Abstract: Objective To assess the prevalence of pertussis infection in children with asthma across different stages and subtypes and to analyze the correlation between the two diseases via a multicenter prospective investigation. Methods Information was collected from children with asthma who had a cough ≥1 week through questionnaires, and pertussis toxin(PT)IgG antibodies levels and/or pertussis nucleic acid tests were performed to interpret the results. The distribution of pertussis antibody, infection and clinical characteristics of different groups were analyzed according to different age, asthma stage and pertussis infection. Results Among the 1,049 asthmatic children, the positive rate of PT-IgG was 26.22%, and the rate was significantly higher in ≥6 years old group compared with 3 months -< 3 years old group and 3 years -< 6 years old group(both P<0.001). The overall rate of pertussis infection in asthmatic children was 25.17%, with an increasing trend in infection rates corresponding to advancing age(P<0.001). The incidence rate of cough variant asthma combined with pertussis infection was significantly higher than classical asthma(28.00% vs. 22.59%, P=0.040). According to the clinical characteristics of 656 children, the incidence rate of pertussis infection was higher in patients with acute asthma attack than in chronic duration and clinical remission(26.15% vs. 10.46%, P<0.001; 26.15% vs. 8.00%, P=0.042). There was no significant difference between newly diagnosed and recurrent cases of asthma(P=0.189). Asthmatic children with pertussis were more likely to have spasmodic cough, facial redness, chickenlike echo and vomiting symptoms than those without pertussis(all P< 0.05). Morning cough was more common in asthmatic children without pertussis(9.36% vs. 4.20%, P=0.047). There was no significant difference in other cough phase characteristics at night, morning or night, day and after exercise between the two groups(all P>0.05). There were no significant differences in leukocyte count, neutrophil count, lymphocyte count, eosinophilic count, and IgE levels between the two groups(all P> 0.05). Conclusion The pertussis detection is prevalent in children with asthma, especially during acute asthma exacerbation. Clinical symptoms have certain significance to distinguish the two diseases, but laboratory examination results show no significance between the two diseases. It is recommended that routine screening for pertussis should be conducted for asthmatic children with cough for more than 2-4 weeks to better identify or judge and guide treatment.

Key words: Child, Pertussis, Infectious disease, Asthma, Correlation