Rats can carry and spread many diseases that can make people seriously ill. They spread these diseases directly, through their bites, urine, droppings, and saliva, as well as indirectly, through fleas, mites, or ticks that have fed on infected rats. Some diseases are spread by touching contaminated surfaces or food, while others can be caught just by breathing in dust mixed with dried rat droppings or urine.

Common Diseases Directly Spread by Rats

• Leptospirosis — Transmission: contact of skin (especially cuts) or mucous membranes with water or soil contaminated by infected rat urine. Symptoms can range from mild fever and headache to serious problems like kidney failure, liver damage, or even death if untreated. (CDC: Leptospirosis)
• Hantavirus — Transmission: breathing dust from dried rat droppings, urine, or nesting material, especially in enclosed spaces. Symptoms can start as fatigue, fever, and muscle aches, but in severe cases, it can cause deadly lung or kidney problems. (CDC: Hantavirus)
• Rat-Bite Fever — Transmission: rat bite, scratch, or contact with rat saliva — sometimes even by handling rats with no visible bite. The bacteria can cause fever, vomiting, rash, and muscle pain. It can be fatal without quick treatment with antibiotics.
• Salmonellosis — Transmission: eating food or water contaminated by rat feces. Rats contaminate food or water with their droppings, and if people eat it, they can get stomach pains, diarrhea, fever, and vomiting. (CDC: Salmonellosis)
• Lymphocytic Choriomeningitis Virus (LCMV): Spread through exposure to fresh rodent urine, droppings, or nesting materials, or after a bite. Symptoms range from no symptoms at all to fever, stiff neck, and even nervous system problems like meningitis.

Diseases Indirectly Spread by Rats

Rats can also carry fleas, mites, and ticks that bite humans and transmit diseases.

• Plague: Best known for causing the Black Death in the Middle Ages, plague is still around today. It's most often spread by the bites of infected fleas that have fed on infected rats. Plague can cause fever, chills, weakness, and swollen, painful lymph nodes. It requires immediate medical treatment. Bubonic plague, while historically associated with rats, is effectively absent from the northeastern United States including NH. The last confirmed case of plague in New England was over a century ago. The primary disease risks in NH from rats are leptospirosis, Hantavirus, and salmonellosis.
• Murine Typhus: This bacterial disease is spread by fleas that have fed on rats. It causes fever, headache, muscle pain, and sometimes a rash. Without treatment, it can get worse, but antibiotics work well if started quickly.
• Tick-Borne Diseases: Certain types of ticks that live on rats can also infect people, potentially spreading diseases like relapsing fever.

Other Risks Associated with Rats

• Allergies and Asthma: Even if a rat isn't carrying a harmful disease, its urine, droppings, hair, and dander can trigger strong allergic reactions or asthma attacks, especially in young children and those with sensitive lungs.

How People Get Infected

Rats and their droppings or body fluids can contaminate the things you eat, drink, or touch. Diseases can also be caught by:

• Consuming food or water contaminated by rat urine or droppings
• Touching surfaces where rat secretions are present
• Being bitten or scratched by a rat
• Breathing in dust from dried droppings or nesting material
• Being bitten by infected fleas, ticks, or mites that lived on rats

How to Protect Yourself from Diseases Spread by Rats

You can lower your risk of disease from rats by:

• Keeping your home clean and making sure food is stored in rat-proof containers
• Patching holes in walls, floors, and screens to keep rats out
• Getting rid of clutter inside and outside the home where rats could hide
• Cleaning up animal droppings promptly and safely, ideally while wearing gloves and a mask
• Avoiding touching dead rats — call pest control if you suspect an infestation
• Treating flea, tick, and mite bites quickly and keeping pets protected against these pests

By understanding these risks and taking simple precautions, you can greatly reduce your chances of getting sick from diseases that rats can spread. If you notice signs of rats in your home, it's important to act quickly to prevent health problems for you and your family.

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