Health Risks of Rat Infestations: Diseases, Property Damage, and Why Speed Matters (2026)
Rats carry 35+ diseases. Hantavirus has a 36% fatality rate. They cause $19 billion in annual property damage in the US. Every week of delay compounds health risk and repair cost.
Diseases Transmitted by Rats
| Disease | How It Spreads | Symptoms | Severity | Treatment |
|---|---|---|---|---|
| Hantavirus (HPS) | Inhaling airborne dust from droppings, urine, or nesting material | Fever, muscle aches, progressing to severe respiratory failure | Potentially fatal (36% fatality rate for HPS) | Intensive hospital care; no specific antiviral |
| Leptospirosis | Contact with water or soil contaminated with rat urine; through skin cuts | Fever, headache, jaundice, muscle pain | Can cause kidney and liver failure; potentially fatal | Antibiotics (doxycycline, penicillin) |
| Salmonella | Eating food contaminated by rat droppings or urine | Diarrhea, fever, abdominal cramps, vomiting | Moderate; severe in young children and elderly | Supportive care; antibiotics for severe cases |
| Rat-bite fever | Bite or scratch from infected rat; also through contaminated food | Fever, rash, joint pain, vomiting | Can be fatal if untreated | Antibiotics (penicillin) |
| Tularemia | Handling infected animal; tick or fly bites; contaminated water | Fever, skin ulcer, swollen lymph nodes | Moderate to severe; potentially fatal | Antibiotics (streptomycin) |
| Plague | Flea bites from infected rats (rare in US) | Fever, chills, swollen lymph nodes (buboes) | Severe; potentially fatal without treatment | Antibiotics (gentamicin, doxycycline) |
| Allergies and asthma | Airborne rat dander, hair, dried droppings | Chronic respiratory symptoms, asthma attacks | Ongoing; can worsen existing conditions | Allergen avoidance; medical management |
Data based on CDC guidelines. See cdc.gov/rodents for current health guidance.
Hantavirus: The Most Dangerous Risk
Hantavirus pulmonary syndrome (HPS) has a 36% fatality rate -- roughly 1 in 3 people who contract it die. The virus spreads when people inhale tiny airborne particles of rodent droppings, urine, or nesting material. You do not need to be bitten. Simply breathing air in an enclosed space that has been contaminated for months can be enough.
Highest risk situations: Cleaning out an attic, shed, cabin, or basement that has been closed for months and shows signs of rodent activity. Opening an old car, RV, or boat stored in a garage. Sweeping or vacuuming dried droppings (this is the most dangerous action -- do not do it).
Property Damage Risks and Costs
Rats chew through electrical insulation, creating exposed wires that can arc and ignite surrounding insulation material. Rodents are estimated to cause 25% of unexplained house fires.
Rats nest in and urinate on insulation, rendering it both contaminated and ineffective for thermal performance. Replacement is costly and sometimes required for health reasons.
Rats readily chew through PVC and plastic plumbing, causing water damage that can be far more expensive than the pipe repair itself.
In severe, long-term infestations, rats can compromise joists, wall studs, and other structural elements through sustained gnawing.
The CDC estimates rats cause over $19 billion in annual damage in the United States. See our damage repair cost guide for a full breakdown by damage type.
The Cost of Delay
| Timeline | What Happens | Treatment Cost | Health Risk Level |
|---|---|---|---|
| Week 1 | 1-3 rats. Droppings near food sources only. | $150 - $300 | Low |
| Month 1 | Colony established. Widespread droppings. Possible food contamination. | $300 - $600 | Moderate |
| Month 3 | First litter born. Gnaw damage to wiring and pipes begins. | $800 - $2,000 | Moderate-High |
| Month 6+ | Multiple generations. Structural damage. Contaminated insulation. Fire risk. | $2,000 - $8,000+ | High |
Safe Cleanup Procedures (EPA Guidelines)
Open windows and doors in the contaminated area for at least 30 minutes before entering. Leave the area during this time. This reduces airborne particle concentration.
Rubber, latex, or vinyl gloves. N95 respirator (not a basic dust mask -- N95 filters particles small enough to carry hantavirus). Goggles if cleaning overhead surfaces. Disposable coveralls for heavily contaminated attics.
This is the most important rule. Sweeping launches virus particles into the air. Instead, spray droppings with a disinfectant solution (1 part bleach, 9 parts water) and let soak 5 minutes.
Use paper towels to wipe up wet, disinfected droppings. Seal in a plastic bag, then in a second bag. Dispose in regular trash.
Wipe all contaminated surfaces with disinfectant solution. Dispose of all cleaning materials in sealed bags. Wash hands and exposed skin thoroughly after removing gloves.
For attic cleanups with significant contamination (more than a few droppings), hire a professional rodent remediation company. They have proper PPE, HEPA vacuums, and experience with safe decontamination. Cost: $300-$600 for basic attic sanitization.