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Published on: February 23, 2014
Pneumococcal colonization rates in children and adults in two developing countries: A prospective cross-sectional
Phoeung Chan Leakhena1, Shally Awasthi2, Muriel Rabilloud3
1University of Health Sciences, 73 Preah Monivong Blvd (93), Phnom Penh, Cambodia.
Insights
Pneumococcal colonization is common in young children in Cambodia and India, even after pneumococcal conjugate vaccine (PCV) introduction. Continued surveillance is vital for guiding vaccine policy and monitoring disease impact.
Area of Science:
- Microbiology
- Epidemiology
- Vaccinology
Background:
- Streptococcus pneumoniae causes significant lower respiratory infections in children under 5.
- Pneumococcal conjugate vaccines (PCVs) have decreased disease burden globally, but data from low- and middle-income countries are scarce.
- Understanding pneumococcal colonization and serotype distribution is crucial for public health interventions.
Purpose of the Study:
- To determine the prevalence of pneumococcal colonization in children under 5 and their caregivers in Cambodia and India.
- To identify the circulating pneumococcal serotypes, including vaccine types (VT) and non-vaccine types (NVT).
- To assess the impact of PCV introduction on colonization patterns in these regions.
Main Methods:
- A prospective, hospital-based, cross-sectional study enrolled 708 child-adult pairs in Cambodia and 770 in India.
- Eligible children were aged 0-59 months without severe respiratory infection; accompanying caregivers without respiratory infection were also recruited.
- Nasopharyngeal swabs were collected and tested for Streptococcus pneumoniae using PCR, followed by serotyping of positive samples.
Main Results:
- Overall pneumococcal carriage was 30.6% in children and 10.8% in adults, with the highest rates in children aged 12-24 months.
- PCV vaccination coverage was high (99.2% in Cambodia, 60.3% in India).
- Vaccine serotypes (VT) accounted for 37.9-48% of pediatric isolates, with serotypes 6A/B, 19F, and 14 being most common. Non-vaccine serotypes were also prevalent, suggesting serotype replacement.
Conclusions:
- Pneumococcal colonization remains a significant issue in young children in Cambodia and India, despite PCV implementation.
- The presence of both VT and NVT highlights the ongoing need for comprehensive surveillance.
- Continued monitoring is essential for refining vaccination strategies and managing the evolving pneumococcal landscape.
Introduction:
Streptococcus pneumoniae is a major cause of lower respiratory infections, especially in children under 5 years old. While pneumococcal conjugate vaccines (PCVs) have reduced disease burden in many countries, data from low- and middle-income countries are still limited. The objective of this prospective, hospital-based, cross -sectional study was to measure the prevalence of pneumococcal colonization and identify circulating serotypes among children <5 years and their caregivers in Cambodia and India.
Methods:
Children aged 0-59 months free of severe respiratory infection according to WHO criteria and consulting at one of the participating hospitals were eligible. For each child, the accompanying guardian or parent residing in the same household as the child and not having respiratory infection was also recruited. Sociodemographic and clinical data were obtained; nasopharyngeal swabs were collected from enrolled child-adult pairs and tested for S. pneumoniae using PCR. Positive samples underwent serotyping.
Results:
A total of 708 adult-child pairs from Cambodia and 770 from India were included. The overall prevalence of nasopharyngeal S. pneumoniae carriage was 30.6 % (Cambodia: 31.4 %, India: 29.9 %) in children and 10.8 % (Cambodia: 8.5 %, India: 13.0 %) in adults. The highest colonization rate was found in children aged 12-24 months. In total, 99.2 % of children in Cambodia and 60.3 % of those in India had received at least one dose of PCV vaccine. Vaccine serotypes (VT) made up 37.9-48 % of isolates in children, the most common being VTs: 6 A/B, 19F, 14. In Cambodia, among vaccinated children, Overall, 52 and 31vaccinated children in Cambodia were carrier of VT in Cambodia and India respectively. Among non-vaccinated children, one in Cambodia and 18 in India carried VT. Non-vaccine serotypes were also common (15B/C, 34, 35B), indicating serotype replacement.
Conclusions:
Pneumococcal colonization remains common in young children, even after PCV introduction. Continued surveillance is essential to guide vaccine policy and monitor impact.
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