No abstract

Laboratory confirmation of pertussis by culture, PCR, or detection of antibody increase in paired sera is hampered by low sensitivity in the later stages of the disease. Therefore, we investigated whether, and at which level, concentrations of immunoglobulin G (IgG) antibodies against pertussis toxin (PT), IgG-PT, in a single serum sample are indicative of active or recent pertussis. IgG-PT, measured by enzyme-linked immunosorbent assay in units per milliliter, was analyzed in 7,756 sera collected in a population-based study in The Netherlands, in the sera of 3,491 patients with at least a fourfold increase of IgG-PT, in paired sera of 89 patients with positive cultures and/or PCR results, and in the sera of 57 patients with clinically documented pertussis with a median follow-up of 1.4 years. We conclude that, independently of age, IgG-PT levels of at least 100 U/ml are diagnostic of recent or active infection with Bordetella pertussis. Such levels are present in less than 1% of the population and are reached in most pertussis patients within 4 weeks after disease onset and persist only temporarily.

RT-PCR testing has a high yield of viral diagnoses, but rapid communication does not lead to decreases in hospital admissions, shorter hospital stays, or less antibiotic use for children with acute respiratory infections.

Real-time medication monitoring (RTMM) is a promising tool for improving adherence to inhaled corticosteroids (ICS), but has not been sufficiently tested in children with asthma. We aimed to study the effects of RTMM with short message service (SMS) reminders on adherence to ICS, asthma control, asthma-specific quality of life and asthma exacerbation rate; and to study the associated cost-effectiveness.In a multicentre, randomised controlled trial, children (aged 4-11 years) using ICS were recruited from five outpatient clinics and were given an RTMM device for 12 months. The intervention group also received tailored SMS reminders, sent only when a dose was at risk of omission. Outcome measures were adherence to ICS (RTMM data), asthma control (childhood asthma control test questionnaire), quality of life (paediatric asthma quality of life questionnaire) and asthma exacerbations. Costs were calculated from a healthcare and societal perspective.We included 209 children. Mean adherence was higher in the intervention group: 69.3% versus 57.3% (difference 12.0%, 95% CI 6.7%-17.7%). No differences were found for asthma control, quality of life or asthma exacerbations. Costs were higher in the intervention group, but this difference was not statistically significant.RTMM with tailored SMS reminders improved adherence to ICS, but not asthma control, quality of life or exacerbations in children using ICS for asthma.

To investigate the possible dependence on age of the rate of decline of IgG antibodies to pertussis toxin (IgG-PT) after natural infection with Bordetella pertussis we measured IgG-PT in follow-up sera of 121 patients (age 0-94 years) obtained after 123 episodes of B. pertussis infection. For analysis we applied a dynamic model for the inactivation of B. pertussis by the immune system. There were no significant differences in rise, peak and decline of IgG-PT between different age groups, although there was a tendency for a more rapid increase, a higher peak and a faster decline with increasing age. The IgG-PT cut-off of 100 U/ml for serodiagnosis of pertussis appeared valid in all age groups. A decline of IgG-PT to < 10 U/ml was associated with increased risk of re-infection with B. pertussis.