A zoonotic disease is a disease which can be passed from animal species to humans. Well known examples of zoonotic infections include plague, rabies, Lyme disease, bird flu, toxoplasmosis, and a number of intestinal parasites. It is probable that zoonotic disease has been an issue for humans ever since they started sharing living space with animal species, and many medical professionals specialize in the study and prevention of zoonotic diseases.
Any organism can cause a zoonotic disease, as long as it can pass from other animals to humans. Viruses, bacteria, fungi, and parasites all demonstrate the adaptability necessary to jump species, and frequently can be carried by multiple animal species. Often, an animal can carry a zoonotic disease without demonstrating any symptoms, as is the case with toxoplasmosis and cats. In other instances, the animal will become ill, as occurs with spongiform diseases like bovine spongiform encephalitis.
There are a number of ways to acquire a zoonotic disease, depending on the agent which causes it. Direct contact with infected animals or their body products such as feces and urine is a common mode of infection. With parasites especially, eating the meat of an infected animal may result in the spread of infection. In other instances, indirect contact can result in infection. The plague, for example, spread from fleas on the bodies of rats.
Prevention of zoonotic diseases is extremely important, as many of them are very virulent. There are a number of approaches, but the primary methods are limiting human and animal contact in situations with increased risk, immunizing humans and animals, and identifying infected species and individuals. Limiting contact is an excellent way to limit the spread of zoonotic disease, although it is not always practical. Immunization is also an important part of prevention, but it can take time to develop an effective vaccine. The most important part of controlling zoonosis, another term for zoonotic disease, is to identify and address it early.
By tracking illness in animals and humans, scientists can determine when there is a link which suggests zoonosis, and they can act quickly. Infected animals are usually eliminated, so that they cannot infect other members of the herd, and the rest of the animal group is carefully monitored for signs of disease outbreak. Infected humans are isolated in quarantine until the disease can be treated. As a patient, you can help a doctor identify a potential zoonotic disease case by disclosing recent contact with animals, especially if you have been bitten, scratched, or exposed to fecal material.