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Seroprevalence of pertussis in the Gambia: evidence for continued circulation of bordetella pertussis despite high vaccination rates.

Scott S, van der Sande M, Faye-Joof T, Mendy M, Sanneh B, Barry Jallow F, de Melker H, van der Klis F, van Gageldonk P, Mooi F, Kampmann B - Pediatr. Infect. Dis. J. (2015)

Bottom Line: 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. 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.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.Re-infection may occur implying that immunity from childhood vaccination may not be lifelong.

View Article: PubMed Central - PubMed

Affiliation: From the *Medical Research Council (MRC) Unit, The Gambia, Fajara, The Gambia, West Africa; †Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom; ‡National Institute of Public Health and the Environment (RIVM), Centre for Infectious Diseases Control (CIb), Bilthoven, The Netherlands; §Julius Centre for Health Sciences and Primary Care, Utrecht University, Utrecht, The Netherlands; ¶International Agency for Research on Cancer, Lyon, France; and ‖Department of Paediatrics, Imperial College, London, United Kingdom.

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.

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Concentrations of Ptx IgG by age group for those with vaccination records (born after January 1, 1996), 2008 serosurvey in Keneba and Manduar, Kiang West Region, The Gambia. Numbers on top of bars Total number sampled by age group.
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Figure 1: Concentrations of Ptx IgG by age group for those with vaccination records (born after January 1, 1996), 2008 serosurvey in Keneba and Manduar, Kiang West Region, The Gambia. Numbers on top of bars Total number sampled by age group.

Mentions: Overall, 76·3% had anti-Ptx concentrations <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. Fewer than 2% of the population had concentrations ≥125 EU/mL. Ptx IgG concentrations by age groups are shown in Figures 1 and 2.


Seroprevalence of pertussis in the Gambia: evidence for continued circulation of bordetella pertussis despite high vaccination rates.

Scott S, van der Sande M, Faye-Joof T, Mendy M, Sanneh B, Barry Jallow F, de Melker H, van der Klis F, van Gageldonk P, Mooi F, Kampmann B - Pediatr. Infect. Dis. J. (2015)

Concentrations of Ptx IgG by age group for those with vaccination records (born after January 1, 1996), 2008 serosurvey in Keneba and Manduar, Kiang West Region, The Gambia. Numbers on top of bars Total number sampled by age group.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4418845&req=5

Figure 1: Concentrations of Ptx IgG by age group for those with vaccination records (born after January 1, 1996), 2008 serosurvey in Keneba and Manduar, Kiang West Region, The Gambia. Numbers on top of bars Total number sampled by age group.
Mentions: Overall, 76·3% had anti-Ptx concentrations <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. Fewer than 2% of the population had concentrations ≥125 EU/mL. Ptx IgG concentrations by age groups are shown in Figures 1 and 2.

Bottom Line: 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. 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.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.Re-infection may occur implying that immunity from childhood vaccination may not be lifelong.

View Article: PubMed Central - PubMed

Affiliation: From the *Medical Research Council (MRC) Unit, The Gambia, Fajara, The Gambia, West Africa; †Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom; ‡National Institute of Public Health and the Environment (RIVM), Centre for Infectious Diseases Control (CIb), Bilthoven, The Netherlands; §Julius Centre for Health Sciences and Primary Care, Utrecht University, Utrecht, The Netherlands; ¶International Agency for Research on Cancer, Lyon, France; and ‖Department of Paediatrics, Imperial College, London, United Kingdom.

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.

Show MeSH
Related in: MedlinePlus