Estimation of the force of infection and infectious period of skin sores in remote Australian communities using interval-censored data

PLoS Comput Biol. 2020 Oct 5;16(10):e1007838. doi: 10.1371/journal.pcbi.1007838. eCollection 2020 Oct.

Abstract

Prevalence of impetigo (skin sores) remains high in remote Australian Aboriginal communities, Fiji, and other areas of socio-economic disadvantage. Skin sore infections, driven primarily in these settings by Group A Streptococcus (GAS) contribute substantially to the disease burden in these areas. Despite this, estimates for the force of infection, infectious period and basic reproductive ratio-all necessary for the construction of dynamic transmission models-have not been obtained. By utilising three datasets each containing longitudinal infection information on individuals, we estimate each of these epidemiologically important parameters. With an eye to future study design, we also quantify the optimal sampling intervals for obtaining information about these parameters. We verify the estimation method through a simulation estimation study, and test each dataset to ensure suitability to the estimation method. We find that the force of infection differs by population prevalence, and the infectious period is estimated to be between 12 and 20 days. We also find that optimal sampling interval depends on setting, with an optimal sampling interval between 9 and 11 days in a high prevalence setting, and 21 and 27 days for a lower prevalence setting. These estimates unlock future model-based investigations on the transmission dynamics of skin sores.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Australia / epidemiology
  • Computational Biology
  • Databases, Factual
  • Humans
  • Impetigo* / epidemiology
  • Impetigo* / microbiology
  • Impetigo* / transmission
  • Models, Biological*
  • Native Hawaiian or Other Pacific Islander / statistics & numerical data
  • Prevalence
  • Streptococcal Infections / epidemiology
  • Streptococcal Infections / microbiology
  • Streptococcal Infections / transmission
  • Streptococcus pyogenes / pathogenicity

Grants and funding

MJL is funded by an Australian Postgraduate Research Training Program scholarship. This work is supported by an NHMRC Project Grant titled ‘Optimising intervention strategies to reduce the burden of Group A Streptococcus in Aboriginal Communities’ (GNT1098319). We thank the NHMRC Centre for Research Excellence in Infectious Disease Modelling to Inform Public Health Policy (GNT1078068). JMV is supported by an NHMRC Principal Research Fellowship (GNT1117140). SYCT is supported by an NHMRC Career Development Fellowship (GNT1145033). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.