PRIMARY HUMAN HERPESVIRUS-6 INFECTION IS FREQUENTLY OVERLOOKED AS A CAUSE OF FEBRILE FITS IN YOUNG-CHILDREN

Sera from 248 children aged 30-179 weeks were tested retrospectively f or human herpesvirus-6 (HHV-6) IgG antibody avidity. Twenty-five child ren presented with febrile fits, in one case with a rash, exanthem sub itum resulting from prima ry HHV-6 infection was diagnosed at the time , but in the others HHV-6 was not considered in the differential diagn osis even though two patients had a rash. In fact, five of the 25 pati ents experienced primary infection as shown by low avidity HHV-6 antib ody. Although nine other of these patients were seronegative in the ac ute phase of the illness, and unfortunately convalescent sera were not available to confirm primary HHV-6 infection, seronegativity was clea rly a risk factor for febrile fits (P = 0.03, odds ratio 3.14 for all children; P = 0.002, odds ratio 7.20 for children aged 70-179 weeks), and primary HHV-6 infection was a very likely diagnosis. The remaining 11 children had high avidity antibody, so HHV-6 was excluded as a cau se of their febrile fits. HHV-6 may frequently be a cause of febrile f its, often without the typical rash of exanthem subitum, and this diag nosis is often overlooked by clinicians, (C) 1994 Wiley-Liss, Inc.