Among individuals being treated in intensive care units, the mortality rate is about 30-50% when systemic candidiasis develops.

"Candida" yeasts are generally present in healthy humans, frequently part of the human body's normal oral and intestinal flora, and particularly on the skin; however, their growth is normally limited by the human immune system and by competition of other microorganisms, such as bacteria occupying the same locations in the human body.

"Candida" requires moisture for growth, notably on the skin. For example, wearing wet swimwear for long periods of time is believed to be a risk factor. In extreme cases, superficial infections of the skin or mucous membranes may enter into the bloodstream and cause systemic "Candida" infections.

Factors that increase the risk of candidiasis include HIV/AIDS, mononucleosis, cancer treatments, steroids, stress, antibiotic usage, diabetes, and nutrient deficiency. Hormone replacement therapy and infertility treatments may also be predisposing factors. Treatment with antibiotics can lead to eliminating the yeast's natural competitors for resources in the oral and intestinal flora; thereby increasing the severity of the condition. A weakened or undeveloped immune system or metabolic illnesses are significant predisposing factors of candidiasis. Almost 15% of people with weakened immune systems develop a systemic illness caused by "Candida" species. Diets high in simple carbohydrates have been found to affect rates of oral candidiases.

"C. albicans" was isolated from the vaginas of 19% of apparently healthy women, i.e., those who experienced few or no symptoms of infection. External use of detergents or douches or internal disturbances (hormonal or physiological) can perturb the normal vaginal flora, consisting of lactic acid bacteria, such as lactobacilli, and result in an overgrowth of "Candida" cells, causing symptoms of infection, such as local inflammation. Pregnancy and the use of oral contraceptives have been reported as risk factors. Diabetes mellitus and the use of antibiotics are also linked to increased rates of yeast infections.

In penile candidiasis, the causes include sexual intercourse with an infected individual, low immunity, antibiotics, and diabetes. Male genital yeast infections are less common, but a yeast infection on the penis caused from direct contact via sexual intercourse with an infected partner is not uncommon.

Causes

Esophagitis cannot be spread. However, infections can be spread by those who have infectious esophagitis. Esophagitis can develop due to many causes. GERD is the most common cause of esophagitis because of the backflow of acid from the stomach, which can irritate the lining of the esophagus.

Other causes include:

- Medicines- Can cause esophageal damage that can lead to esophageal ulcers

- Nonsteroidal anti-inflammatory drugs (NSAIDS)-aspirin, naproxen sodium, and ibuprofen. Known to irritate the GI tract.

- Antibiotics- doxycycline and tetracycline

- Quinidine

- Biphosphonates- used to treat osteoporosis

- Steroids

- Potassium chloride

- Chemical injury by alkaline or acid solutions

- Physical injury resulting from nasogastric tubes.

- Alcohol abuse- Can wear down the lining of the esophagus.

- Crohn's disease – a type of IBD and an autoimmune disease that can cause esophagitis if it attacks the esophagus.

- Stress- Can cause higher levels of acid reflux

- Radiation therapy-Can affect the immune system.

- Allergies (food, inhalants)- Allergies can stimulate eosinophilic esophagitis.

- Infection-People with an immunodeficiencies have a higher chance of developing esophagitis.

- Vitamins and supplements (iron, Vitamin C, and potassium)-Supplements and minerals can be hard on the GI tract.

- Vomiting- Acid can irritate esophagus.

- Hernias-A hernia can poke through the diaphragm muscle and can inhibit the stomach acid and food from draining quickly.

- Surgery

Prevention

Since there can be many causes underlying esophagitis, it is important to try to find the cause to help to prevent esophagitis. To prevent reflux esophagitis, avoid acidic foods, caffeine, eating before going to bed, alcohol, fatty meals, and smoking. To prevent drug-induced esophagitis, drink plenty of liquids when taking medicines, take an alternative drug, and do not take medicines while lying down, before sleeping, or too many at one time. Esophagitis is more prevalent in adults and does not discriminate.

Esophageal candidiasis is an opportunistic infection of the esophagus by "Candida albicans". The disease usually occurs in patients in immunocompromised states, including post-chemotherapy and in AIDS. However, it can also occur in patients with no predisposing risk factors, and is more likely to be asymptomatic in those patients. It is also known as candidal esophagitis or monilial esophagitis.

Reflux esophagitis

A backflow of stomach acids into the esophagus that causes irritation, chronic inflammation, and tissue damage in the esophagus.

Infectious esophagitis

Esophagitis that happens due to a viral, fungal, parasitic or bacterial infection. More likely to happen to people who have an immunodeficiency. Types include:

Fungal

- Candida (Esophageal candidiasis)

Viral

- Herpes simplex (Herpes esophagitis)

- Cytomegalovirus

Drug-induced esophagitis

Damage to the esophagus due to medications. If the esophagus is not coated or if the medicine is not taken with enough liquid, it can damage the tissues.

Eosinophilic esophagitis

This esophagitis is caused by a high concentration of eosinophils in the esophagus. The presence of eosinophils in the esophagus may be due to an allergen or acid reflux. This esophagitis can be triggered by allergies to food or to inhaled allergens. This type is still poorly understood.

Lymphocytic esophagitis

Lymphocytic esophagitis is when there is an increased amount of lymphocytes in the lining of the esophagus. It is a rare condition. It could be connected to eosinophilic esophagitis.

The current first-line treatment is fluconazole, 200 mg. on the first day, followed by daily dosing of 100 mg. for at least 21 days total. Treatment should continue for 14 days after relief of symptoms.

Other therapy options include:

- nystatin is not an effective treatment for esophageal candidiasis. It can be used as (swish, do not swallow) treatment for oral candidiasis that occurs with the use of asthma pumps.

- other oral triazoles, such as itraconazole

- caspofungin, used in refractory or systemic cases

- amphotericin, used in refractory or systemic cases

Herpes esophagitis is a viral infection of the esophagus caused by "Herpes simplex virus" (HSV).

While the disease most often occurs in immunocompromised patients, including post-chemotherapy, immunosuppression with organ transplants and in AIDS, herpes esophagitis can also occur in immunocompetent individuals.

Herpes simplex virus is commonly found in humans, yet uncommonly results in systemic manifestations. Suppression of HIV with antiretroviral medications, careful monitoring of immunosuppressive medications are important means of prevention. Antiviral prophylaxis such as daily acyclovir in immunocompromised individuals may be considered.

Cytomegalovirus esophagitis is a form of esophagitis associated with cytomegalovirus.

It is likely to present with a single, deep ulcer as opposed to the multiple shallow ulcers seen in herpes esophagitis.

Though it is widely held that fungal infections of the nose and paranasal sinuses are not common, most agree that their frequency has been increasing over past decades.

Fungal sinusitis is the inflammation of the lining mucosa of the paranasal sinuses due to fungal infection. It occurs in people with reduced immunity. The maxillary sinus is the most commonly involved. Fungi responsible for fungal sinusitis are "Aspergillus fumigatus" (90%), "Aspergillus flavus", and "Aspergillus niger". Fungal sinusitis occurs most commonly in middle-aged populations. Diabetes mellitus is the most common risk factor involved.

Otomycosis is treated by debridment followed with topical azole antifungals, and symptomatically managed with oral antihistamines. Per a study in Iran 10cc acetic acid 2% plus 90 cc of isopropyl alcohol 70% was effective.

Systemic mycoses due to opportunistic pathogens are infections of patients with immune deficiencies who would otherwise not be infected. Examples of immunocompromised conditions include AIDS, alteration of normal flora by antibiotics, immunosuppressive therapy, and metastatic cancer. Examples of opportunistic mycoses include Candidiasis, Cryptococcosis and Aspergillosis.

Systemic mycoses due to primary pathogens originate primarily in the lungs and may spread to many organ systems. Organisms that cause systemic mycoses are inherently virulent. In general primary pathogens that cause systemic mycoses are dimorphic.

Otomycosis is a fungal ear infection, a superficial mycotic infection of the outer ear canal. It is more common in the tropical countries. The infection may be either subacute or acute and is characterized by malodorous discharge, inflammation, pruritus, scaling, and severe discomfort. Suppuration can occur due to superimposed bacterial infection commonly due to pseudomonas species and proteus species. The mycosis results in inflammation, superficial epithelial exfoliation, masses of debris containing hyphae, suppuration, and pain.

The incidence of otitis externa is high. In the Netherlands, it has been estimated at 12–14 per 1000 population per year, and has been shown to affect more than 1% of a sample of the population in the United Kingdom over a 12-month period.

It can also be caused by certain medical conditions, such as:

- Ulcers

- Abscesses

- Upper respiratory tract infections

- Inflammation or infection of the mouth, tongue, or throat (esophagitis, pharyngitis, tonsillitis, epiglottitis)

- Immune disorders

- Oral or throat cancer

EoE is a relatively poorly understood disease of which awareness is rising.

At a tissue level, EoE is characterized by a dense infiltrate with white blood cells of the eosinophil type into the epithelial lining of the esophagus. This is thought to be an allergic reaction against ingested food, based on the important role eosinophils play in allergic reactions. Eosinophils are inflammatory cells that release a variety of chemical signals which inflame the surrounding esophageal tissue. This results in the signs and symptoms of pain, visible redness on endoscopy, and a natural history that may include stricturing.

Gastroesophageal reflux disease (GERD) affects approximately 40% of adults. Strictures occur in 7 to 23% of patients with GERD who are untreated.

Filamentous fungi

- Aspergillus flavus

- Aspergillus fumigatus

- Fusarium spp.

- Alternaria spp.

- Curvularia

- Acremonium

Yeasts

- Candida

Fusarium spp. is most common then Aspergillus spp. and thirdly Dematitious fungi causing fungal keratitis in India.

Treatment strategies may include medication, dietary modification to exclude food allergens, and mechanical dilatation of the esophagus.

The current recommendation for first line treatment is PPI in lieu of diet as more than half of people with EOE respond to this, and it is a low risk, low cost treatment. The next step treatment is topical corticosteroids (topical viscous budesonide or fluticasone).

Dietary treatment can be effective, as there does appear to be a role of allergy in the development of EOE. Allergy testing is not particularly effective in predicting which foods are driving the disease process. Various approaches have been tried, where either six food groups (cow´s milk, wheat, egg, soy, nuts and fish/seafood), four groups (animal milk, gluten-containing cereals, egg, legumes) or two groups (animal milk and gluten-containing cereals) are excluded for a period of time, usually six weeks. Endoscopy is required to measure the response to the dietary measure. A "top down" (starting with six foods, then reintroducing) approach may be very restrictive. Four- or even two-group exclusion diets may be less difficult to follow and reduce the need for many endoscopies if the response to the limited restriction is good.

Endoscopic dilatation is sometimes required if there is significant narrowing of the esophagus. This is effective in 84% of people who require this procedure.

Prevention of trauma with vegetable / organic matter, particularly in agricultural workers while harvesting can reduce the incidence of fungal keratitis. Wearing of broad protective glasses with side shields is recommended for people at risk for such injuries.

A 2003 survey of diseases of the foot in 16 European countries found onychomycosis to be the most frequent fungal foot infection and estimates its prevalence at 27%. Prevalence was observed to increase with age. In Canada, the prevalence was estimated to be 6.48%. Onychomycosis affects approximately one-third of diabetics and is 56% more frequent in people suffering from psoriasis.

No preventive measure is known aside from avoiding the traumatic inoculation of fungi. At least one study found a correlation between walking barefoot in endemic areas and occurrence of chromoblastomycosis on the foot.

As the skull base is progressively involved, the adjacent exiting cranial nerves and their branches, especially the facial nerve and the vagus nerve, may be affected, resulting in facial paralysis and hoarseness, respectively. If both of the recurrent laryngeal nerves are paralyzed, shortness of breath may develop and necessitate tracheotomy. Profound deafness can occur, usually later in the disease course due to relative resistance of the inner ear structures. Gallium scans are sometimes used to document the extent of the infection but are not essential to disease management. Skull base osteomyelitis is a chronic disease that can require months of IV antibiotic treatment, tends to recur, and has a significant mortality rate.