Severe complications of varicella in previously healthy children in Germany: A 1-year survey

Objective. Varicella is a common infectious disease, usually benign and sel f-limited, and complications are believed to be rare. The purpose of this s tudy was to describe the epidemiology of severe varicella complications in immunologically healthy children in Germany. Methods. Information on any admission of children with a severe complicatio n associated with chickenpox was solicited throughout 1997 from all 485 ped iatric hospitals in Germany using an established surveillance system. The c ase definition included nonimmunocompromised individuals who were up to 16 years of age and hospitalized with neurologic complications, bacterial supe rinfections, or hematologic complications. Results. The response rate to the surveillance questionnaire during the obs ervation period was high: 93.4%. Of the 153 reported cases, 119 met the cas e definition. There was a seasonal distribution of reported complications w ith a peak in March. The majority of complications occurred in preschool-ag e children with a maximum age of 4 years. No gender predominance was found with a distribution of 56 female and 63 male patients. Multiple entries for complications were allowed. The most frequent complications were neurologi c, which were reported in 73 children (61.3%); cerebellitis was the leading diagnosis (n = 48), followed by encephalitis (n = 22), meningitis (n = 2), and central facial palsy (n = 1). A total of 46 (38.6%) infectious complic ations were identified. Superinfections of the skin were present in 31 (26. 0%), pyogenic arthritis was present in 5 (4.2%), osteomyelitis was present in 4 (3.3%), necrotizing fasciitis was present in 3 (2.5%), orbital celluli tis was present in 2 (1.6%), and pneumonia was present in 1 (0.8%). Strepto coccus pyogenes was the leading cause of bacterial infections (18 cases [15 .1%]), with invasive disease in 6 patients (8.4%) and linked to 4 of 8 case s with defect healing. Infectious complications were reported in the majori ty in younger children up to 4 years of age, whereas neurologic complicatio ns occurred more frequently in an older age range. Five children experience d thrombocytopenia or severe anemia. There was no bleeding disorder, no fat ality, and no case of Reye syndrome reported during the 1-year observation period. In total, 8 (6.7%) of 119 patients reported having long-term sequel ae, 6 attributable to infectious complications and 2 to persistent deficits after neurologic complications. Conclusion. This is the first prospective nationwide study of severe compli cations of varicella in immunologically healthy children. Related to 14 025 867 children up to the age of 16, a crude incidence of severe chickenpox c omplications of 8.5/100 000 could be calculated. The actual hospitalization rate attributable to complicated chickenpox is probably much higher, becau se this calculation refers to a population theoretically at risk and not th e truly susceptible individuals. The results of this study demonstrate cons iderable morbidity with a comparatively high rate of encephalitis, osteomye litis, and pyogenic arthritis. Although infectious complications were prese nt in only 38.6% of the reported cases, they contributed disproportionately to the cases with chronic sequelae. Looking at these cases in more detail, S pyogenes involvement was identified as the major risk factor for invasiv e disease with an unfavorable long-term outcome.