An anthroponotic disease, or anthroponosis, is an infectious disease in which a disease causing agent carried by humans is transferred to other animals. It may cause the same disease or a different disease in other animals. Since humans do not generally inflict bite wounds on other animals, the method of transmissions is always a "soft" contact such as skin to skin transmission. An example is chytridiomycosis which can be spread by humans with the fungus on their skin handling frogs with bare hands.

The reverse situation, a disease transmitted from animals to humans, is known as zoonotic.

It can also be defined as a human-to-human infection with no animal vector.

Tyzzer’s disease is an acute epizootic bacterial disease found in rodents, rabbits, dogs, cats, birds, pandas, deer, foals, cattle, and other mammals including gerbils. It is caused by the spore-forming bacterium "Clostridium piliforme", formerly known as "Bacillus piliformis". It is an infectious disease characterized by necrotic lesions on the liver, is usually fatal, and is present worldwide. Animals with the disease become infected through oral ingestion of the bacterial spores and usually die within a matter of days. Animals most commonly affected include young, stressed animals in laboratory environments, such as immature rodents and rabbits. Most commonly affected wild animals include muskrats "(Ondatra zibethicus)" and occasionally cottontail rabbits "(Lepus sylvaticus)". Even today, much remains unknown about Tyzzer’s disease, including how and why it occurs.

In rabbits of the genus "Sylvilagus" (cottontail rabbits) living in the Americas, myxomatosis causes only localized skin tumors, but the European rabbit ("Oryctolagus cuniculus") is more severely affected. At first, normally the disease is visible by lumps (myxomata) and puffiness around the head and genitals. It may progress to acute conjunctivitis and possibly blindness; however, this also may be the first visible symptom of the disease. The rabbits become listless, lose appetite, and develop a fever. Secondary bacterial infections occur in most cases, which cause pneumonia and purulent inflammation of the lungs. In cases where the rabbit has little or no resistance, death may take place rapidly, often in as little as 48 hours; most cases result in death within 14 days. Often the symptoms like blindness make the infected rabbit more vulnerable to predators.

Foot-and-mouth disease or hoof-and-mouth disease (Aphthae epizooticae) is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, including domestic and wild bovids. The virus causes a high fever for approximately two to six days, followed by blisters inside the mouth and on the feet that may rupture and cause lameness.

Foot-and-mouth disease (FMD) has very severe implications for animal farming, since it is highly infectious and can be spread by infected animals comparatively easily through contact with contaminated farming equipment, vehicles, clothing, feed and by domestic and wild predators. Its containment demands considerable efforts in vaccination, strict monitoring, trade restrictions, quarantines and occasionally the culling of animals.

Susceptible animals include cattle, water buffalo, sheep, goats, pigs, antelope, deer, and bison. It has also been known to infect hedgehogs and elephants; llamas and alpacas may develop mild symptoms, but are resistant to the disease and do not pass it on to others of the same species. In laboratory experiments, mice, rats, and chickens have been successfully infected by artificial means, but they are not believed to contract the disease under natural conditions. Humans are very rarely infected.

The virus responsible for the disease is a picornavirus, the prototypic member of the genus "Aphthovirus". Infection occurs when the virus particle is taken into a cell of the host. The cell is then forced to manufacture thousands of copies of the virus, and eventually bursts, releasing the new particles in the blood. The virus is genetically highly variable, which limits the effectiveness of vaccination.

Most cases of CWD occur in adult animals; the youngest animal diagnosed with natural CWD was 17 months. The disease is progressive and always fatal. The first signs are difficulties in movement. The most obvious and consistent clinical sign of CWD is weight loss over time. Behavioral changes also occur in the majority of cases, including decreased interactions with other animals, listlessness, lowering of the head, tremors, repetitive walking in set patterns, and nervousness. Excessive salivation and grinding of the teeth also are observed. Most deer show increased drinking and urination; the increased drinking and salivation may contribute to the spread of the disease.

Zoonoses are infectious diseases of animals (usually vertebrates) that can naturally be transmitted to humans.

Major modern diseases such as Ebola virus disease and salmonellosis are zoonoses. HIV was a zoonotic disease transmitted to humans in the early part of the 20th century, though it has now evolved to a separate human-only disease. Most strains of influenza that infect humans are human diseases, although many strains of swine and bird flu are zoonoses; these viruses occasionally recombine with human strains of the flu and can cause pandemics such as the 1918 Spanish flu or the 2009 swine flu. "Taenia solium" infection is one of the neglected tropical diseases with public health and veterinary concern in endemic regions. Zoonoses can be caused by a range of disease pathogens such as viruses, bacteria, fungi and parasites; of 1,415 pathogens known to infect humans, 61% were zoonotic. Most human diseases originated in animals; however, only diseases that routinely involve animal to human transmission, like rabies, are considered direct zoonosis.

Zoonoses have different modes of transmission. In direct zoonosis the disease is directly transmitted from animals to humans through media such as air (influenza) or through bites and saliva (rabies). In contrast, transmission can also occur via an intermediate species (referred to as a vector), which carry the disease pathogen without getting infected. When humans infect animals, it is called reverse zoonosis or anthroponosis. The term is from Greek: ζῷον "zoon" "animal" and νόσος "nosos" "sickness".

A notifiable disease is any disease that is required by law to be reported to government authorities. The collation of information allows the authorities to monitor the disease, and provides early warning of possible outbreaks. In the case of livestock diseases, there may also be the legal requirement to destroy the infected livestock upon notification. Many governments have enacted regulations for reporting of both human and animal (generally livestock) diseases.

Common clinical signs of Tyzzer’s Disease include watery diarrhea, depression, emaciation, and a ruffled coat. Other observed clinical signs include melena, depression, lethargy, and decreased temperature. In muskrats, this disease is characterized by extensive hemorrhaging within the lower intestine and abdomen. Due to the fast-acting nature of this disease, infected individuals often do not live long enough to exhibit symptoms. It is not uncommon for an infected animal to die within 1-10 days of disease contraction.

During necropsy, inflammation of the ileum, cecum, and colon are commonly present. Perhaps the most distinctive trait of this disease, however, is the grayish yellow necrotic lesions found on the liver of diseased animals. The number of these spots present can range from one to countless. Occasionally, lesions are discovered in the lower intestinal tract and heart as well. Even with physical signs and symptoms present, a conclusive diagnosis is dependent upon the presence of "C. piliforme" within the liver of the infected animal.

The incubation period for foot-and-mouth disease virus has a range between one and 12 days. The disease is characterized by high fever that declines rapidly after two or three days, blisters inside the mouth that lead to excessive secretion of stringy or foamy saliva and to drooling, and blisters on the feet that may rupture and cause lameness. Adult animals may suffer weight loss from which they do not recover for several months, as well as swelling in the testicles of mature males, and in cows, milk production can decline significantly. Though most animals eventually recover from FMD, the disease can lead to myocarditis (inflammation of the heart muscle) and death, especially in newborn animals. Some infected ruminants remain asymptomatic carriers, but they nonetheless carry FMDV and may be able to transmit it to others. Pigs cannot serve as asymptomatic carriers.

Zoonotic transmission can occur in any context in which there is companionistic (pets), economic (farming, etc.), predatory (hunting, butchering or consuming wild game) or research contact with or consumption of animals, animal products, or animal derivatives (vaccines, etc.).

Paratuberculosis or Johne's disease is a contagious, chronic and sometimes fatal infection that primarily affects the small intestine of ruminants. It is caused by the bacterium "Mycobacterium avium" subspecies "paratuberculosis". Infections normally affect ruminants (mammals that have four compartments of their stomachs, of which the rumen is one), but have also been seen in a variety of nonruminant species, including rabbits, foxes, and birds. Horses, dogs, and nonhuman primates have been infected experimentally. Paratuberculosis is found worldwide, with some states in Australia (where it is usually called bovine Johne's disease or BJD) as the only areas proven to be free of the disease.

Some sources define "paratuberculosis" by the lack of "Mycobacterium tuberculosis", rather than the presence of any specific infectious agent, leaving ambiguous the appropriateness of the term to describe Buruli ulcer or Lady Windermere syndrome.

Myxomatosis (sometimes shortened to "myxo" or "myxy") is a disease that affects rabbits, caused by the "myxoma" virus. It was first observed in Uruguay in laboratory rabbits in the late 19th century. It was introduced into Australia in 1950 in an attempt to control the rabbit population (see Rabbits in Australia). Affected rabbits develop skin tumors, and in some cases blindness, followed by fatigue and fever; they usually die within 14 days of contracting the disease.

The disease is spread by direct contact with an affected animal or by being bitten by fleas or mosquitoes that have fed on an infected rabbit. The myxomatosis virus does not replicate in these insect hosts, but can be physically carried by an insect's mouthparts, i.e. from an infected rabbit to another susceptible animal. Due to the potential of insect vector transmission, pet rabbits may be susceptible in enzootic areas and vaccination is highly recommended.

The symptoms are like those associated with many other febrile diseases, but with emphasis on muscular pain and night sweats. The duration of the disease can vary from a few weeks to many months or even years.

In the first stage of the disease, sepsis occurs and leads to the classic triad of undulant fevers, sweating (often with characteristic foul moldy smell sometimes likened to wet hay), and migratory arthralgia and myalgia (joint and muscle pain). Blood tests characteristically reveal a low number of white blood cells and red blood cells, show some elevation of liver enzymes such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and demonstrate positive Bengal Rose and Huddleston reactions. Gastrointestinal symptoms occur in 70% of cases and include nausea, vomiting, decreased appetite, unintentional weight loss, abdominal pain, constipation, diarrhea, an enlarged liver, liver inflammation, liver abscess, and an enlarged spleen.

This complex is, at least in Portugal, Israel, and Jordan, known as Malta fever. During episodes of Malta fever, melitococcemia (presence of brucellae in blood) can usually be demonstrated by means of blood culture in tryptose medium or Albini medium. If untreated, the disease can give origin to focalizations or become chronic. The focalizations of brucellosis occur usually in bones and joints and spondylodiscitis of the lumbar spine accompanied by sacroiliitis is very characteristic of this disease. Orchitis is also common in men.

Diagnosis of brucellosis relies on:

1. Demonstration of the agent: blood cultures in tryptose broth, bone marrow cultures. The growth of brucellae is extremely slow (they can take up to two months to grow) and the culture poses a risk to laboratory personnel due to high infectivity of brucellae.

2. Demonstration of antibodies against the agent either with the classic Huddleson, Wright, and/or Bengal Rose reactions, either with ELISA or the 2-mercaptoethanol assay for IgM antibodies associated with chronic disease

3. Histologic evidence of granulomatous hepatitis on hepatic biopsy

4. Radiologic alterations in infected vertebrae: the Pedro Pons sign (preferential erosion of the anterosuperior corner of lumbar vertebrae) and marked osteophytosis are suspicious of brucellic spondylitis.

The consequences of "Brucella" infection are highly variable and may include arthritis, spondylitis, thrombocytopenia, meningitis, uveitis, optic neuritis, endocarditis, and various neurological disorders collectively known as neurobrucellosis.

In cattle, the main signs of paratuberculosis are diarrhea and wasting. Most cases are seen in 2- to 6-year-old animals. The initial signs can be subtle, and may be limited to weight loss, decreased milk production, or roughening of the hair coat. The diarrhea is usually thick, without blood, mucus, or epithelial debris, and may be intermittent. Several weeks after the onset of diarrhea, a soft swelling may occur under the jaw. Known as "bottle jaw" or intermandibular edema, this symptom is due to protein loss from the bloodstream into the digestive tract. Paratuberculosis is progressive; affected animals become increasingly emaciated and usually die as the result of dehydration and severe cachexia.

Signs are rarely evident until two or more years after the initial infection, which usually occurs shortly after birth. Animals are most susceptible to the infection in the first year of life. Newborns most often become infected by swallowing small amounts of infected manure from the birthing environment or udder of the mother. In addition, newborns may become infected while in the uterus or by swallowing bacteria passed in milk and colostrum. Animals exposed at an older age, or exposed to a very small dose of bacteria at a young age, are not likely to develop clinical disease until they are much older than two years.

The clinical signs are similar in other ruminants. In sheep and goats, the wool or hair is often damaged and easily shed, and diarrhea is uncommon. In deer, paratuberculosis can progress rapidly. Intestinal disease has also been reported in rabbits and nonhuman primates.

Unlike cattle and sheep, infections in deer often present with clinical illness in animals under one year of age.

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of mule deer, white-tailed deer, elk (or "wapiti"), moose, and reindeer. As of 2016, CWD had only been found in members of the deer family. First recognized as a clinical "wasting" syndrome in 1967 in mule deer in a wildlife research facility in northern Colorado, USA, it was identified as a TSE in 1978 and has spread to free-ranging and captive populations in 23 US states and two Canadian provinces. CWD is typified by chronic weight loss leading to death. No relationship is known between CWD and any other TSE of animals or people.

Although reports in the popular press have been made of humans being affected by CWD, a study by the Centers for Disease Control and Prevention suggests, "[m]ore epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions".

The epidemiological study further concluded, "[a]s a precaution, hunters should avoid eating deer and elk tissues known to harbor the CWD agent (e.g., brain, spinal cord, eyes, spleen, tonsils, lymph nodes) from areas where CWD has been identified".

Brucellosis is a highly contagious zoonosis caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions.

"Brucella" species are small, gram-negative, nonmotile, nonspore-forming, rod-shaped (coccobacilli) bacteria. They function as facultative intracellular parasites, causing chronic disease, which usually persists for life. Four species infect humans: "B. abortus", "B. canis", "B. melitensis", and "B. suis". "B. abortus" is less virulent than "B. melitensis" and is primarily a disease of cattle. "B. canis" affects dogs. "B. melitensis" is the most virulent and invasive species; it usually infects goats and occasionally sheep. "B. suis" is of intermediate virulence and chiefly infects pigs. Symptoms include profuse sweating and joint and muscle pain. Brucellosis has been recognized in animals and humans since the 20th century.

Three stages of rabies are recognized in dogs and other animals.

1. The first stage is a one- to three-day period characterized by behavioral changes and is known as the prodromal stage.

2. The second stage is the excitative stage, which lasts three to four days. It is this stage that is often known as "furious rabies" due to the tendency of the affected animal to be hyperreactive to external stimuli and bite at anything near.

3. The third stage is the paralytic stage and is caused by damage to motor neurons. Incoordination is seen due to rear limb paralysis and drooling and difficulty swallowing is caused by paralysis of facial and throat muscles. This disables the victim's ability to swallow, which causes saliva to pour from the mouth also the reason bites are the most clear way for the infection to spread is because the virus is most concentrated in the throat and cheeks causing major contamination to saliva. Death is usually caused by respiratory arrest.

The period between infection and the first symptoms (incubation period) is typically 1–3 months in humans. Incubation periods as short as four days and longer than six years have been documented, depending on the location and severity of the contaminated wound and the amount of virus introduced. Initial signs and symptoms of rabies are often nonspecific such as fever and headache. As rabies progresses and causes inflammation of the brain and/or meninges, signs and symptoms can include slight or partial paralysis, anxiety, insomnia, confusion, agitation, abnormal behavior, paranoia, terror, and hallucinations, progressing to delirium, and coma. The person may also have hydrophobia.

Death usually occurs 2 to 10 days after first symptoms. Survival is rare once symptoms have presented, even with the administration of proper and intensive care. Jeanna Giese, who in 2004 was the first patient treated with the Milwaukee protocol, became the first person ever recorded to have survived rabies without receiving successful post-exposure prophylaxis. An intention-to-treat analysis has since found this protocol has a survival rate of about 8%.

East Coast fever (theileriosis) is an animal disease in Africa caused by the protozoan parasite "Theileria parva". It excludes diseases caused by other "Theileria"

Rabies is a viral zoonotic neuroinvasive disease which causes inflammation in the brain and is usually fatal. Rabies, caused by the rabies virus, primarily infects mammals. In the laboratory it has been found that birds can be infected, as well as cell cultures from birds, reptiles and insects. Animals with rabies suffer deterioration of the brain and tend to behave bizarrely and often aggressively, increasing the chances that they will bite another animal or a person and transmit the disease. Most cases of humans contracting the disease from infected animals are in developing nations. In 2010, an estimated 26,000 people died from rabies, down from 54,000 in 1990.

Tick paralysis results from injection of a toxin from tick salivary glands during a blood meal. The toxin causes symptoms within 2–7 days, beginning with weakness in both legs that progresses to paralysis. The paralysis ascends to the trunk, arms, and head within hours and may lead to respiratory failure and death. The disease can present as acute ataxia without muscle weakness.

Patients may report minor sensory symptoms, such as local numbness, but constitutional signs are usually absent. Deep tendon reflexes are usually decreased or absent, and ophthalmoplegia and bulbar palsy can occur.

Electromyographic (EMG) studies usually show a variable reduction in the amplitude of compound muscle action potentials, but no abnormalities of repetitive nerve stimulation studies. These appear to result from a failure of acetylcholine release at the motor nerve terminal level. There may be subtle abnormalities of motor nerve conduction velocity and sensory action potentials.

Rabies is a viral disease that causes inflammation of the brain in humans and other mammals. Early symptoms can include fever and tingling at the site of exposure. These symptoms are followed by one or more of the following symptoms: violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness. Once symptoms appear, the result is nearly always death. The time period between contracting the disease and the start of symptoms is usually one to three months; however, this time period can vary from less than one week to more than one year. The time is dependent on the distance the virus must travel along nerves to reach the central nervous system.

Rabies is caused by "lyssaviruses", including the rabies virus and Australian bat lyssavirus. Rabies is spread when an infected animal scratches or bites another animal or human. Saliva from an infected animal can also transmit rabies if the saliva comes into contact with the eyes, mouth, or nose. Globally, dogs are the most common animal involved. More than 99% of rabies cases in countries where dogs commonly have the disease are caused by dog bites. In the Americas, bat bites are the most common source of rabies infections in humans, and less than 5% of cases are from dogs. Rodents are very rarely infected with rabies. The rabies virus travels to the brain by following the peripheral nerves. The disease can only be diagnosed after the start of symptoms.

Animal control and vaccination programs have decreased the risk of rabies from dogs in a number of regions of the world. Immunizing people before they are exposed is recommended for those who are at high risk. The high-risk group includes people who work with bats or who spend prolonged periods in areas of the world where rabies is common. In people who have been exposed to rabies, the rabies vaccine and sometimes rabies immunoglobulin are effective in preventing the disease if the person receives the treatment before the start of rabies symptoms. Washing bites and scratches for 15 minutes with soap and water, povidone iodine, or detergent may reduce the number of viral particles and may be somewhat effective at preventing transmission. Only six people have survived a rabies infection after showing symptoms, and this was with extensive treatment known as the Milwaukee protocol.

Rabies caused about 17,400 deaths worldwide in 2015. More than 95% of human deaths caused by rabies occur in Africa and Asia. About 40% of deaths occur in children under the age of 15. Rabies is present in more than 150 countries and on all continents but Antarctica. More than 3 billion people live in regions of the world where rabies occurs. A number of countries, including Australia and Japan, as well as much of Western Europe, do not have rabies among dogs. Many small island nations do not have rabies at all. It is classified as a neglected tropical disease.

In epizoology, an epizootic (from Greek: "epi-" upon + "zoon" animal) is a disease event in a nonhuman animal population, analogous to an epidemic in humans. An epizootic may be: restricted to a specific locale (an "outbreak"), general (an "epizootic") or widespread ("panzootic"). High population density is a major contributing factor to epizootics. Aquaculture is an industry sometimes plagued by disease because of the large number of fish confined to a small area.

Defining an epizootic can be subjective; it is based upon the number of new cases in a given animal population, during a given period, and must be judged to be a rate that substantially exceeds what is expected based on recent experience ("i.e." a sharp elevation in the incidence rate). Because it is based on what is "expected" or thought normal, a few cases of a very rare disease (like a TSE outbreak in a cervid population) might be classified as an "epizootic", while many cases of a common disease (like lymphocystis in esocids) would not.

Common diseases that occur at a constant but relatively high rate in the population are said to be "enzootic" ("cf." the epidemiological meaning of "endemic" for human diseases). An example of an enzootic disease would be the influenza virus in some bird populations or, at a lower incidence, the Type IVb strain of VHS in certain Atlantic fish populations.

An example of an epizootic would be the 1990 outbreak of Newcastle disease virus in double-crested cormorant colonies on the Great Lakes that resulted in the death of some 10,000 birds.

Feline zoonosis are the viral, bacterial, fungal, protozoan, nematode and arthropod infections that can be transmitted to humans from the domesticated cat, "Felis catus". Some of these are diseases are reemerging and newly emerging infections or infestations caused by zoonotic pathogens transmitted by cats. In some instances, the cat can display symptoms of infection (these may differ from the symptoms in humans) and sometimes the cat remains asymptomatic. There can be serious illnesses and clinical manifestations in people who become infected. This is dependent on the immune status and age of the person. Those who live in close association with cats are more prone to these infections. But those that do not keep cats as pets are also able to acquire these infections because of the transmission can be from cat feces and the parasites that leave their bodies.

People can acquire cat-associated infections through bites, scratches or other direct contact of the skin or mucous membranes with the cat. This includes 'kissing' or letting the animal lick the mouth or nose. Mucous membranes are easily infected when the pathogen is in the mouth of the cat. Pathogens can also infect people when there is contact with animal saliva, urine and other body fluids or secretions, When fecal material is unintentionally ingested, infection can occur. Feline zooinosis can be acquired by a person by inhalation of aerosols or droplets coughed up by the cat.

In the United States, forty percent of homes have at least one cat. Some contagious infections such as campylobacteriosis and salmonellosis cause visible symptoms of the disease in cats. Other infections, such as cat scratch disease and toxoplasmosis, have no visible symptoms and are carried by apparently healthy cats.

Tick paralysis is the only tick-borne disease that is not caused by an infectious organism. The illness is caused by a neurotoxin produced in the tick's salivary gland. After prolonged attachment, the engorged tick transmits the toxin to its host. The incidence of tick paralysis is unknown. Patients can experience severe respiratory distress (similar to anaphylaxis).