Bordetella pertussis infection in northern Taiwan, 1997-2001.

The clinical presentations of laboratory-confirmed Bordetella pertussis infection in Chang Gung Children's Hospital during 1997 and 2001 were analyzed. Of the 46 cases, 25 (54.3%) were male. The patients ages ranged from 24 days to 37 years, with a mean and median of 4.3 years and 10.5 years, respectively. Forty four patients had vaccination records, among them 23 patients (52.2%) had received > or = 3 doses of pertussis vaccine. Of the patients who were partially vaccinated (received 1 or 2 doses vaccine) or unvaccinated, 16 (69.6%) presented with whooping cough, 5 (22.2%) with post-tussive vomiting, and 13 (59.1%) with cyanosis. Leukocytosis (white blood cells > or = 15,000 cells/microL) and lymphocytosis (lymphocytes > or = 10,000 cells/microL) were observed in 17 (47.2%) and 16 (44.4%) of the patients, respectively. Fourteen patients (30.4%) developed complications, among which pneumonia was the most common (92.3%). Among infants < or = 1 year of age, 95.2% were partially vaccinated (20/21), compared with 5% (1/20) of the patients > 1 year of age (p<0.05). The overall complication rate was 37.5%, compared with 18.2% for patients > 1 year of age (p<0.05). One 2-month-old patient required ventilatory support after the development of cardiopulmonary failure. There was no mortality in this study. In summary, pertussis most commonly occurred in infants who were unvaccinated or partially vaccinated. These patients usually presented with atypical symptoms such as cyanosis or apnea. The importance of vaccination still cannot be overemphasized because immunized patients usually present with milder disease than those who are not immunized.