HHV6 & HHV7. Dr Kate Ward UCLH. 3.3.24. SEIZURES. 13% (21/160) c. 1 O HHV-6 Median age 14 months 2 children hospitalised for seizures. NEJM 331 (1994) 432. HHV-6 & -7 ANTIBODIES IN BRITISH CHILDREN. Ward. J Clin Virol (2005) 183-193.
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Dr Kate Ward
13% (21/160) c. 1O HHV-6
Median age 14 months
2 children hospitalised for seizures
NEJM 331 (1994) 432
Ward. J Clin Virol (2005) 183-193
1O HUMAN HERPESVIRUSES-6 & -7 (HHV-6/-7) INFECTIONSMAY BEIMPORTANT CAUSES OF ENCEPHALITIS IN 1ST 3 YEARS BRITISH ISLES-WIDE SURVEY STARTED OCT 1998USING THE NETWORK OF THE BRITISH PAEDIATRIC SURVEILLANCE UNIT (BPSU)
ENCEPHALITIS IN FIRST 3 YEARS – THE STUDYDesign: Prospective thro’out UK & Republic of IrelandPopulation: Children aged 2-35 months
ENCEPHALITIS IN FIRST 3 YEARS – THE STUDYCase ascertainment: BPSU via telephoning reportingReporting definition: Suspected encephalitis &/or severe convulsions c fever Follow up of cases: Regardless of aetiologyLaboratory analysis: HHV-6 & -7 at UCL Other infections at local labs
Use indirect immunofluorescence:
1. Ag fixed on slide.
2. Incubate with test serum.
3. Wash off serum +/- urea
(Urea breaks low avidity Ag-Ab bond)
4. Incubate with FITC-anti human IgG
5. Compare ab titres –
8-FOLD REDUCTN = LOW AVIDITY
Ward et al., J. Clin. Micro 2001
Ward et al., J. Virol. Methods 2002
HHV-6 IgG HHV-7 IgG DNA
Titre Avidity Titre Avidity
3 <8 - <8 - HHV-6
7 <8 - <8 - HHV-6
13 2048 Low NT - -
58 512 High <16 - -
No. of cases 13 15
Days in hospital 9 5
Max temperature O C 39 38.7
No. c. convulsions
None 1 0
<15 minutes 2 1
15-30 minutes 3 1
(status epilepticus) 7 13
No. ventilated/sedated 6 6
1O HHV-6 & -7 infections:
1. Are equally important causes of febrile status epilepticus in the first 2 years of life.
2. Burden of disease at c. one year old around time of MMR vaccine.
HHV-6/7 tests needed to exclude misdiagnosis of neurological disease as a vaccine reaction.