclusion criteria and 525 (97%) were tested for HIV. Overall HIV seroprevalence was 10%. Infection with HIV was associated with Kaposi sarcoma (29 cases; OR = 93.5, 95% CI 26.9 to 324.4) and with non-Burkitt, non-Hodgkin lymphoma (33 cases; OR = 4.4, 95% CI 1.1 to 17.9) but not with Burkitt lymphoma (269 cases; OR = 2.2, 95% CI 0.8 to 6.4).

CONCLUSIONS

In this study, only Kaposi sarcoma and non-Burkitt, non-Hodgkin lymphoma were associated with HIV infection. The endemic form of Burkitt lymphoma, which is relatively frequent in Malawi, was not significantly associated with HIV. While the relatively small numbers of children with other cancers, together with possible limitations of diagnostic testing may limit our conclusions, the findings may suggest differences in the pathogenesis of HIV-related malignancies in different parts of the world.

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Affiliation(s)

Nora Mutalima Epidemiology and Genetics Unit, Department of Health Sciences, Seebohm Rowntree Building, Area 3, University of York, York YO10 5DD, UK
Elizabeth M Molyneux Department of Paediatrics, University of Malawi, College of Medicine, P/Bag 360 Chichiri, Blantyre 3, Malawi
William T Johnston Epidemiology and Genetics Unit, Department of Health Sciences, Seebohm Rowntree Building, Area 3, University of York, York YO10 5DD, UK
Harold W Jaffe Department of Public Health, University of Oxford, Rosemary Rue Building, Old Road Campus, Roosevelt Drive, Headington, Oxford OX3 7LF, UK
Steve Kamiza Department of Histopathology, University of Malawi, College of Medicine, P/Bag 360 Chichiri, Blantyre 3, Malawi
Eric Borgstein Department of Surgery, University of Malawi, College of Medicine, P/Bag 360 Chichiri, Blantyre 3, Malawi
Nyengo Mkandawire Department of Surgery, University of Malawi, College of Medicine, P/Bag 360 Chichiri, Blantyre 3, Malawi
George N Liomba Department of Histopathology, University of Malawi, College of Medicine, P/Bag 360 Chichiri, Blantyre 3, Malawi
Mkume Batumba Department of Ophthalmology, University of Malawi, College of Medicine, P/Bag 360 Chichiri, Blantyre 3, Malawi
Lucy M Carpenter Department of Public Health, University of Oxford, Rosemary Rue Building, Old Road Campus, Roosevelt Drive, Headington, Oxford OX3 7LF, UK
Robert Newton Epidemiology and Genetics Unit, Department of Health Sciences, Seebohm Rowntree Building, Area 3, University of York, York YO10 5DD, UK

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Both hemolytic anemia and malaria parasite-specific factors increase susceptibility to Nontyphoidal Salmonella enterica serovar typhimurium infection in mice

Severe pediatric malaria is an important risk factor for developing disseminated infections with nontyphoidal Salmonella serotypes (NTS). While recent animal studies on this subject are lacking, early work suggests that an increased risk for developing systemic NTS infection during malaria is caused by hemolytic anemia, which leads to reduced macrophage microbicidal activity. Here we established a model for oral Salmonella enterica serotype Typhimurium challenge in mice infected with Plasmodium yoelii nigeriensis. Initial characterization of this model showed that 5 days after coinoculation, P. yoelii nigeriensis infection increased the recovery of S. Typhimurium from liver and spleen by approximately 1,000-fold. The increased bacterial burden could be only partially recapitulated by antibody-mediated hemolysis, which increased the recovery of S. Typhimurium from liver and spleen by 10-fold. These data suggested that both hemolysis and P. yoelii nigeriensis-specific factors contributed to the increased susceptibility to S. Typhimurium. The mechanism by which hemolysis impaired resistance to S. Typhimurium was further investigated. In vitro, S. Typhimurium was recovered 24 h after infection of hemophagocytic macrophages in 2-fold-higher numbers than after infection of mock-treated macrophages, making it unlikely that reduced macrophage microbicidal activity was solely responsible for hemolysis-induced immunosuppression during malaria. Infection with P. yoelii nigeriensis, but not antibody-mediated hemolysis, reduced serum levels of interleukin-12p70 (IL-12p70) in response to S. Typhimurium challenge. Collectively, studies establishing a mouse model for this coinfection suggest that multiple distinct malaria-induced immune defects contribute to increased susceptibility to S. Typhimurium.

Lack of fluoroquinolone resistance in non-typhoidal salmonella bacteremia in HIV-infected patients in an urban US setting

Non-typhoidal salmonella (NTS) bacteremia is a significant cause of morbidity and mortality in HIV-infected individuals worldwide. Recent reports have noted increasing resistance of NTS isolates to fluoroquinolones, the recommended first-line therapy for NTS bacteremia. The outcomes and risk factors for NTS bacteremia in HIV-infected patients in an urban US setting were evaluated. From January 2002 to December 2006, 26 episodes of NTS bacteremia were identified in 16 patients. The risk factors for NTS bacteremia were low CD4 count, high viral load, and lack of antiretroviral therapy (ART). Recurrences appeared related to lack of immune reconstitution in patients not on ART. Unlike reports from Asia, no fluoroquinolone resistance was identified in any of the Salmonella strains isolated in this setting. Optimal treatment of NTS in the HIV-infected patient in the United States should include therapy with fluoroquinolones as well as attaining complete viral suppression and immune reconstitution with ART.

Effect of Plasmodium and Salmonella co-infection in a murine model

The present study was designed to evaluate the effect of Plasmodium and Salmonella co-infection in LACA mice. The parasitaemic level, bacterial load, histological alterations and levels of oxidants/antioxidant activity were measured. Co-infected mice had a high parasitaemic level, increased bacterial load, and died earlier than Plasmodium-infected mice. Histologically, co-infected mice had more architectural damage in the liver, spleen, kidney, and brain than the control groups. The level of lipid peroxidation was significantly increased and the activities of antioxidative enzymes (superoxide dismutase and catalase) were decreased in all organs of co-infected mice compared to the control groups, indicating depression of the antioxidant defense system. The present study demonstrates more severe histological and biochemical alterations in co-infected mice, highlighting the importance of early diagnosis for selection of appropriate treatments and reducing the likelihood of further complications.

Bacterial contamination of pediatric whole blood transfusions in a Kenyan hospital

BACKGROUND:

Hospitalized children in sub-Saharan Africa frequently receive whole blood transfusions for severe anemia. The risk from bacterial contamination of blood for transfusion in sub-Saharan Africa is not known. This study assessed the frequency of bacterial contamination of pediatric whole blood transfusions at a referral hospital in Kenya.

STUDY DESIGN AND METHODS:

This was an observational study. Over the course of 1 year, bacteriologic cultures were performed on 434 of the 799 blood packs issued to children by the blood bank of Coast Provincial General Hospital, Mombasa. Clinical outcome was not assessed.

RESULTS:

Forty-four bacterial contaminants were isolated from 38 blood packs—an overall contamination frequency of 8.8% (95% confidence interval, 6.1%-11.4%). Sixty-four percent of the bacteria isolated were Gram-negative. Many of the isolates are usually found in the environment and the most likely source of contamination was considered to be the hospital blood bank.

CONCLUSION:

Bacterial contamination of whole blood may be a significant but unrecognized hazard of blood transfusion for children in sub-Saharan Africa. Further work is needed to clarify the extent of the problem and its clinical consequences. Increased awareness and adherence to basic principles of asepsis in the hospital blood bank may be important immediate interventions.

HIV infection, malnutrition, and invasive bacterial infection among children with severe malaria

BACKGROUND

Human immunodeficiency virus (HIV) infection, malnutrition, and invasive bacterial infection (IBI) are reported among children with severe malaria. However, it is unclear whether their cooccurrence with falciparum parasitization and severe disease happens by chance or by association among children in areas where malaria is endemic.

METHODS

We examined 3068 consecutive children admitted to a Kenyan district hospital with clinical features of severe malaria and 592 control subjects from the community. We performed multivariable regression analysis, with each case weighted for its probability of being due to falciparum malaria, using estimates of the fraction of severe disease attributable to malaria at different parasite densities derived from cross-sectional parasitological surveys of healthy children from the same community.

RESULTS

HIV infection was present in 133 (12%) of 1071 consecutive parasitemic admitted children (95% confidence interval [CI], 11%-15%). Parasite densities were higher in HIV-infected children. The odds ratio for admission associated with HIV infection for admission with true severe falciparum malaria was 9.6 (95% CI, 4.9-19); however, this effect was restricted to children aged 1 year. Malnutrition was present in 507 (25%) of 2048 consecutive parasitemic admitted children (95% CI, 23%-27%). The odd ratio associated with malnutrition for admission with true severe falciparum malaria was 4.0 (95% CI, 2.9-5.5). IBI was detected in 127 (6%) of 2048 consecutive parasitemic admitted children (95% CI, 5.2%-7.3%). All 3 comorbidities were associated with increased case fatality.

CONCLUSIONS

HIV, malnutrition and IBI are biologically associated with severe disease due to falciparum malaria rather than being simply alternative diagnoses in co-incidentally parasitized children in an endemic area.

Severe malaria and concomitant bacteraemia in children admitted to a rural Mozambican hospital

OBJECTIVES

To describe the prevalence, aetiology and prognostic implications of coexisting invasive bacterial disease in children admitted with severe malaria in a rural Mozambican Hospital.

METHODS

Retrospective study of data systematically collected from June 2003 to May 2007 in a rural Mozambican hospital, from all children younger than 5 years admitted with severe malaria.

RESULTS

Seven thousand and forty-three children were admitted with a diagnosis of malaria. 25.2% fulfilled the criteria for severe malaria. 5.4% of the children with severe malaria and valid blood culture results had a concomitant bacteraemia. Case fatality rates of severe malaria cases rose steeply when bacteraemia was also present (from 4.0% to 22.0%, P < 0.0001), and bacteraemia was an independent risk factor for death among severe malaria patients (adjusted OR 6.2, 95% CI 2.8-13.7, P = 0.0001). Streptococcus pneumoniae, Gram-negative bacteria, Staphilococcus aureus and non-typhoid Salmonella (NTS) were the most frequently isolated microorganisms among severe malaria cases. Their frequency and associated case fatality rates (CFR) varied according to age and to syndromic presentation. Streptococcus pneumoniae had a relatively low CFR, but was consistently associated with severe malaria syndromes, or anaemia severity groups. No clear-cut relationship between malarial anaemia and NTS bacteraemia was found.

CONCLUSIONS

The coexistence of malaria and invasive bacterial infections is a frequent and life-threatening condition in many endemic African settings. In Mozambique, S. pneumoniae is the leading pathogen in this interaction, possibly as a consequence of the high HIV prevalence in the area. Measures directed at reducing the burden of both those infections are urgently needed to reduce child mortality in Africa.

Structure-activity study of pentamidine analogues as antiprotozoal agents

Diamidine 1 (pentamidine) and 65 analogues (2-66) have been tested for in vitro antiprotozoal activities against Trypanosoma brucei rhodesiense, Plasmodium falciparum, and Leishmania donovani, and for cytotoxicity against mammalian cells. Dications 32, 64, and 66 exhibited antitrypanosomal potencies equal or greater than melarsoprol (IC(50) = 4 nM). Nine congeners (2-4, 12, 27, 30, and 64-66) were more active against P. falciparum than artemisinin (IC(50) = 6 nM). Eight compounds (12, 32, 33, 44, 59, 62, 64, and 66) exhibited equal or better antileishmanial activities than 1 (IC(50) = 1.8 microM). Several congeners were more active than 1 in vivo, curing at least 2/4 infected animals in the acute mouse model of trypanosomiasis. The diimidazoline 66 was the most promising compound in the series, showing excellent in vitro activities and high selectivities against T. b. rhodesiense, P. falciparum, and L. donovani combined with high antitrypanosomal efficacy in vivo.

Malaria primes the innate immune response due to interferon-gamma induced enhancement of toll-like receptor expression and function

Malaria-induced sepsis is associated with an intense proinflammatory cytokinemia for which the underlying mechanisms are poorly understood. It has been demonstrated that experimental infection of humans with Plasmodium falciparum primes Toll-like receptor (TLR)-mediated proinflammatory responses. Nevertheless, the relevance of this phenomenon during natural infection and, more importantly, the mechanisms by which malaria mediates TLR hyperresponsiveness are unclear. Here we show that TLR responses are boosted in febrile patients during natural infection with P. falciparum. Microarray analyses demonstrated that an extraordinary percentage of the up-regulated genes, including genes involving TLR signaling, had sites for IFN-inducible transcription factors. To further define the mechanism involved in malaria-mediated "priming," we infected mice with Plasmodium chabaudi. The human data were remarkably predictive of what we observed in the rodent malaria model. Malaria-induced priming of TLR responses correlated with increased expression of TLR mRNA in a TLR9-, MyD88-, and IFNgamma-dependent manner. Acutely infected WT mice were highly susceptible to LPS-induced lethality while TLR9(-/-), IL12(-/-) and to a greater extent, IFNgamma(-/-) mice were protected. Our data provide unprecedented evidence that TLR9 and MyD88 are essential to initiate IL12 and IFNgamma responses and favor host hyperresponsiveness to TLR agonists resulting in overproduction of proinflammatory cytokines and the sepsis-like symptoms of acute malaria.

Complement consumption in children with Plasmodium falciparum malaria

BACKGROUND

Complement (C) can be activated during malaria, C components consumed and inflammatory mediators produced. This has potential to impair host innate defence.

METHODS

In a case-control study, C activation was assessed by measuring serum haemolytic activity (CH50), functional activity of each pathway and levels of C3a, C4a and C5a in children presenting at Kisumu District Hospital, western Kenya, with severe malarial anaemia (SMA) or uncomplicated malaria (UM).

RESULTS

CH50 median titers for lysis of sensitized sheep erythrocytes in SMA (8.6 U/mL) were below normal (34-70 U/mL) and were one-fourth the level in UM (34.6 U/mL (P < 0.001). Plasma C3a median levels were 10 times higher than in normals forSMA (3,200 ng/ml) and for UM (3,500 ng/ml), indicating substantial C activation in both groups. Similar trends were obtained for C4a and C5a. The activities of all three C pathways were greatly reduced in SMA compared to UM (9.9% vs 83.4% for CP, 0.09% vs 30.7% for MBL and 36.8% vs 87.7% for AP respectively, P < 0.001).

CONCLUSION

These results indicate that, while C activation occurs in both SMA and UM, C consumption is excessive in SMA. It is speculated that in SMA, consumption of C exceeds its regeneration.

Caring for children with cerebral malaria: insights gleaned from 20 years on a research ward in Malawi

Clinicians treating patients with severe malaria in endemic areas confront a variety of challenges inherent to resource-poor settings, but it is possible to provide excellent care. The basic requirements, in addition to a thorough clinical examination of the patient, include assessing parasitaemia; determining anaemia (via haematocrit or haemoglobin); estimating blood glucose and lactate concentrations; establishing and maintaining i.v. access; measuring oxygen saturation and providing supplemental oxygen when necessary; grouping, cross-matching and transfusing blood. This paper provides practical information on determining the Blantyre Coma Score, collecting cerebrospinal fluid and measuring the opening pressure, and administering controlled volumes of i.v. fluids. Included is a narrative protocol describing the approach to patients with cerebral malaria used on the research ward at the Queen Elizabeth Central Hospital in Blantyre, Malawi.

Polymorphic variability in the interleukin (IL)-1beta promoter conditions susceptibility to severe malarial anemia and functional changes in IL-1beta production

Interleukin (IL)-1beta is a cytokine released as part of the innate immune response to Plasmodium falciparum. Because the role played by IL-1beta polymorphic variability in conditioning the immunopathogenesis of severe malarial anemia (SMA) remains undefined, relationships between IL-1beta promoter variants (-31C/T and -511A/G), SMA (hemoglobin [Hb] level <6.0 g/dL), and circulating IL-1beta levels were investigated in children with parasitemia (n= 566) from western Kenya. The IL-1beta promoter haplotype -31C/-511A (CA) was associated with increased risk of SMA (Hb level <6.0 g/dL; odds ratio [OR], 1.98 [95% confidence interval {CI}, 1.55-2.27]; P < .05) and reduced circulating IL-1beta levels (p <.05). The TA (-31T/-511A) haplotype was nonsignificantly associated with protection against SMA (OR, 0.52 [95% CI, 0.18-1.16]; p =.11) and elevated IL-1beta production ( p<.05). Compared with the non-SMA group, children with SMA had significantly lower IL-1beta levels and nonsignificant elevations in both IL-1 receptor antagonist (IL-1Ra) and the ratio of IL-1Ra to IL-1beta. The results presented demonstrate that variation in IL-1beta promoter conditions susceptibility to SMA and functional changes in circulating IL-1beta levels.

Using malarial retinopathy to improve the classification of children with cerebral malaria

The mechanisms leading to death in cerebral malaria (CM) remain unclear. We compared clinical and laboratory data among children with CM, categorized by ocular fundus findings, to elucidate differences that suggest different underlying pathological processes. From 1999-2005, standard examinations, treatment and record keeping were used for children with a clinical diagnosis of CM. Children were divided into ocular subgroups: normal fundus (N), malarial retinopathy (R), or papilloedema alone (P) and appropriate statistical tests were used to compare clinical and laboratory findings among groups. Eight hundred and eighty children who had eye examinations within 6 h of admission were included in the analysis. The groups differed significantly in case-fatality rates: Group P, 44.4% (95% CI 25.3-63.2), Group R, 18.0% (95% CI 15.6-22.3) and Group N, 7.0% (95% CI 4.2-9.8). There were also significant differences among the groups in blood pressure, prevalence of deep breathing, haematocrit, parasite density, platelet concentration and, among survivors, hours taken to recover from coma. Differences among groups suggest that different underlying pathophysiological processes are operating in children with CM defined by existing criteria. Our proposed classification, by improving the specificity of diagnosis, would enhance consistency among different study sites and prove useful in future research studies.

Associations between Burkitt lymphoma among children in Malawi and infection with HIV, EBV and malaria: results from a case-control study

BACKGROUND

Burkitt lymphoma, a childhood cancer common in parts of sub-Saharan Africa, has been associated with Epstein Barr Virus (EBV) and malaria, but its association with human immunodeficiency virus (HIV) is not clear.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a case-control study of Burkitt lymphoma among children (aged < or = 15 years) admitted to the pediatric oncology unit in Blantyre, Malawi between July 2005 and July 2006. Cases were 148 children diagnosed with Burkitt lymphoma and controls were 104 children admitted with non-malignant conditions or cancers other than hematological malignancies and Kaposi sarcoma. Interviews were conducted and serological samples tested for antibodies against HIV, EBV and malaria. Odds ratios for Burkitt lymphoma were estimated using unconditional logistic regression adjusting for sex, age, and residential district. Cases had a mean age of 7.1 years and 60% were male. Cases were more likely than controls to be HIV positive (Odds ratio (OR)) = 12.4, 95% Confidence Interval (CI) 1.3 to 116.2, p = 0.03). ORs for Burkitt lymphoma increased with increasing antibody titers against EBV (p = 0.001) and malaria (p = 0.01). Among HIV negative participants, cases were thirteen times more likely than controls to have raised levels of both EBV and malaria antibodies (OR = 13.2; 95% CI 3.8 to 46.6; p = 0.001). Reported use of mosquito nets was associated with a lower risk of Burkitt lymphoma (OR = 0.2, 95% CI, 0.03 to 0.9, p = 0.04).

CONCLUSIONS

Our findings support prior evidence that EBV and malaria act jointly in the pathogenesis of Burkitt lymphoma, suggesting that malaria prevention may decrease the risk of Burkitt lymphoma. HIV may also play a role in the etiology of this childhood tumor.

Plasmodium vivax and mixed infections are associated with severe malaria in children: a prospective cohort study from Papua New Guinea

BACKGROUND

Severe malaria (SM) is classically associated with Plasmodium falciparum infection. Little information is available on the contribution of P. vivax to severe disease. There are some epidemiological indications that P. vivax or mixed infections protect against complications and deaths. A large morbidity surveillance conducted in an area where the four species coexist allowed us to estimate rates of SM among patients infected with one or several species.

METHODS AND FINDINGS

This was a prospective cohort study conducted within the framework of the Malaria Vaccine Epidemiology and Evaluation Project. All presumptive malaria cases presenting at two rural health facilities over an 8-y period were investigated with history taking, clinical examination, and laboratory assessment. Case definition of SM was based on the World Health Organization (WHO) criteria adapted for the setting (i.e., clinical diagnosis of malaria associated with asexual blood stage parasitaemia and recent history of fits, or coma, or respiratory distress, or anaemia [haemoglobin < 5 g/dl]). Out of 17,201 presumptive malaria cases, 9,537 (55%) had a confirmed Plasmodium parasitaemia. Among those, 6.2% (95% confidence interval [CI] 5.7%-6.8%) fulfilled the case definition of SM, most of them in children <5 y. In this age group, the proportion of SM was 11.7% (10.4%-13.2%) for P. falciparum, 8.8% (7.1%-10.7%) for P. vivax, and 17.3% (11.7%-24.2%) for mixed P. falciparum and P. vivax infections. P. vivax SM presented more often with respiratory distress than did P. falciparum (60% versus 41%, p = 0.002), but less often with anaemia (19% versus 41%, p = 0.0001).

CONCLUSION

P. vivax monoinfections as well as mixed Plasmodium infections are associated with SM. There is no indication that mixed infections protected against SM. Interventions targeted toward P. falciparum only might be insufficient to eliminate the overall malaria burden, and especially severe disease, in areas where P. falciparum and P. vivax coexist.

Salmonella infections in immunocompromised adults

Clinical syndromes caused by Salmonella infection in humans are divided into typhoid fever, caused by Salmonella typhi and Salmonella paratyphi, and a range of clinical syndromes, including diarrhoeal disease, caused by a large number of non-typhoidal salmonella serovars (NTS). Typhoid is a human-restricted and highly adapted invasive disease, but shows little association with immunocompromise. In contrast, NTS have a broad vertebrate host range, epidemiology that often involves food animals, and have a dramatically more severe and invasive presentation in immunocompromised adults, in particular in the context of HIV. Immunocompromise among adults, including underlying severe or progressive disease, chronic granulomatous disease, defects or blockade of specific cytokines (particularly IL-12/IL-23/IL-17 and TNF), and HIV, is associated with suppurative foci and with primary bacteraemic disease, which may be recurrent. These patients have markedly increased mortality. Worldwide, invasive recurrent NTS bacteraemia associated with advanced HIV disease is a huge problem, and the epidemiology in this context may be more human-restricted than in other settings. This review will describe the presentation and pathogenesis of NTS in different categories of immunocompromised adults, contrasted to typhoid fever.

Brain abscesses in Malawian children: value of CT scan

The clinical presentation and management of brain abscess in three HIV-uninfected Malawian children are reported. One case was associated with staphylococcal empyema and severe malarial anaemia and another case with chronic suppurative otitis media and mastoiditis. The third case had no identified extracranial focus of infection. These cases illustrate the difficulties of diagnosis and management of brain abscesses in the resource-poor setting where other causes of encephalopathy caused by infection are common, and highlight the value of neuroradiological imaging.

Severe anemia in Malawian children

BACKGROUND

Severe anemia is a major cause of sickness and death in African children, yet the causes of anemia in this population have been inadequately studied.

METHODS

We conducted a case-control study of 381 preschool children with severe anemia (hemoglobin concentration, <5.0 g per deciliter) and 757 preschool children without severe anemia in urban and rural settings in Malawi. Causal factors previously associated with severe anemia were studied. The data were examined by multivariate analysis and structural equation modeling.

RESULTS

Bacteremia (adjusted odds ratio, 5.3; 95% confidence interval [CI], 2.6 to 10.9), malaria (adjusted odds ratio, 2.3; 95% CI, 1.6 to 3.3), hookworm (adjusted odds ratio, 4.8; 95% CI, 2.0 to 11.8), human immunodeficiency virus infection (adjusted odds ratio, 2.0; 95% CI, 1.0 to 3.8), the G6PD(-202/-376) genetic disorder (adjusted odds ratio, 2.4; 95% CI, 1.3 to 4.4), vitamin A deficiency (adjusted odds ratio, 2.8; 95% CI, 1.3 to 5.8), and vitamin B12 deficiency (adjusted odds ratio, 2.2; 95% CI, 1.4 to 3.6) were associated with severe anemia. Folate deficiency, sickle cell disease, and laboratory signs of an abnormal inflammatory response were uncommon. Iron deficiency was not prevalent in case patients (adjusted odds ratio, 0.37; 95% CI, 0.22 to 0.60) and was negatively associated with bacteremia. Malaria was associated with severe anemia in the urban site (with seasonal transmission) but not in the rural site (where malaria was holoendemic). Seventy-six percent of hookworm infections were found in children under 2 years of age.

CONCLUSIONS

There are multiple causes of severe anemia in Malawian preschool children, but folate and iron deficiencies are not prominent among them. Even in the presence of malaria parasites, additional or alternative causes of severe anemia should be considered.

Clinical management of HIV infection in children

PURPOSE OF REVIEW

The aim of this article is to review recent advances in the clinical care of HIV-infected children.

RECENT FINDINGS

Obstacles to diagnosing HIV in children and providing clinical care to those HIV infected relate to a number of technical and operational factors. Most countries now have antiretroviral treatment guidelines and have incorporated co-trimoxazole prophylaxis for infected and exposed infants and children. Implementation lags behind policy and technical recommendations. Optimal early infant feeding remains difficult and, while breastfeeding remains the safest feeding option for child survival, it carries with it the risk of HIV acquisition. Recent data suggest HIV-free survival at 18 months is comparable in infants who are replacement-fed or exclusively breastfed for the first 6 months of life. Antiretroviral treatment efficacy in children is now well documented. Optimal timing of initiation of antiretroviral treatment remains uncertain; in general it is started earlier, especially in infants. Children starting treatment in infancy are surviving and reaching adulthood; new problems of managing the highly treatment-experienced and adolescents are emerging.

SUMMARY

New antiretroviral drugs and classes will be needed for the future; research is urgently required to characterize optimal nutritional interventions, interpretation of immunological and virological parameters, and develop diagnostic tools for use in health services with limited infrastructure and capacity.

Plasmodium falciparum infection causes proinflammatory priming of human TLR responses

TLRs are a major group of pattern recognition receptors that are crucial in initiating innate immune responses and are capable of recognizing Plasmodium ligands. We have investigated TLR responses during acute experimental P. falciparum (P.f.) infection in 15 malaria-naive volunteers. TLR-4 responses in whole blood ex vivo stimulations were characterized by significantly (p < 0.01) up-regulated proinflammatory cytokine production during infection compared with baseline, whereas TLR-2/TLR-1 responses demonstrated increases in both proinflammatory and anti-inflammatory cytokine production. Responses through other TLRs were less obviously modified by malaria infection. The degree to which proinflammatory TLR responses were boosted early in infection was partially prognostic of clinical inflammatory parameters during the subsequent clinical course. Although simultaneous costimulation of human PBMC with P.f. lysate and specific TLR stimuli in vitro did not induce synergistic effects on cytokine synthesis, PBMC started to respond to subsequent TLR-4 and TLR-2 stimulation with significantly (p < 0.05) increased TNF-alpha and reduced IL-10 production following increasing periods of preincubation with P.f. Ag. In contrast, preincubation with preparations derived from other parasitic, bacterial, and fungal pathogens strongly suppressed subsequent TLR responses. Taken together, P.f. primes human TLR responses toward a more proinflammatory cytokine profile both in vitro and in vivo, a characteristic exceptional among microorganisms.

Treatment acceleration program and the experience of the DREAM program in prevention of mother-to-child transmission of HIV

BACKGROUND

The Drug Resource Enhancement against AIDS and Malnutrition (DREAM) program is a large antiretroviral therapy treatment program financed by the Treatment Acceleration Program (TAP) of the World Bank. In addition to provision of antiretroviral treatment to individuals infected with human immunodeficiency virus (HIV) in sub-Saharan Africa, one major aspect of the DREAM program is nutritional supplementation and prevention of mother-to-child transmission (PMTCT) of HIV.

METHODS

HIV-positive pregnant women enrolled in the DREAM program receive highly active antiretroviral therapy (HAART) free of charge from the 25th week of gestation, irrespective of clinical stage, CD4 count, and viral load. Their infants receive post-exposure prophylaxis. From 2004 to 2006, women enrolled in the DREAM program in Mozambique, Tanzania, and Malawi received water filters and formula for the first 6 months of lactation. In a second cohort starting in 2005 until 2006 in Mozambique, women received HAART for up to 6 months after delivery and were given the option to breastfeed. We conducted a comparative analysis of the two cohorts of HIV-positive pregnant women followed prospectively and evaluated HIV-1 mother-to-child transmission rates, infant morbidity, and mortality in both cohorts.

RESULTS

In the first cohort, 879 live-born children were delivered, with 809 evaluable infants at 1 and 6 months. In the second cohort, 341 infants were delivered and evaluable at 1 month, and 251 infants were evaluable at 6 months. At age 1 month, HIV-1 transmission rates were 4/341 (1.2%) among breastfed infants and 7/809 (0.8%) among formula-fed infants. At age 6 months, HIV-1 mother-to-child transmission rates were 2/251 (0.8%) among breastfed infants of women receiving HAART and 15/809 (1.8%) among formula-fed infants (chi = 0.77, P = 0.38 [NS]). The cumulative incidence rate at 6 months of age was 2.7% for formula-fed infants and 2.2% for breastfed infants (chi = 0.27, P = 0.60 [NS]). There was a trend for HIV-1 infection rates to be slightly greater among formula-fed infants, but overall mother-to-child transmission rates in both cohorts were extremely low. Most infants did relatively well on both feeding regimens. Observed Z scores were greater than among the general infant population in the community. Z scores < or =2.0 for weight by age occurred in 92/809 formula-fed infants (11.4%) and in 28/251 breastfed infants (11.1%). The rates of anemia in the study infant population were also lower than that of the general population. A hemoglobin value <8 g/dl was found in 40/809 formula-fed infants (4.9%) and in 17/251 breastfed infants (6.8%) (chi = 0.92, P = 0.33). The mortality rate at 6 months of age was 27 per 1000 person-years among formula-fed infants and 28.5 per 1000 person-years in breastfed infants--both considerably lower than the rates of 101 per 1000 person-years observed in Mozambique.

CONCLUSIONS

The DREAM HIV-1 PMTCT protocol was safe and efficacious in reducing transmission in infants of 1 and 6 months of age. Results were comparable to those from developed countries. Breastfeeding among HIV-1 infected mothers receiving HAART posed no additional risk of late postnatal HIV-1 transmission to the infant by 6 months of age.