Pertussis diagnosis in Belgium: results of the National Reference Centre for Bordetella anno 2015

Abstract

In 2015, the Belgian National Reference Centre for Bordetella analyzed 4110 respiratory samples by qPCR and 4877 serum samples by serology. Whereas about 50% of respiratory samples were from infants and children below the age of five, serum samples were distributed among all age categories. A total of 394 (9·6%) cases was diagnosed as positive for Bordetella pertussis by qPCR and 844 (17·3%) cases were diagnosed as acute infection by serology (anti-pertussis toxin (PT) IgG > 125 IU/ml). Another 1042 (21·4%) sera had anti-PT IgG between 55 and 125 IU/ml reflecting a vaccination or pertussis infection during the last 1-2 years. Seventy per cent of the pertussis cases diagnosed by qPRC were in infants and children younger than 14 years old, whereas the highest number of sera with anti-PT levels >125 IU/ml was in the age group of 10-14 years old. Based on the limited data of the last vaccination (reported for only 15% of the samples), recent booster vaccination in the teenager group may have contributed only minimally to these elevated anti-PT levels. The highest number of sera with anti-PT titers between 55 and 125 IU/ml was found in the age category 50-59 years old. It is clear that pertussis continues to be a problem in Belgium and that other vaccination strategies (maternal vaccination, cocoon vaccination) and ultimately better vaccines will be needed to control this highly infectious respiratory disease.

Pertussis among patients with clinically compatible illness in the Amhara Regional State, Ethiopia

“…Overall, of the 515 patients with available nasopharyngeal swabs, multiplex RT-PCR at the CDC detected Bordetella species in specimens from 156. Of the Bordetella-positive specimens, 65 were confirmed B. pertussis, 89 et al, 2017) and China (48.8%) (Jiang et al, 2020) but higher than estimates from studies in Uganda (15%) (Kayina et al, 2015), South Africa (1.3%) (Moosa et al, 2019), Tunisia (21%) (Zouari et al, 2012), Niger (11.2%) (Jusot et al, 2014), South Africa (7%) (Muloiwa et al, 2016), and Belgium (9.6%) (Martini et al, 2017). Possible reasons for these differences in prevalence might relate to the patient population that was studied, improved public awareness of pertussis vaccination and early diagnosis, sample size or laboratory test protocols.…”

Clinical Experiences in Pertussis in a Population with High Vaccination Rate

“…These changes have led to an increase in the number of reported cases, but there is also evidence of increased circulation of the bacteria in the population. There are several other explanations for increased epidemics: changes in circulating pertussis virulence, vaccine failure against new bacteria, vaccine failure to block transmission of infection, decreased adherence to vaccination, rapid loss of immunity in adolescents and adults due to the vaccine or due to the disease itself over time, making the vaccinated individuals susceptible, and also the increase of susceptible individuals in the population [10,17,[23][24][25].…”

“…Loss of protection occurs from 4 to 12 years after the last dose of vaccine and from 7 to 20 years after an episode of disease. The duration of protection of the whole-cell vaccine corresponds to that of the natural infection [3,25].…”

“…In this same study, 60% of the cases were positive in serology with anti-PT antibodies, two serology samples were required, and rare cases were positive for both methods, with which it was demonstrated that diagnosis may require both microbiological and immunological methods [3,25,33]. In Portugal, there was a significant increase in incidence in infants under 1 year of age, suggesting a true resurgence of the disease, although the increased incidence may also be associated with the increased use of the PCR test.…”

“…Some studies have shown that women who were vaccinated after 32 weeks of pregnancy did not have the best level of passive protection for the newborn. In Belgium, the orientation for pregnant women is from 24 to 32 weeks of gestation [19,25,54,55].…”