Highlights This study proved of Cambodia achieving WHO 2017 target of <1% HBsAg prevalence. HBsAg prevalence in 5–7 years old children was 0.56% (95%CI: 0.32%–0.98%). HBsAg prevalence among the mothers was 4.39% (3.53%–5.45%). Among children with HBsAg-positive mother, prevalence was as high as 10.11%. 78.4% of children received HepB birth-dose and 58.7% were administered ≤24 h.
Background Cambodia introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in January 2015 using a 3 + 0 dosing schedule and no catch-up campaign. We investigated the effects of this introduction on pneumococcal colonization and invasive disease in children aged <5 years. Methods There were 6 colonization surveys done between January 2014 and January 2018 in children attending the outpatient department of a nongovernmental pediatric hospital in Siem Reap. Nasopharyngeal swabs were analyzed by phenotypic and genotypic methods to detect pneumococcal serotypes and antimicrobial resistance. Invasive pneumococcal disease (IPD) data for January 2012–December 2018 were retrieved from hospital databases. Pre-PCV IPD data and pre-/post-PCV colonization data were modelled to estimate vaccine effectiveness (VE). Results Comparing 2014 with 2016–2018, and using adjusted prevalence ratios, VE estimates for colonization were 16.6% (95% confidence interval [CI] 10.6–21.8) for all pneumococci and 39.2% (95% CI 26.7–46.1) for vaccine serotype (VT) pneumococci. There was a 26.0% (95% CI 17.7–33.0) decrease in multidrug-resistant pneumococcal colonization. The IPD incidence was estimated to have declined by 26.4% (95% CI 14.4–35.8) by 2018, with a decrease of 36.3% (95% CI 23.8–46.9) for VT IPD and an increase of 101.4% (95% CI 62.0–145.4) for non-VT IPD. Conclusions Following PCV13 introduction into the Cambodian immunization schedule, there have been declines in VT pneumococcal colonization and disease in children aged <5 years. Modelling of dominant serotype colonization data produced plausible VE estimates.
Background: This study aimed to detect Hepatitis B virus (HBV) genome sequences and their variants as of nationwide scale using dried blood spot (DBS) samples and to provide up-to-date reference data for infection control and surveillance in Cambodia. Method: Among 2518 children age 5-7 years and their 2023 mothers participated in 2017 Cambodia nationwide sero-survey on hepatitis B surface antigen (HBsAg) prevalence using multistage random sampling strategy, 95 mothers and 13 children positive to HBsAg were included in this study. HBV DNA was extracted from DBS, then performed polymerase chain reaction. HBV genotypes and potential variants were examined by partial and full length genomic analysis. Results: HBsAg positive rate was 4.7% (95/2023) in mothers and 0.52% (13/2518) in their children. Genotype C (80.49%) was abundantly found throughout the whole Cambodia whilst genotype B (19.51%) was exclusively found in regions bordering Vietnam. S gene mutants of HBV were found in 24.29% of mothers and 16.67% of children with HBV DNA positive sera. Full-length genome analysis revealed the homology of 99.62-100% in each motherchild pair. Genotype B was clarified to recombinant genotype B4/C2 and B2/C2. Double (48.39%) and combination mutation (32.26%) were observed in core promoter region of HBV C1 strains. Conclusions: This study showed the capable of DBS for large-scale molecular epidemiological study of HBV in resource limited countries. Full-genome sequences yield the better understanding of sub-genotypes, their variants and the degree of homology between strains isolated from mother-child pairs calls for effective strategies on prevention, control and surveillance of mother-to-child HBV transmission in Cambodia.
The B. pertussis population in Cambodia, where a whole-cell pertussis vaccine (WCV) has been continuously used, resembled those observed previously in developed countries where acellular pertussis vaccines are used. Circulating B. pertussis strains in Cambodia were distinct from those in other countries using WCVs.
This study determined the prevalence of total hepatitis A antibody (anti-HAV) among 5–7 years old children and their mothers in the whole Cambodia, using a nationwide study, and examined the differences between the two cohorts. A total of 4535 dried blood spot-driven (DBS) samples (2021 mothers and their 2514 children of 5–7 years old) and the concomitant 922 whole blood samples (subset of the whole participants) were collected using a multistage random sampling strategy throughout Cambodia in 2017. Total anti-HAV was detected using the chemiluminescence enzyme immunoassay method. Compared to gold standard whole blood samples, the sensitivity and specificity of DBS mediated anti-HAV detection were 94.8% and 98%, respectively. Total anti-HAV prevalence among mothers was 91.2% (95%CI: 90.0–92.5%), and that of their children was 31.5% (95%CI: 29.7–33.3%). In our study, the low prevalence of total anti-HAV among children indicates the country’s improvement of safe water and food supply, hygiene and sanitation. If the hygiene and sanitation are consistently improved in Cambodia, the prevalence might be no longer increased when the children become adults.
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