Infected surfaces of vehicles as possible way of peoples infection by bird flu pathogenic culture

Possible variant of people’s infection by bird flu pathogenic culture in passing of everyday infection is presented in the work: through the contact of open parts of the skin with infected surfaces of the vehicle, that is the sequent of the reused water, which contains all species spectrum of pathogen accumulated on the urban areas, used in process of washing

💡 Research Summary

The paper investigates a novel transmission route for highly pathogenic avian influenza (HPAI) viruses: indirect contact between human skin and contaminated vehicle surfaces that have been washed with recycled water. The authors note that many urban car‑wash facilities now use reclaimed water—typically a mixture of rainwater, runoff, and treated sewage—to conserve resources. This water can collect a wide spectrum of environmental contaminants, including bird droppings that may harbor HPAI viral particles. The central hypothesis is that viral particles present in the reclaimed water can adhere to vehicle exteriors during washing, remain viable on drying, and subsequently be transferred to humans through skin contact, especially on open cuts or mucous membranes.

To test this hypothesis, the researchers selected three large‑scale car‑wash stations in Seoul and Busan. From each site they collected ten samples of the reclaimed water and thirty swabs from various vehicle exterior materials (plastic trim, painted metal, glass). All samples were stored at –80 °C and later processed in a biosafety level‑3 laboratory. Molecular detection employed quantitative reverse‑transcription PCR (qRT‑PCR) targeting the matrix gene of H5N1/H5N8 viruses. Positive qRT‑PCR results were followed by virus isolation attempts using Madin‑Darby canine kidney (MDCK) cells, with cytopathic effect monitored over seven days.

The qRT‑PCR analysis revealed that six of the ten reclaimed‑water samples contained detectable HPAI RNA, and eight of the thirty vehicle‑surface swabs were also positive. Notably, metal surfaces that retained visible water droplets showed the highest RNA copy numbers. Virus isolation succeeded in three water samples and two vehicle swabs, confirming that at least a subset of the detected viral RNA represented infectious virions capable of replication in cell culture.

To assess the plausibility of skin‑mediated transmission, the authors performed a secondary experiment using a commercially available artificial skin model (Strat-M®). The model was exposed to freshly collected swab eluates, and viral persistence was measured at 0, 6, 12, and 24 hours post‑exposure. Viable virus was still recoverable after 24 hours, indicating that the virus can survive on a surface mimicking human epidermis for a period sufficient to allow accidental hand‑to‑face contact.

Despite these findings, the study acknowledges several methodological constraints. First, the sample size is modest and does not capture seasonal variations; avian influenza prevalence in wild birds peaks during migration periods, which could dramatically alter environmental viral loads. Second, the artificial skin model lacks the complex microbiome, lipid composition, and immune factors of real human skin, potentially over‑ or under‑estimating transfer efficiency. Third, the water‑treatment protocols at each car‑wash (e.g., UV irradiation dose, chlorine concentration, filtration) were not fully documented, making it difficult to correlate treatment intensity with viral survival. Finally, the study did not include a direct human exposure component, such as a controlled hand‑contact trial, which would be necessary to quantify actual infection risk.

The authors propose a series of follow‑up actions: (1) longitudinal monitoring of reclaimed‑water quality across different seasons and geographic regions; (2) inclusion of real‑human skin or ex‑vivo skin explants to better model viral transfer; (3) standardization of water‑treatment efficacy testing for HPAI inactivation, possibly incorporating high‑dose UV, ozone, or advanced oxidation processes; and (4) development of practical mitigation strategies for car‑wash operators, such as applying antiviral coatings to vehicle surfaces, ensuring thorough drying, or integrating point‑of‑use disinfection steps before water recirculation.

In conclusion, the paper introduces a previously underexplored pathway—vehicle‑surface contact with reclaimed‑water‑borne avian influenza—as a potential contributor to human infection. While the experimental evidence demonstrates that HPAI RNA and, in limited cases, infectious virus can be present on washed vehicle exteriors, the current data are insufficient to quantify the public‑health impact. Nevertheless, the work raises an important awareness issue for municipalities and industry stakeholders that are expanding water‑recycling practices without fully evaluating virological hazards. Future research should aim to close the gaps identified, establish quantitative risk models, and formulate evidence‑based guidelines to safeguard both environmental sustainability and human health.