Clinical Manifestations and Seasonality of Pertussis in Azerbaijan, Iran

Abstract

Background: Nowadays, a shift in age distribution and the increasing incidence of pertussis among adolescents and adults have been reported in the world. The aim of this study was to evaluate the prevalence, clinical characteristics, and seasonality of pertussis in Azerbaijan, Iran. Methods: A total of 368 nasopharyngeal swabs of 184 patients were taken for culture and polymerase chain reaction (PCR). Simultaneously, 2 blood samples from 111 participants aged 12 to 70 years were obtained to perform enzyme-linked immunosorbent assay (ELISA) test. Whooping cough cases were considered as being the level of anti-pertussis toxin (anti-PT) immunoglobulin G higher than 24 IU/mL or positive culture and PCR positive. Results: Of 184 patients, the PT gene was detected in 23.37% (43/184) by PCR test, whereas only 4.35% (8/184) by culture were positive. The overall seropositive rate of immunoglobulin G-PT was 62.16% (69/111). The highest positivity of the PCR and ELISA was detected in the age group 31 to 40 years. Paroxysmal cough (100%), inspiratory whoop (63.6%), and posttussive vomiting (45.5%) in children with pertussis were the most frequent symptoms reported. These symptoms in adolescents and adults were prolonged cough (100% and 94.9%, respectively) and gagging (38.5% and 30.5%, respectively). Conclusions: The most sensitive assay for pertussis detection is the ELISA. The continuous presence of pertussis is alarming to health care professionals. Our findings suggest a high prevalence of pertussis in Azerbaijan indicates that childhood national immunization program may not provide adequate protective immunity in the population. Booster vaccination is necessary in adolescence and adulthood and development of highly efficacious pertussis vaccine.