Do Rats & Mice Carry Disease?

Rat and mouse diseases that can be spread directly include rat-bite fever, salmonellosis, leptospirosis, and E. coli infection. Likewise, rodents are known carriers of Hantavirus, which is usually spread to humans when rodent droppings or nests are disturbed and pathogens become airborne. Hantavirus causes a rare but serious lung disease. Rodents also transmit the infamous plague, although it’s a rare disease in North America today. In addition to diseases spread through direct contact, fleas, ticks, and mites in the pests’ fur can infect humans with Rocky Mountain spotted fever, tularemia, or Lyme disease.

How Do Rodent Diseases Spread?

Mice rightfully cause concern when they infest homes. A threat to humans and pets alike, mice can transmit harmful, sometimes life-threatening diseases through their waste (feces or urine) or via direct contact. In addition to transmitting diseases directly, mice can be vehicles for other disease-carrying pests to enter the home.

As they migrate regularly between buildings and fields, the pests’ transient behavior makes them the perfect reservoir for pathogens such as Hantavirus and Salmonella. These rodents sneak into houses through small holes in exterior walls, quickly establishing their newfound residence. Once inside, mice diseases are spread freely in the pests’ waste as they scavenge for food, which often contaminates entire pantries and cupboards in the process.

Rats urinate and leave droppings anywhere they forage or congregate. Humans who come into contact with infected feces or urine become vulnerable to the diseases rats carry. Fleas or ticks that have bitten infected rats may move on to human hosts or domesticated animals and spread diseases like the bubonic plague. Humans, pets, or farm animals often contract tapeworm or salmonella after ingesting food contaminated by rat feces or urine. As indicated by the name, rat bite fever typically infects individuals bitten or scratched by rats, but the disease may also be spread via contaminated foods.

Directly Transmitted by Diseases

Hantavirus Pulmonary Syndrome

Hantavirus pulmonary syndrome, or HPS, is a severe respiratory disease that can be fatal. The disease has two distinct stages. In the first stage, infected individuals may experience flu-like symptoms, such as fever, chills, and vomiting. Symptoms worsen in the second stage with shortness of breath, fluid accumulation in the lungs, and reduced heart efficiency. A serious health risk, HPS has no vaccine or treatment. Deer mice, which are common in the US, may carry the virus that causes the disease and spread it through their droppings, urine, and saliva. Humans can also contract the disease via airborne transmission by inhaling dust particles containing the virus.

Lymphocytic Choriomeningitis

Lymphocytic choriomeningitis is a disease with varying health effects. Many people infected with the virus show no symptoms, while others may develop fever, muscle aches, headaches, and nausea. A serious concern to pregnant women, lymphocytic choriomeningitis can cause birth defects such as poor vision and mental retardation. The house mouse, one of the most prevalent species of mice in the world, can vector lymphocytic choriomeningitis to humans. The disease is usually picked up through direct contact with droppings or urine, or by breathing in dust contaminated by the waste. Mouse bites, though uncommon, may also transmit the disease to humans.


Salmonellosis is a bacterial infection caused by Salmonella spp. Individuals with the infection usually experience fever, vomiting, diarrhea, and abdominal cramps. Severe cases can lead to hospitalization from dehydration. Humans contract salmonella bacteria by eating food contaminated with rodent feces.

Hemorrhagic Fever with Renal Syndrome

Hemorrhagic fever with renal syndrome, also known as HFRS, is a cluster of related diseases caused by the hantavirus. Early symptoms include headaches, chills, and body pains. Later symptoms may progress into low blood pressure, acute shock, and kidney failure. Similar to hantavirus pulmonary syndrome, the virus causing hemorrhagic fever with renal syndrome can similarly be contracted through particles containing droppings or urine. Humans may also contract the condition if rodent waste comes in contact with the eyes, nose, or mouth.

Rat-Bite Fever

Rat-bite fever is an infectious bacterial disease transmitted through bites from rats or mice. Symptoms include fever, rashes, joint and muscle pain, and headaches. In more severe cases, individuals may experience swollen lymph nodes, and bite wounds may develop into ulcers. Handling rodents infected with the disease and ingesting contaminated food or water are other ways to contract the bacteria.

Indirectly Transmitted Diseases


Deer mice can carry ticks infected with babesiosis. Most commonly found in the Northeast and Upper Midwest, this tick borne illness can range in severity. The parasitic disease can be asymptomatic to some individuals and life threatening to others. Symptoms consist of fever, chills, sweats, nausea, and fatigue. In severe cases, victims may experience vital organ failure or death. Dogs and cats may also contract the parasite and exhibit symptoms like lack of energy, reduced appetite, enlarged abdomen, and discolored stool. Severity of the disease also varies by type of animal.


Ticks carrying anaplasmosis are often transported by deer mice. A nonfatal disease, anaplasmosis can be transmitted to both humans and pets. Humans usually experience chills, headaches, and muscle pains. Pets may exhibit loss of appetite, lethargy, and delayed movement.


Plague can affect humans as well as household pets. Yersinia pestis, the bacterium that causes plague, may be contracted through direct contact with mice or fleas the rodents carry. Symptoms vary depending on how an individual is exposed to the bacteria. In most cases, the symptoms include fever, headaches, chills, and muscle weakness. Known for killing millions in the 14th century, plague is uncommon and treatable with antibiotics today.