Incidence and aetiology of serious viral infections in young febrile infants.

AIM: While the incidence and aetiology of serious bacterial infections among febrile infants younger than 90 days old are well studied, those concerning viral infection are not. There are severe life-threatening viral infections requiring immediate intense therapy. The objective of the study is to describe the incidence and aetiology of serious viral infections (SVI) among young febrile infants.

METHODS: A retrospective audit was performed covering all the febrile infants younger than 90 days old admitted to a paediatric emergency department in Japan from 2011 to 2013. SVI was defined as a viral illness that may result in permanent organ dysfunctions or life-threatening complications. Diagnostic investigation consisted of urine and blood culture for all infants, cerebrospinal fluid cultures for infants who do not fulfil the low-risk criteria, rapid antigen tests for several viruses in infants with specific symptoms and blood and/or cerebrospinal fluid polymerase chain reaction of possible viruses for infants with fever without a localising source.

RESULTS: Of 275 cases, 32 and 45 cases were diagnosed as serious viral and bacterial infections, respectively. Intensive care unit admission occurred for three viral and four bacterial infections. Viral aetiology consisted of respiratory syncytial virus (11 cases), aseptic meningitis (9 cases), enterovirus (6 cases), influenza virus (3 cases), rotavirus (2 cases) and herpes simplex virus-1 (1 case). Respiratory (14 cases), central nervous (12 cases) and circulatory (6 cases) systems were affected.

CONCLUSION: SVI was observed in 11.6% of febrile young infants in a paediatric emergency department.