Mice are making droppings all over the house. They also carry foul odors. Mice are also vectors for the transmission of hantavirus, which causes respiratory problems. After getting rid of the mice, you will have to decontaminate the house with caution. Find out how to recognize mouse droppings.
If the infestation is still active, i.e. if mice continue to circulate at night, decontaminating them before eliminating them is a wasted effort. Our guide to catching a mouse covers trapping and baiting prior to the cleanup phase.
How do you disinfect a mouse-infested house?
Put on gloves
Before you start decontaminating, you need to protect yourself against germs. Put on rubber gloves and spray them with disinfectant. You should never assume that a surface is clean because it appears to be.
Avoid sweeping or vacuuming dust
Most people would tend to take a broom or vacuum cleaner to remove dust and feces. This will only release the airborne particles. You will also contribute to the spread of viral particles, which increases the risk of contamination.
Bleach: your best ally
The best way to decontaminate a mouse-infested home is to use bleach. Clean all surfaces well with a mop. Not just the ones where you suspect the presence of mice. Clean carpets and rugs as well.
Anything that has been brought into contact with the surfaces to be cleaned should then be thrown away. All mouse droppings should be picked up carefully before being disposed of.
How can a new invasion be prevented?
Block entrances and exits
The best way to avoid another mouse invasion is to block the entrances and exits where mice pass. Look along the walls and check for holes or cavities. Then block any cavities you see.
Avoid attracting them again
Mice that live in homes are often looking for food. They don’t just like cheese, but also fruits, vegetables, grains, and other types of foods that can be eaten. By cleaning your kitchen, you will take away their food source and prevent them from attracting them back into your home.
For a home with multiple rooms affected or a recurring infestation year after year, a simple cleaning is not enough. Our rodent extermination program combines intensive trapping, closure of entry points and final decontamination with follow-up over several passes.
Decontaminate your mouse-infested home with Nova Extermination
Decontaminating your mouse-infested home can be complex to achieve. In the best case, it is best to call a professional pest control exterminator. The latter has the expertise and know-how to get rid of mice in your home and decontaminate the premises.
For many years, Nova extermination has specialized in the extermination of mice and the extermination of rats. Our expertise and listening skills have made us leaders in the field of extermination.
If you need an expert to disinfect your mouse-infested home, talk to us now. We will be happy to answer all your questions.
Five Health Risks of a Mouse Infestation
The droppings and urine of mice can transmit several pathogens to humans. The table below summarizes the five risks documented in Canada, their route of transmission, and their severity.
| Pathogen | Type | Route of transmission | Symptoms | Severity |
|---|---|---|---|---|
| Hantavirus | Virus | Inhalation dust urine/faeces | Fever, muscle aches, respiratory syndrome | High to very high |
| Salmonellosis | Bacteria | Hand-to-mouth contact contaminated surfaces | Diarrhea, fever, cramps | Moderate |
| Leptospirosis | Bacteria | Urine contaminated water | Fever, jaundice, muscle aches | High if left untreated |
| Lymphocytic choriomeningitis | Virus | Inhalation, mucosal contact | Fever, meningitis | Moderate to high |
| Allergies to feces | Immune reaction | Inhalation dust Cough | , asthma, eczema | Variable |
Hantavirus is the most serious risk: transmission by inhalation of very fine particles during sweeping or dry handling of excrement. This is the main reason why we always moisten before cleaning, and why a minimum N95 mask is required.
Three typical cases of disinfection
Disinfection of a kitchen after a short infestation
The most frequent case. The infestation lasted a few weeks, with droppings on counters and in the supply cabinets. Protocol: remove all exposed food (throw away even what appears intact), clean surfaces with a 1:10 diluted bleach solution, wash salvageable glass containers with boiling water, completely disinfect the inside of cabinets. Cost: $30 to $80 worth of cleaning supplies and discarded food. Duration: one working weekend.
Disinfection of a heavily contaminated basement
More complex: infestation lasting several months, large quantities of droppings in stored boxes, sometimes visible nests. Full PPE mandatory (N95 mask, gloves, goggles, disposable coveralls), systematic humidification before any trip, collection in sealable bags, disinfection of surfaces. If the insulation is deeply affected, professional removal is recommended. Duration: 1 to 2 days minimum, plus possible release of stored boxes.
Disinfection after a mouse dies in a wall
Special case: strong odour localised in a room after poisoning or natural death of a mouse in an inaccessible cavity. Solutions: opening the partition at the identified location to remove the corpse (the most effective method but requires work), or patience with a dehumidifier and activated carbon (4 to 6 weeks). Complete disinfection after removal of the corpse, plus reconstruction of the partition.
Recommended PPE for disinfection
Personal protective equipment significantly reduces the risk of exposure to pathogens during disinfection. Four minimum elements for a safe intervention.
Respirator Mask
An N95 mask is the minimum acceptable for dry surfaces. For heavy or prolonged accumulations, upgrade to a P100 half-mask with filter cartridges. Surgical masks and bandanas are insufficient: they do not stop fine viral particles.
Durable nitrile gloves
Prefer nitrile to latex (superior chemical resistance to chlorinated disinfectants). Minimum 5 mils thickness to resist tearing when handling debris. Wear gloves if exposure is intense or prolonged.
Waterproof goggles
Scientific goggles with all-round seal, not just safety goggles open on the sides. Protect against splashes when spraying disinfectant and against airborne particles.
Coveralls or disposable clothing
For heavy contamination, a disposable Tyvek suit avoids transporting contaminants to the rest of the house. Otherwise, dedicated clothes should be washed immediately after the intervention at a minimum of 60°C.
Questions
What are the first signs of a mouse infestation?
Five practical signs appear in the weeks following the arrival of a mouse:
- Black droppings in the shape of a grain of rice along the baseboards (3 to 5 mm each).
- Traces of fluorescent urine under UV lamp : useful to confirm a suspicion without seeing the animal.
- Scratching or squeaking noises at night, especially in the walls and ceiling.
- Tooth marks on food packaging : cardboard, thin plastic, bags of rice or cereals.
- Ammonia urine smell in confined areas (under the sink, behind the fridge, in the pantry).
How many mice can a typical infestation hold?
A single female can produce 5-10 litters of 5-8 young per year, so an uncontrolled infestation grows from 2-3 mice to more than 50 individuals in 6 months. When the first signs (droppings) are signed, there are usually 5 to 15 mice already present. Infestations that last more than a year can exceed 100 individuals in a standard home. The speed of intervention is the most important factor in limiting the scale.
How to disinfect after an infestation?
Four mandatory steps: wear an N95 mask, gloves and goggles (mouse urine and droppings may contain hantavirus, leptospirosis, salmonella), moisten all surfaces with a bleach solution diluted 1:10 before wiping (never vacuum or dry sweep: aerosolization of pathogens), clean hard surfaces with the same solution, and wash all contaminated textiles in hot water (60 °C minimum). Ventilate the room for 30 minutes before and after cleaning.
Should you throw away food exposed to mice?
Yes for any food whose packaging is gnawed or opened, and for any food that has traces of droppings, urine or hair. Food in sealed metal cans remains edible after external disinfection. So do food in airtight glass containers. Thin plastic packaging (cereal bags, bread, sugar) must be systematically thrown away even without visible signs: mice can gnaw without leaving an obvious mark.
How long does it take to sanitize a house after an infestation?
For a short infestation (less than 4 weeks): a weekend of thorough cleaning is usually enough, with 2 to 3 days of aeration before returning to normal. For a prolonged infestation (several months or more than a year), allow 1 to 2 weeks for removal and replacement of contaminated insulation, complete disinfection, and closure of access points. Lingering odors can take 4 to 6 weeks to fade even after cleaning.
How long does the smell of a dead mouse last?
The smell of a dead mouse in a wall or under a floor develops 3 to 5 days after death, reaches its maximum intensity around the 10th day, and gradually fades over 4 to 6 weeks depending on temperature and humidity (faster in heated winter, slower in a cool and humid basement). During this period, the odor absorber (activated carbon, bicarbonate, enzyme packets) placed near the area helps to mitigate the nuisance. No product completely neutralizes the odor without removing the corpse.
When to call an exterminator after an infestation?
Three situations justify intervention: doubt about complete elimination (mice still alive potentially present behind walls), damage to insulation or wiring that requires professional replacement, and any human or animal exposure to droppings (decontamination requires specialized products and equipment). A certified service guarantees the end of the infestation within 30 to 90 days and provides a useful certificate for food businesses subject to MAPAQ standards.
{ “@context”: “https://schema.org”, “@type”: “FAQPage”, “mainEntity”: [ { “@type”: “Question”, “name”: “Quels sont les premiers signes d’une infestation de souris ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “Cinq signes : 1. Déjections noires en grain de riz le long des plinthes (3-5 mm). 2. Traces d’urine fluorescentes sous lampe UV. 3. Bruits de grattements ou couinements la nuit. 4. Traces de dents sur emballages alimentaires (carton, plastique fin). 5. Odeur d’urine ammoniacale dans zones confinées (sous évier, derrière frigo).” }, { “@type”: “Question”, “name”: “Combien de souris peut contenir une infestation typique ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “Une seule femelle peut produire 5 à 10 portées de 5 à 8 petits par an, donc une infestation non contrôlée passe de 2-3 souris à plus de 50 individus en 6 mois. À la signature des premiers signes (déjections), il y a généralement 5 à 15 souris déjà présentes. Les infestations qui durent plus d’un an peuvent dépasser 100 individus dans une maison standard. La rapidité d’intervention est le facteur le plus important pour limiter l’ampleur.” }, { “@type”: “Question”, “name”: “Comment désinfecter après une infestation ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “Quatre étapes obligatoires : porter masque N95, gants et lunettes (urine et déjections de souris peuvent contenir hantavirus, leptospirose, salmonelle), humidifier toutes les surfaces avec une solution d’eau de Javel diluée 1:10 avant d’essuyer (ne jamais aspirer ou balayer à sec : aérosolisation des pathogènes), nettoyer les surfaces dures avec la même solution, et laver tout le textile contaminé à l’eau chaude (60 °C minimum). Ventiler la pièce pendant 30 minutes avant et après le nettoyage.” }, { “@type”: “Question”, “name”: “Faut-il jeter la nourriture exposée aux souris ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “Oui pour tout aliment dont l’emballage est rongé ou ouvert, et pour tout aliment qui présente des traces de déjections, d’urine ou de poils. Les aliments en boîte de conserve métallique scellée restent consommables après désinfection extérieure. Les aliments dans des contenants en verre hermétiques aussi. Les emballages plastiques fins (sacs de céréales, pain, sucre) doivent être jetés systématiquement même sans signe visible : les souris peuvent ronger sans laisser de marque évidente.” }, { “@type”: “Question”, “name”: “Combien de temps pour assainir une maison après infestation ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “Pour une infestation courte (moins de 4 semaines) : un week-end de nettoyage approfondi suffit généralement, avec 2 à 3 jours d’aération avant retour à la normale. Pour une infestation prolongée (plusieurs mois ou plus d’un an), prévoir 1 à 2 semaines pour le retrait et le remplacement de l’isolant contaminé, la désinfection complète, et la fermeture des points d’accès. Les odeurs persistantes peuvent prendre 4 à 6 semaines à s’estomper même après nettoyage.” }, { “@type”: “Question”, “name”: “L’odeur d’une souris morte dure combien de temps ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “L’odeur d’une souris morte dans un mur ou sous un plancher se développe 3 à 5 jours après le décès, atteint son intensité maximale autour du 10e jour, et s’estompe progressivement sur 4 à 6 semaines selon la température et l’humidité (plus rapide en hiver chauffé, plus lent dans un sous-sol frais et humide). Pendant cette période, l’absorbeur d’odeur (charbon actif, bicarbonate, sachets enzymatiques) placé près de la zone aide à atténuer la nuisance. Aucun produit ne neutralise complètement l’odeur sans retrait du cadavre.” }, { “@type”: “Question”, “name”: “Quand appeler un exterminateur après une infestation ?”, “acceptedAnswer”: “@type”: “Answer”, “text”: “Trois situations justifient l’intervention : doute sur l’élimination complète (souris encore vivantes potentiellement présentes derrière les murs), dégâts sur l’isolant ou le câblage qui demandent un remplacement professionnel, et toute exposition humaine ou animale aux déjections (la décontamination demande des produits et un équipement spécialisés). Un service certifié garantit la fin de l’infestation sur 30 à 90 jours et fournit une attestation utile pour les commerces alimentaires soumis aux normes MAPAQ.” } ] }Areas Served
Our teams decontaminate mouse-infested homes throughout the South Shore and the Richelieu Valley. We intervene in Longueuil (Vieux-Longueuil where century-old plexes are particularly affected), in Boucherville for homes bordering Parc national des Îles, and our Brossard service serves the entire South Shore in the same day.
