7 Serious Illnesses Carried by Rats and Mice

7 Serious Illnesses Carried by Rats and Mice

Rats and mice scurrying through the walls and floors of your home are more than just a nuisance, and the danger they pose goes beyond the damage caused if they gnaw on building materials and belongings. Rats, mice, and other rodents can pose a serious health risk to your family through the various disease-causing microbes and parasites they may carry.

The Center for Disease Control and Prevention) lists at least seven known illnesses caused by rats, mice, and other vermin.

Hantavirus Pulmonary Syndrome

The deer mouse (Peromyscus maniculatus), cotton rat (Sigmodon Hispidus), rice rat (Oryzomys palustris), and white-footed mouse (Peromyscus leucopus) all can carry and spread hantavirus pulmonary syndrome (also called HPS or simply hantavirus). This is one of the most serious illnesses that can be carried by rodents, receiving a good deal of attention in recent years, especially in Western regions of the U.S.

Hantavirus pulmonary syndrome is caused by a number of different viruses, and it most typically affects people’s lungs, heart, and kidneys. The symptoms are similar to those of the flu, but they quickly grow worse and can be life-threatening if not treated. Rodents are unaffected by the viruses, but they spread them through saliva, urine, and feces.

The mice capable of carrying the bacteria are all found throughout most of North and South America and are common intruders in homes and outbuildings. Transmission of HPS-causing viruses to humans can occur through:

  • Breathing in dust contaminated with rodent urine or feces
  • Touching infected rodents or their urine and feces
  • Getting bitten by an infected mouse or rat

Diagnosis can be difficult, since the disease closely resembles the flu in its symptoms. Treatment of HPS requires intensive-care hospitalization with supplemental oxygen, and serious infections are fatal about 40 percent of the time. This is a very serious disease, for which the best prevention is to avoid all contact with the rodents known to carry the viruses causing HPS. Fortunately, the disease is relatively rare, though it receives lots of publicity due to its severity.


Leptospirosis is caused by a genus of bacteria (Leptospira spp.) passed by rodents and many other animals around the world. In addition to rodents, farm animals are especially likely to carry the bacteria. While the animals themselves are unaffected by the bacteria, it can cause serious problems to humans who become infected.

People can be infected with this disease by:

  • Eating food or drinking water contaminated with urine from infected animals, including rodents
  • Touching the skin or mucous membranes (such as inside the nose) with water or soil that has been contaminated with the urine of infected animals

Symptoms in milder cases resemble a serious case of the flu, with headache, fever, vomiting, and diarrhea. Serious cases may evolve to include meningitis, and liver and kidney failure. Treatment with antibiotics is quite successful when the disease is diagnosed early. Untreated victims usually recover, although it can take months. There is some risk of death if the disease progresses to meningitis (inflammation of the brain and spinal tissues) or kidney or liver failure.

Lymphocytic Choriomeningitis (LCM)

The lymphocytic choriomeningitis (LCM) virus is carried and transmitted by the common house mouse (Mus musculus) and may occur anywhere around the world. The virus is not normally carried by domesticated rodents, such as hamsters or guinea pigs, but these pets may become infected in a home where disease-carrying wild mice are present.

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LCM is a disease that principally affects neurological function. The first symptoms are fever, lack of appetite, muscle aches, headache, nausea, and vomiting. In the second stage, the disease may cause meningitis (inflammation of tissues surrounding the brain and spinal cord) and encephalitis (inflammation of brain tissues, causing confusion and other symptoms).

You can get LCM by:

  • Breathing in dust that is contaminated with rodent urine or feces
  • Touching a diseased rat or mouse or its urine and feces

Treatment requires hospitalization and treatment with heavy doses of anti-inflammatory drugs. Prevention involves carefully avoiding contact with rodents or areas where rodents have been present.


Once a fearsome scourge that wiped out a large percentage of the population of medieval Europe, plague is caused by the bacterium Yersinia pestis. It is now easily treated with antibiotics when diagnosed promptly, but it is still a serious illness. The bacteria that causes plague is carried by fleas found on many wild rodents found in the Western U.S. and other parts of the world, including rock squirrels, prairie dogs, wood rats, fox squirrels, ground squirrels, and chipmunks. Plague is now relatively rare, affecting only about 1,000 to 2,000 people annually worldwide, most of them in undeveloped areas.

The disease bacteria is contracted through:

  • Touching an infected animal
  • Being bitten by an infected flea

The most common early symptoms of plague include abdominal pain, diarrhea, nausea and vomiting, fever and chills, and extreme weakness. Precise diagnosis is made from blood tests. Treatment of plague involves the use of powerful antibiotics and care to alleviate symptoms. There are vaccinations available for people who are at ongoing risk of contracting plague.

Rat-Bite Fever (RBF)

Rats and mice can both carry and spread the bacteria causing rat-bite fever. While it can occur worldwide, the strain most commonly found in North America and Europe is Streptobacillus moniliformis. (An Asian form of the disease is caused by Spirrilum minus.)

Symptoms of rat-bite fever include fever, vomiting, headache, and muscle pain. Soon after the fever begins, a rash may develop on hands and feet. Untreated, the disease may progress into lung, liver, and kidney infection; brain and heart infections may also occur.

You can get the rat-bite fever from:

  • Being bitten or scratched by an infected rodent
  • touching a dead rodent that is infected
  • Eating or drinking food or water that is contaminated by rat feces

Treatment for RBF consists of heavy antibiotics, which is generally effective. But untreated RBF may cause very serious problems and can sometimes be fatal.


Salmonellosis is a very common foodborne illness in the U.S. and around the world. It can be transmitted in many different ways, including rats and mice contaminating food and water with feces containing salmonella bacteria. Direct contact with infected rodents can also cause the disease.

Symptoms of salmonellis are sometimes mild, since the bacteria is commonly found in the intestinal systems of most animals, including humans. However, an extreme infection can cause nausea, vomiting, abdominal cramps, diarrhea, fever, chills, headache, and blood in the stool.

Salmonellosis can be contracted by:

  • Eating food or drinking water containing salmonella bacteria from rodent feces and other sources
  • Direct contact with rodents or other animals carrying the bacteria
  • Poor person-to-person hygiene
  • Consuming uncooked or undercooked meats, or fruits and vegetables containing the bacteria
  • Contact with pet birds and reptiles that carry the Salmonella bacteria

Treatment for salmonellosis is often unnecessary, since the illness typically resolves on its own after a short time. In cases of serious infection, treatment with anti-diarrheal medications is sometimes prescribed. If it’s suspected that the bacteria has caused blood infection, treatment with antibiotics may be prescribed.

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Prevention involves avoiding uncooked or undercooked foods and practicing good personal hygiene, and avoiding contact with animals (including rodents) known to carry the bacteria.

Tularemia (Rabbit Fever)

Tularemia is a disease that is caused by a bacteria (Francisella tularensis), carried and spread by wild rodents around the world, including muskrats, ground squirrels, and beavers. When caused by an insect bite, the disease often causes an ulcer at the site of the bite. When contracted through eating and drinking, the disease may cause glandular swelling, cough, or lung infection. The symptoms can range from very mild to life-threatening. Definitive diagnosis can be difficult, requiring blood tests.

The disease can be contracted if you:

  • Handle infected animal carcasses
  • Are bitten by an infected insect, such as a tick or deerfly
  • Eat or drink contaminated food or water
  • Breathe in the airborne bacteria from landscape dust

Once diagnosed, tularemia is treated by heavy doses of antibiotics. Symptoms can last for many weeks, but victims usually recover fully with treatment. Prevention involves avoiding insect bites through the use of repellants, avoiding direct handling of rodents, and wearing breathing protection to avoid inhaling landscape dust during gardening and agricultural work.


Rodent Dangers

Rodents as Disease Vehicles

In the past century alone, more than 10 million people have died from rodent-borne diseases. Although rodents are not major threats to our everyday health, it is justified to be concerned over the potential for rodents to transmit diseases. By their very nature and design, rodents make excellent “vehicles” for harboring and rapidly transporting diseases.

More Resources


Lyme Disease


Skin lesions, fever, headaches, arthralgias


All rodents; most commonly deer mice

Mode of Transmission

Rodent tick bite


This is the most common and widespread tick-borne disease in the U.S.

Salmonella (Food Poisoning)


Causes intestinal disorders


Mode of Transmission

Rodent feces contamination


The World Health Organization estimates that 20% of food is destroyed or contaminated every year by rodents.

Rat-Bite Fever


Relapsing fever that may last several months


Mode of Transmission

Bacteria in mouth and nose of rodent, transmitted via bite or scratch


Occurs worldwide, but is most common in Asia



Flu-like symptoms, renal failure, severe respiratory distress


Various rodents; primarily deer mice

Mode of Transmission

In feces, urine, body fluids


HV outbreak in 1994 resulted in more than 50 deaths in 17 states. At least 7 different strains of HV have been identified



Fever, headache, rash, respiratory attack


Mode of Transmission


Port cities or riverine environments, often serve as havens for rats harboring fleas.



Attacks circulatory & respiratory systems


Mode of Transmission

Rodent flea bite or by handling an infected animal


Millions of people in Europe died from plague in the Middle Ages; Plague still occurs in many parts of the world

Pox (Rickettsial)


Lesion followed by fever, headache, rash


Mode of Transmission

Bite of a mite which lives on mice


An outbreak of this disease occurred in 1946 in housing developments in New York City which were overrun with mite-infested mice


Six Dangerous Diseases Spread by Rats and Rodents

While the pitter-patter of little feet can be a welcome sound in many a household, one can make the argument that the happiness scale is directly correlated with the type of feet attached to that sound. Namely, the species. We’re talking rodents people!

Millions of homes in the United States have unwelcomed guests in the form of rats and other rodents. And while the presence of these pests can affect the emotional wellbeing of an individual or family, the health risks of having an unchecked rodent population in a home is far more dangerous than one might originally think.

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Rats and rodents are known to be carriers of several types of diseases that can lead to serious illness and in some cases, even death.

To properly understand the dangers of rodents in the home, one must understand the basics of how disease can be spread.

Transmission of diseases usually occurs through several routes:

1. Exposure to (handling of, ingesting of, and airborne particles from) infected rodent waste including: feces, urine, saliva, and nesting material.

2. Bites from infected rodent or insect.

3. Handling of infected rodents or insects – some viruses can transfer from skin to skin contact with no bite or scratch mark necessary.

The following is a list of diseases spread by rats, rodents and insects that feed or travel on these rodents like: fleas, ticks or mites.


Most commonly found in the white-footed mouse, cotton rat and rice rat, the Hantavirus is a potentially life-threatening disease that currently has no specific treatment, cure or vaccine.

Symptoms include: fever, fatigue, muscle aches (generally in hips, backs and thighs) and may include, diarrhea abdominal pain, nausea and vomiting.


Lymphocytic choriomeningitis virus, or LCMV, most popular host is the common house mouse. LCMV usually occurs in two stages. The first stage includes symptoms such as nausea, vomiting, headache, muscle aches and lack of appetite. The second stage is primarily more neurological in nature including the occurrence of: meningitis, encephalitis, or meningoencephalitis.


Yes, you read that right. The same plague that killed millions of people during the Middle Ages could be creeping around your floor boards and behind your walls. The most basic form of plague may be as close as one infected flea bite away. Of the different types of plague (there are several: Bubonic, Septicemic, Pneumonic) all are caused by the same bacterium: Yersinia pestis. The different types are classified by which level of the body the plague has reached: the immune system, the blood system and the lungs. Symptoms are dependent on the type. Prompt medical treatment through antibiotics is necessary to treat illness and possible death.


Some rodents carry the salmonella bacteria in their digestive tract, (who knew?) making any contact with rodent waste, especially the consumption of contaminated food, a potential risk to contract salmonella.

Symptoms include: chills, fever, abdominal cramps, nausea, vomiting, and diarrhea.


No, this is not the latest dance craze. As the name suggests, Rat Bite Fever is spread when a person has been bitten by a rodent who is infected, has handled an infected rodent (even when no bite or scratch occurs) or has consumed the bacteria in some form.

Symptoms include: fever, skin rash, headaches, vomiting, rash and muscle pain.


Caused by the bacterium Francisella tularenis, Tularemia is often found in rodents, rabbits and hares who are especially prone. Tularemia is most commonly transferred to humans by an infected tick or deer fly bite, or by handling of an animal that is infected. Reported in almost every state in America, Tularemia can be life a threatening illness, though most cases can be treated with the use of antibiotics.

Most common symptom: fever.

For more information about rodents and how you can prevent or eliminate infestations in your home, contact our trained Sacramento pest control professionals at 916-457-7605.


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