[Characteristics of children with diagnosed pertussis]

In 1997 a significant increase in the incidence of pertussis in the Łódź voivodship was noticed--the incidence increased from 3.32 in 1996 to 26.34. The aim of this work was the analysis of the course of pertussis in the Łódź voivodeship. Epidemiological history was analysed of 331 children with diagnosed pertussis from the end of 1996 to February 1998. The diagnosis was made on the basis of clinical picture and passive haemagglutination reaction (PHR). The highest incidence occurred between September and November 1997 (196/331--59.2%). Children aged 7-15 years and toddlers constituted the most numerous groups (respectively: 60.7% and 24.5%). The majority of children with pertussis (83%) received four doses of DTP vaccine, according to the current vaccination schedule. Only 8.2% of children did not receive DTP vaccination or received only 1 or 2 doses. In the majority of properly vaccinated children (73.5%--202/275) the disease appeared mainly after 6-15 years from the last 4th dose of DTP vaccine. From the group of children with pertussis, 18.7% required hospitalisation--these were mainly neonates and children aged 2 and 3 years. The number of children who developed pertussis was highest in school age children after 6-15 years from the last dose of vaccine. The severity of the disease, evaluated on the basis of the percentage of hospitalisations, was highest in the youngest age groups. The laboratory methods used (PHR) are not sufficient for proper diagnosis of pertussis, and cannot provide epidemiological data to assess the incidence of the disease. Increasing number of pertussis cases requires a revision in the schedule of prophylactic vaccination.