Major Article Underdetection and underreporting of pertussis in children attended in primary health care centers: Do surveillance systems require improvement? Rubén Solano MSc, MPH, FETP a,b,c, *, Inma Crespo PhD, MSc a,c , María Isabel Fernández PhD, MPH d , Carles Valero MSc, MPH d , María Isabel Álvarez MD, MSc e , Pere Godoy PhD, MPH, FETP a,f , Joan A. Caylà PhD, MPH a,b , Àngela Domínguez PhD, MSc, MPH a,c a CIBER Epidemiology and Public Health, Carlos III Institute of Health, Madrid, Spain b Epidemiology Department, Barcelona Public Health Agency, Barcelona, Spain c Department of Public Health, University of Barcelona, Barcelona, Spain d Evaluation and Quality Assessment Systems Unit, Primary Health Care Center, Catalan Institute of Health, Barcelona, Spain e La Sagrera Primary Health Care Center, Catalan Institute of Health, Barcelona, Spain f Public Health Agency of Catalonia, Barcelona, Spain Key Words: Infection control Epidemiology Pediatric infection Disease notification Family physicians Whooping cough Background: Pertussis is an underestimated disease. Several European countries have developed models to account for underreporting of pertussis. The aim of this study was to estimate pertussis underdetection and underreporting in pediatric patients attending primary health care centers (PHCCs). Methods: We reviewed clinical records of PHCCs in Barcelona in 2012. Factors associated with underdetection and underreporting were analyzed by logistic regression. Adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) were calculated. Results: We included 3,505 children aged < 7 years (mean age, 34 ± 20.7 months; range, 0-82 months) presenting with cough; 9.3% (326 out of 3,505) of patients also had ≥ 1 symptoms related to pertussis accompanied by cough for a duration ≥ 2 weeks. Of the 326 children receiving clinical criteria, only 31 (9.5%) were laboratory-confirmed and 6 (1.8%) were detected but not reported. There were 295 (90.5%) undetected suspected pertussis cases. Age ≥ 18 months (aOR, 8.51; 95% CI, 1.82-39.86), cyanosis (aOR, 6.71; 95% CI, 1.43-31.39), request for chest radiograph (aOR, 0.26; 95% CI, 0.07-0.99), and request for other laboratory tests (aOR, 5.39; 95% CI, 2.19-13.27) were associated with underdetection. Paroxysmal cough (aOR, 5.77; 95% CI, 1.05-31.76) and request for other laboratory tests (aOR, 2.91; 95% CI, 1.11-7.62) were associated with underreporting. Conclusions: Both underdetection and underreporting complicate the understanding of pertussis epidemi- ology. Correct assessment of pertussis symptoms and notification of cases must be improved to control pertussis. © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. Pertussis, a highly contagious, vaccine-preventable disease of the upper respiratory tract caused by Bordetella pertussis, causes about 20-40 million cases and 600,000 deaths worldwide each year, of which a disproportionate number occur in unvaccinated infants. 1 In Catalonia, Spain, the primary series of diphtheria, tetanus, and acellular pertussis vaccine was initially administered at ages 2, 4, and 6 months with a booster dose at age 18 months. In 2000, another booster dose was added at age 4-6 years. 2 The incidence of pertussis has increased in recent years in Bar- celona despite high vaccine coverages. 3 The reemergence of pertussis has led to more frequent diagnoses and new vaccination strate- gies, including vaccination of pregnant women to prevent pertussis during pregnancy and the neonatal period. 4 The recent death from pertussis of 3 newborns in Spain (whose mothers had not been vaccinated during pregnancy) has increased social alarm and renewed the focus on vaccination. 5 * Address correspondence to Rubén Solano, MSc, MPH, FETP, CIBER Epidemiology and Public Health, Epidemiology Service-Barcelona Public Health Agency, Pl Lesseps 1, Barcelona 08023, Spain. E-mail address: rsolanosilveira@gmail.com (R. Solano). Supported by the Institute of Health Carlos III and the Catalan Agency for the Management of Grants for University Research (AGAUR grant No. 2014/ SGR 1403). Conflicts of Interest: None to report. ARTICLE IN PRESS 0196-6553/© 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2016.03.033 American Journal of Infection Control ■■ (2016) ■■-■■ Contents lists available at ScienceDirect American Journal of Infection Control journal homepage: www.ajicjournal.org American Journal of Infection Control