Causes of fever in primary care in Southeast Asia and the performance of C-reactive protein in discriminating bacterial from viral pathogens

We investigated causes of fever in the primary levels of care in Southeast Asia, and evaluated whether C-reactive protein (CRP) could distinguish bacterial from viral pathogens. Blood and nasopharyngeal swab specimens were taken from children and adults with fever (>37.5˚C) or history of fever (<14 days) in Thailand and Myanmar. Of 773 patients with at least one blood or nasopharyngeal swab specimen collected, 227 (29.4%) had a target organism detected. Influenza virus type A was detected in 85/227 cases (37.5%), followed by dengue virus (30 cases, 13.2%), respiratory syncytial virus (24 cases, 10.6%) and Leptospira spp. (9 cases, 4.0%). Clinical outcome was similar between patients with a bacterial or a viral organism, regardless of antibiotic prescription. CRP was higher among patients with a bacterial organism compared to those with a viral organism (median 18mg/L, interquartile range [10-49] versus 10mg/L [≤8-22], p-value 0.003), with an area under the curve of 0.65, 95% confidence interval (0.55-0.75). Serious bacterial infections requiring antibiotics are exceptions rather than the rule in the first lines of care. CRP-testing could assist in ruling out such cases in settings where diagnostic uncertainty is high and routine antibiotic prescription is common. The original CRP randomised-controlled trial (RCT) was registered with ClinicalTrials.gov, number NCT02758821