RESUMEN
OBJECTIVE: To determine age-dependent pertussis specific IgG and IgA antibodies seroprevalence in apparently healthy subjects. METHODS: A total of 595 healthy 1-35-y-old individuals divided into 5 different age groups were selected from Sari district. Antipertussis IgG and IgA antibodies levels were measured quantitatively by ELISA method. Positive sera for IgA and also IgG titer ≥150 were considered for recent pertussis infection. RESULTS: High seroprevelence levels (72% and 71%) were observed among preschool (<7 y) children. After decreasing the seroprevelence rates significally to lowest level (54.4%) among school aged (7-11 y), the rates increased again to the highest levels of 60% and 73% at adulthood (P = 0.03 and P = 0.003). In total, 1.55% of study subjects were IgA positive, and 5.7% showed high IgG titers. CONCLUSIONS: The present study reveals, vaccine induced immunity has decreased among school-aged children and natural pertussis infection is common among adolescent and young adults. Also, asymptomatic/sub-clinical recent pertussis infection was prevalent among studied population. These findings necessitate developing new strategies to reduce and control pertussis infection in Iran.