The efficacy of two acellular pertussis vaccines was estimated for various clinical case definitions, with and without the requirement of culture confirmation, from a randomized trial in Sweden. Efficacy increased with duration of coughing spasms and when the case definition included whoops or whoops plus at least nine coughing spasms a day. After deletion of clinical cases not believed to be caused by pertussis, efficacies were closer to the higher values for culture-confirmed disease. Nonspecificity of the clinical criterion "21 days of coughing spasms with whoops" resulted in estimates of predictive value for pertussis of 85% for placebo recipients and 56% for vaccinees. We conclude that laboratory confirmation of suspected cases is needed in pertussis vaccine trials. A suggested case definition is 21 days or more of coughing spasms with confirmation by culture, serologic study, or household exposure to culture-confirmed pertussis.
Bordetella holmesii is a Gram-negative bacterium first identified in 1995. It can cause pertussis-like symptoms in humans. B. holmesii contains insertion sequences IS481 and IS1001, two frequently used targets in the PCR diagnosis of Bordetella pertussis and Bordetella parapertussis infections. To investigate the prevalence of B. holmesii in Finnish and Dutch patients with pertussis-like symptoms and whether B. holmesii has caused any false-positive results in diagnostic PCRs, B. holmesii-specific real-time PCRs were developed. The Finnish methods were conventional IS481 PCR and B. holmesii-specific real-time PCR (LightCycler, Roche) targeting the B. holmesii recA gene. The Dutch methods were IS481 and IS1001 PCRs with conventional or real-time formats and B. holmesii-specific real-time PCR targeting the homologue of IS1001. Of 11,319 nasopharyngeal swabs, 2804 were collected from Finnish patients from 2000 to 2003, and 8515 from Dutch patients from 1992 to 2003. B. holmesii DNA was not found in the samples analysed. The results suggest that B. holmesii is not among the causative agents of pertussis-like symptoms in Finnish and Dutch patients and thus does not in practice confound IS481 and IS1001 PCRs.
To characterize the morbidity of pertussis in Canada, we did a retrospective review of all children with laboratory-confirmed pertussis seen at the Hospital for Sick Children, Toronto, between 1980 and 1990. A total of 975 patients were identified, of which 223 (23%) were admitted to hospital. The peak incidence of disease was observed in the fall. The incidence of disease did not vary with gender. Only 41% of children admitted had the classical symptoms of pertussis (paroxysmal cough and whoop). Compared with children older than 6 months of age, children younger than 6 months of age were more likely to be hospitalized, tended to be hospitalized longer, were less likely to be age-appropriately vaccinated and were more likely to require intensive care unit monitoring. Seventeen (8%) of 223 children required intensive care unit monitoring, and 12 of these children required mechanical ventilation therapy, for a duration of 3.5 +/- 0.6 days (mean +/- SD). One (0.1%) patient with secondary bacterial pneumonia died. This hospital-based study indicates that pertussis continues to be a cause of serious illness in children, particularly those younger than 6 months of age.
The pertussis vaccination programme was started in Finland in 1952. Since then the incidence of the disease has decreased. No major epidemics have occurred during the last two decades. The majority of the patients with pertussis are children of school age. Their disease is characterized by prolonged cough without whooping and it is difficult to diagnose. The patients with atypical pertussis are, however, the major reservoir for transmission of the disease to young infants, in whom it can be serious. Recently developed ELISA for measuring antipertussis IgM and IgA antibodies is a valuable aid in the diagnosis of these cases. Pertussis vaccination has been a subject of considerable controversy in recent years. The vaccine used in Finland has proved to be safe and effective. This observation emphasizes the need for careful comparison of the vaccines used in different countries.
We describe incidence and age distribution of laboratory-confirmed pertussis in Denmark from 1995 to 2013. Notification has been mandatory since 2007. Since 1997, an acellular monocomponent vaccine has been used. The latest epidemic occurred in 2002 with an incidence of 36 per 100,000; since 1995, only six infant deaths have been recorded. The inter-epidemic incidence lies below 10 per 100,000. In 1995, the mean age of confirmed cases was 9.2 years (95% confidence interval (CI): 7.9-10.5; median: 5.1), this gradually increased to 23.9 years in 2013 (95% CI: 22.0-25.8; median: 15.7). In 1995, 14% of laboratory-confirmed cases were 20 years and older, 43% in 2013. In the study period, the highest incidence among children was among those younger than one year with incidences between 84 and 331 per 100,000 in inter-epidemic periods (mean: 161/100,000) and 435 for the epidemic in 2002. After introduction of a preschool booster in 2003, the highest incidence among children one year and older changed gradually from three to five-year-olds in 2003 to 12 to 14-year-olds in 2013. In 2013, PCR was the primary method used for laboratory-diagnosis of pertussis in Denmark, while serology was the method with the highest percentage of positive results.
Clinico-epidemiological analysis and etiological verification of the outbreak of respiratory infection among school children in a rural district of the Khabarovsk territory, registered in spring 1997, were made. According to clinical signs, one-third of the patients had whooping cough, while the rest of the children exhibited the signs of respiratory infection with the symptoms of longering bronchitis. A half of the children had not been vaccinated against whooping cough, as they had been given injections of adsorbed DT vaccine with reduced antigen content. Etiologically, the diagnosis of whooping cough was confirmed in 57% of the patients with 47.4% of them having Bordetella pertussis monoinfection and 52.6% having mixed infection, mainly in combination with chlamydiosis. Whooping cough took an abnormal course under these circumstances. Treatment with erythromycin produced a good effect.
An outbreak of pertussis in Manitoba, Canada, provided an opportunity to evaluate the recently developed monoclonal antibody (MAb) BL-5 for the direct detection of Bordetella pertussis. The MAb recognizes a lipooligosaccharide epitope. A total of 1,507 consecutive nasopharyngeal swabs for culture and companion smears for direct fluorescent-antibody (DFA) detection were evaluated at Cadham Provincial Laboratory between September and November 1994. The cutoff for DFA positivity was four fluorescing organisms with morphology characteristic of B. pertussis. PCR analysis for B. pertussis DNA was performed on a subset of 100 smears by eluting material from the slides after DFA examination. In comparison with culture, the sensitivity, specificity, and positive and negative predictive values of BL-5 were 65.1% (41 of 63 samples), 99.6% (1,438 of 1,444 samples), 87.2% (41 of 47 samples), and 98.5% (1,438 of 1,460 samples), respectively. The sensitivity of culture compared with PCR was 45.5% (10 of 22 samples) for the subset of 100 specimens tested by both procedures. An expanded "gold standard" of positivity by culture or PCR for these 100 specimens resulted in DFA sensitivity, specificity, and positive and negative predictive values of 32.3, 97.1, 83.3, and 76.1%, respectively. The utility of MAb BL-5 for direct detection of B. pertussis in a clinical laboratory setting has been demonstrated by this investigation.
To determine the ability of physicians to make a diagnosis of pertussis and factors associated with improved diagnosis, 8,235 children from 88 child care centers and 14 elementary schools from Quebec City, Quebec, Canada, were evaluated by using a questionnaire completed by parents and a medical record review. Children must have consulted a physician to be included in the evaluation. There were 558 children meeting the surveillance case definition and 416 meeting a modified World Health Organization case definition who consulted a physician. A diagnosis of pertussis was considered in 24%-26% of children meeting either case definition, made in 12%-14%, and reported for 6%. Pertussis diagnosis was significantly associated with having a history of pertussis exposure (P or = 5 weeks (P