Seroprevalence of Pertussis in The Gambia: Evidence for Continued Circulation of Bordetella pertussis Despite High Vaccination Rates
Author(s)
Type
Journal Article
Abstract
Background: Bordetella pertussis can cause severe respiratory disease and death in children. In recent years, large outbreaks have occurred in high-income countries; however, little is known about pertussis incidence in sub-Saharan Africa.
Methods: We evaluated antibody responses to pertussis toxin (Ptx) from individuals aged between 2 and 90 years in rural Gambia. IgG-Ptx was measured using luminex xMAP technology. IgG-Ptx geometric mean concentrations (GMC) and their 95% confidence intervals were calculated. The proportion seropositive (>20 EU/mL or ≥62.5 EU/mL) and GMCs were compared by age, sex, ethnic group, vaccination status, birth order and number of siblings per household using logistic and linear regression.
Results: 76.3% had anti-Ptx levels <20 EU/mL, 17.5% had concentrations between 20 and 62.5 EU/mL, 4.4% had concentrations between 62.5 and 125 EU/mL and 1.8% had concentrations ≥125 EU/mL. The overall Ptx antibody GMC was 6.4 EU/mL (95% confidence interval: 5.8–6.9). Higher antibody concentrations were observed in older populations with evidence for an increase in infection risk with increasing age (1.9% yearly increase, 95% confidence interval: 1.3–2.5). No child under 6 years of age had GMC above 62.5 EU/mL but 29.5% had concentrations between 20 and 62.5 EU/mL.
Conclusions: These data provide evidence that B. pertussis is being transmitted within this population despite high vaccination coverage. Re-infection may occur implying that immunity from childhood vaccination may not be lifelong. In the absence of data on actual clinical cases of pertussis, seroprevalence studies remain valuable tools to assess the transmission dynamics of B. pertussis.
Methods: We evaluated antibody responses to pertussis toxin (Ptx) from individuals aged between 2 and 90 years in rural Gambia. IgG-Ptx was measured using luminex xMAP technology. IgG-Ptx geometric mean concentrations (GMC) and their 95% confidence intervals were calculated. The proportion seropositive (>20 EU/mL or ≥62.5 EU/mL) and GMCs were compared by age, sex, ethnic group, vaccination status, birth order and number of siblings per household using logistic and linear regression.
Results: 76.3% had anti-Ptx levels <20 EU/mL, 17.5% had concentrations between 20 and 62.5 EU/mL, 4.4% had concentrations between 62.5 and 125 EU/mL and 1.8% had concentrations ≥125 EU/mL. The overall Ptx antibody GMC was 6.4 EU/mL (95% confidence interval: 5.8–6.9). Higher antibody concentrations were observed in older populations with evidence for an increase in infection risk with increasing age (1.9% yearly increase, 95% confidence interval: 1.3–2.5). No child under 6 years of age had GMC above 62.5 EU/mL but 29.5% had concentrations between 20 and 62.5 EU/mL.
Conclusions: These data provide evidence that B. pertussis is being transmitted within this population despite high vaccination coverage. Re-infection may occur implying that immunity from childhood vaccination may not be lifelong. In the absence of data on actual clinical cases of pertussis, seroprevalence studies remain valuable tools to assess the transmission dynamics of B. pertussis.
Date Issued
2015-04-30
Date Acceptance
2014-09-18
Citation
Pediatric Infectious Disease Journal, 2015, 34 (4), pp.333-338
ISSN
1532-0987
Publisher
Wolters Kluwer
Start Page
333
End Page
338
Journal / Book Title
Pediatric Infectious Disease Journal
Volume
34
Issue
4
Copyright Statement
© 2014 Wolters Kluwer Health, Inc. All rights reserved. This is an open access article distributed under the Creative Commons Attribution Non Commercial License, where it is permissible to download, share and reproduce the work in any medium, provided it is properly cited. The work cannot be used commercially.
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Subjects
Science & Technology
Life Sciences & Biomedicine
Immunology
Infectious Diseases
Pediatrics
pertussis
whooping cough
seroprevalence
sub-Saharan Africa
vaccine
WHOLE-CELL
IGG ANTIBODIES
INFECTION
DISEASE
EPIDEMIOLOGY
INFANTS
TOXIN
AGE
SPECIFICITY
SENSITIVITY
Adolescent
Adult
Aged
Aged, 80 and over
Antibodies, Bacterial
Antitoxins
Bordetella pertussis
Child
Child, Preschool
Cohort Studies
Female
Gambia
Humans
Immunoglobulin G
Incidence
Male
Middle Aged
Pertussis Toxin
Prospective Studies
Seroepidemiologic Studies
Whooping Cough
Young Adult
1114 Paediatrics And Reproductive Medicine
Publication Status
Published