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

BACKGROUND: Previous prospective studies of bacteremia in African children with severe malaria have mainly included children with cerebral malaria, and no study has examined the impact of human immunodeficiency virus (HIV) infection. We examined the prevalence and etiology of bacteremia and the impact of HIV infection on bacteremia in Malawian children with severe malaria, as well as the impact of bacteremia and HIV infection on outcome. METHODS: From 1996 until 2005, blood for culture was obtained on admission from all children admitted with severe malaria during the rainy season to the Paediatric Research Ward at the Queen Elizabeth Central Hospital in Blantyre, Malawi. HIV testing was performed prospectively from 2001 to 2005 and retrospectively for those admitted from 1996 to 2000. Multivariate regression analysis examined independent risk factors for bacteremia and death. RESULTS: Sixty-four (4.6%) of 1388 children with severe malaria had bacteremia; nontyphoidal Salmonellae (NTS) accounted for 58% of all bacteremias. The prevalence of any bacteremia and of NTS bacteremia was highest in children with severe malarial anemia (11.7% and 7.6%), compared with the prevalence in children with cerebral malaria and severe anemia (4.7% and 3.8%) and in those with cerebral malaria alone (3.0% and 0.9%). HIV infection status was determined in 1119 patients. HIV prevalence was 16% (and was highest in those with severe malaria anemia, at 20.4%), but HIV infection was not significantly associated with bacteremia. Neither bacteremia nor HIV infection was associated with death. CONCLUSIONS: Antibiotics are not routinely indicated for children with severe malaria in this region, in which HIV is endemic. However, antibiotic therapy should be used to treat NTS infection if bacteremia is suspected in children with severe malarial anemia.

Genetic analysis of circulating and sequestered populations of Plasmodium falciparum in fatal pediatric malaria.

Falciparum malaria is characterized by cytoadherence of host erythrocytes containing mature asexual-stage parasites and the consequent sequestration of these forms in tissue microvasculature. A postmortem study of pediatric malaria provided us with the opportunity to compare the genetic complexity of circulating and sequestered Plasmodium falciparum populations, in patients with fatal cerebral malaria (CM) versus control subjects with incidental P. falciparum parasitemia who died of causes other than malaria. Parasite genotypes identified in peripheral blood collected at the time of admission to the hospital constituted a subset of those detected in the tissues at death. Despite a higher tissue burden of parasitized erythrocytes in patients with CM than in parasitemic control subjects, parasite populations in tissues from patients with CM were less genetically complex, and the genotypes were more homogeneously distributed throughout the body, than in patients with incidental infection. Our findings support the notion that CM is associated with the emergence of a small number of dominant genotypes in an infected individual.

Metabolites of the kynurenine pathway of tryptophan metabolism in the cerebrospinal fluid of Malawian children with malaria.

A retrospective study of 100 Malawian children (87 with malaria and 13 with a diagnosis other than malaria) was conducted to determine the relationship between levels of metabolites of the kynurenine pathway in cerebrospinal fluid (CSF) and disease outcome. Three metabolites were measured: quinolinic acid (QA), an excitotoxin; kynurenic acid (KA), a neuroprotective receptor antagonist; and picolinic acid (PA), a proinflammatory mediator. Elevated levels of QA and PA in CSF were associated with a fatal outcome in Malawian children with cerebral malaria (CM). QA was associated with a history of convulsions. An increase in the QArcolon;KA ratio, which favors neurotoxicity, was observed only in the 3 patients with tuberculosis meningitis. Compared with Vietnamese adults with malaria, Malawian children with malaria had higher concentrations of KA. Elevated levels of KA in children with CM may serve to contain injury in the developing brain, which is more susceptible to excitotoxic damage than is the adult brain.