Evaluation of Haemophilus influenzae type b carrier status among children 10 years after the introduction of Hib vaccine in Brazil

The aim of the present study was to assess the prevalence of Haemophilus influenzaetype b (Hib) nasopharyngeal (NP) colonisation among healthy children where Hib vaccination using a 3p+0 dosing schedule has been routinely administered for 10 years with sustained coverage (> 90%). NP swabs were collected from 2,558 children who had received the Hib vaccine, of whom 1,379 were 12-< 24 months (m) old and 1,179 were 48-< 60 m old. Hi strains were identified by molecular methods. Hi carriage prevalence was 45.1% (1,153/2,558) and the prevalence in the 12-< 24 m and 48-< 60 m age groups were 37.5% (517/1,379) and 53.9% (636/1,179), respectively. Hib was identified in 0.6% (16/2,558) of all children in the study, being 0.8% (11/1,379) and 0.4% (5/1,179) among the 12-< 24 m and 48-< 60 m age groups, respectively. The nonencapsulate Hi colonisation was 43% (n = 1,099) and was significantly more frequent at 48-< 60 m of age (51.6%, n = 608) compared with that at 12-< 24 m of age (35.6%, n = 491). The overall resistance rates to ampicillin and chloramphenicol were 16.5% and 3.7%, respectively; the co-resistance was detected in 2.6%. Our findings showed that the Hib carrier rate in healthy children under five years was very low after 10 years of the introduction of the Hib vaccine.

Vigilancia de serotipos en infecciones invasivas por Haemophilus influenzae en la Argentina en la era de la vacuna conjugada contra el serotipo b durante el período 2005-2010 / Surveillance of Haemophilus influenzae serotypes in Argentina from 2005 to 2010 during the Haemophilus influenzae type b conjugate vaccine era

La introducción de la vacuna contra Haemophilus influenzae tipo b en los programas de inmunización de muchos países produjo una reducción marcada en la incidencia de enfermedad invasiva causada por este serotipo y en su portación y un incremento de otros tipos capsulares y de aislamientos no capsulados. Se estudiaron 313 aislamientos de H. influenzae recuperados de sitio estéril, provenientes de pacientes pediátricos y adultos con enfermedad invasiva atendidos en 90 hospitales de la Red Nacional de Laboratorios para Meningitis e Infecciones Respiratorias Agudas Bacterianas durante el período 2005-2010. Las patologías más frecuentes fueron neumonía, 40,3 % (n = 126), meningitis, 30,0 % (n = 94) y bacteriemia, 26,5 % (n = 83). En los pacientes pediátricos (n = 279), la mayor frecuencia de aislamientos correspondió a menores de 2 años, 74,5 % (n = 208). Con respecto a la distribución de tipos, el 61,3 %, correspondió a H. influenzae no capsulados (n = 192); el 20,1 % al b (n = 63); 11,2 % al a (n = 35); 4,8 % al f y 2,6 % a otros. En meningitis predominaron H. influenzae capsulados mientras que en neumonía y bacteriemia resultaron dominantes los tipos no capsulados. Se determinó el biotipo en 306 aislamientos. Todos los aislamientos de tipo a correspondieron al biotipo II; el 66,7 % de los tipo b pertenecieron al biotipo I. Mediante las técnicas de aglutinación en lámina y PCR se estudiaron 220 aislamientos; la concordancia entre ambas fue de 0,982 (IC: 0,92-1,00). En el último año se encontró un aumento significativo del tipo b, lo cual indica la importancia de mantener la vigilancia clínica y laboratorial de la enfermedad invasiva por H. influenzae.

The introduction of the Haemophilus influenzae type b vaccine in the immunization programs of many countries has greatly reduced this invasive disease and the carriage caused by this serotype, also increasing other capsular types and non-capsular isolations. There were 313 isolations of H. influenzae under study, which were recovered from a sterile site coming from pediatric and adult patients carrying the invasive disease. Patients were treated at 90 different hospitals belonging to the Red Nacional de Laboratorios para Meningitis e Infecciones Respiratorias Agudas Bacterianas (National Lab Network for Meningitis and Acute Bacterial Respiratory Infections) from 2005 to 2010 for the following disorders: pneumonia, 40.3% (n = 126), meningitis, 30.0% (n = 94) and bacteremia, 26.5% (n = 83). In pediatric patients (n = 279), the highest frequency of isolations corresponded to children under the age of 2 years, 74.5% (n = 208). Regarding type distribution, 61.3% corresponded to non-capsular H. influenzae (n = 192), 20.1% to type b (n = 63), 11.2% to type a (n = 35), 4.8% to type f, and 2.6% to other types. Capsular H. influenzae was predominant in meningitis whereas non-capsular H. influenzae in pneumonia and bacteremia. The biotype was determined in 306 isolations. The totality (100%) of type a (n = 35) was biotype II whereas 66.7% of type b (n = 63) was biotype I. Slide agglutination and PCR tests were used in 220 isolations. There was a match of 0.982 (IC: 0.92-1.00) between them. During the last year, there was a great increase in type b, showing the importance of clinical and laboratory-based surveillance of the invasive disease caused by H. influenzae.

Inmunogenicidad y reactogenicidad de la vacuna cubana Quimiohib en lactantes sanos. Cárdenas. 2005 / Immunogenicity and reactogenecity of the cuban vaccine Quimiohib in health breastfed children. Cardenas. 2005

Las infecciones por el Haemophilus Influenzae Tipo B (Hib) son frecuentes en edades pediátricas, causando infecciones graves que llevan a la muerte. Al iniciarse la aplicación de la vacuna cubana contra este germen realizamos un estudio prospectivo, de corte longitudinal, con los lactantes sanos del policlínico “José A. Echeverría”, Cárdenas, para determinar la inmunogenicidad y reactogenicidad de esta vacuna. Nuestro universo fueron los niños nacidos entre el 1º. de septiembre y el 31 de octubre del 2004, quedando como muestra sólo 32 lactantes sanos. Para seleccionarlos aplicamos criterios de inclusión y exclusión; a los lactantes reclutados, previo consentimiento informado de sus padres, se les aplicó tres dosis de la vacuna cubana QuimiHib® según el esquema 2-4-6 meses, por vía intramuscular, en la cara anterolateral del muslo izquierdo. Los eventos adversos ocurridos en los tres días consecutivos a la vacuna, a los 7 y 30 días después de la administración de cada dosis se siguieron estrechamente por un médico especialista en Pediatría y la enfermera de vacunación. Calculamos los porcentajes de presentación de éstas, clasificándolas en leves, moderadas y severas.Determinamos a qué tiempo después de administradas las vacunas aparecieron con mayor frecuencia. La inmunogenicidad del producto se evaluó a los 30 días de culminada la serie completa de inmunización por las determinaciones de los títulos de anticuerpos IgG contra el Hib. Obtuvimos que las reacciones adversas en su mayoría leves se resolvieron sin aplicar medicamentos. Todos los niños que concluyeron el estudio adquirieron el nivel de anticuerpos requeridos.

The infections by Haemophilus Influenzae tipe b (Hib) are very frequent in paediatric ages, causing serious infections leading to death. When the application of the Cuban vaccine against this germ began, we carried out a longitudinal, prospective study with the healthy breastfed children of the Policlinic “José Antonio Echeverría”, Cardenas, to determine the immunogenicity and reactogenecity of this vaccine. Our universe was the children born between September 1 st and October 31 st , 2004, taking as sample only 32 healthy breastfed children. To select them we applied criteria of inclusion and exclusion; to the recruited children, with the previous informed consent of their parents, were applied three doses of the Cuban vaccine QuimiHib®, following the scheme 2-4-6 months, intramuscular way, on the anterior side of the right thigh. A specialist in paediatrics and the vaccinating nurse rigorously followed the adverse events taken place during the three consecutive days after vaccination, and during the 7-to-30 days period after the administration of each doses. We calculated the percentages of presentation of these events by levels, from moderated to severe. We determined at what time they appeared more frequently after vaccination, and we evaluated the immunogenicity of the product at the 30 th day of finishing the complete series of immunization by determination the titles of IgG antibodies against Hib. The adverse reactions, most of them insubstantial, were solved without applying drugs. All the children coming to the end of the treatment acquired the required level of antibodies.

Occurrence of Haemophilus influenzae strains in three Brazilian states since the introduction of a conjugate Haemophilus influenzae type b vaccine

Few vaccines in history have induced such a dramatic decline in incidence over such a short period of time as the Haemophilus influenzae type b (Hib) conjugate. This vaccine was introduced in 1988 in the United States, but only in 1999 was Hib immunization introduced by the Brazilian Ministry of Health as part of the routine infant National Immunization Program. The authors analyzed 229 H. influenzae (Hi) isolates from Public Health Laboratories in three Brazilian states: Pernambuco (Northeast, N = 54), Santa Catarina (South, N = 19), and Rio de Janeiro (Southeast, N = 156). The isolates were collected from Brazilian children 0-10 years of age with meningitis and other infections from 1990 to 2003 and were part of the research collection of the National Institute of Quality Control in Health, FIOCRUZ. Bacterial strains were characterized by serotyping and biotyping. During the pre-vaccination period the prevalence infection due to Hib was of 165 isolates and only 2 non-b Hi among all the notified meningitis infections caused by Hi. Our results showed a significant decrease in the prevalence of Hib meningitis from 165 to 33 isolates after 1999. However, during the post-vaccination period of 2001-2003 we observed an increase in the number of non-b Hi isolates: only 2 non-b strains isolated from 1990 to 1999 and 29 from 1999 to 2003. Based on the present data, the authors emphasize the need for more sensitive epidemiological and bacteriological studies aiming the improvement of the available Hib vaccine, in order to protect the susceptible population to infections due to other serological types of Hi and the reevaluation of immunization schedules used by the National Immunization Program.