What Diseases Can Rats Spread?

Leptospirosis is caused by Leptospira bacteria spread in infected animals' urine, which can survive in water or soil for weeks to months. CDC says it "generally takes 2-30 days to get sick," with symptoms ranging widely — fever, chills, headache, muscle aches, vomiting — and a severe second phase that can bring kidney or liver failure or meningitis. CDC's guidance is direct: "If you think you may have leptospirosis, see a healthcare provider right away."

Salmonellosis is a bacterial infection people get by ingesting germs from droppings, contaminated surfaces, or food. CDC lists watery diarrhea (sometimes with blood or mucus), stomach cramps, and sometimes headache, nausea, vomiting, or loss of appetite. Symptoms "usually start 6 hours to 6 days after infection and usually last 4 to 7 days."

Rat-bite fever (RBF) spreads "through scratches, bites, or contact with a rodent's saliva or pee" — infection is possible even without an actual bite. In North America, symptoms typically include fever, vomiting, headache, and muscle pain, with about half of cases developing joint pain and three in four a rash, appearing 3 to 10 days after exposure. CDC warns RBF "must be treated quickly, or it can cause severe illness and possibly death."

Rats also carry fleas, ticks, and mites capable of spreading additional diseases indirectly. One clarification worth making explicit: hantavirus, often grouped with 'rodent diseases,' is not primarily a rat-transmitted illness in the United States — the deer mouse is the documented U.S. reservoir species for the hantavirus that causes hantavirus pulmonary syndrome.