Rats are a huge pest problem: they eat and contaminate food, they cause damage to homes and structures, and they transmit diseases to humans and other animals. Rats will make a home anywhere they can access food and cover, including farm buildings, under houses, rubbish dumps and even sewage systems.
Rat bites and scratches can result in disease and rat-bite fever. Rat urine is responsible for the spread of leptospirosis, which can result in liver and kidney damage. It can also be contracted through handling or inhalation of scat. Complications include renal and liver failure, as well as cardiovascular problems.
Lymphocytic choriomeningitis (LCMV), a viral infectious disease, is transmitted through the saliva and urine of rats. Some individuals experience long-term effects of lymphocytic choriomeningitis, while others experience only temporary discomfort.
One of the most historically dangerous rat-borne diseases is the bubonic plague, also called "Black Plague," and its variants. Transfer occurs when fleas from the rats bite human beings. Fleas transported on rats are considered responsible for this plague during the Middle Ages, which killed millions. From the transmission of bubonic plague to typhus and hantavirus, rat infestations can prove harmful to human health.
Rats also are a potential source of allergens. Their droppings, dander and shed hair can cause people to sneeze and experience other allergic reactions.
Diseases transmitted by rats fall into one of two categories: diseases transmitted directly from exposure to rat-infected feces, urine or bites and diseases indirectly transmitted to people by an intermediate arthropod vector such as fleas, ticks or mites. While the following list of diseases or medical conditions are all associated with rats, most are not commonly encountered in the United States.