Rats are known to bite and scratch when they feel they are being threatened or cornered. These bites can carry a wide variety of diseases like leptospirosis, hantavirus pulmonary syndrome, and even rat bite fever. It is also possible for people who are bitten to suffer from tetanus infections. These bites can be shallow or deep, have single or multiple puncture wounds, and are often bloody. They can become infected as well. If someone is bitten, it is wise to seek medical attention as a precaution because it is impossible to look at a rat and tell if it has a particular disease or not.
Depending on the severity of the bite and whether or not a disease was transmitted, there are a wide range of different symptoms that can occur. The bite, itself, can cause pain, swelling, and redness around the bite. It is also possible for the bite to get infected and become filled with pus. Rat-bite fever is characterized by fever, an ulcer at the bite site, swollen lymph nodes, and a rash and these symptoms will arise anywhere from one to three weeks after the bite. A case of rabies has never been attributed to a rat bite.