Backgrounds:

Microscopy is the gold standard for malaria diagnosis but is time intensive and often requires repeat hospital visits. Rapid diagnostic tests (RDT) form the mainstay of diagnosis in many endemic areas. Could an RDT alone rule out imported malaria in children presenting to UK Emergency Departments (ED)?

Methods

UK-based, multi-centre, retrospective, diagnostic accuracy study. Cases: any child <16 years presenting to ED with history of fever and travel to a malaria endemic area, between 01/01/2016 and 31/12/2017. Diagnosis: microscopy for malarial parasites (clinical reference standard) and RDT (index test). UK Health Research Authority approval: 20/HRA/1341.

Results:

51 malaria cases were reported in 1,472 patients documented at 15 sites (prevalence 3.5%), of which 44% female, median age 5 years (interquartile range 2-9 years). There were two deaths but not from malaria. Sensitivity of RDT alone to detect malaria infection was 94.1% (95% CI 83.8%-98.8%), specificity 99.4% (95% CI 98.8-99.7%), positive predictive value (PPV) 84.2% (95% CI 72.1-92.5%) and negative predictive value (NPV) 99.8% (95% CI 99.4-100.0%) (see Figure 1).

Figure 1. Personogram showing expected numbers of RDT results in hypothetical sample of 1000 children (all malaria species).

Forty (78%) cases were due to P falciparum. Sensitivity of RDT alone to detect P falciparum was 100% (95% CI 91.2-100%), specificity 98.8% (95% CI 98.1-99.3%), PPV 70.2% (95% CI 56.6%-81.6%) and NPV 100% (95% CI 99.7-100%).

Conclusions/Learning Points:

Standard RDTs were 100% sensitive in detecting P falciparum malaria in children in this study, with a lower point estimate for all malaria species. RDT alone can likely rule out imported P falciparum malaria in well-appearing children but a prospective study should confirm this, especially with the emergence of pfhrp2/3 gene deletions in the P falciparum parasite.

Backgrounds:

Microscopy is the gold standard for malaria diagnosis but is time intensive and often requires repeat hospital visits. Rapid diagnostic tests (RDT) form the mainstay of diagnosis in many endemic areas. Could an RDT alone rule out imported malaria in children presenting to UK Emergency Departments (ED)?

Methods

UK-based, multi-centre, retrospective, diagnostic accuracy study. Cases: any child <16 years presenting to ED with history of fever and travel to a malaria endemic area, between 01/01/2016 and 31/12/2017. Diagnosis: microscopy for malarial parasites (clinical reference standard) and RDT (index test). UK Health Research Authority approval: 20/HRA/1341.

Results:

51 malaria cases were reported in 1,472 patients documented at 15 sites (prevalence 3.5%), of which 44% female, median age 5 years (interquartile range 2-9 years). There were two deaths but not from malaria. Sensitivity of RDT alone to detect malaria infection was 94.1% (95% CI 83.8%-98.8%), specificity 99.4% (95% CI 98.8-99.7%), positive predictive value (PPV) 84.2% (95% CI 72.1-92.5%) and negative predictive value (NPV) 99.8% (95% CI 99.4-100.0%) (see Figure 1).

Figure 1. Personogram showing expected numbers of RDT results in hypothetical sample of 1000 children (all malaria species).

Forty (78%) cases were due to P falciparum. Sensitivity of RDT alone to detect P falciparum was 100% (95% CI 91.2-100%), specificity 98.8% (95% CI 98.1-99.3%), PPV 70.2% (95% CI 56.6%-81.6%) and NPV 100% (95% CI 99.7-100%).

Conclusions/Learning Points:

Standard RDTs were 100% sensitive in detecting P falciparum malaria in children in this study, with a lower point estimate for all malaria species. RDT alone can likely rule out imported P falciparum malaria in well-appearing children but a prospective study should confirm this, especially with the emergence of pfhrp2/3 gene deletions in the P falciparum parasite.