FMF affects groups of people originating from around the Mediterranean Sea (hence its name). It is prominently present in the Armenians, Sephardi Jews (and, to a much lesser extent, Ashkenazi Jews), Cypriots and Arabs.

Virtually all cases are due to a mutation in the "Mediterranean Fever (MEFV)" gene on the sixteenth chromosome, which codes for a protein called "pyrin" or "marenostrin". Various mutations of this gene lead to FMF, although some mutations cause a more severe picture than others. Mutations occur mainly in exons 2, 3, 5 and 10.

The function of pyrin has not been completely elucidated, but in short, it is a protein that binds to the adaptor ASC and the pro form of the enzyme caspase-1 to generate multiprotein complexes called inflammasomes in response to certain infections. In healthy individuals, pyrin-mediated inflammasome assembly (which leads to the caspase 1) dependent processing and secretion of the pro-inflammatory cytokines (such as interleukin-18 (IL-18) and IL-1β) is a response to enterotoxins from certain bacteria. The gain-of-function mutations in the MEFV gene render Pyrin hyperactive, and subsequently, the formation of the inflammasomes becomes more frequent. It is not conclusively known what exactly sets off the attacks, and why overproduction of IL-1 would lead to particular symptoms in particular organs (e.g. joints or the peritoneal cavity).

Cold agglutinins develop in more than 60% of patients with infectious mononucleosis, but hemolytic anemia is rare.

Classic chronic cold agglutinin disease is idiopathic, associated with symptoms and signs in relation to cold exposure.

Causes of the monoclonal secondary disease include the following:

- B-cell neoplasms - Waldenström macroglobulinemia, lymphoma, chronic lymphoid leukemia, myeloma

- Non hematologic neoplasms

Causes of polyclonal secondary cold agglutinin disease include the following:

- Mycoplasma infections.

- Viral infections: Infectious mononucleosis due to Epstein-Barr virus (EBV) or CMV, Mumps, varicella, rubella, adenovirus, HIV, influenza, hepatitis C.

- Bacterial infections: Legionnaire disease, syphilis, listeriosis and "Escherichia coli."

- Parasitic infections: Malaria and trypanosomiasis.

- Trisomy and translocation: Cytogenetic studies in patients with cold agglutinin disease have revealed the presence of trisomy 3 and trisomy 12. Translocation (8;22) has also been reported in association with cold agglutinin disease.

- Transplantation: Cold agglutinin–mediated hemolytic anemia has been described in patients after living-donor liver transplantation treated with tacrolimus and after bone marrow transplantation with cyclosporine treatments. It is postulated that such calcineurin inhibitors, which selectively affect T-cell function and spare B-lymphocytes, may interfere with the deletion of autoreactive T-cell clones, resulting in autoimmune disease.

- Systemic sclerosis: Cold agglutinin disease has been described in patients with sclerodermic features, with the degree of anemia being associated with increasing disease activity of the patient’s systemic sclerosis. This may suggest a close association between systemic rheumatic disease and autoimmune hematologic abnormalities.

- Hyperreactive malarial splenomegaly: Hyperreactive malarial splenomegaly (HMS) is an immunopathologic complication of recurrent malarial infection. Patients with HMS develop splenomegaly, acquired clinical immunity to malaria, high serum concentrations of anti-"Plasmodium" antibodies, and high titers of IgM, with a complement-fixing IgM that acts as a cold agglutinin.

- DPT vaccination: Diphtheria-pertussis-tetanus (DPT) vaccination has been implicated in the development of autoimmune hemolytic anemia caused by IgM autoantibody with a high thermal range. A total of 6 cases have been reported; 2 followed the initial vaccination and 4 followed the second or third vaccinations.

- Other: Equestrian perniosis is a rare cause of persistent elevated titers of cold agglutinins. Also rarely, the first manifestations of cold agglutinin disease can develop when a patient is subjected to hypothermia for cardiopulmonary bypass surgery.

Vaccination

There is one intra-nasal FIP vaccine available: its use is controversial but in an independent study the authors concluded that vaccination can protect cats with no or low FCoV antibody titres and that in some cats vaccine failure was probably due to pre-existing infection.

Prevention of FCoV infection, and therefore FIP, in kittens

Kittens are protected from infection by maternally derived antibody until it wanes, usually around 5–7 weeks of age, therefore it is possible to prevent infection of kittens by removing them from sources of infection. However, FCoV is a very contagious virus and such prevention does require rigorous hygiene.

Cold agglutinins, or cold autoantibodies, occur naturally in nearly all individuals. These natural cold autoantibodies occur at low titers, less than 1:64 measured at 4 °C, and have no activity at higher temperatures. Pathologic cold agglutinins occur at titers over 1:1000 and react at 28-31 °C and sometimes at 37 °C.

Cold agglutinin disease usually results from the production of a specific IgM antibody directed against the I/i antigens (precursors of the ABH and Lewis blood group substances) on red blood cells (RBCs). Cold agglutinins commonly have variable heavy-chain regions encoded by VH, with a distinct idiotype identified by the 9G4 rat murine monoclonal antibody.

Inflammation can spread to other parts of the gut in patients with typhlitis. The condition can also cause the cecum to become distended and can cut off its blood supply. This and other factors can result in necrosis and perforation of the bowel, which can cause peritonitis and sepsis.

Historically, the mortality rate for typhlitis was as high as 50%, mostly because it is frequently associated with bowel perforation. More recent studies have demonstrated better outcomes with prompt medical management, generally with resolution of symptoms with neutrophil recovery without death

The go-to immunosuppressive drug in FIP is prednisolone.

An experimental polyprenyl immunostimulant (PI) is manufactured by Sass and Sass and tested by Dr. Al Legendre, who described survival over 1 year in three cats diagnosed with FIP and treated with the medicine. In a subsequent field study of 60 cats with non-effusive FIP treated with PI, 52 cats (87%) died before 200 days, but eight cats survived over 200 days from the start of PI treatment for and four of those survived beyond 300 days. There are anecdotal reports on the internet of cats surviving even longer.

Although CPH is often compared to cluster headaches, it is much less prevalent, occurring in only 1–3% of those who experience cluster headaches. CPH occurs roughly in 1 in 50,000 people, while cluster headaches are comparatively more common and are found in 1 in 1000 people.

Cluster headaches occur primarily in men, while CPH is more commonly diagnosed in women. The female to male ratio of diagnosed patients can range anywhere from 1.6:1 to 2.36:1. Symptoms may begin to appear at any age, but onset usually occurs in adulthood with a mean starting age within the thirties.

Streptococcus species are the cause of opportunistic infections in poultry leading to acute and chronic conditions in affected birds. Disease varies according to the Streptococcal species but common presentations include septicaemia, peritonitis, salpingitis and endocarditis.

Common species affecting poultry include:

- "S. gallinaceus" in broiler chickens

- "S. gallolyticus" which is a pathogen of racing pigeons and turkey poults

- "S. dysgalactiae" in broiler chickens

- "S. mutans" in geese

- "S. pluranimalium" in broiler chickens

- "S. equi subsp. zooepidemicus" in chickens and turkeys

- "S. suis" in psittacine birds

The prevalence of migraine and vertigo is 1.6 times higher in 200 dizziness clinic patients than in 200 age- and sex-matched controls from an orthopaedic clinic. Among the patients with unclassified or idiopathic vertigo, the prevalence of migraine was shown to be elevated. In another study, migraine patients reported 2.5 times more vertigo and also 2.5 more dizzy spells during headache-free periods than the controls.

MAV may occur at any age with a female:male ratio of between 1.5 and 5:1. Familial occurrence is not uncommon. In most patients, migraine headaches begin earlier in life than MAV with years of headache-free periods before MAV manifests.

In a diary study, the 1-month prevalence of MAV was 16%, frequency of MAV was higher and duration longer on days with headache, and MAV was a risk factor for co-morbid anxiety.

Acquired hemolytic anemia can be divided into immune and non-immune mediated forms of hemolytic anemia.

A ten-patient study conducted by Pareja et al. found that all patients diagnosed with CPH were responsive to indomethacin and were able to completely control their symptoms. Doses of the drug ranged from 25 mg per day to 150 mg per day with a median dose of 75 mg per 24-hour period.

Almost all cases of CPH respond positively and effectively to indometacin, but as much as 25 percent of patients discontinued use of the drug due to adverse side effects, namely complications in the gastrointestinal tract.

According to a case study by Milanlioglu et al., 100mg of lamotrigine, an antiepileptic drug, administered twice daily alleviated all painful symptoms. No side effects were noted after two months of treatment. Dosage of lamotrigine was decreased to 50mg a day after the first two months, and no symptoms or side-effects were recorded after a three-month followup.

Use of topiramate has also been found to be an effective treatment for CPH, but cluster headache medications have been found to have little effect.

The condition is usually caused by Gram-positive enteric commensal bacteria of the gut (gut flora). "Clostridium difficile" is a species of Gram-positive bacteria that commonly causes severe diarrhea and other intestinal diseases when competing bacteria are wiped out by antibiotics, causing pseudomembranous colitis, whereas Clostridium septicum is responsible for most cases of neutropenic enterocolitis.

Typhlitis most commonly occurs in immunocompromised patients, such as those undergoing chemotherapy, patients with AIDS, kidney transplant patients, or the elderly.

Clostridial necrotizing enteritis (CNE), also called enteritis necroticans and pigbel, is an often fatal type of food poisoning caused by a β-toxin of "Clostridium perfringens", Type C. It occurs in some developing countries, but was also documented in Germany following World War II. The toxin is normally inactivated by certain proteolytic enzymes and by normal cooking, but when these protections are impeded, the disease emerges.

The papules characteristic for this disease develop due to infractions, or blockages in small-medium arteries and veins. The underlying cause is unknown for this disease. Though not confirmed, some cases have shown signs of inheritance between first-degree relatives. It has been suggested that the disease has a familial inheritance pattern; it is thought to be an autosomal dominant disorder. In most cases of familial inheritance, the benign variant of the disease has been present.

Due to the lack of knowledge of the pathomechanism for this condition prevention strategies are not known. However, in order to prevent worsening of symptoms, consistent evaluations should be conducted by a physician.

In general, AIHA in children has a good prognosis and is self-limiting. However, if it presents within the first two years of life or in the teenage years, the disease often follows a more chronic course, requiring long-term immunosuppression, with serious developmental consequences. The aim of therapy may sometimes be to lower the use of steroids in the control of the disease. In this case, splenectomy may be considered, as well as other immunosuppressive drugs. Infection is a serious concern in patients on long-term immunosuppressant therapy, especially in very young children (less than two years).

Non-immune mediated hemolytic anemia (direct Coombs test is negative)

- Drugs (i.e., some drugs and other ingested substances lead to hemolysis by direct action on RBCs, e.g., ribavirin )

- Toxins (e.g., snake venom; plant poisons such as aesculin)

- Trauma

- Mechanical (from heart valves, extensive vascular surgery, microvascular disease, repeated mechanical vascular trauma)

- Microangiopathic hemolytic anemia (a specific subtype with causes such as TTP, HUS, DIC and HELLP syndrome)

- Infections (Note: Direct Coombs test is sometimes positive in hemolytic anemia due to infection)

- Malaria

- Babesiosis

- Septicemia

- Membrane disorders

- Paroxysmal nocturnal hemoglobinuria (rare acquired clonal disorder of red blood cell surface proteins)

- Liver disease

The organism should be cultured and antibiotic sensitivity should be determined before treatment is started. Amoxycillin is usually effective in treating streptococcal infections.

Biosecurity protocols and good hygiene are important in preventing the disease.

Vaccination is available against "S. gallolyticus" and can also protect pigeons.

CNE is a necrotizing inflammation of the small bowel (especially the jejunum but also the ileum). Clinical results may vary from mild diarrhea to a life-threatening sequence of severe abdominal pain, vomiting, bloody stool, ulceration of the small intestine with leakage (perforation) into the peritoneal cavity and possible death within a single day due to peritonitis. Many patients exhibit meteorism. Treatment involves suppressing the toxin-producing organisms with antibiotics such as penicillin G or metronidazole. About half of seriously ill patients require surgery for perforation, persistent intestinal obstruction, or failure to respond to the antibiotics. An investigational toxoid vaccine has been used successfully in some developing countries but is not available outside of research.

Although this disease has been known for around 70 years, the pathomechanism underlying it is still unknown. Several hypotheses have been developed regarding the underlying mechanism for Degos disease. One theory suggests that inflammation of blood vessels may trigger development of the condition. Another theory has to do with Degos disease as a coagulopathy. Development of a thrombus and resulting reduction of blood flow is common in this condition. A reduction in blood flow throughout the body can lead to damaged endothelial cells and may perhaps lead to the formation of the characteristic papules. Another hypothesis suggests that abnormal swelling and proliferation of the vascular endothelium can lead to intestinal and central nervous system thrombosis, and ultimately lead to development of symptoms associated with Degos disease. Overall, individuals with Degos disease have abnormal blockages in their arteries and veins; however, the cause of these blockages is unknown.

Benign paroxysmal vertigo of childhood is an uncommon neurological disorder which presents with recurrent episodes of dizziness. The presentation is usually between the ages of 2 years and 7 years of age and is characterised by short episodes of vertigo of sudden onset when the child appears distressed and unwell. The child may cling to something or someone for support. The episode lasts only minutes and resolves suddenly and completely. It is a self-limiting condition and usually resolves after about eighteen months, although many go on to experience migrainous vertigo (or vertiginous migraine) when older.

Benign paroxysmal vertigo of childhood is a migrainous phenomenon with more than 50% of those affected having a family history of migraines affecting a first-degree relative. It has no relationship to benign paroxysmal positional vertigo which is a different condition entirely.

Benign paroxysmal torticollis disappears in the early years of life with no medical intervention.

However, some cases of benign paroxysmal torticollis cases can evolve into benign paroxysmal vertigo of childhood, migrainous vertigo or typical migraines.

The cause of benign paroxysmal torticollis in infants is thought to be migrainous. More than 50% of infants have a family history of migraine in first degree relatives. The cause is likely to be genetic.

Treatment of migraine-associated vertigo is the same as the treatment for migraine in general.

Trigeminal autonomic cephalgia (TAC) is the name for a type of primary headache that occurs with pain on one side of the head in the trigeminal nerve area and symptoms in autonomic systems on the same side, such as eye watering and redness or drooping eyelids. TACs include

- Cluster headache

- Paroxysmal hemicrania (chronic or episodic)

- Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)

- Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA)

- Long-lasting autonomic symptoms with hemicrania (LASH)

TACs can be differentiated by the length and frequency of recurrence of the headaches.

Treatment for TACs varies depending on the exact type, but can include medication such as Indomethacin (in the case of chronic paroxysmal hemicrania) or acute and prophylactic therapy (in the case of cluster headache).