Full body or localized pain to the extremities (known as acroparesthesia) or gastrointestinal (GI) tract is common in patients with Fabry disease. This acroparesthesia is believed to be related to the damage of peripheral nerve fibers that transmit pain. GI tract pain is likely caused by accumulation of lipids in the small vasculature of the GI tract which obstructs blood flow and causes pain.

Symptoms are typically first experienced in early childhood and can be very difficult to understand; the rarity of Fabry disease to many clinicians sometimes leads to misdiagnoses. Manifestations of the disease usually increase in number and severity as an individual ages.

Various systems are affected.

- CNS abnormalities – microcephaly, mental retardation, spasticity, epilepsy, periventricular calcification

- Eye – choroidoretinitis and optic atrophy

- Ear – sensorineural deafness

- Liver – hepatosplenomegaly and jaundice due to hepatitis

- Lung – pneumonitis (interstitial pneumonitis)

- Heart – myocarditis

- Thrombocytopenic purpura, haemolytic anaemia

- Late sequelae in individuals asymptomatic at birth – hearing defects and reduced intelligence

Cytomegalic inclusion body disease (CIBD) is a series of signs and symptoms caused by cytomegalovirus infection, toxoplasmosis or other rare infections such as herpes or rubella viruses. It can produce massive calcification of the central nervous system, and often the kidneys.

Cytomegalic inclusion body disease is the most common cause of congenital abnormalities in the United States. It can also cause pneumonia and other diseases in immunocompromised patients, such as those with HIV/AIDS or recipients of organ transplants.

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.

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.

Pacheco's disease is an acute and often lethal infectious disease in psittacine birds. The disease is caused by a group of herpesviruses, "Psittacid herpesvirus 1" (PsHV-1), which consists of four genotypes. Birds which do not succumb to Pacheco's disease after infection with the virus become asymptomatic carriers that act as reservoirs of the infection. These persistently infected birds, often Macaws, Amazon parrots and some species of conures, shed the virus in feces and in respiratory and oral secretions. Outbreaks can occur when stress causes healthy birds who carry the virus to shed it. Birds generally become infected after ingesting the virus in contaminated material, and show signs of the disease within several weeks.

The main sign of Pacheco's disease is sudden death, sometimes preceded by a short, severe illness. If a bird survives Pacheco's disease following infection with PsHV-1 genotypes 1, 2 or 3, it may later develop internal papilloma disease in the gastrointestinal tract.

Susceptible parrot species include the African gray parrot, and cockatoo. Native Australian birds, such as the eclectus parrot, Bourke's parrot, and budgerigar are susceptible to Pacheco's disease, although the disease itself has not been found in Australia.

This disease affects the external genitalia, and is caused by equine herpesvirus 3. This disease remains with the horse for all its life. Equine coital exanthema is believed to only be transmitted during the acute phase of the disease through serous fluid from the blisters during sexual intercourse, and via breeding tools, handlers, etc.

Clinical signs include cute small lesions, no bigger than 2 mm in diameter around the vulva in mares, and on the sheath in stallions. The small bumps blister and then rupture, leaving raw, ulcerated, painful sores. While the majority of the symptoms are external, the presence of the virus can cause small and large plaque variants in tissues.

It is usually asymptomatic unless the complication and infection is severe. But in some recorded cases, symptoms include nasopharyngitis accompanied by pain, itching of throat and ears. Coughing, hemoptysis and vomiting are verifiable indications as well as sneezing, bleeding, dyspnea, and inflammation.

Equine venereal diseases are sexually transmitted infections in horses. They include contagious equine metritis (CEM) (caused by "Taylorella equigenitalis") and equine coital exanthema (caused by equine herpesvirus 3).

Eating raw or semi-cooked infected liver or lymph nodes infected with nymphal L. serrata causes severe symptoms in the human nasopharynx. Submaxillary and cervical lymph nodes sometimes enlarge and the neck is swollen. Complications include abscesses in the auditory canals, facial paralysis, and enlarged tonsils producing asphyxiation. These symptoms are well recognized as a disease call “halzoun syndrome” in Lebanon and nearby countries.

In Egypt, infected camels and buffalo may also be a source of infection for dogs, which are companions of man in desert and semi-desert areas where grazing is a major profession, and in villages, where dogs are also common. Infected dogs, in turn, are a source of infection to man who may be an intermediate host.

A subclinical infection (sometimes called a preinfection) is an infection that, being , is nearly or completely asymptomatic (no signs or symptoms). A subclinically infected person is thus an asymptomatic carrier of a microbe, intestinal parasite, or virus that usually is a pathogen causing illness, at least in some individuals. Many pathogens spread by being silently carried in this way by some of their host population. Such infections occur both in humans and nonhuman animals. An example of an asymptomatic infection is a mild common cold that is not noticed by the infected individual. Since subclinical infections often occur without eventual overt sign, their existence is only identified by microbiological culture or DNA techniques such as polymerase chain reaction.

The secondary stages of syphilis persists to be more dangerous to the systems of the human body. The disseminated disease can cause constitutional symptoms and condylomata lata. Many treponemes are present in chancres in the primary stage; however, condylomata lata is usually present in the secondary stage. The pathogen can spread through blood, which can infect the vessels in the body. The infection of the heart, muscles, and vessels in the body can lead to meningovascular syphilis. Generally, rashes may start developing on the hands and soles of the feet, and it can spread to various parts of skin on the body. Other symptoms may include sore throat, headache, joint pain, fever, and patches of hair loss. As in stage one, lesions may start to form on the body, but in this stage in particular, lesions are found in mucous membranes of the mouth, throat, bones, and internal organs. Also common with stage one, the symptoms and signs of secondary syphilis will go away with or without treatment and medication. The diagnosis includes serology nonspecific and specific, both positive. The secondary stage is however highly infectious because the bacteria is spreading drastically throughout the body.

The types of neurosyphilis include asymptomatic, acute syphilitic meningitis, meningovascular syphilis, parenchymatous syphilis (which includes general paresis and tabes dorsalis), and optic atrophy.

Cryofibrinogenmic disease commonly begins in adults aged 40–50 years old with symptoms of the diseases occurring in the almost always affected organ, skin. Cutaneous symptoms include on or more of the following: cold contact-induced urticarial (which may be the first sign of the disease); painful episodes of finger and/or toe arterial spasms termed Ranaud phenomena; cyanosis, s palpable purpura termed Cryofibrinogenemic purpura), and a lace-like purplish discoloration termed livedo reticularis all of which occur primarily in the lower extremities but some of which may occur in the nose, ears, and buttocks; non-healing painful ulcerations and gangrene of the areas impacted by the cited symptoms. Patients also have a history of cold sensitivity (~25% of cases), arthralgia (14-58%), neuritis (7-19%), myalgia (0-14%); and overt thrombosis of arteries and veins (25-40%) which may on rare occasions involve major arteries such of those of the brain and kidney. Signs of renal involvement (proteinuria, hematuria, decreased glomerular filtration rate, and/or, rarely, renal failure) occur in 4-25% of cases. Compared to secondary cryofibrinogemia, primary crygofibrinogenemia has a higher incidence of cutaneous lesions, arthralgia, and cold sensitivity while having a far lower incidence of renal involvement. Patients with secondary cryofibrinogenemia also exhibit signs and symptoms specific to the infectious, malignant, premalignant vasculitis, and autoimmune disorders associated with their disease. While rare, individuals with cryofibrinogemic disease may experience pathological bleeding due to the consumption of blood clotting factors consequential to the formation of cryofibrinogen precipitates.

A broad range of autoimmune diseases have been reported to be associated with cryofibrinogenemia. These diseases include systemic lupus erythematosis, Sjorgren's syndrome, rheumatoid arthritis, mixed connective tissue disease, polymyositis, dermatomyositis, systemic sclerosis, antiphospholipid antibody syndrome, Hashimoto disease, Graves disease, sarcoidosis, pyoderma gangrenosum, spondyloarthropathy, Crohn disease, and ulcerative colitis.

The most commonly reported symptoms in conjunction with infection with "D. fragilis" include abdominal pain (69%) and diarrhea (61%). Diarrhea may be intermittent and may not be present in all cases. It is often chronic, lasting over two weeks. The degree of symptoms may vary from asymptomatic to severe, and can include weight loss, vomiting, fever, and involvement of other digestive organs.

Symptoms may be more severe in children. Additional symptoms reported have included:

1. Weight loss

2. Fatigue

3. Nausea and vomiting

4. Fever

5. Urticaria (skin rash)

6. Pruritus (itchiness)

7. Biliary infection

An individual may only develop signs of an infection after a period of subclinical infection, a duration that is called the incubation period. This is the case, for example, for subclinical sexually transmitted diseases such as AIDS and genital warts. Individuals with such subclinical infections, and those that never develop overt illness, creates a reserve of individuals that can transmit an infectious agent to infect other individuals. Because such cases of infections do not come to clinical attention, health statistics can often fail to measure the true prevalence of an infection in a population, and this prevents the accurate modeling of its infectious transmission.

Patients are often asymptomatic in the initial stages of retinal perivasculitis. Some patients may develop symptoms such as floaters, blurring vision, or even gross diminution of vision due to massive vitreous hemorrhage. Vision in these patients can be normal to hand movements or light perception only. Bilaterality is quite common (50–90%) patients.

Fish infected with typical BCWD have lesions on the skin and fins. Fins may appear dark, torn, split, ragged, frayed and may even be lost completely. Affected fish are often lethargic and stop feeding. Infection may spread systemically. Salmonid fish can also get a chronic form of BCWD following recovery from typical BCWD. It is characterised by erratic “corkscrew” swimming, blackened tails and spinal deformities.

In rainbow trout fry syndrome, acute disease with high mortality rates occurs. Infected fish may show signs of lethargy, inappetance and exopthalmos before death.

A presumptive diagnosis can be made based on the history, clinical signs, pattern of mortality and water temperature, especially if there is a history of the disease in the area. The organism can be cultured for definitive diagnosis. Alternatively, histology should show periostitis, osteitis, meningitis and ganglioneuritis.

Cutaneous lymphoid hyperplasia refers to a groups of benign cutaneous disorders characterized by collections of lymphocytes, macrophages, and dendritic cells in the skin. Conditions included in this groups are:

- Cutaneous lymphoid hyperplasia with nodular pattern, a condition of the skin characterized by a solitary or localized cluster of asymptomatic erythematous to violaceous papules or nodules

- Cutaneous lymphoid hyperplasia with bandlike and perivascular patterns, a condition of the skin characterized by skin lesions that clinically resemble mycosis fungoides

Jessner lymphocytic infiltrate of the skin is a cutaneous condition characterized by a persistent papular and plaque-like skin eruption which can occur on the neck, face and back and may re-occur. This is an uncommon skin disease and is a benign collection of lymph cells. Its cause is not known and can be hereditary. It is named for Max Jessner. It is thought to be equivalent to lupus erythematosus tumidus.

It can occur as the result of ACE inhibitors and a number of medications used to treat multiple sclerosis including glatiramer acetate.

Dientamoebiasis is a medical condition caused by infection with "Dientamoeba fragilis", a single-cell parasite that infects the lower gastrointestinal tract of humans. It is an important cause of traveler's diarrhea, chronic abdominal pain, chronic fatigue, and failure to thrive in children.

Nephropathia epidemica ("NE" or epidemic nephropathy) is a type of viral haemorrhagic fever with renal syndrome (HFRS) caused by the Puumala virus. The incubation period is three weeks. Nephropathia epidemica has a sudden onset with fever, abdominal pain, headache, back pain and gastrointestinal symptoms. More severe symptoms include internal hemorrhaging. Although fatal in a small percentage of cases, nephropathia epidemica is generally milder than the HFRS that is caused by hantaviruses in other parts of the world. The bank vole is the reservoir for the virus, which humans contract through inhalation of aerosolised vole droppings.

The majority of infected individuals are asymptomatic or develop only mild symptoms, and the disease is not known to spread from human to human.

This infection is known as "sorkfeber" in Swedish and "myyräkuume" in Finnish (vole fever). In Norway, it is called "musepest" (mouse plague).

Eales disease is a type of obliterative vasculopathy, also known as angiopathia retinae juvenilis, periphlebitis retinae, primary perivasculitis of the retina, is an ocular disease characterized by inflammation and possible blockage of retinal blood vessels, abnormal growth of new blood vessels (neovascularization), and recurrent retinal and vitreal hemorrhages. Eales' disease with a characteristic clinical picture, fluorescein angiographic finding, and natural course is considered a specific disease entity.