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.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Bordetella pertussis/inmunología , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Vacuna contra la Tos Ferina/inmunología , Tos Ferina/inmunología , Adolescente , Adulto , Factores de Edad , Infecciones Asintomáticas , Niño , Preescolar , Estudios Transversales , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Lactante , Irán/epidemiología , Masculino , Estudios Seroepidemiológicos , Tos Ferina/epidemiología , Tos Ferina/prevención & control , Adulto JovenRESUMEN
OBJECTIVE: The policy of administering the second dose of measles-mumps-rubella (MMR) vaccine (MMR(2)) has recently changed in Iran, at age 1.5 years instead of 4-6 years previously. The effects of such a change on the immune status of the individual are evaluated in this study. METHODS: Totally 249 and 228 children aged 18 months and 4- to 6-year-olds, respectively, with a documented receipt of primary MMR vaccine at the age of ≥ 1 year were enrolled. Before, and 4-6 weeks after MMR(2) administration, anti-MMR IgG antibody levels were measured using ELISA method. IgM antibody levels were also assessed in measles-rubella seronegative children that responded to MMR(2). Collected data for each component from both age groups were compared by using Fischer's exact probability and chi-square tests. RESULTS: Before revaccination, measles seroimmunity rate was similar between the two groups, but rates to mumps and rubella were significantly higher in younger children-measles: 74 vs. 78.3%; mumps: 82.3 vs. 68.4% and rubella: 75% vs. 67%, respectively. After administration of MMR(2), all seroimmune subjects were IgG boosted. Except for rubella, older seronegative children showed significantly higher seroconvertion rate to MMR(2) and seroprevalence rates increased in vaccinees--measles: 98.2 vs. 94%, mumps: 97 vs. 94.4% and rubella: 87 vs. 92.4%, respectively. Only few measles-rubella seronegative children showed IgM response to MMR(2). CONCLUSION: This study showed that the majority of younger children were susceptible to MMR infection before revaccination. Earlier age policy provides more protection against MMR in preschool-aged children. Rubella strain seems to be less potent than reported.