Nobody wants to share a home with a rat, and the reasons run deeper than the ick factor. Rodents can put your health at risk, and that risk hit close to home in early 2025, when three residents of Mammoth Lakes died of hantavirus. It was a sobering reminder that the rats and rodents slipping through our walls can carry serious illness. If rats have moved into your home or business, it pays to know what they spread and how to shut it down. Below, we walk through hantavirus and the other diseases rats and rodents carry, how those diseases reach people, and how Dewey clears rodents out of our California locations.
Can you get hantavirus from rats?
Yes, though the species matters more than you might think. The hantavirus behind most serious illness in the United States, Sin Nombre virus, rides along with the deer mouse, not the common house rat. Norway rats carry a different one called Seoul virus. Either way, the route is the same: contact with infected rodent urine, droppings, or saliva, usually by breathing in contaminated dust (CDC).
What is hantavirus, and why is it back in California news?
Hantavirus is a family of rodent-borne viruses, and its worst form, hantavirus pulmonary syndrome (HPS), is a rare but severe lung disease. The numbers explain the worry. According to the CDC, 890 cases were reported in the United States between 1993 and the end of 2023, and roughly one in three people who develop HPS do not survive it.
California landed in the headlines in early 2025, when Mono County confirmed three hantavirus deaths in Mammoth Lakes. All three first felt sick in February, oddly early for a disease that usually surfaces later in the year, as reported by The Washington Post. Mono County has now logged 27 cases since 1993, more than any other county in the state. The California Department of Public Health keeps statewide tabs on hantavirus, and its advice is blunt: prevention starts with keeping rodents out of homes and cabins.
Hantavirus Symptoms to Watch For
Hantavirus is sneaky at the start. Symptoms usually surface one to eight weeks after exposure and mimic the flu: fever, fatigue, and deep muscle aches in the thighs, hips, and back, often paired with headache, dizziness, chills, and nausea. The turn comes fast. As the lungs fill with fluid, coughing and shortness of breath set in, and at that point it is a medical emergency. Anyone with these symptoms and recent rodent exposure should get care right away (CDC).
How does hantavirus spread?
Here is the part that catches people off guard: you do not have to touch a rodent to get sick. Most infections happen when someone stirs up fresh urine, droppings, or nesting material and breathes in the airborne particles, often while clearing out a shed, cabin, garage, or storage room that rodents have claimed. A bite can pass it along too, though that is rarer. The bit of good news is that in the United States, hantavirus does not spread from person to person (CDC).
What diseases do rats carry?
Hantavirus grabs the headlines, but rats and rodents come with a whole roster of illnesses. Some spread through direct contact, others hitch a ride on fleas or sneak in through contaminated food. Here are the rodent-borne diseases worth knowing:
| Disease | How it spreads | Common symptoms |
| Hantavirus (HPS) | Inhaling dust contaminated by rodent urine, droppings, or saliva | Fever, muscle aches, fatigue, then severe shortness of breath |
| Leptospirosis | Contact with water, soil, or food contaminated with rodent urine | High fever, headache, chills, vomiting, jaundice, kidney damage |
| Rat-bite fever | Bites or scratches from infected rats, or contact with urine or feces | Fever, vomiting, rash, muscle and joint pain |
| Salmonella | Eating food or water contaminated by rodent feces | Diarrhea, fever, abdominal cramps, vomiting |
| LCMV | Contact with rodent saliva, urine, droppings, or nesting material | Flu-like illness, with added risk in pregnancy |
| Tularemia | Handling infected rodents, or bites from infected fleas or ticks | Skin ulcers, swollen glands, fever, respiratory issues |
| Toxoplasmosis | Through rodent feces, sometimes reaching people by way of cats | Often mild or symptom-free, but serious in pregnancy |
| E. coli | Contact with food or water contaminated by rodent feces | Diarrhea, abdominal pain, sometimes kidney complications |
| Murine typhus | Fleas that infest rats | Fever, rash, headache, muscle pain |
A few of these are more common than you would guess. The CDC estimates Salmonella alone causes about 1.35 million infections in the United States every year, and reported leptospirosis cases, while smaller at 100 to 150 a year, have been climbing. Several of these illnesses also travel by flea, which is why a rodent problem and a flea problem so often show up as a package deal.
How to Prevent Rodent-Borne Disease at Home
Keep Rodents Out
Rodents are opportunists, so the goal is to make your home a lousy place to settle. Keep pantry items in airtight containers, seal the cracks and gaps around walls, floors, and pipes, lock down your trash bins, and clear the yard debris where rodents like to nest. For seasonal pointers, see our guides on keeping mice outside and keeping rats out as winter approaches.
Clean Up Droppings Safely
If you do find droppings, resist the urge to grab a broom or vacuum, because that is exactly what launches hantavirus particles into the air. The CDC lays out a safer routine: open things up and ventilate for 30 minutes, put on gloves, then soak the droppings with disinfectant or a bleach solution of one part bleach to ten parts water. Give it five minutes, wipe everything up with paper towels, and double-bag the waste.
How Professional Rodent Control Reduces Health Risks
Traps and bait treat the symptoms. Professional rodent control treats the cause. Dewey leans on rodent exclusion, which means tracking down the entry points and sealing the gaps around doors, windows, walls, and floors so rodents cannot simply waltz back in, then backing that up with targeted trapping and baiting. Our pest control methods are built to be tough on rodents while staying harmless to humans and pets. We handle this work across California, including Los Angeles, San Francisco, San Jose, and Anaheim. After nearly 100 years in business, serving the state since 1929, we have seen just about every way a rodent can get in. Learn more about Dewey.
Protect Your California Home From Rodent-Borne Illness
Rodent problems do not wait around, and neither should you since California rodents are plentiful. Rats reach breeding age in as little as five to twelve weeks, females can come back into heat within hours of giving birth and produce a new litter roughly every three weeks, and one pair can snowball into dozens, then hundreds, within a few months. The sooner you step in, the smaller the health risk to your household. If you are in California and want the problem handled by people who do this for a living, contact Dewey or find your nearest location today.
Frequently Asked Questions About Hantavirus and Rodents
Is hantavirus common in California?
It is rare, but it is out there, especially in rural, foothill, and mountain areas where deer mice thrive. Mono County alone has recorded 27 cases since 1993, the most of any county in the state. The risk climbs whenever people disturb closed-up spaces that rodents have been nesting in.
Can house mice give you hantavirus?
The hantavirus that causes severe illness in the United States comes mainly from deer mice, not the house mouse you are more likely to find indoors. Even so, treat any infestation with care, because rats and mice carry plenty of other illnesses through their urine, droppings, and saliva.
What should I do if I find rodent droppings?
Whatever you do, do not sweep or vacuum them. Ventilate the area, glove up, dampen the droppings with disinfectant or diluted bleach, let it sit, then wipe up and double-bag the waste. If they keep reappearing, bring in a professional to find the entry points and nests behind the problem.