Surface touch network structure determines bacterial contamination spread on surfaces and occupant exposure.

Area of Science:

• Infectious disease transmission
• Microbiology
• Network science

Background:

• Fomites are recognized vectors for infectious diseases.
• The precise role of fomites in transmission risk and their association with surface touch networks (STNs) remain underexplored.
• Demonstrating the link between STNs and real-world surface contamination is crucial.

Purpose of the Study:

• To investigate the association between surface touch networks (STNs) and actual fomite contamination.
• To quantify the contribution of different surfaces and contact patterns to disease spread.
• To assess the potential for superspreading events via fomite transmission.

Main Methods:

• Collected surface touch data from 23-26 participants over 13-hour experiments in office settings.
• Introduced a tracer bacterium (Lactobacillus bulgaricus) by a designated carrier to simulate real-world contamination.
• Assessed surface contamination using quantitative polymerase chain reaction (qPCR) and analyzed touch data with an agent-based model.

Main Results:

• Touching both public (door handles) and less visible public surfaces (desks, chair seatbacks) significantly contributed to contamination spread.
• Sparse hand-to-hand contact and the presence of active carriers were key factors in contamination.
• Contamination levels correlated with the size of the social group and simulated realistic exposure levels for human mucous membranes.

Conclusions:

• The contamination level of both visible and hidden public surfaces serves as an indicator of fomite exposure risk.
• The size of the social group can influence contamination spread, potentially triggering superspreading events through fomite transmission.
• This study provides empirical evidence linking surface touch networks to fomite contamination, enhancing our understanding of infectious disease transmission dynamics.