Black rat (Rattus rattus) Credit: Lise Ruffino /SINC.
Ways rats transmit disease to humans:
By infecting human food with droppings;
By infecting human food with urine;
By infecting skin wounds with urine;
Indirectly, by blood-sucking insects;
Indirectly, by mites;
Indirectly, by means of cats and dogs;
By dying in a water source drunk by humans.
Diseases carried by rats include, but are not limited too, the following:
Plague Map (click to enlarge)
Bubonic plague — Rats are the primary source of plague infection in human populations. This horrific disease is spread to humans from rats by fleas. It's present in rodents throughout the western United States, and in many other parts of the world (see map). The bite of a plague-infected flea or the inhalation of just a few cells of plague bacterium (Yersinia pestis) can kill a human being. Plague is usually fatal within a few days of infection. Like smallpox, it can spread and kill large numbers of people very quickly. Fortunately, the disease can usually be treated with antibiotics.
Salmonella — Mice and rats are both frequent carriers. Spreads to humans by contact with mouse droppings, especially through consumption of contaminated food. Causes serious, sometimes fatal gastroenteritis. Household pets are also frequently infected with Salmonella by this means and often die as a result.
Rat-bite Fever — Fatal in 10 percent of untreated cases. The bacterium causing this disease enters the body through bites, as its name suggests, or from urine contaminating either food or preexisting skin wounds.
Murine Typhus (typhus transmitted from rats and mice via flea bite) — This disease is treatable with antibiotics, but can cause death in elderly or infirm individuals. Symptoms include vomiting, fever, headache, myalgia, and cough.
Rat-bite Fever - Fatal in 10 percent of untreated cases. Usually contracted from rats, but infection can also occur from mice. The bacterium causing this disease enters the body through bites, as its name suggests, or from urine contaminating either food or preexisting skin wounds.