Epidemiology of chickenpox in France (1991-1995).

STUDY OBJECTIVES

To decide whether a mass immunisation against chickenpox should be or should not be organised, it is important to have up to date data on the disease and to have baseline data to further assess a mass immunisation strategy, if any.

DESIGN

Recent chickenpox epidemiology (age and sex distribution, seasonal dynamic and complications) in France are reviewed.

SETTING

The system works with about 500 Sentinelle general practitioners (SGPs) and has provided surveillance of frequent communicable diseases in continental France since 1984.

PARTICIPANTS

The data were collected by the computerised Sentinelle system. The Sentinelle system uses a videotex server that allows information exchange, data entry, and synthetic return of information. Chickenpox was defined as a sudden onset of typical skin eruption with pruritus, leaving scabs and associated with moderate fever. For each reported case, the SGP gave information on the age of the patient, sex, prevailing childcare for the children, contacts and complications (skin superinfections, lower and upper respiratory infections, conjunctivitis and corneal infections, nervous system injuries, stomatitis and others). Spectral analysis was used to detect cyclical patterns.

MAIN RESULTS

Between 1991 and 1995, 15,817 cases of chickenpox were reported and provided the basis for the analysis. The yearly national incidence was 1.0-1.35 cases per 100 inhabitants. A pronounced annual periodicity of the incidence was observed and confirmed by spectral analysis. Ninety two per cent of chickenpox cases occurred in children under 14 years of age with about 5% being under one. Complications were reported in 2% of the cases. Common complications reported were skin superinfections, lower and upper respiratory tract infections. However, 21 cases out of 318 complications were nervous system injuries including six encephalitis or cerebellar ataxia. All these cases recovered completely.

CONCLUSIONS

Chickenpox is usually a benign childhood disease. This study affords up to date observations on the disease in France. A large panel of complications has been reported. This paper provides the first attempt to describe the epidemiology of chickenpox in France.