Incidence of invasive group A streptococcal infections and comparison of emm types from invasive infections, pharyngitis, and throat carriage in American Indian communities in the Southwest United States.

Sutcliffe CG, Sergent VM, Pitalua J, +28 more, Hammitt LL.

Journal ArticleAbstract only — full text under license

AI summary — for doctors, generated from the abstract only

Invasive group A streptococcal disease rates in two Southwest American Indian communities ran 3 to 35 times the US national average, with strain types that barely overlapped those causing pharyngitis or carriage.

What was studied

Active laboratory-based surveillance for invasive group A streptococcal infection was conducted in White Mountain Apache tribal lands (2019-2024, all ages) and Navajo Nation (2023-2024, all ages), alongside pharyngitis surveillance in children 0-17 years (2023-2024) and oropharyngeal carriage cultures in children 0-14 years (2019, 2022-2023), with emm typing by whole-genome sequencing and incidence estimated by Poisson regression.

Key findings

White Mountain Apache age-standardised invasive rates ranged 80-270 per 100,000 persons from 2019 to 2024
Navajo Nation rates were 40-60 per 100,000 in 2023-2024, versus a US national average of 12.2 per 100,000 in 2024
Predominant invasive emm types shifted over time (WMA: 91 and 49 in 2019-2020; 43 and 53 in 2023)
Navajo Nation invasive isolates were commonly emm 53 (28%), 101 (18%), and 12 (16%)
Pharyngitis isolates were mostly emm 1, 12, and 53; carriage isolates emm 1, 12, and 91
Limited overlap between invasive strains and those from pharyngitis or carriage

Clinical relevance

These prospective surveillance data document a severe and shifting disease burden in specific communities, and the strain mismatch means throat isolates are a poor guide to invasive strain circulation; implications for vaccine coverage require community engagement in development and evaluation.

Who should care

Infectious Disease

Limitations

Surveillance periods differed between the two communities, isolate numbers for typing were modest, and findings are specific to these populations.

Invasive group A strep hits these communities far harder than the US average, and surveillance of throat isolates alone would miss the responsible strains.

This is an AI-generated summary of the published abstract, not a clinical recommendation. It may not reflect the full text or subsequent updates — verify against the original source before acting on it.

Abstract

Background

American Indian/Alaska Native (AI/AN) communities in the US have high rates of group A streptococcal (GAS) infections. We determined the incidence of invasive infections in AI communities in the Southwest and compared emm types from invasive infections, pharyngitis, and throat carriage.

Methods

Activities conducted in the White Mountain Apache Tribal lands (WMA) and Navajo Nation (NN) included active, laboratory-based surveillance for invasive GAS infections (WMA: 2019─2024; NN: 2023─2024; all ages); surveillance for GAS pharyngitis (2023-2024; children 0─17 years); and culture for GAS from oropharyngeal carriage samples (2019 and 2022─2023; children 0─14 years). Emm types were determined by whole-genome sequencing. Annual incidence rates were calculated using Poisson regression.

Results

In WMA, age-standardized rates of invasive infections ranged from 80-270/100,000 persons between 2019-2024. Predominant emm types varied (n=74 isolates): 91 (59%) and 49 (32%) in 2019-2020, and 43 (40%) and 53 (30%) in 2023. In NN, rates were 40-60/100,000 persons in 2023-2024; common emm types (n=51) were 53 (28%), 101 (18%), and 12 (16%). In WMA and NN, emm types 1, 12, and 53 predominated in pharyngitis (n=190), and 1, 12, and 91 in throat carriage (n=119).

Conclusions

Rates of invasive GAS infections in these communities were 3-35 times higher than the national US average (12.2/100,000 in 2024). Emm types varied over time with limited overlap in strains from throat carriage or pharyngitis isolates and those from invasive infections. Findings support continuing GAS surveillance and engaging AI/AN communities throughout vaccine development and evaluation.

DOI

10.1093/infdis/jiag462

PMID

42704722

Research metadata (titles, abstracts, authors, publication dates) is sourced from Europe PMC, which aggregates content from PubMed/MEDLINE, PubMed Central, and other providers under the U.S. National Library of Medicine (NLM/NCBI). NLM does not claim copyright on abstracts; the original journal publishers or authors may hold rights to the full articles. AI-generated summaries are derived only from the abstract, never the full text, and are always labeled as AI-generated.

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