Rat Bite Fever caused by Streptobacillus moniliformis or Spirillum minus is a bacterial infection of rodents that is transmitted through bites, scratches, direct contact with animals and their urine, saliva and feces or ingestion of contaminated food or water. Infected rodents typically exhibit no symptoms of disease. Tularemia is another bacterial infection of rodents. Infected rodents appear lethargic, but they may shed bacteria before showing illness. Tularemia is transmitted to people in the same manner as rat bite fever but in addition can be transmitted through the bite of an infected tick and via airborne transmission if feces, urine or body fluids are aerosolized.  Both diseases in humans initially present as a fever, headache, swollen lymph nodes and possibly a rash or ulcer in the area of a recent bite or scratch wound. Any bites or scratches should be thoroughly washed immediately to minimize the chance of infection.

Rodents with hantavirus, lymphocytic choriomeningitis virus (LCMV) and leptospirosis usually do not exhibit signs of disease. The disease agents are typically shed in the urine of infected animals and people acquire the infection by inhalation, accidental ingestion and direct contact with contaminated urine or feces. These are occasionally transmitted from bite wounds and Leptospira can infect people through abraded skin. These diseases often initially appear as a mild flu-like illness in people but may progress to severe disease. LCMV infection can cause severe meningitis and hemorrhagic fever in people and is considered hazardous to the unborn fetus and may cause pre-term delivery or other complications in pregnant women. Please refer to the CDC Hantavirus guidelines (CDC Hantavirus) if working with wild rodents or in rodent-infested areas and buildings.

Salmonellosis, campylobacterosis, and giardiasis are acquired by contact and accidental ingestion of fecal material from infected rodents. Animals infected with these diseases may have diarrhea, but some may show no symptoms of disease. Any animal with diarrhea should be suspected of having a zoonotic disease. Symptoms in people include diarrhea, vomiting, and abdominal cramps.

Individuals with exposure to rodents and rodent housing environments may develop allergic reactions to animal proteins (allergens). Approximately 11-44% percent of individuals working with rats and mice will develop an allergic reaction to animal proteins and 5-10 percent of individuals will develop asthma. Personnel may be exposed to allergens through inhalation and contact with skin, eyes and mucous membranes. Animal allergens may be present in animal dander, hair, skin, urine, saliva, serum and any contaminated feed or bedding materials. Risk factors for developing an allergic reaction include history of previous allergies to animals. The signs and symptoms of an allergic reaction are nasal discharge and congestion, conjunctivitis, tearing and eye itching, skin redness, rash or hives and lower airway symptoms (coughing, wheezing and shortness of breath). Severe anaphylactic reactions to rodent bites have been reported. Individuals with symptoms suggestive of an allergic reaction related to a workplace allergen should report their concerns to their supervisor and consult a physician.

Wild, outdoor-housed and pet-store purchased rodents are much more likely to carry infections than those raised and housed in a laboratory setting. Transmission of zoonotic diseases from rodents is primarily by direct contact, bites, indirect contact with contaminated objects, oral ingestion or inhalation of aerosolized bedding, feces, and urine.

Symptoms of zoonotic rodent diseases may include:

• Allergic reactions (nasal discharge and congestion, conjunctivitis, tearing and eye itching, skin redness, rash or hives, lower airway symptoms [coughing, wheezing, shortness of breath]).
• Headache, skin rash, fever, joint and muscle pain, swollen lymph glands
• Skin ulcers, swollen and painful lymph glands, inflamed eyes, sore throat, mouth sores, diarrhea, pneumonia
• Fever, chills, body aches, headache, nausea, vomiting, abdominal pain, dry cough, difficulty breathing
• Fever, stiff neck, lack of appetite, muscle aches, headache, nausea, vomiting
• Fever, headache, chills, body or muscle aches, vomiting, nausea, yellowed skin and eyes, red eyes, stomach pain
• Diarrhea, stomach cramps, fever, nausea, vomiting, chills, headache, blood in stool

Revision History

07-2025 v.1