Seasonal fluctuations of head lice infestation in Germany.

Pediculosis capitis is one of the most frequent infectious diseases in childhood. If not diagnosed and treated rapidly, considerable clinical pathology may develop. The ubiquitous parasitic skin disease is characterized by a lack of sound epidemiological data, and factors which influence disease occurrence are still enigmatic. To investigate whether, in Germany, head lice infestation follows a seasonal pattern, we analyzed the weekly head lice consultations at the Health Department of Braunschweig City, Lower Saxony, for a period of 5 years, and compared the data with the units of pediculocides sold by two wholesalers to German pharmacies during a period of 2 and 3 years, respectively. The number of consultations did not show a clear seasonality, although there was a tendency of fewer consultations during school holidays, and an increase when schools opened again after Christmas, Easter, summer, and autumn holidays. In contrast, the number of packages of pediculocides sold followed a distinct seasonal rhythm with a maximum between calendar week 34 and 40, i.e., from mid September to end of October. In Germany, occurrence of pediculosis capitis varies according to the season of the year with a maximum in late summer and early autumn.