Decontamination: why you wet surfaces instead of sweeping

When the MV Hondius docked at Rotterdam on 18 May 2026, one instruction struck viewers of France 2's lunchtime news: "every surface must be drenched with disinfectant." Drenched — not scrubbed dry, not vacuumed. That precision is no housekeeping detail : it follows directly from the way hantavirus infects people. Here is why, on a ship as in a home, you decontaminate wet.

The principle: a virus that travels through the air #

For most strains, hantavirus does not spread through casual person-to-person contact. Its dominant route of infection is the inhalation of aerosols — fine particles suspended in the air.

The mechanism, described by the U.S. CDC, fits in one sentence : "When fresh urine, droppings or nesting materials of an infected rodent are stirred up, the virus can get into the air. You can become infected by breathing in the contaminated air."

Everything is in the words stirred up. Reservoir rodents shed the virus in their urine, faeces and saliva without being sick themselves. These droppings dry, mix with dust — and it then takes a single air-disturbing motion to turn an inert floor contamination into a cloud of breathable particles.

Why the broom and the vacuum are off-limits #

This is the whole paradox : the two most natural cleaning reflexes are precisely the most dangerous.

• Dry sweeping lifts dust and propels viral particles to breathing height.
• Vacuuming is worse : it agitates the material and then exhausts a fine aerosol out the back, scattered across the whole room.

The CDC is unambiguous : "Do not use a vacuum or high-pressure sprayer on rodent urine, droppings, or contaminated surfaces until they have been disinfected." The goal of the entire procedure is the exact opposite of sweeping : to weigh down and fix the particles rather than disperse them. And to weigh particles down, you wet them.

The CDC protocol, step by step #

The method recommended for a home, a cabin or a vehicle always follows the same "all-wet" logic :

1. Air it out for 30 minutes. Open doors and windows and leave the area during this time, so the air can refresh before any handling.
2. Protect yourself. Rubber or plastic gloves at a minimum.
3. Spray until soaked. Mist the urine and droppings with a household disinfectant or a bleach solution — 1 part bleach to 9 parts water (about 1.5 cups of bleach per gallon of water), made fresh.
4. Let it sit 5 minutes (or per the product label).
5. Wipe with paper towels, thrown into a sealed bag, itself placed in a second knotted bag.
6. Mop or sponge all hard surfaces with disinfectant.
7. Wash your hands gloved then bare, with soap and water.

At no point is dry dust raised. The "drench" instruction heard about the MV Hondius is the exact operational translation of this doctrine.

When contamination is heavy: PPE steps up #

For light household cleaning, gloves are enough. But for heavy infestation — a long-closed space, a large volume of droppings, or confirmed contamination — the CDC recommends enhanced personal protective equipment :

• disposable coveralls ;
• rubber boots or shoe covers ;
• rubber, latex or vinyl gloves ;
• protective goggles ;
• and above all a suitable respiratory protection device : a half-mask respirator with a HEPA filter (high-efficiency particulate air), or a powered air-purifying respirator with HEPA filters.

It is this level — closer to a professional intervention than ordinary cleaning — that applies to an entire vessel that carried sick people.

The MV Hondius case #

The decontamination of the MV Hondius was entrusted, at Rotterdam, to the company EWS Group, in consultation with the RIVM (the Dutch national institute for public health and the environment). The operation was announced for a duration of about three days, ahead of a cruise resumption planned for 29 May 2026.

The exact protocol applied on board has not been made public — but the instruction relayed by France 2, "drench every surface," conveys the essence : cleaning wet, surface by surface, the spaces where infected passengers and crew stayed (cabins, infirmary, care areas). Unlike a home contaminated by rodents, the stakes on the ship are precautionary : removing any viral residue linked to infected people, Andes virus being the only hantavirus strain for which person-to-person transmission is documented. Nothing indicates the presence of rodents on board.

The virus is fragile — and that is reassuring #

One last point, and not the least for keeping perspective : hantavirus is an enveloped virus, therefore fragile in the environment. It forms no resistant spores and does not survive long on surfaces. It is inactivated by :

• ordinary household detergents ;
• diluted bleach solutions ;
• the sun's ultraviolet rays ;
• heat.

It is precisely because the virus is sensitive that the CDC allows, for items that cannot be treated with liquid disinfectant (books, papers), a very simple alternative : leave them in sunlight for several hours, or in a rodent-free room for at least three weeks (six recommended). Time and light do the work.

Key takeaways #

• Hantavirus spreads mainly through inhaled aerosols from dried, re-suspended rodent droppings.
• Never sweep or vacuum a contaminated area dry : these motions create the very particle cloud you want to avoid. This is an explicit CDC recommendation.
• The correct protocol is "all-wet" : air out 30 min, spray disinfectant or bleach (1:9) until soaked, let sit 5 min, wipe with paper, mop with disinfectant.
• Heavy contamination → enhanced PPE with a HEPA-filter respirator.
• The MV Hondius disinfection (EWS Group + RIVM, ~3 days, resumption 29 May) applies this wet-cleaning logic, as a precaution.
• Hantavirus is fragile : detergents, bleach, UV and heat inactivate it — a reassuring message, provided the method is followed.

To understand where the virus comes from and the role of carrier rodents, see our article on the Andes virus rodent reservoir. For a deeper dive on the strain, read everything about the Andes virus.