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What Kind of Germs Do Field Mice Have?

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Hundreds of species of field mice scamper about in meadows, woodlands, parks, fields and backyards throughout North America. And let's face it -- they're adorable -- tiny, fuzzy creatures with sparkling eyes and twitching noses that seem to beckon for a treat or a cuddle. But stop yourself before reaching for that little charmer. Field mice are known carriers of disease and disease vectors that can easily be passed to humans.


Field mice and other rodents are known carriers of hantavirus. Hantavirus is spread to humans through direct contact with rodents, their urine or feces, or by breathing dust contaminated by their urine or feces. According to the Centers for Disease Control and Prevention, bite transmission is possible but rare. Hantavirus infection can lead to hantavirus pulmonary syndrome, a serious, often fatal, respiratory disease.


Leptospirosis is a bacterium that spreads to humans when water or soil contaminated by the urine or semen of field mice or other rodents comes into contact with the eyes, mucous membranes or skin wounds. It can also be transmitted through the consumption of contaminated food or water. Without treatment, leptospirosis can lead to respiratory illness, kidney failure, liver damage, meningitis and death.

Borrelia Burgdorferi

Field mice can carry deer ticks, which are known vectors of Borrelia burgdorferi, the bacterium that causes Lyme disease. Borrelia burgdorferi is passed to humans via the bite of an infected tick. It's usually treatable with antibiotics. If left untreated, it can lead to joint disease, neurological disorders, heart rhythm irregularities and cognitive dysfunction.

Lymphocytic Chorio-Meningitis

LCM is a viral infection that manifests as aseptic meningitis or encephalitis. It's spread to humans through contact with infected rodents, their urine or feces, or by inhaling dust contaminated by urine or feces. It is possible, but rare, for the virus to be contracted via bite wounds. LCM-related illnesses are rarely fatal, but always require hospitalization and aggressive treatment.

Murine Typhus

Field mice often play host to fleas, which are known vectors of the bacterial infection murine typhus. According to the State of California Health and Human Services Agency, most cases of murine typhus in the U.S. occur in Hawaii, Texas and California. It's treatable with antibiotics, but can be fatal in the elderly or people with compromised immune systems.


Salmonellosis is a microscopic bacterium passed to humans via contact with rodent feces, most often through the consumption of contaminated food and water. It presents as severe gastroenteritis. Most people recover without treatment, but in severe cases hospitalization is required. If the salmonellosis spreads unchecked to the bloodstream and internal organs, it can be fatal.

Francisella Tularensis

Field mice and other rodents are known carriers of the bacterium Francisella tularensis, which causes the disease tularemia. Humans become infected by handling infected mice or their carcasses, via the bite of an infected tick or fly, inhaling airborne bacterium, or by consuming contaminated food or water. Symptoms of tularemia vary widely depending on the bacterium's mode of entry into the body. Although life-threatening, most cases can be successfully treated.