In the Journals

Low parasite density hints at comorbidity in children with malaria

Researchers discovered that blood levels of malaria parasites were inversely correlated with the likelihood of a child developing a comorbidity with a nonmalarial disease. Parasite densities, they said, could be an important indicator of coinfection.

“A recent study at the household level, addressing the underestimation of [nonmalarial fever] in African children, found that a majority of febrile illness is caused by pathogens other than [Plasmodium falciparum] malaria, even in areas where malaria is highly endemic,” Benedikt Hogan, MD, of the department of infectious disease epidemiology at the Bernhard Nocht Institute for Tropical Medicine in Hamburg, Germany, and colleagues wrote. “While most studies focus on [nonmalarial fever] alone, or either investigate bacterial or viral coinfections, to our knowledge no study has yet looked at the whole spectrum of fever causes in a West African region where the malaria parasite is still highly prevalent.”

The researchers conducted a prospective study of children (n = 1,238) in a 250-bed hospital in the Asante Akim North municipality in Ghana. All patients were aged between 30 days and 15 years, and all had a fever of 38°C (100.4°F) or higher. The researchers tested blood, stool, urine, respiratory and cerebrospinal fluid specimens for bacterial, viral and parasitic pathogens, and measured levels of malaria parasitemia in the pediatric patients. Hogan and colleagues then calculated the associations of Plasmodium densities with the presence of other pathogens.

The researchers made a clinical diagnosis in 90% of patients (n = 1,109). Plasmodium parasitemia was the most common, occurring in 59% (n = 728) of children, followed by pneumonia or lower respiratory tract infections (34%; n = 411), Hogan and colleagues reported.

Beyond this, the researchers detected a wide array of infections. Eighteen percent of children (n = 218) had urinary tract infections, with pathogens identified in 32 (15%) cases, the researchers wrote. Of these, the most common pathogen was Escherichia coli (n = 25; 78%). According to Hogan and colleagues, 210 children had gastrointestinal infections, 45% of whom had pathogens found in testing. Of these children, rotavirus was the most common pathogen (n = 32; 33%). Sixty-two patients had bacterial bloodstream infections (5%), with Salmonella (n = 28; 45%) and Salmonella Typhi (n = 19; 31%) being the most frequently detected pathogens. Central nervous system infections or meningitis occurred in 11 (1%) children.

Those who had high levels of parasitemia were less likely to be diagnosed with lower respiratory infections, pneumonia and bloodstream infections, Hogan and colleagues wrote. As a result, children who had low levels of parasitemia were more frequently found to have Plasmodium coinfections.

“Parasite densities provide important information for patient management, in particular for antimicrobial medication,” the researchers wrote. “Currently available rapid malaria tests might not be sufficient for this decision, and semiquantitative rapid tests of malarial parasitemia are required as long as reliable microscopic malaria diagnosis and extensive diagnostics of nonmalarial causes of pediatric febrile illness are not available in resource-poor settings.” – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.

Researchers discovered that blood levels of malaria parasites were inversely correlated with the likelihood of a child developing a comorbidity with a nonmalarial disease. Parasite densities, they said, could be an important indicator of coinfection.

“A recent study at the household level, addressing the underestimation of [nonmalarial fever] in African children, found that a majority of febrile illness is caused by pathogens other than [Plasmodium falciparum] malaria, even in areas where malaria is highly endemic,” Benedikt Hogan, MD, of the department of infectious disease epidemiology at the Bernhard Nocht Institute for Tropical Medicine in Hamburg, Germany, and colleagues wrote. “While most studies focus on [nonmalarial fever] alone, or either investigate bacterial or viral coinfections, to our knowledge no study has yet looked at the whole spectrum of fever causes in a West African region where the malaria parasite is still highly prevalent.”

The researchers conducted a prospective study of children (n = 1,238) in a 250-bed hospital in the Asante Akim North municipality in Ghana. All patients were aged between 30 days and 15 years, and all had a fever of 38°C (100.4°F) or higher. The researchers tested blood, stool, urine, respiratory and cerebrospinal fluid specimens for bacterial, viral and parasitic pathogens, and measured levels of malaria parasitemia in the pediatric patients. Hogan and colleagues then calculated the associations of Plasmodium densities with the presence of other pathogens.

The researchers made a clinical diagnosis in 90% of patients (n = 1,109). Plasmodium parasitemia was the most common, occurring in 59% (n = 728) of children, followed by pneumonia or lower respiratory tract infections (34%; n = 411), Hogan and colleagues reported.

Beyond this, the researchers detected a wide array of infections. Eighteen percent of children (n = 218) had urinary tract infections, with pathogens identified in 32 (15%) cases, the researchers wrote. Of these, the most common pathogen was Escherichia coli (n = 25; 78%). According to Hogan and colleagues, 210 children had gastrointestinal infections, 45% of whom had pathogens found in testing. Of these children, rotavirus was the most common pathogen (n = 32; 33%). Sixty-two patients had bacterial bloodstream infections (5%), with Salmonella (n = 28; 45%) and Salmonella Typhi (n = 19; 31%) being the most frequently detected pathogens. Central nervous system infections or meningitis occurred in 11 (1%) children.

Those who had high levels of parasitemia were less likely to be diagnosed with lower respiratory infections, pneumonia and bloodstream infections, Hogan and colleagues wrote. As a result, children who had low levels of parasitemia were more frequently found to have Plasmodium coinfections.

“Parasite densities provide important information for patient management, in particular for antimicrobial medication,” the researchers wrote. “Currently available rapid malaria tests might not be sufficient for this decision, and semiquantitative rapid tests of malarial parasitemia are required as long as reliable microscopic malaria diagnosis and extensive diagnostics of nonmalarial causes of pediatric febrile illness are not available in resource-poor settings.” – by Andy Polhamus

Disclosures: The authors report no relevant financial disclosures.