Summary

A 22-month-old boy presented with repeated enterovirus infections including two episodes of encephalitis at the age of 8 months and 16 months and two episodes of febrile illnesses at 14 and 19 months old. These episodes were associated with at least two different serotypes of enterovirus. There were no residual neurological deficits and he underwent complete recovery in between. Immunology workup showed normal circulating leucocyte differential counts and lymphocyte subsets. His serum IgG concentration was persistently low but could mount satisfactory specific antibody responses to booster vaccines. The clinical picture was compatible with transient hypogammaglobulinaemia of infancy (THI) which was traditionally believed not to be associated with serious viral infections. This is the first case report to alert physicians that repeated serious enterovirus infections can happen in a relatively benign immunodeficiency disease.