High fever and serious infection

Parents worry when their child has a very high fever, but as paediatricians we are often more relaxed; we assume that such high temperatures in otherwise healthy children are more likely to be due to viral infection, while those with serious sepsis often have only a mild fever. Is our assumption justified? Researchers from Israel did a systematic review (Rosenfeld-Yeoshua et al. Eur J Pediatrics doi.org/10.1007/s00431-018-3098-x). They looked for studies comparing rates of serious bacterial infection (SBI) depending on the child’s presenting temperature. They found 11, and distinguished those looking at hyperpyrexia (> 41°C) and high fever (>40 °C). The two hyperpyrexia studies showed a significantly higher risk of SBI at all ages (pooled OR 1.96; 95% CI 1.3 to 2.0), but both studies were old (1976 and 1990) and pre-dated routine vaccination against H. influenza B, pneumococcus and meningococcus. Five studies looked at otherwise healthy older children with a temperature of >40 °C. Together these gave a risk of SBI only slightly greater than for those with a lower temperature (OR 1.36; 95% CI 1.2 to 1.6). However in collating results from 5 studies of infants under 3 months they found the risks to be much higher: those with …