Transmission of Bordetella pertussis to young infants. Pediatr Infect Dis J

Baylor College of Medicine, Houston, Texas, United States
The Pediatric Infectious Disease Journal (Impact Factor: 2.72). 04/2007; 26(4):293-9. DOI: 10.1097/01.inf.0000258699.64164.6d
Source: PubMed

ABSTRACT Pertussis vaccination has reduced the number of notified cases in industrialized countries from peak years by more than 95%. The effect of recently recommended adult and adolescent vaccination strategies on infant pertussis depends, in part, on the proportion of infants infected by adults and adolescents. This proportion, however, remains unclear, because studies have not been able to determine the source case for 47%-60% of infant cases.
A prospective international multicenter study was conducted of laboratory confirmed infant pertussis cases (aged <or=6 months) and their household and nonhousehold contacts. Comprehensive diagnostic evaluation (including PCR and serology) was performed on all participants independent of symptoms. Source cases were identified and described by relationship to the infant, age and household status.
The study population comprised 95 index cases and 404 contacts. The source of pertussis was identified for 48% of infants in the primary analysis and up to 78% in sensitivity analyses. In the primary analysis, parents accounted for 55% of source cases, followed by siblings (16%), aunts/uncles (10%), friends/cousins (10%), grandparents (6%) and part-time caretakers (2%). The distribution of source cases was robust to sensitivity analyses.
This study provides solid evidence that among infants for whom a source case was identified, household members were responsible for 76%-83% of transmission of Bordetella pertussis to this high-risk group. Vaccination of adolescents and adults in close contact with young infants may thus eliminate a substantial proportion of infant pertussis if high coverage rates can be achieved.

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Available from: Flor M Munoz, Sep 28, 2015
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    • "In older children, adolescents and adults, pertussis typically causes a prolonged cough illness which may be associated with complications and a substantial economic cost [3] [4]. Older age groups are the primary source of pertussis transmission to infants who are at greatest risk of severe pertussis disease and death [5] [6] [7]. "
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    ABSTRACT: Background: Regular booster vaccination might be necessary throughout life to protect against pertussis infection. Nevertheless the duration of protection after booster vaccination remains unclear. In this study, antibody persistence up to 10 years after previous vaccination of adolescents (N=478) with combined reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine (dTpa, Boostrix™, GlaxoSmithKline Belgium) containing 0.5mg, 0.3mg or 0.133mg of aluminium was assessed. The immunogenicity, reactogenicity and safety of a decennial booster dTpa dose were also investigated. Methods: Young adults vaccinated as adolescents in the initial booster study were invited to participate in an assessment of antibody persistence at years 8.5 and 10, and to receive a dTpa booster dose at year 10 with immunogenicity assessment one month later. Those who originally received the 0.5mg or 0.3mg formulations received the same vaccine at year 10. Those in the 0.133mg group received the 0.5mg formulation. Reactogenicity and safety endpoints were captured until 30 days after booster vaccination. Results: Prior to the decennial booster at year 8.5 and year 10, all participants had seroprotective antibodies for diphtheria (ELISA or neutralisation assay) and tetanus. At least 77.8% were seropositive for anti-pertussis toxin (PT) antibodies at year 8.5 and 82.8% at year 10. All participants were seropositive for antibodies for filamentous haemagglutinin and pertactin at both time points. The decennial booster dose induced robust increases in antibody GMCs to all antigens. The post-booster anti-PT geometric mean concentration was 82.5EL.U/ml (95%CI 67.0-101.6) and 124.0 (103.5-148.5) in the 0.3mg and 0.5mg groups, respectively. The reactogenicity and safety profile of the decennial booster dose was consistent with the known safety profile of dTpa. No serious adverse events were reported. Conclusions: Decennial booster vaccination with either of the two licensed formulations of dTpa was highly immunogenic and well tolerated in young adults. Either formulation could be confidently used as a decennial booster. This study is registered at www.clinicaltrials.govNCT01147900.
    Vaccine 01/2015; 98(26). DOI:10.1016/j.vaccine.2014.10.049 · 3.62 Impact Factor
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    • "Although vaccination of infants over the first 18 months of life is common in many countries, including Mexico, there is still a window of time before vaccination can produce its full effect. During this period, newborns are vulnerable if they come in contact with infected people who are actively shedding bacteria (Wendelboe et al., 2007). Even in a country with long-standing universal childhood vaccination, waning immunity makes adolescents and adults susceptible to reinfections with subclinical disease who then become carriers and transmitters of the bacteria. "
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    ABSTRACT: In recent decades there has been an increase in the reported incidence of clini-cal pertussis in many countries. Estimation of the true circulation of the bacterium Bordetella pertussis is most reliably made on the basis of studies that measure antibody concentrations against pertussis toxin. Antibody levels decay over time and provide a fading memory of the infection. We develop a discrete bivariate mixture model for paired antibody levels in a cohort of 1002 Mexican adolescents who were followed over the 2008–2009 school year. This model postulates three groups of children based on past pertussis infection; never, prior and new. On the basis of this model we directly estimate incidence and prevalence, and select a diagnostic cut-off for classifying children as recently infected. We also discuss a relatively simple approach that uses only 'discordant' children who test positively on one visit and negatively on the other. The discordant approach provides inferences that are very similar to those of the full model when the data follow the assumed full model. Additionally, the discordant method is much more robust to model misspecification than the full model which has substantial problems with optimization. We estimate the school year incidence of pertussis to be about 3% and the prevalence to be about 8%. A cut-off of 50 was estimated to have about 99.5% specificity and 68% sensitvity.
    Journal of the Royal Statistical Society Series C Applied Statistics 02/2014; 63(4). DOI:10.1111/rssc.12051 · 1.49 Impact Factor
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    • "The lower test positivity rate in infants and young children in sporadic setting could be due to over sampling, which suggested that the disease burden in adolescent and young adults were underestimated in Alberta with their high test positivity rate. One extensive case-based study found that household contacts were the cause of 48-55% of B. pertussis transmission to the <1 year age group, which support the importance of disease control and prevention in adolescents and adults [33]. The severity of pertussis in young infants was shown in a study in 25 pediatric intensive care units in United Stated where 83% of the 124 critical cases were younger than 3 months old and had a 10% mortality rate [34]. "
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    ABSTRACT: ProvLab Alberta provides all laboratory testing for Bordetella pertussis including sporadic cases and outbreak investigations through collaborations with provincial public health partners. We describe B. pertussis activity in Alberta from July 2004 to December 2012. Laboratory testing for pertussis were analyzed using interpreted laboratory data that was generated by DIAL, a secure web-based platform. Duplicate specimens from the same individual <=90 days were excluded to generate a case-based dataset. Immunization status of confirmed pertussis cases from the provincial immunization repository was reviewed. Overall, 7.1% of suspected pertussis cases tested positive with a higher positivity rate in outbreak as compared to sporadic setting. Annual variations in sporadic pertussis cases were observed across the province with higher positivity rates in 2005, 2008, 2009 and 2012. A significantly higher positivity rate was observed in a northern region of Alberta. While the positivity rate in sporadic setting was highest in adolescents aged 10 to <15 years old (14.8%), population-based disease burden was highest in young children <5 years old. Of the 81.6% (n = 1,348) pertussis cases with immunization records, 48.3% were up-to-date with immunization. The pertussis cases that were up-to-date with their immunization were older (median age 12.9 years) as compared to those with incomplete (median age 9.7 years) or no pertussis immunization (median age 3.8 years). Cyclic pattern of annual pertussis activity with geographic variation was observed in Alberta with no obvious case finding effect from outbreak investigations. The high positivity rates in adolescents suggested an underestimation of disease burden in this age group.
    BMC Infectious Diseases 01/2014; 14(1):48. DOI:10.1186/1471-2334-14-48 · 2.61 Impact Factor
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