Cats can sometimes transmit diseases to their owners.
While most diseases do not transmit between species, there are a number of illnesses caused by bacteria, viruses and parasites that can be transmitted between pets and their owners. These are called zoonotic diseases. If a disease uses an animal as a means of transmitting itself to other organisms, that animal is a vector. There are a number of infections in which cats can be, and sometimes are, the vector of transmission.
Viral
Rabies is a viral disease that is passed via the bite of an infected animal. Rabies causes encephalitis and attacks the central nervous system. Signs and symptoms develop rapidly and the disease is nearly always fatal. Thanks to mandatory vaccination, human cases have become increasingly rare.
Bacterial
In bacterial diseases, the primary vector is often external parasites that are carried by cats and other pets, such as fleas and ticks. However, some bacterial infections can also be transmitted directly by the scratch or bite of a cat, such as cat scratch disease. Many bacterial infections do not present with symptoms in the cat, but cause a wide variety of symptoms in humans. Other common bacterial diseases that can be transmitted by cats include salmonellosis, Lyme disease, Rocky Mountain Spotted Fever, ehrlichia and even leptosporosis (which is more commonly associated with dogs and is asymptomatic in cats). The sooner bacterial infections are diagnosed and treated, the better the prognosis.
Protozoan
Protozoa are single-celled organisms that can cause a wide array of severe health concerns. Most infections cause persistent diarrhea in both feline and human hosts. Protozoan infections are not directly transmitted from cats to their owners, but if a cat becomes infected it can be a warning sign to the humans of the household, as these infections originate from a common source (undercooked meat, contaminated water or contaminated soil). The most common include cryptosporidiosis, giardiasis and toxoplasmosis. In the latter, pregnant women need to be especially careful as they can pass the infection to their fetus, resulting in miscarriage or severe developmental defects.
Parasitic
Parasitic infections can be internal or external. Many internal parasites are not zoonotic, but roundworms and hookworms are two exceptions. These parasites can be transmitted through fecal matter and contact with litter and can potentially transmit more serious infections.
Examples of external parasites are fleas and ticks, both of which are very common vectors for illness in themselves. Fleas and ticks prefer to living on a cat over living on a human because of their higher body temperature and the parasitic preference for warmer "climates." However, because these parasites feed on the blood, they are capable of transmitting any zoonotic infection your cat may be carrying. Additionally, if fleas are ingested by cats (or even children), they can cause tapeworms.
Fungal
Ringworm is the primary fungal infection transmitted from cats to human. It is named for the round, dry rash it causes on the skin; it is not an actual parasite. In cats it presents as a bald, scaly area and it is extremely contagious. The spores that spread the infection are difficult to remove from the home environment and are capable of transmitting infection for months.
Tags: bacterial infections, their owners, bacterial diseases, capable transmitting, cause wide