[Pertussis in Poland in 2004].

Reemergence of pertussis in a form of epidemic was observed in Poland in 1997/1998. Since that time we observe rather sustained trend of increased incidence and shift in the age of infected to the older age groups. 2954 cases were reported in 2004, an increase from the previous year (2034 in 2003) More cases occurred among females (1668 cases, 8.5/100,000) than among males (1286 cases, 7.0/ 100,000) and in urban areas 2258 (9.6/100,000) than in the rural ones 696 (4.7/100,000). Big differences in numbers of cases reported between different districts and between urban and rural areas bring strong possibility of insufficient sensitivity of the surveillance in many regions of Poland. Since in most cases diagnosis was based on serological tests, assessment or the fraction of parapertussis cases is impossible. It remains obscure to what extend recurrence of pertussis depends solely on the shift of incidence to older ages, to the decrease of vaccine efficiency or to the independent increase of parapertussis.