Disease Associated With Urban Rodents

Historically, rodents have been involved in the spread of major disease and epidemics. Their behavior and biology lend them to be excellent “vehicles of disease.” It is known that mice can spread more than 20 kinds of organisms that can cause diseases in humans and pets. These include a variety of food poisoning bacteria like Salmonella, Shigella, E. coli, and other disease causing organisms like: tapeworms, mites, ticks, fleas, and rickemial pox. Other rodents, which are widespread and may also come indoors for the winter such as deer mice, can carry and spread disease organisms like hantavirus and plague.

Hantavirus

Hantavirus is a group of viruses that are carried by rodents. One of them, Sin Nombre virus; is found in deer mice in North America. Sin Nombre virus is the cause of Hantavirus Pulmonary Syndrome (HPS) in people. HPS is contracted primarily by inhaling airborne particles from rodent droppings, urine or saliva left by infected rodents or through direct contact with infected rodents. The deer mouse is the most common carrier of hantavirus, but other rodents can be possible carriers without showing any signs of illness. Anyone who comes into contact with an infected rodent is at risk. HPS was first recognized in 1993 and has since been identified throughout the United States. Although rare, HPS is potentiaily deadly. There is no treatment for hantavirus, so preventing rodent infestations and taking precautions when cleaning rodent infested areas is important. Rodent control in and around the home remains the primary strategy for preventing hantavirus infection.

Black Rat		Brown (Common) Rat

House Mouse		White Footed Mouse

Most Common Diseases and Disease Associated Organisims

• Hantavirus
• Leptospirosis
• Plague
• Food poisioning bacterial agents
• Rabies
• LCMV (Lymphocytic choriomeningitis virus)
• Ectoparasites (ticks, fleas, lice and mites)

The deer mouse (Peromyscus maniculatus) is the main carrier of hantavirus rn the United States; however, all wild rodents are suspect. Deer mice live in rural areas. They pass the virus to each other and Some of the population is usually infected. The deer mouse can carry and shed the virus without showing any signs of being sick.

In humans, the disease begins with “flu-like” symptoms including fever, sore muscles, headaches, nausea, vomiting, and fatigue. As the disease gets worse, it causes shortness of breath due to fluid filled lungs and hospital care is then required. It is usually a serious infection and about one out of three people diagnosed with HPS have died. There are no cases in the U.S. of the disease being spread from one person to another.

The length of time hantaviruses can remain infectious in the environment is variable and depends on environmental conditions. The bottom line is that you can’t tell how old a dropping is, so all rodent droppings should be handled as if they are infectious. Areas with ongoing rodent infestation are particularly risky and the recommendations for prevention should be followed.

Rabies
Small rodents, such as squirrels, rats, mice, and chipmunks, are almost never found to be infected with rabies and have not been known to cause rabies among humans in the United States. Bites by these animals are usually not considered a risk of rabies, unless the animal was sick or behaving in any unusual manner and rabies is widespread in your area. However, from 1985 through 1994, woodchucks accounted for 86 percent of the 368 cases of rabies among rodents reported to Center for Disease Control (CDC). Woodchucks or groundhogs (Marmota monax) are the only rodents that may be submitted to state health department because of a suspicion of rabies.