Analysis with a combination of macrorestriction endonucleases reveals a high degree of polymorphism among Bordetella pertussis isolates in eastern France.
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From 1990 to 1996, routine screening for whooping cough identified 399 patients with a calmodulin-dependent adenylate cyclase-positive test result and yielded 69 Bordetella pertussis isolates. None of the patients were fully vaccinated, and most were less than 6 months old. Analysis of total DNA by pulsed-field gel electrophoresis (PFGE) after XbaI, SpeI, or DraI macrorestriction yielded 19, 15, and 5 different patterns, respectively, whereas ribotyping failed to demonstrate any strain polymorphism. Discrimination among the isolates was improved by combining the PFGE profiles. Some patterns were more frequent, but the corresponding patients were not clearly epidemiologically related. The patterns for two strains obtained during a 3-month period from patients who were neighbors differed by the length of a single DNA fragment. These data strongly suggest that one type of isolate is widely spread throughout the world and is carried by individuals other than patients who develop a true illness. (+info)
Serum IgG antibody responses to pertussis toxin and filamentous hemagglutinin in nonvaccinated and vaccinated children and adults with pertussis.
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Levels of IgG antibody to pertussis toxin (PT) and filamentous hemagglutinin (FHA) were measured in paired serum samples from 781 patients fulfilling at least one laboratory criterion for pertussis that was suggested by an ad hoc committee sponsored by the World Health Organization. The patients were participants or family members of participants in a double-blind efficacy trial of a monocomponent pertussis toxoid vaccine. Of 596 nonvaccinated children, 90% had significant (two-fold or more) rises in PT IgG and FHA IgG levels. Only 17 (32%) of 53 children previously vaccinated with three doses of pertussis toxoid had rises in PT IgG levels because they already had elevated PT IgG levels in their acute-phase serum samples. PT IgG and FHA IgG levels were significantly higher in acute-phase serum samples from 29 adults than in acute-phase serum samples from the nonvaccinated children. Nevertheless, significant rises in levels of PT IgG (79% of samples) and FHA IgG (90%) were demonstrated in adults. In conclusion, assay of PT IgG and FHA IgG in paired serum samples is highly sensitive for diagnosing pertussis in nonvaccinated individuals. Assay of PT IgG levels in paired sera is significantly less sensitive for diagnosis of pertussis for children vaccinated with pertussis toxoid. (+info)
Evidence of efficacy of the Lederle/Takeda acellular pertussis component diphtheria and tetanus toxoids and pertussis vaccine but not the Lederle whole-cell component diphtheria and tetanus toxoids and pertussis vaccine against Bordetella parapertussis infection.
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A subanalysis of a recent cohort efficacy trial of a pertussis vaccine was performed to determine its efficacy against cough illnesses due to Bordetella parapertussis infections. Infants received four doses of either the Lederle/Takeda acellular pertussis component diphtheria and tetanus toxoids and pertussis (DTaP) vaccine or the Lederle whole-cell component diphtheria and tetanus toxoids and pertussis (DTP) vaccine at 3, 4.5, 6, and 15-18 months of age; controls received three doses of diphtheria and tetanus toxoids (DT) vaccine only. All subjects were prospectively followed for cough illnesses of > or = 7 days' duration; cases of B. parapertussis infection were confirmed by positive culture, household contact, or serology. Seventy-six cough illnesses due to B. parapertussis were identified; 24 occurred in 929 DTaP recipients, 37 in 937 DTP recipients, and 15 in 321 DT recipients, resulting in an efficacy of 50% for DTaP vaccine (95% CI [confidence interval], 5% to 74%) and 21% for DTP vaccine (95% CI, -45% to 56%). The data in the present analysis suggest that the Lederle/Takeda DTaP vaccine but not the Lederle whole-cell component DTP vaccine has efficacy against B. parapertussis infection. (+info)
Capture-recapture method for estimating misclassification errors: application to the measurement of vaccine efficacy in randomized controlled trials.
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BACKGROUND: The measure of efficacy is optimally performed by randomized controlled trials. However, low specificity of the judgement criteria is known to bias toward lower estimation, while low sensitivity increases the required sample size. A common technique for ensuring good specificity without a drop in sensitivity is to use several diagnostic tests in parallel, with each of them being specific. This approach is similar to the more general situation of case-counting from multiple data sources, and this paper explores the application of the capture-recapture method for the analysis of the estimates of efficacy. METHOD: An illustration of this application is derived from a study on the efficacy of pertussis vaccines where the outcome was based on > or =21 days of cough confirmed by at least one of three criteria performed independently for each subject: bacteriology, serology, or epidemiological link. Log-linear methods were applied to these data considered as three sources of information. RESULTS: The best model considered the three simple effects and an interaction term between bacteriology and epidemiological linkage. Among the 801 children experiencing > or =21 days of cough, it was estimated that 93 cases were missed, leading to a corrected total of 413 confirmed cases. The relative vaccine efficacy estimated from the same model was 1.50 (95% confidence interval: 1.24-1.82), similar to the crude estimate of 1.59 and confirming better protection afforded by one of the two vaccines. CONCLUSION: This method allows supporting analysis to interpret primary estimates of vaccine efficacy. (+info)
Pertussis is increasing in unimmunized infants: is a change in policy needed?
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The proportion and trend in absolute number of pertussis notifications in young infants has increased each year in England and Wales since the accelerated immunization schedule was introduced. We report five infants all less than 3 months of age admitted with life threatening pertussis infection to two paediatric intensive care units. Despite aggressive cardiorespiratory support measures, three of the infants died. Pertussis remains a significant cause of morbidity and mortality in unimmunized infants. In this age group presentation is likely to be atypical and infection more severe. Public health measures to prevent the disease could be strengthened. Chemoprophylaxis should be offered to susceptible contacts and booster vaccinations against pertussis considered. (+info)
Respiratory diseases among U.S. military personnel: countering emerging threats.
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Emerging respiratory disease agents, increased antibiotic resistance, and the loss of effective vaccines threaten to increase the incidence of respiratory disease in military personnel. We examine six respiratory pathogens (adenoviruses, influenza viruses, Streptococcus pneumoniae, Streptococcus pyogenes, Mycoplasma pneumoniae, and Bordetella pertussis) and review the impact of the diseases they cause, past efforts to control these diseases in U.S. military personnel, as well as current treatment and surveillance strategies, limitations in diagnostic testing, and vaccine needs. (+info)
Bordetella holmesii-like organisms isolated from Massachusetts patients with pertussis-like symptoms.
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We isolated Bordetella holmesii, generally associated with septicemia in patients with underlying conditions, from nasopharyngeal specimens of otherwise healthy young persons with a cough. The proportion of B. holmesii-positive specimens submitted to the Massachusetts State Laboratory Institute increased from 1995 to 1998. (+info)
Stochastic dynamics and a power law for measles variability.
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Since the discovery of a power law scaling between the mean and variance of natural populations, this phenomenon has been observed for a variety of species. Here, we show that the same form of power law scaling also occurs in measles case reports in England and Wales. Remarkably this power law holds over four orders of magnitude. We consider how the natural experiment of vaccination affects the slope of the power law. By examining simple generic models, we are able to predict the effects of stochasticity and coupling and we propose a new phenomenon associated with the critical community size. (+info)