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%.

Hydrophobia ("fear of water") is the historic name for rabies. It refers to a set of symptoms in the later stages of an infection in which the person has difficulty swallowing, shows panic when presented with liquids to drink, and cannot quench his or her thirst. Any mammal infected with the virus may demonstrate hydrophobia.

Saliva production is greatly increased, and attempts to drink, or even the intention or suggestion of drinking, may cause excruciatingly painful spasms of the muscles in the throat and larynx. This can be attributed to the fact that the virus multiplies and assimilates in the salivary glands of the infected animal for the purpose of further transmission through biting. The ability to transmit the virus would decrease significantly if the infected individual could swallow saliva and water.

Hydrophobia is commonly associated with furious rabies, which affects 80% of rabies-infected people. The remaining 20% may experience a paralytic form of rabies that is marked by muscle weakness, loss of sensation, and paralysis; this form of rabies does not usually cause fear of water.

Rabies is a viral disease that exists in Haiti and throughout the world. It often causes fatal inflammation of the brain in humans and other mammals, such as dogs and mongooses in Haiti. The term "rabies" is derived from a Latin word that means "to rage"; rabid animals sometimes appear to be angry. Early symptoms can include fever and tingling at the site of exposure, 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, death is nearly always the outcome. The time period between contracting the disease and showing symptoms is usually one to three months; however, this time period can vary from less than a week to more than a year. The time between contraction and the onset of symptoms is dependent on the distance the virus must travel to reach the central nervous system.

Haiti is one of five remaining countries in the Americas where canine rabies is still a problem. It has the highest rate of human rabies deaths in the western hemisphere with an estimated two deaths each week. Only about seven deaths are reported to health authorities each year due to poor surveillance, limitations in diagnostic capacity, and lack of awareness and education about the disease among Haitians.

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.

Globally, 59,000 people die from rabies each year. This is the equivalent of one person dying every nine minutes, with half of the people who die from rabies being under the age of 15. The Pan American Health Organization (PAHO) and the Pan American Center of foot-and-mouth disease (PANAFTOSA) led a mission to eliminate dog-mediated rabies in the American region by 2015. These organizations are cognizant of the regional control of rabies. The PAHO and PANAFTOSA visited Haiti in early December, 2013, and the objectives of the mission were to assess the status of Haiti’s rabies program as delivered by the Haitian Ministry of Agriculture, Natural Resources and Rural Development (MARNDR) and the Ministry of Health (MSPP). The mission was to seek opportunities for collaboration between Haiti, Brazil, and the Centers for Disease Control and Prevention (CDC) in Haiti.

Even in 2017, rabies in Haiti is still identified as a national problem, even with PEP proposed.

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.

Most people who are infected have no or few symptoms. Otherwise the most common signs and symptoms of Zika fever are fever, rash, conjunctivitis (red eyes), muscle and joint pain, and headache, which are similar to signs and symptoms of dengue and chikungunya fever. The time from a mosquito bite to developing symptoms is not yet known, but is probably a few days to a week. The disease lasts for several days to a week and is usually mild enough that people do not have to go to a hospital.

Due to being in the same family as dengue, there has been concern that it could cause similar bleeding disorders. However that has only been documented in one case, with blood seen in semen, also known as hematospermia.

Zika virus infections have been strongly associated with Guillain–Barré syndrome (GBS), which is a rapid onset of muscle weakness caused by the immune system damaging the peripheral nervous system, and which can progress to paralysis. While both GBS and Zika infection can simultaneously occur in the same individual, it is difficult to definitively identify Zika virus as the cause of GBS. Several countries affected by Zika outbreaks have reported increases in the rate of new cases of GBS. During the 2013–2014 outbreak in French Polynesia there were 42 reported cases of GBS over a 3-month period, compared to between 3 and 10 annually prior to the outbreak.

A "vaccine-preventable disease" is an infectious disease for which an effective preventive vaccine exists. If a person acquires a vaccine-preventable disease and dies from it, the death is considered a vaccine-preventable death.

The most common and serious vaccine-preventable diseases tracked by the World Health Organization (WHO) are: diphtheria, "Haemophilus influenzae" serotype b infection, hepatitis B, measles, meningitis, mumps, pertussis, poliomyelitis, rubella, tetanus, tuberculosis, and yellow fever. The WHO reports licensed vaccines being available to prevent, or contribute to the prevention and control of, 25 vaccine-preventable infections.

Mayaro virus disease is a mosquitoborne zoonotic pathogen endemic to certain humid forests of tropical South America. Infection with Mayaro virus causes an acute, self-limited dengue-like illness of 3–5 days' duration. The causative virus, abbreviated MAYV, is in the family Togaviridae, and genus Alphavirus. It is closely related to other alphaviruses that produce a dengue-like illness accompanied by long-lasting arthralgia. It is only known to circulate in tropical South America.

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".

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.).

Respiratory infection is usually asymptomatic in pigs more than 2 months old, but it can cause abortion, high mortality in piglets, and coughing, sneezing, fever, constipation, depression, seizures, ataxia, circling, and excess salivation in piglets and mature pigs. Mortality in piglets less than one month of age is close to 100%, but it is less than 10% in pigs between one and six months of age. Pregnant swine can reabsorb their litters or deliver mummified, stillborn, or weakened piglets. In cattle (see next section), symptoms include intense itching followed by neurological signs and death. In dogs, symptoms include intense itching, jaw and pharyngeal paralysis, howling, and death Any infected secondary host generally only lives two to three days.

Genital infection appears to have been common in a great part of the 20th century in many European countries in swine herds, where boars from boar centres were used for natural service of sows or gilts. This disease manifestation has always been asymptomatic in affected pigs, and presence of the infection on a farm was detected only because of cases in cattle showing pruritus on the hindquarters (vaginal infection, see below).

In susceptible animals other than swine, infection is usually fatal, and the affected animals most often show intense pruritus in a skin area.

Pruritus in Aujeszky's disease is considered a phantom sensation, and virus has never been found at the site of pruritus.

Aujeszky's disease, usually called pseudorabies in the United States, is a viral disease in swine that has been endemic in most parts of the world. It is caused by "Suid herpesvirus 1" (SuHV1). Aujeszky's disease is considered to be the most economically important viral disease of swine in areas where hog cholera has been eradicated. Other mammals, such as humans, cattle, sheep, goats, cats, dogs, and raccoons, are also susceptible. The disease is usually fatal in these animal species bar humans.

The term "pseudorabies" is found inappropriate by many people, as SuHV1 is a herpesvirus and not related to the rabies virus.

Research on SuHV1 in pigs has pioneered animal disease control with genetically modified vaccines. SuHV1 is now used in model studies of basic processes during lytic herpesvirus infection, and for unravelling molecular mechanisms of herpesvirus neurotropism.

A number of studies have demonstrated adverse reactions in pets after administering vaccines to both dogs and cats. Concern about adverse effects has led to revised guidelines that alter the recommended frequency and methods/locations for both vaccination of dogs and feline vaccination.

The MAYV infection is characterized by fever, headache, myalgia, rash, prominent pain in the large joints, and association with rheumatic disease, but these signs and symptoms are unspecific to distinguish from other Arbovirus. The MAYV infection can be confirmed by laboratory testing such us virus isolation, RT-PCR and serology. The virus isolation in cell culture is effective during viremia. RT-PCR helps to identify virus. Serology tests detect antibodies like IgM and the most common assay is IgM-capture enzyme-linked immunosorbant assays (ELISA). This test usually requires a consecutive retest to confirm increasing titers. While the IgG detection is applied for epidemiology studies.

Cat bites are bites inflicted upon humans, other cats, and other animals by the domestic cat. () Though uncommon, sometimes cat bites can lead to complications and very rarely, death.

A little known and often misdiagnosed reaction to the rabies vaccine in dogs, this problem may develop near or over the vaccine administration site and around the vaccine material that was injected, or as a more widespread reaction. Symptoms include ulcers, scabs, darkening of the skin, lumps at the vaccine site, and scarring with loss of hair. In addition to the vaccination site, lesions most often develop on the ear flaps (pinnae), on the elbows and hocks, in the center of the footpads and on the face. Scarring may be permanent. Dogs do not usually seem ill, but may develop fever. Symptoms may show up within weeks of vaccination, or may take months to develop noticeably.

Dogs with active lesion development and / or widespread disease may be treated with pentoxyfylline, a drug that is useful in small vessel vasculitis, or tacrolimus, an ointment that will help suppress the inflammation in the affected areas.

Owners and veterinarians of dogs who have developed this type of reaction should review the vaccination protocol critically and try to reduce future vaccinations to the extent medically and legally possible. At the very least, vaccines from the same manufacturer should be avoided. It is also recommended that the location in which future vaccinations are administered should be changed to the rear leg, as far down on the leg as possible and should be given in the muscle rather than under the skin.

The symptoms of diphtheria usually begin two to seven days after infection. Symptoms of diphtheria include fever of 38 °C (100.4 °F) or above, chills, fatigue, bluish skin coloration (cyanosis), sore throat, hoarseness, cough, headache, difficulty swallowing, painful swallowing, difficulty breathing, rapid breathing, foul-smelling and bloodstained nasal discharge, and lymphadenopathy. Within two to three days, diphtheria may destroy healthy tissues in the respiratory system. The dead tissue forms a thick, gray coating that can build up in the throat or nose. This thick gray coating is called a “pseudomembrane.” It can cover tissues in the nose, tonsils, voice box, and throat, making it very hard to breathe and swallow. Symptoms can also include cardiac arrhythmias, myocarditis, and cranial and peripheral nerve palsies.

Cat bites are usually considered as minor injuries but can result in serious infection. Not all infections that can be obtained from exposure to a cat are transmitted through a cat bite, like plague.

In 2012, the World Health Organization estimated that vaccination prevents 2.5 million deaths each year. If there is 100% immunization, and 100% efficacy of the vaccines, one out of seven deaths among young children could be prevented, mostly in developing countries, making this an important global health issue. Four diseases were responsible for 98% of vaccine-preventable deaths: measles, "Haemophilus influenzae" serotype b, pertussis, and neonatal tetanus.

The Immunization Surveillance, Assessment and Monitoring program of the WHO monitors and assesses the safety and effectiveness of programs and vaccines at reducing illness and deaths from diseases that could be prevented by vaccines.

Vaccine-preventable deaths are usually caused by a failure to obtain the vaccine in a timely manner. This may be due to financial constraints or to lack of access to the vaccine. A vaccine that is generally recommended may be medically inappropriate for a small number of people due to severe allergies or a damaged immune system. In addition, a vaccine against a given disease may not be recommended for general use in a given country, or may be recommended only to certain populations, such as young children or older adults. Every country makes its own vaccination recommendations, based on the diseases that are common in its area and its healthcare priorities. If a vaccine-preventable disease is uncommon in a country, then residents of that country are unlikely to receive a vaccine against it. For example, residents of Canada and the United States do not routinely receive vaccines against yellow fever, which leaves them vulnerable to infection if travelling to areas where risk of yellow fever is highest (endemic or transitional regions).

Laryngeal diphtheria can lead to a characteristic swollen neck and throat, or "bull neck". The swollen throat is often accompanied by a serious respiratory condition, characterized by a brassy or "barking" cough, stridor, hoarseness, and difficulty breathing, and historically referred to variously as "diphtheritic croup", "true croup", or sometimes simply as "croup". Diphtheritic croup is extremely rare in countries where diphtheria vaccination is customary. As a result, the term "croup" nowadays most often refers to an unrelated viral illness that produces similar but milder respiratory symptoms.

An emerging infectious disease (EID) is an infectious disease whose incidence has increased in the past 20 years and could increase in the near future. Emerging infections account for at least 12% of all human pathogens. EIDs are caused by newly identified species or strains (e.g. Severe acute respiratory syndrome, HIV/AIDS) that may have evolved from a known infection (e.g. influenza) or spread to a new population (e.g. West Nile fever) or to an area undergoing ecologic transformation (e.g. Lyme disease), or be "reemerging" infections, like drug resistant tuberculosis. Nosocomial (hospital-acquired) infections, such as methicillin-resistant Staphylococcus aureus are emerging in hospitals, and extremely problematic in that they are resistant to many antibiotics. Of growing concern are adverse synergistic interactions between emerging diseases and other infectious and non-infectious conditions leading to the development of novel syndemics. Many emerging diseases are zoonotic - an animal reservoir incubates the organism, with only occasional transmission into human populations.

Yellow fever begins after an incubation period of three to six days. Most cases only cause a mild infection with fever, headache, chills, back pain, fatigue, loss of appetite, muscle pain, nausea, and vomiting. In these cases, the infection lasts only three to four days.

In 15% of cases, however, people enter a second, toxic phase of the disease with recurring fever, this time accompanied by jaundice due to liver damage, as well as abdominal pain. Bleeding in the mouth, the eyes, and the gastrointestinal tract cause vomit containing blood, hence the Spanish name for yellow fever, "vómito negro" ("black vomit"). There may also be kidney failure, hiccups, and delirium.

The toxic phase is fatal in about 20 to 50% of cases, making the overall fatality rate for the disease about 3.0 to 7.5%. However, the fatality rate of those with the toxic phase of the disease may exceed 50%.

Surviving the infection provides lifelong immunity, and normally no permanent organ damage results.

Surra (from the Marathi "sūra", meaning the sound of heavy breathing through nostrils, of imitative origin) is a disease of vertebrate animals. The disease is caused by protozoan trypanosomes, specifically "Trypanosoma evansi", of several species which infect the blood of the vertebrate host, causing fever, weakness, and lethargy which lead to weight loss and anemia. In some animals the disease is fatal unless treated.