Rodents, especially rats, are the most diverse order of the mammals, with over 2,200 species. They, therefore, inhabit all continents except Antarctica and are adapted to a wide range of habitats. Nonetheless, rats have a large reproductive potential. Rats carry a wide range of disease-causing organisms, including many species of bacteria and viruses as well as protozoa and helminths (worms). Nevertheless, rats act as reservoirs for many diseases via their ecto-parasites such as fleas and ticks as well as lice and mites. Below are some of the diseases associated with rats that have infested a home.


Rats and other rodents carry the Salmonella bacteria that cause illness in both humans and pets. Salmonellosis infection normally occurs through the consumption of either food or water that is contaminated with rat’s fecal matter. The most common of the salmonella species is the Salmonella enterica serovar Typhimurium. It causes a typhoid-like disease in rats, but it is not fatal in human. However, salmonellosis can be fatal in immune-compromised individuals such as the elderly if they do not get treated with antibiotics. The symptoms of this disease include vomiting and diarrhea as well as nausea and abdominal cramps.


Leptospirosis infection is usually caused by a species of the Leptospira bacteria that is normally found in rats and other rodents. When a person comes in contact with urine of infected rats, they get the disease. Thus, an individual can contract the disease either by coming into direct contact with the urine of the infected rats or the soil, water and food that has been contaminated with the urine from the infected rats. The bacteria not only enter the body through the mouth but also through the skin especially if broken by a scratch or cut. In addition, the bacteria also enter the body through the eyes and the mucus membranes.

Leptospirosis occurs throughout temperate and tropical zones, but it is more common in tropical and sub-tropical areas of the world where the temperature and humidity are more favorable for its growth. Some of the symptoms of this disease include headaches, chills and muscle pain as well as redness of the eyes and skin rash.

Rat-bite fever

Rat bite fever is an infection caused by either of the two bacteria Streptobacillus moniliformis and Spirillum minus. These bacteria are present in rat fecal matter and urine as well as secretions from the mouth and the nose as well as the eyes. Rat-bite fever develops only after either a rat bite or scratch. Alternatively, it can be contracted by handling infected animals and ingesting food or drinks contaminated with the rat urine or fecal matter.

The symptoms of rat-bite fever differ with the kind of bacteria that lead to its development. With Streptobacillus, the symptoms include fever and vomiting as well as muscle pain and headaches. These symptoms normal develop within 3-10 days after infection. On the other hand, the symptoms associated with Spirillum include repeated fever and ulcer at the bite wound as well as swelling around the wound and lymph nodes. The symptoms develop within 7-21 days.


Plague is the most common classic disease associated with rats in the human environment, causing any epidemics through history and wiping out large populations. The plague infection is transmitted by the bacteria Yersinia pestis that completes its cycles within rats and fleas. Plague is transmitted to humans in three ways. The first transmission mechanism is through flea bites. This mechanism is achieved when fleas move from rats to humans upon the death of their hosts, rats. In humans, the fleas cause bubonic plague.

Alternatively, plague can be transmitted through handling infected animals and getting direct contact with their tissues and fluids. On the other hand, cats can get the disease by eating infected rats and pass it on to humans. Lastly, plague can get to humans through infectious particles. When the plague in the host gets into the lungs, coughing is usually produced thus airborne particles that can be breathed in by people in close proximity are produced that cause pneumonic plague.