Can clothes contribute to the spread of ToBRFV?

Can clothes contribute to the spread of ToBRFV? And can they successfully been cleaned with regular laundry products? That’s what scientists from Humboldt-Universität zu Berlin dove into. The answer on the first question is easy: yes, they do contribute. The second question is answered negatively: Household laundry products do not remove the virus from contaminated clothing. According to the research, the use of special agricultural detergents or a disinfectant is needed to remove the virus from clothing.

“Since there are no curative crop protectants available to ToBRFV, interruption of all transmission pathways is crucial. This includes among others cleaning and disinfection of seeds, tools, shoes, gloves and clothing”, says Jens Ehlers, with Menno Chemie, a company whose products were tested in the research. “Yet we found that studies on the cleaning and/or disinfection of clothing, shoes and gloves from ToBRFV were missing so far.”

The researchers from the Humboldt-Universität tested whether household laundry products, commercial agricultural detergents, and an authorized plant protectant are suitable for cleaning contaminated clothing, and whether infectious viruses remain in the resulting cleaning water – relevant, since the cleaning water is normally discharged directly into the sewer system from the washing machine. “There would not be an inconsiderable risk of ToBRFV being carried over into the sewage treatment plant or the water treatment system. Due to phytosanitary and regulatory requirements for the inactivation of Tomato brown rugose fruit virus, the discharge of the virus from the greenhouse, for instance, by contaminated laundry water, must be prevented.”

So how big is the risk of virus transmission via clothes? “We were able to demonstrate that the single-use jumpsuit worn became sufficiently highly contaminated to transmit ToBRFV to non-infected test plants after approximately 30 min of wear in the infected crop. New results showed that any shirt that was worn in an affected farm was contaminated with the virus”, gives Jens as an example. “If contact occurs between clothing and plants, microlesions can be caused on the plant, allowing ToBRFV particles to be transferred to the clothing and transmitted to a plant the next time it comes into contact with it, potentially causing infection. The risk of spreading the virus through contaminated clothing must be classified as high.”

The results of the cleaning procedure then indicate that commercially available laundry products do not sufficiently remove ToBRFV from fabric. “Depending on the product, the reduction was 45.1% and 89.7%, respectively. In addition to the clothing, the resulting cleaning solutions were alsohighly contaminated with ToBRFV”, says Jens. The extent to which a longer contact times in the cleaning solution and higher washing temperature could lead to a better washing result remains to be investigated.

In comparison to the tested household products, the detergents FADEX H+ and MENNO Hortisept Clean Plus, as well as the disinfectant MENNO Florades , led to an almost complete removal of ToBRFV from contaminated fabrics in just 10 minutes After a 16-h treatment with the disinfectant MENNO Florades, infectious ToBRFV was no longer present in all cleaning solutions.

“In Europe, disinfectants for plant disease control must be regulated as crop protection products and require approval. MENNO Florades is such an approved plant protection product to control, among others, phytopathogenic viruses such as ToBRFV.”

Jens says these results demonstrate that an effective and approved disinfection product is available to growers. “But when applying the product, the pH of the solution to be treated must always be considered.”

And how about the water ”It must be assumed that the viruses removed from the fabric remain in the cleaning solutions and are infectious, if washed with an laundry product”, Jens concludes. “In contrast to these household products, the agricultural detergents used, MENNO Hortisept Clean Plus, and FADEX H+, as well as the disinfectant MENNO Florades, were able to achieve the safe cleaning of ToBRFV from clothing and even the resulting cleaning solutions of these products posed no risk of further infection.”

So what to do now? “The results and recommendations of the present study are addressed in particular for practical use as there are, e.g., smaller companies that carry out their laundry operations on site. We recommend to place potentially contaminated (working) clothing in a tube filled with cleaning solutions of MENNO Hortisept Clean Plus, FADEX H+, or the disinfectant MENNO Florades and to leave the clothing for about 10 minutes inside. Afterwards the “pre-cleaned” clothing can be washed in a conventional washing machine. Afer disinfecting the cleaning solution with MENNO Florades, this working solution can be used for the disinfection of various surfaces, tools or machines. Only by implementing an effective hygiene strategy, ranging from virus-free seeds/seedlings to the effective disinfection measures of surfaces, tools and sewage, to the effective cleaning of the clothing of farm workers, it is possible to prevent or reduce the risk of introduction and spread of ToBRFV in tomato crops.”

Menno Chemie is present at the GreenTech Amsterdam.