Amoebiasis, also known amoebic dysentery, is an infection caused by any of the amoebas of the "Entamoeba" group. Symptoms are most common during infection by "Entamoeba histolytica". Amoebiasis can be present with no, mild, or severe symptoms. Symptoms may include abdominal pain, diarrhea, or bloody diarrhea. Complications can include inflammation of the colon with tissue death or perforation, which may result in peritonitis. People affected may develop anemia due to loss of blood.

Cysts of "Entamoeba" can survive for up to a month in soil or for up to 45 minutes under fingernails. Invasion of the intestinal lining can cause bloody diarrhea. If the parasite reaches the bloodstream it can spread through the body, most frequently ending up in the liver where it can cause amoebic liver abscesses. Liver abscesses can occur without previous diarrhea. Diagnosis is typical by stool examination using a microscope, but may not reliably exclude infection or separate between specific types. An increased white blood cell count may be present in severe cases. The most accurate test is finding specific antibodies in the blood, but it may remain positive following treatment. Bacterial colitis can result in similar symptoms.

Prevention of amoebiasis is by improved sanitation, including separating food and water from faeces. There is no vaccine. There are two treatment options depending on the location of the infection. Amoebiasis in tissues is treated with either metronidazole, tinidazole, nitazoxanide, dehydroemetine or chloroquine, while luminal infection is treated with diloxanide furoate or iodoquinoline. Effective treatment against all stages of the disease may require a combination of medications. Infections without symptoms do not require treatment but infected individuals can spread the parasite to others and treatment can be considered. Treatment of other "Entamoeba" infections apart from "E. histolytica" is not needed.

Amoebiasis is present all over the world. About 480 million people are infected with amoebiasis and this results in the death of between 40,000–110,000 people a year. Most infections are now believed due to "E. dispar". "E. dispar" is more common in certain areas and symptomatic cases may be less common than previously reported. The first case of amoebiasis was documented in 1875 and in 1891 the disease was described in detail, resulting in the terms "amoebic dysentery" and "amoebic liver abscess". Further evidence from the Philippines in 1913 found that upon swallowing cysts of "E. histolytica" volunteers developed the disease.

Most infected people, about 90%, are asymptomatic, but this disease has the potential to make the sufferer dangerously ill. It is estimated that about 40,000 to 100,000 people worldwide die annually due to amoebiasis.

Infections can sometimes last for years. Symptoms take from a few days to a few weeks to develop and manifest themselves, but usually it is about two to four weeks. Symptoms can range from mild diarrhea to severe dysentery with blood and mucus. The blood comes from lesions formed by the amoebae invading the lining of the large intestine. In about 10% of invasive cases the amoebae enter the bloodstream and may travel to other organs in the body. Most commonly this means the liver, as this is where blood from the intestine reaches first, but they can end up almost anywhere in the body.

Onset time is highly variable and the average asymptomatic infection persists for over a year. It is theorized that the absence of symptoms or their intensity may vary with such factors as strain of amoeba, immune response of the host, and perhaps associated bacteria and viruses.

In asymptomatic infections the amoeba lives by eating and digesting bacteria and food particles in the gut, a part of the gastrointestinal tract. It does not usually come in contact with the intestine itself due to the protective layer of mucus that lines the gut. Disease occurs when amoeba comes in contact with the cells lining the intestine. It then secretes the same substances it uses to digest bacteria, which include enzymes that destroy cell membranes and proteins. This process can lead to penetration and digestion of human tissues, resulting first in flask-shaped ulcers in the intestine. "Entamoeba histolytica" ingests the destroyed cells by phagocytosis and is often seen with red blood cells (a process known as erythrophagocytosis) inside when viewed in stool samples. Especially in Latin America, a granulomatous mass (known as an amoeboma) may form in the wall of the ascending colon or rectum due to long-lasting immunological cellular response, and is sometimes confused with cancer.

"Theoretically, the ingestion of one viable cyst can cause an infection."

The most common form of dysentery is bacillary dysentery, which is typically a mild illness, causing symptoms normally consisting of mild stomach pains and frequent passage of stool or diarrhea. Symptoms normally present themselves after one to three days, and are usually no longer present after a week. The frequency of urges to defecate, the large volume of liquid feces passed, and the presence of mucus, pus, and blood depends on the pathogen causing the disease. Temporary lactose intolerance can occur, as well. In some caustic occasions severe abdominal pain, fever, shock, and delirium can all be symptoms.

In extreme cases, dysentery patients may pass more than one litre of fluid per hour. More often, individuals will complain of nausea, abdominal pain, and frequent watery and usually foul-smelling diarrhea, accompanied by mucus, blood, rectal pain, and fever. Vomiting, rapid weight-loss, and generalized muscle aches sometimes also accompany dysentery. On rare occasions, the amoebic parasite will invade the body through the bloodstream and spread beyond the intestines. In such cases, it may more seriously infect other organs such as the brain, lungs, and most commonly the liver.

Dysentery is a type of gastroenteritis that results in diarrhea with blood. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation.

It is caused by several types of infections such as bacteria, viruses, parasitic worms, or protozoa. The mechanism is an inflammatory disorder of the intestine, especially of the colon.

Onset of symptoms begins one to nine days following exposure (with an average of five). Initial symptoms include changes in taste and smell, headache, fever, nausea, vomiting, back pain, and a stiff neck. Secondary symptoms are also meningitis-like including confusion, hallucinations, lack of attention, ataxia, cramp and seizures. After the start of symptoms, the disease progresses rapidly over three to seven days, with death usually occurring anywhere from seven to fourteen days later, although it can take longer. In 2013, a man in Taiwan died twenty-five days after being infected by "Naegleria fowleri".

It affects healthy children or young adults who have recently been exposed to bodies of fresh water. Some people have presented with a clinical triad of edematous brain lesions, immune suppression, and fever.

How myiasis affects the human body depends on where the larvae are located. Larvae may infect dead, necrotic (prematurely dying) or living tissue in various sites: the skin, eyes, ears, stomach and intestinal tract, or in genitourinary sites. They may invade open wounds and lesions or unbroken skin. Some enter the body through the nose or ears. Larvae or eggs can reach the stomach or intestines if they are swallowed with food and cause gastric or intestinal myiasis.

Several different presentations of myiasis and their symptoms:

Naegleriasis (also known as primary amoebic meningoencephalitis) is an infection of the brain by the free-living unicellular "Naegleria fowleri".

"N. fowleri" is typically found in warm bodies of fresh water, such as ponds, lakes, rivers, and hot springs. It is also found in soil, poorly maintained municipal water supplies, water heaters, near warm-water discharges of industrial plants, and in poorly chlorinated or unchlorinated swimming pools, in an amoeboid or temporary flagellate stage. There is no evidence of it living in salt water. As the disease is rare, it is often not considered. Symptoms are similar to those of meningitis.

Although infection occurs rarely, it nearly always results in death, with a case fatality rate greater than 95%.

Nosocomial myiasis is myiasis acquired in a hospital setting. It is quite frequent, as patients with open wounds or sores can be infested if flies are present. To prevent nosocomial myiasis, hospital rooms must be kept free of flies.

"Acanthamoeba spp." causes mostly subacute or chronic granulomatous amoebic encephalitis (GAE), with a clinical picture of headaches, altered mental status, and focal neurologic deficit, which progresses over several weeks to death. In addition, "Acanthamoeba spp." can cause granulomatous skin lesions and, more seriously, keratitis and corneal ulcers following corneal trauma or in association with contact lenses.

Free-living amoebae (or "FLA") in the Amoebozoa group are important causes of disease in humans and animals.

"Naegleria fowleri" is sometimes included in the group "free-living amoebae", and it causes a condition traditionally called primary amoebic meningoencephalitis. However, Naegleria is now considered part of the Excavata, not the Amoebozoa, and is considered to be much more closely related to "Leishmania" and "Trypanosoma".

Cutaneous amoebiasis refers to a form of amoebiasis that presents primarily in the skin.

It can be caused by "Acanthamoeba" or "Entamoeba histolytica". When associated with "Acanthamoeba", it is also known as "cutaneous acanthamoebiasis".

It is also known as "amoebiasis cutis".

"Balamuthia mandrillaris" can cause cutaneous amoebiasis, but can prove fatal if the amoeba enters the bloodstream

Symptoms

- Pain right hypochondrium referred to right shoulder

- Pyrexia (100.4 F)

- Profuse sweating and rigors

- Loss of weight

- Earthy complexion

Signs

- Pallor

- Tenderness and rigidity in right hypochondrium

- Palpable liver

- tenderness

- Basal lung signs

A amoebic liver abscess is a type of liver abscess caused by amebiasis. It is the involvement of liver tissue by trophozoites of the organism "Entamoeba histolytica" and of is abscess due to necrosis.

Genitourinary amoebiasis or renal amoebiasis is a rare complication to amoebic liver abscess, which in turn is a complication of amoebiasis. It is believed to result from liver abscesses breaking open, whereupon the amoebas spread through the blood to the new locale. Genital involvement is thought to result from fistula formation from the liver or through rectocolitis. The involvement causes lesions which exude a high degree of pus.

Liver fluke is a collective name of a polyphyletic group of parasitic trematodes under the phylum Platyhelminthes.

They are principally parasites of the liver of various mammals, including humans. Capable of moving along the blood circulation, they can occur also in bile ducts, gallbladder, and liver parenchyma. In these organs, they produce pathological lesions leading to parasitic diseases. They have complex life cycles requiring two or three different hosts, with free-living larval stages in water.

Human’s clinical signs consisted of swelling and eye infections. There were nodules underneath the skin, abscesses or cysts, and lesions running throughout the body. There were papules, plaques and granulomatous damages on the body. In extreme cases there were deep infections within the eyes, bones, heart and central nervous system.

A fungus ball in the lungs may cause no symptoms and may be discovered only with a chest X-ray, or it may cause repeated coughing up of blood, chest pain, and occasionally severe, even fatal, bleeding. A rapidly invasive "Aspergillus" infection in the lungs often causes cough, fever, chest pain, and difficulty breathing.

Poorly controlled aspergillosis can disseminate through the blood stream to cause widespread organ damage. Symptoms include fever, chills, shock, delirium, seizures and blood clots. The person may develop kidney failure, liver failure (causing jaundice), and breathing difficulties. Death can occur quickly.

Aspergillosis of the ear canal causes itching and occasionally pain. Fluid draining overnight from the ear may leave a stain on the pillow. Aspergillosis of the sinuses causes a feeling of congestion and sometimes pain or discharge. It can extend beyond the sinuses.

In addition to the symptoms, an X-ray or computerised tomography (CT) scan of the infected area provides clues for making the diagnosis. Whenever possible, a doctor sends a sample of infected material to a laboratory to confirm identification of the fungus.

Intestinal infectious diseases include a large number of infections of the bowels including: cholera, typhoid fever, paratyphoid fever, other types of salmonella infections, shigellosis, botulism, gastroenteritis, and amoebiasis among others.

Typhoid and paratyphoid resulted in 221,000 deaths in 2013 down from 259,000 deaths in 1990. Other diseases which result in diarrhea caused another 1.3 million additional deaths in 2013 down from 2.6 million deaths in 1990.

Symptoms are different for every person depending on the type of rat-bite fever with which the person is infected. Both spirillary and streptobacillary rat-bite fever have a few individual symptoms, although most symptoms are shared. Streptobacillosis is most commonly found in the United States and spirillary rat-bite fever is generally diagnosed in patients in Africa. Rat-bite symptoms are visually seen in most cases and include inflammation around the open sore. A rash can also spread around the area and appear red or purple. Other symptoms associated with streptobacillary rat-bite fever include chills, fever, vomiting, headaches, and muscle aches. Joints can also become painfully swollen and pain can be experienced in the back. Skin irritations such as ulcers or inflammation can develop on the hands and feet. Wounds heal slowly, so symptoms possibly come and go over the course of a few months.

Symptoms associated with spirillary rat-bite fever include issues with the lymph nodes, which often swell or become inflamed as a reaction to the infection. The most common locations of lymph node swelling are in the neck, groin, and underarm. Symptoms generally appear within 2 to 10 days of exposure to the infected animal. It begins with the fever and progresses to the rash on the hands and feet within 2 to 4 days. Rash appears all over the body with this form, but rarely causes joint pain.

GAE may present in numerous ways. There is no solid definition, as only a handful of patients have presented thus far with GAE. GAE can present with: focal paralysis, seizures, brainstem symptoms, and other neurological problems, some of which may mimic glioma (especially brainstem glioma), or other brain diseases, which may hamper timely diagnosis. These symptoms are caused by inflammatory necrosis of brain tissue brought on by amoebic infiltrates.

The streptobacillosis form of rat-bite fever is known by the alternative names Haverhill fever and epidemic arthritic erythema. It is a severe disease caused by "Streptobacillus moniliformis", transmitted either by rat bite or ingestion of contaminated products (Haverhill fever). After an incubation period of 2–10 days, Haverhill fever begins with high prostrating fevers, rigors (shivering), headache, and polyarthralgia (joint pain). Soon, an exanthem (widespread rash) appears, either maculopapular (flat red with bumps) or petechial (red or purple spots) and arthritis of large joints can be seen. The organism can be cultivated in blood or articular fluid. The disease can be fatal if untreated in 20% of cases due to malignant endocarditis, meningoencephalitis, or septic shock. Treatment is with penicillin, tetracycline, or doxycycline.

Swimmer’s itch or cercarial dermatitis, is a short-term immune reaction occurring in the skin of humans that have been infected by water-borne schistosomatidae. Symptoms, which include itchy, raised papules, commonly occur within hours of infection and do not generally last more than a week. It is common in freshwater, brackish and marine habitats worldwide. Incidence may be on the rise, although this may also be attributed to better monitoring. Nevertheless, the condition has been regarded as emerging infectious disease.

There are no permanent effects to people from this condition. Orally administered hydroxyzine, an antihistamine, is sometimes prescribed to treat swimmer's itch and similar dermal allergic reactions. In addition, bathing in oatmeal, baking soda, or Epsom salts can also provide relief of symptoms.

"Balamuthia" infection is a cutaneous condition resulting from "Balamuthia" that may result in various skin lesions.

"Balamuthia mandrillarisis" a free-living amoeba (a single-celled living organism) found in the environment. It is one of the causes of granulomatous amoebic encephalitis (GAE), a serious infection of the brain and spinal cord. "Balamuthia" is thought to enter the body when soil containing it comes in contact with skin wounds and cuts, or when dust containing it is breathed in or gets in the mouth. The "Balamuthia" amoebae can then travel to the brain through the blood stream and cause GAE. GAE is a very rare disease that is usually fatal.

Scientists at the Centers for Disease Control and Prevention (CDC) first discovered "Balamuthia mandrillaris" in 1986. The amoeba was found in the brain of a dead mandrill. After extensive research, "B. mandrillaris" was declared a new species in 1993. Since then, more than 200 cases of "Balamuthia" infection have been diagnosed worldwide, with at least 70 cases reported in the United States. Little is known at this time about how a person becomes infected.

Granulomatous amoebic encephalitis (GAE) is a central nervous system disease caused by certain species of free-living amoebae, especially species of "Acanthamoeba" and "Balamuthia mandrillaris".

The term is most commonly used with "Acanthamoeba". In more modern references, the term "balamuthia amoebic encephalitis" (BAE) is commonly used when "Balamuthia mandrillaris" is the cause.

From birds to equines, Phaeohyphomycosis persists and has a massive range of clinical signs throughout differing species. Poultry and wild birds had neurological disorders and a loss of movement control. They experienced severe torticollis, which are severe muscle spasms that compromise the bird’s ability to hold up its head. The birds exhibited a loss of balance due to the rigidity of their legs.

Cats showed signs of difficulty breathing due to excessive swelling of the nose. There were also lesions found throughout the body, including the brain. In extreme cases dogs exhibited vision impairment and had deep infections in the nasal cavity, kidneys, and the cerebellum. In dogs, brain infections were found similar to infections that were found in humans. Other clinical signs were lesions, abscesses, and severe inflammation throughout the dog’s body.

Ruminants and equines were affected the same way from Phaeohyphomycosis. They showed respiratory distress through constant coughing and a fever. They demonstrated signs of anorexia, lethargy, and hypothermia. There was inflammation, hair loss, scaling, and damage to their cerebellum.