Despite universal immunization programs, pertussis remains a major public health concern. This study aimed to describe the pertussis epidemiology in the Puglia region in 2006–2015 and to identify recent polymorphisms in Bordetella pertussis (BP) virulence-associated genes.
The pertussis cases in 2006–2015 were identified from the National Hospital Discharge Database and the Information System of Infectious Diseases. Samples of pertussis cases in 2014–2016 that were confirmed by the Regional Reference Laboratory were subjected to ptxA, ptxP, and prn gene sequencing and, in 10 cases, multiple-locus variable-number tandem repeat analysis (MLVA).
In Puglia in 2006–2015, the pertussis incidence rose from an average of 1.39/100,000 inhabitants in 2006–2013 to 2.56–2.54/100,000 in 2014–2015. In infants <1 year of age, the incidence rose from an average of 60.4/100,000 infants in 2006–2013 to 149.9/100,000 in 2015. Of the 661 cases recorded in 2006–2015, 80.3% required hospitalization; of these, 45.4% were aged <1 year. Of the 80 sequenced samples, the allelic profile ptxA1-ptxP3-prn2 was detected in 74. This variant was detected in both vaccinated and unvaccinated people. Six BP samples were prn-deficient. The MLVA cases exhibited MLVA-type 27.
The pertussis incidence in Puglia has risen. The hypervirulent strain was also found in vaccinated people. This suggests bacterial adaptation to the vaccine and raises questions about acellular vaccine effectiveness. Prevention of infant pertussis cases is best achieved by immunizing the pregnant mother. Enhanced surveillance and systematic laboratory confirmation of pertussis should be improved in Italy.
Conflicts of Interest and Source of Funding: None of the authors have conflicts of interest. This study was supported by grants from the Osservatorio Epidemiologico Regionale (OER – Puglia).
Acknowledgments: We thank Maria Giovanna Cappelli and Davide Parisi for data collection and Donatella Pepe and Daniele Casulli for technical assistance in the laboratory investigations.
Address for correspondence: Maria Chironna, PhD, Department of Biomedical Sciences and Human Oncology-Hygiene Section, University of Bari, Azienda Ospedaliera-Universitaria Ospedale Policlinico Consorziale, Piazza G. Cesare 11, 70124 Bari, Italy Phone: +390805592328; Fax: +390805478472 E-mail: firstname.lastname@example.org
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