Jada Hackman, United Kingdom

The London School of Hygiene and Tropical Medicine Infectious Disease Epidemiology

Presenter Of 1 Presentation

PHYLOGENETIC INFERENCE OF THE TRANSMISSION DIRECTION OF PNEUMOCOCCAL INFECTION, A VALIDATION STUDY (ID 719)

Abstract

Background

Sustaining herd protection via reduced dose schedules may ameliorate pneumococcal conjugate vaccine costs. However, there is limited understanding of pneumococcal transmission pathways and their role in herd immunity. We aimed to develop and validate phylogenetic methods for detecting the occurrence and direction of pneumococcal transmission.

Methods

Based on the timing of serotype-specific carriage within a household, 10 likely transmission pairs and the corresponding transmission direction were identified from a longitudinal study of nasopharyngeal carriage in the UK and sequenced by whole genome sequencing. Any metadata were blinded, and linkage and the transmission direction inferred from the genomic data alone using Phyloscanner.

Results

Unblinding revealed that transmission pair linkage via genomics was identical to that based on epidemiological criteria. One instance of co-colonization was detected and only the dominant serotype was transmitted. All transmission pairs had moderate to strong phylogenetic signals suggesting transmission direction, however, only 6/10 directions were concordant with the epidemiological metadata.

Conclusions

Phylogenetics did successfully predict transmission pairs in this small sample. To improve the inference of transmission direction we will consider factors including sequencing coverage, degrees of intra-host diversity, and phylogenetic uncertainty, although concordance with epidemiolocal metadata may be limited by imperfect sensitivity of culture-based tests for pneumococcal detection.

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Author Of 1 Presentation

PHYLOGENETIC INFERENCE OF THE TRANSMISSION DIRECTION OF PNEUMOCOCCAL INFECTION, A VALIDATION STUDY (ID 719)

Abstract

Background

Sustaining herd protection via reduced dose schedules may ameliorate pneumococcal conjugate vaccine costs. However, there is limited understanding of pneumococcal transmission pathways and their role in herd immunity. We aimed to develop and validate phylogenetic methods for detecting the occurrence and direction of pneumococcal transmission.

Methods

Based on the timing of serotype-specific carriage within a household, 10 likely transmission pairs and the corresponding transmission direction were identified from a longitudinal study of nasopharyngeal carriage in the UK and sequenced by whole genome sequencing. Any metadata were blinded, and linkage and the transmission direction inferred from the genomic data alone using Phyloscanner.

Results

Unblinding revealed that transmission pair linkage via genomics was identical to that based on epidemiological criteria. One instance of co-colonization was detected and only the dominant serotype was transmitted. All transmission pairs had moderate to strong phylogenetic signals suggesting transmission direction, however, only 6/10 directions were concordant with the epidemiological metadata.

Conclusions

Phylogenetics did successfully predict transmission pairs in this small sample. To improve the inference of transmission direction we will consider factors including sequencing coverage, degrees of intra-host diversity, and phylogenetic uncertainty, although concordance with epidemiolocal metadata may be limited by imperfect sensitivity of culture-based tests for pneumococcal detection.

Hide