Evaluation of a New Environmental Sampling Protocol for Detection of Human Norovirus on Inanimate Surfaces

Area of Science:

• Environmental microbiology
• Virology
• Public health

Background:

• Inanimate surfaces facilitate human norovirus transmission during outbreaks.
• Current ISO method 15216 uses cotton swabs for environmental norovirus sampling.
• Optimizing sampling methods is essential for accurate norovirus detection.

Purpose of the Study:

• To evaluate factors influencing human norovirus recovery from surfaces.
• To compare the efficacy of different swab materials and surface types.
• To validate a novel swab protocol for norovirus outbreak investigations.

Main Methods:

• Assessed virus drying time (1-48h), swab material (cotton, polyester, rayon, macrofoam, antistatic wipe), surface type (stainless steel, toilet seat), and swabbing area (25.8-645.0 cm²).
• Utilized macrofoam swabs for environmental sampling on a cruise ship with reported viral gastroenteritis.
• Quantified norovirus genogroup I (GI) and GII RNA copies using RT-qPCR.

Main Results:

• Macrofoam swabs demonstrated the highest norovirus recovery rates across tested surfaces and areas.
• Recovery rates varied from 1.2% to 36.0% depending on swab material, surface, and drying time.
• Detected norovirus GII in 18.5% of cruise ship environmental samples, with high viral loads in case cabins.

Conclusions:

• Macrofoam swabs offer a superior method for environmental norovirus sampling compared to standard cotton swabs.
• The developed swab protocol is effective for norovirus detection in outbreak settings, especially when clinical samples are limited.
• This method can aid in identifying sources and extent of norovirus contamination during public health emergencies.