Declining incidence of chickenpox in the absence of universal childhood immunisation.
OBJECTIVE
To examine the epidemiology of chickenpox in Wales from 1986 to 2001.


METHODS
Descriptive analysis of chickenpox consultations reported by the Welsh general practice sentinel surveillance scheme for infectious diseases, compared with annual shingles consultation rates from the same scheme to exclude reporting fatigue and data from a general practice morbidity database to validate results.


METHODS
A total of 226,884 patients registered with one of 30 volunteer general practices participating in the sentinel surveillance scheme.


METHODS
Age standardised and age specific incidence of chickenpox.


RESULTS
Crude and age standardised consultation rates for chickenpox declined from 1986 to 2001, with loss of epidemic cycling. Rates remained stable in 0-4 year olds but declined in all older age groups, particularly those aged 5-14 years. Shingles consultation rates remained constant over the same period. Data from the morbidity database displayed similar trends.


CONCLUSIONS
General practitioner consultation rates for chickenpox are declining in Wales except in pre-school children. These findings are unlikely to be a reporting artefact but may be explained either by an overall decline in transmission or increased social mixing in those under 5 years old, through formal child care and earlier school entry, and associated increasing rates of mild or subclinical infection in this age group. Further investigation, particularly by serological surveillance, is necessary before universal varicella immunisation can be considered in the UK.
Lowe
G L
GL
National Public Health Service Communicable Disease Surveillance Centre, Abton House, Cardiff CF14 3QX, UK. Gwen.lowe@nphs.wales.nhs.uk
Salmon
R L
RL
Thomas
D Rh
DR
Evans
M R
MR
D000293:Adolescent; D017677:Age Distribution; D002644:Chickenpox / Q000453:epidemiology* / Q000517:prevention & control; D019433:Chickenpox Vaccine; D002648:Child; D002675:Child, Preschool; D005260:Female; D006562:Herpes Zoster / Q000453:epidemiology; D006801:Humans; D017589:Immunization Programs / Q000592:standards*; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D014852:Wales / Q000453:epidemiology
D019433:Chickenpox Vaccine