[Epidemiological characteristics and clinical features of pertussis in Shandong Province from 2007 to 2022]

Objective: To analyze the epidemiological characteristics and clinical features of pertussis cases reported in Shandong Province of China. Methods: Data on pertussis cases in Shandong Province from 2007 to 2022 were collected from China Information System for Disease Control and Prevention. At the same time, some case information was collected from the database of notifiable pertussis in Shandong Province from 2007 to 2022. The distribution characteristics and clinical features of pertussis were analyzed. A spatial distribution map of pertussis cases in Shandong Province was drawn. Results: A total of 26 122 pertussis cases were reported in Shandong Province during 2007-2022, with an annual incidence rate ranging from 0.11 to 5.77 cases per 100 000 people. Cases occurred throughout the whole year, with a seasonal peak occurring in spring and summer, especially in July and August. In recent years, reported cases were mainly distributed in the central and western regions of Shandong Province, with fewer cases in the eastern region. The hot spots of the disease shifted from Heze and Dezhou City in 2007-2013 to Jinan and Tai'an city in 2014-2022. The age range of onset was from 1 day to 93 years old. The proportion of cases with age≤1 year was the largest (41.81%, 10 922/26 122), and the proportion of cases aged 0-6 months decreased from 32.21% (67/208)-55.67% (157/282) within the period of 2007 to 2013 to 16.78% (883/5 263)-41.97% (444/1 058) within the period of 2014 to 2022, with a statistically significant trend (χ² trend=670.01, P<0.001). There were 13 682 male cases and 12 440 female cases, with a male-female ratio of 1.10∶1. The male-female ratio was 1.45∶1 (806∶556) from 2007 to 2013 and 1.08∶1 (12 876∶11 884) from 2014 to 2022. The proportion of women increased from 42.31% (88/208) in 2007 to 47.84% (2 518/5 263) in 2022, and with a significant trend (χ² trend=22.25, P<0.001). In pertussis cases, the proportions of scattered children, kindergarten children and students were 71.38% (18 645/26 122), 15.13% (3 951/26 122), and 11.60% (3 031/26 122), respectively. The top five clinical symptoms of pertussis cases were paroxysmal spasmodic cough (86.33%, 21 411 cases), flushing (39.61%, 9 824 cases), restless sleep (34.51%, 8 558 cases), fever (30.80%, 7 638 cases), and crowing (27.53%, 6 829 cases). Among 24 802 cases, there were 15 542 cases (62.66%) with a history of immunization against pertussis vaccine. Conclusion: From 2007 to 2022, the incidence rate of pertussis cases in Shandong Province shows an upward trend, with the majority being young children, and the clinical symptoms are relatively typical.