Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Meta-Analysis
. 2025 Sep 4:13:1630054.
doi: 10.3389/fpubh.2025.1630054. eCollection 2025.

It's not just droplets: a systematic review and meta-analysis of the modes of transmission of Group A Streptococcus

Dylan D Barth #  1   2 , Jessica Daw #  1 , Stephanie L Enkel  1   2 , Tracy McRae  1   2 , Jonathan R Carapetis  1   2   3 , Rosemary Wyber  1   2   4 , Asha C Bowen  1   2   3 , Mark E Engel  5   6
Affiliations
Meta-Analysis

It's not just droplets: a systematic review and meta-analysis of the modes of transmission of Group A Streptococcus

Dylan D Barth et al. Front Public Health. .

Abstract

Background: The transmission of Group A Streptococcus (Strep A) through respiratory droplets has been considered the dominant mode of transmission to date; however, little is known about the relative contribution of other modes of transmission. This review systematically summarises the contemporary evidence regarding the transmission of Strep A.

Methods: A comprehensive search strategy was implemented to identify studies on Strep A transmission published in English between 1980 and 2019. Full-text articles were screened and included based on the predefined criteria. Studies were included if molecular techniques were used to identify the same Strep A strain in both clinical and environmental swabs. A random-effects meta-analysis model was used to aggregate attack rate estimates with 95% confidence intervals (CI), incorporating the Freeman-Tukey transformation to account for variability between studies.

Results: A total of 34 transmission cohorts were included in this study. The overall attack rate of Strep A was 18.4% (95% CI, 13.1-24.2%, I2 = 95.9%), for direct contact, it was 20.5% (95% CI, 8.3-35.4%), and for indirect contact, it was 19.1% (95% CI, 13.2-25.7%). When pooled by geographical location, the attack rate was 30.38% (95% CI, 20.89-40.75%) in non-urban settings and 7.36% (95% CI, 2.60-14.21%) in urban settings.

Conclusion: Direct contact is no longer the dominant form of Strep A transmission. Our contemporary findings have implications for the development of evidence-based environmental health strategies aimed at reducing Strep A transmission.

Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD42019138472, CRD42019138472.

Keywords: Group A Streptococcus; environmental health; epidemiology; infectious diseases; meta-analysis; primordial prevention; systematic review; transmission.

PubMed Disclaimer

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Flow diagram of search results and screening process.
Figure 2
Figure 2
Summary of the modes of Strep A transmission in the included cohorts.
Figure 3
Figure 3
Strep A’s attack rate by type of contact. ES, effect size; CI, confidence interval.
Figure 4
Figure 4
Pooled Strep A attack rate by mode of transmission. ES, effect size; CI, confidence interval.
Figure 5
Figure 5
Pooled Strep A attack rate according to the geographical setting. ES, effect size; CI, confidence interval.
See this image and copyright information in PMC

References

    1. Carapetis JR, Steer AC, Mulholland EK, Weber M. The global burden of group a streptococcal diseases. Lancet Infect Dis. (2005) 5:685–94. doi: 10.1016/S1473-3099(05)70267-X, PMID: - DOI - PubMed
    1. Watkins DA, Johnson CO, Colquhoun SM, Karthikeyan G, Beaton A, Bukhman G, et al. Global, regional, and National Burden of rheumatic heart disease, 1990–2015. N Engl J Med. (2017) 377:713–22. doi: 10.1056/NEJMoa1603693, PMID: - DOI - PubMed
    1. Osowicki J, Vekemans J, Kaslow DC, Friede MH, Kim JH, Steer AC. WHO/IVI global stakeholder consultation on group a Streptococcus vaccine development: report from a meeting held on 12-13 December 2016. Vaccine. (2018) 36:3397–405. doi: 10.1016/j.vaccine.2018.02.068, PMID: - DOI - PubMed
    1. Lemon HM, Loosli CG, Hamburger M, Jr. Transmission and control of respiratory diseases in army barracks: II. The spread of haemolytic streptococcal infections among enlisted personnel. J Infect Dis. (1948) 82:72–85. - PubMed
    1. Cordery R, Purba AK, Begum L, Mills E, Mosavie M, Vieira A, et al. Frequency of transmission, asymptomatic shedding, and airborne spread of Streptococcus pyogenes in schoolchildren exposed to scarlet fever: a prospective, longitudinal, multicohort, molecular epidemiological, contact-tracing study in England, UK. Lancet Microbe. (2022) 3:e366–75. doi: 10.1016/S2666-5247(21)00332-3, PMID: - DOI - PMC - PubMed

MeSH terms

LinkOut - more resources