Severe pertussis infection in infants less than 6 months of age: Clinical manifestations and molecular characterization

Abstract

We conducted a study to determine the main traits of pertussis among unimmunized infants less than 6 months of age. From August 2012 to March 2015, 141 nasopharyngeal aspirates (NPAs) were collected from infants with respiratory symptoms attending 2 major hospitals in Rome. Clinical data were recorded and analyzed. Lab-confirmation was performed by culture and realtime PCR. B. pertussis virulence-associated genes (ptxP, ptxA and prn), together with multilocus variable-number tandem repeat analysis (MLVA), were also investigated by the sequence-based analysis on the DNAs extracted from positive samples. Antibiotic susceptibility with Etest was defined on 18 viable B. pertussis isolates. Samples from 73 infants resulted positives for B. pertussis. The median age of the patients was 45 d (range 7–165); 21 infants were treated with macrolides before hospital admission. Cough was reported for a median of 10 d before admission and 18 d after hospital discharge among infected infants, 84% of whom showed paroxysmal cough. No resistance to macrolides was detected. Molecular analysis identified MT27 as the predominant MLVA profile, combined with ptxP3-ptxA1-prn2 associated virulence genes.Although our data may not be generalized to the whole country, they provide evidence of disease severity among infants not vaccinated against pertussis. Moreover, genetically related B. pertussis strains, comprising allelic variants of virulence associated genes, were identified.

Lurking Infantile Pertussis: Experience from a Tertiary Care Center in Northern India

“…Prenatal pertussis vaccination is currently not a common practice in our country as it is probably assumed that women of childbearing age of our country have adequate immunity against pertussis owing to childhood immunization or disease. 14 In our study, nearly 40% developed pertussis in later part of infancy, among them 12 patients (80%) gave history of completing primary vaccination series, consisting of three doses of wP (whole-cell vaccine) containing vaccine at 6, 10, and 14 weeks after birth. Though, in some of them we could not verify this immunization history as we had to solely rely on verbal communication with the parent since no documents were available.…”

Maternal immunisation: What have been the gains? Where are the gaps? What does the future hold?

“…A more recent example of gains afforded by maternal immunisation relates to pertussis infection. Hospitalisation and infant mortality due to pertussis disproportionately affect children less than six months of age 13 . This is likely because children require at least two doses of pertussis-containing vaccine before they are adequately protected, and, in most vaccination programmes, the first immunisation is not given until two months of age.…”

Update on Epidemiology, Diagnosis, and Treatment of Pertussis

“…The maximal risk of pertussis infection and severe morbidity takes place before infants are old enough to have received the primary series of vaccination. [23][24][25]. In recent years, waning immunity seems to be the main cause for pertussis in adults and adolescents [26][27][28], and for this reason, these persons constitute a significant reservoir of infection.…”