[The status of pertussis infection and molecular epidemiological characteristics of pertussis in Tianjin, 2013].

OBJECTIVE

To understand the status of pertussis infection and characteristics of molecular epidemiology of pertussis in 2013 in Tianjin.

METHODS

Totally, 181 suspected pertussis cases were selected and their nasopharyngeal swabs and serum were sampled at the Disease Monitoring Settings in Tianjin. Real-time PCR was used to detect Bordetella pertussis double target genes and enzyme linked immune-sorbent assay (ELISA) method was used to detect the specific pertussis toxin IgG (PT-IgG) antibody. Fimbriae 2 (FIM2) and Fimbriae 3 (FIM3) genes of pertussis was amplified by PCR for sequencing, from 30 pertussis DNA positive samples.

RESULTS

The positive rate of Real-time PCR was 68.24% in 148 cases and the positive rate of PT-IgG antibody was 55.56% in 108 cases. Among 101 cases that nucleic acid were positive, the median duration of disease was 11 days. Among the PT-IgG Positive cases (60 cases), the median duration of disease was 21 days. In cases under 1 year old, the Real-time PCR testing positive rate was 84.28%. Positive rates among other age groups, the differences were statistically significant. Nucleotide homologies of FIM2 and FIM3 genes from 30 pertussis strains were 99.6%-100.0%, while it was 99% when compared to both international standard Tohama strain and Chinese vaccine strain.

CONCLUSION

Detection of pertussis by Real-time PCR from clinical nasopharyngeal swab sample was quick and sensitive for the diagnosis. Bordetella pertussis epidemic strains in Tianjin area appeared close relation with both the international standards and China vaccine strains.