Objectives:To examine the role of viruses in febrile seizures (FS) by comparing the relative risk of developing FS with common viral infections and the subsequent risk of recurrence.
Methods:We performed a medical record review for all children admitted with FS during a 5-year period. In our hospital, virological studies, including nasopharyngeal aspirate (NPA) and stool viral studies, were routinely performed for all admitted children with symptoms suggestive of infection independent of whether they had FS or not. We also performed a contemporary record review for all admissions due to febrile illnesses associated with the 5 common viruses [influenza, adenovirus, parainfluenza, respiratory syncytial virus (RSV) and rotavirus] identified. We matched the 2 groups using our computerized patient management system to calculate the relative risk of FS following these 5 viral infections. For patients admitted for the first episode of FS, we did a multivariate analysis for the following factors: type of viral infection, age of onset, family history, complex features of FS, and maximum temperature during the episode, to identify the risk factors of recurrence.
Results:There were 923 admissions for FS in which 565 were admitted for the first seizures. The 5 commonest viruses identified in patients with FS were Influenza (163/923, 17.6%), adenovirus (63/923, 6.8%), parainfluenza (55/923, 6%), RSV (25/923, 2.7%) and rotavirus (12/923, 1.3%). The incidences of FS in admissions with febrile illnesses due to these viruses were: 20.8%(163/785) for influenza, 20.6%(55/267) for parainfluenza, 18.4%(63/343) for adenovirus, 5.3% (25/468) for RSV and 4.3%(12/280) for rotavirus. The relative risks (RRs) of developing FS were similar among patients admitted with influenza, parainfluenza and adenovirus but significantly higher than those with RSV and rotavirus. Complex FS occurred in 20.6% (n=191) and the risk of developing complex FS was similar among these 5 viruses. The overall recurrence rate was 20.5% in a median follow up of 3.08 years. Multi-variate analysis showed that type of viral infection did not predict future recurrence.
Conclusion:The risk of developing FS is similar with influenza, adenovirus or parainfluenza, which is contradictory to previous reported findings. The risk of FS due to RSV or rotavirus is lower but other studies had shown an ″afebrile variant″ of FS associated with these viruses. The type of viral infection is not important in predicting complex features or future recurrences. Our findings could not be completely explained by ″viral neurotropism″ and other factors like individual susceptibilities should be explored in future studies.
- febrile Seizure
- influenza A and B