If symptoms of histoplasmosis infection occur, they will start within 3 to 17 days after exposure; the average is 12–14 days. Most affected individuals have clinically silent manifestations and show no apparent ill effects. The acute phase of histoplasmosis is characterized by non-specific respiratory symptoms, often cough or flu-like. Chest X-ray findings are normal in 40–70% of cases. Chronic histoplasmosis cases can resemble tuberculosis; disseminated histoplasmosis affects multiple organ systems and is fatal unless treated.

While histoplasmosis is the most common cause of mediastinitis, this remains a relatively rare disease. Severe infections can cause hepatosplenomegaly, lymphadenopathy, and adrenal enlargement. Lesions have a tendency to calcify as they heal.

Presumed ocular histoplasmosis syndrome (POHS) causes chorioretinitis, where the choroid and retina of the eyes are scarred, resulting in a loss of vision not unlike macular degeneration. Despite its name, the relationship to "Histoplasma" is controversial. Distinct from POHS, acute ocular histoplasmosis may rarely occur in immunodeficiency.

In absence of proper treatment and especially in immunocompromised individuals, complications can arise. These include recurrent pneumonia, respiratory failure, fibrosing mediastinitis, superior vena cava syndrome, pulmonary vessel obstruction, progressive fibrosis of lymph nodes. Fibrosing mediastinitis is a serious complication and can be fatal. Smokers with structural lung disease have higher probability of developing chronic cavitary histoplasmosis.

After healing of lesions, hard calcified lymph nodes can erode the walls of airway causing hemoptysis.

Progressive disseminated histoplasmosis is an infection caused by Histoplasma capsulatum, and most people who develop this severe form of histoplasmosis are immunocompromised or taking systemic corticosteroids. Skin lesions are present in approximately 6% of patients with dissemination.

Pulmonary infection

- Produces a virulent form of pneumonia (progressive)

- Night sweats, fever, cough, chest pain

- Pulmonary nocardiosis is subacute in onset and refractory to standard antibiotherapy

- Symptoms are more severe in immunocompromised individuals

- Radiologic studies show multiple pulmonary infiltrates with tendency to central necrosis

Neurological infection

- Headache, lethargy, confusion, seizures, sudden onset of neurological deficit

- CT scan shows cerebral abscess

- Nocardial meningitis is difficult to diagnose

Cardiac conditions

- Nocardia has been highly linked to endocarditis as a main manifestation

- In recorded cases, it has caused damage to heart valves whether natural or prosthetic

Lymphocutaneous disease

- Nocardial cellulitis is akin to erysipelas but is less acute

- Nodular lymphangeitis mimics sporotrichosis with multiple nodules alongside a lymphatic pathway

- Chronic subcutaneous infection is a rare complication and osteitis may ensue

- May be misidentified and treated for as a staph infection, specifically superficial skin infections

- Cultures must sit more than 48 hours to guarantee an accurate test

Ocular disease

- Very rarely nocardiae cause keratitis

- Generally there is a history of ocular trauma

Disseminated nocardiosis

- Dissemination occurs through the spreading enzymes possessed by the bacteria

- Disseminated infection can occur in very immunocompromised patients

- It generally involves both lungs and brain

- Fever, moderate or very high can be seen

- Multiple cavitating pulmonary infiltrates develop

- Cerebral abscesses arise later

- Cutaneous lesions are very rarely seen

- If untreated, the prognosis is poor for this form of disease

Nocardiosis is an infectious disease affecting either the lungs ("pulmonary nocardiosis") or the whole body ("systemic nocardiosis"). It is due to infection by bacterium of the genus Nocardia, most commonly "Nocardia asteroides" or "Nocardia brasiliensis".

It is most common in men, especially those with a weakened immune system. In patients with brain infection, mortality exceeds 80%; in other forms, mortality is 50%, even with appropriate therapy.

It is one of several conditions that have been called the great imitator. Cutaneous nocardiosis commonly occurs in immunocompetent hosts.

Systemic candidiasis is an infection of Candida albicans causing disseminated disease and sepsis, invariably when host defenses are compromised.

Fungal meningitis refers to meningitis caused by a fungal infection.

Mendelian susceptibility to mycobacterial disease, also called familial disseminated atypical mycobacterial infection, is a rare genetic disease characterized by susceptibility to mycobacteria and Salmonella infection outside of the intestinal tract.

Blastomycosis can present in one of the following ways:

- a flu-like illness with fever, chills, arthralgia (joint pain), myalgia (muscle pain), headache, and a nonproductive cough which resolves within days.

- an acute illness resembling bacterial pneumonia, with symptoms of high fever, chills, a productive cough, and pleuritic chest pain.

- a chronic illness that mimics tuberculosis or lung cancer, with symptoms of low-grade fever, a productive cough, night sweats, and weight loss.

- a fast, progressive, and severe disease that manifests as ARDS, with fever, shortness of breath, tachypnea, hypoxemia, and diffuse pulmonary infiltrates.

- skin lesions, usually asymptomatic, can be verrucous (wart-like) or ulcerated with small pustules at the margins.

- bone lytic lesions can cause bone or joint pain.

- prostatitis may be asymptomatic or may cause pain on urinating.

- laryngeal involvement causes hoarseness.

- 40% immunocompromised individuals have CNS involvement and present as brain abscess, epidural abscess or meningitis.

Symptoms of fungal meningitis are generally similar to those of other types of meningitis, and include: a fever, stiff neck, severe headache, photophobia (sensitivity to light), nausea and vomiting, and altered mental status (drowsiness or confusion).

Disseminated disease refers to a diffuse disease-process, generally either infectious or neoplastic. The term may sometimes also characterize connective tissue disease.

A disseminated infection, for example, has extended beyond its origin or nidus and involved the bloodstream to "seed" other areas of the body. Similarly, one can view metastatic cancer as a disseminated infection in that it has extended into the bloodstream or into the lymphatic system and thus "seeded" distant sites (a process known as metastasis).

Disseminated disease often contrasts localized disease.

As in the majority of paracoccidioidomycosis cases, pulmonary involvement results in shortness of breath, a productive cough and hemoptysis, as well as general symptoms of weight loss, fever and fatigue. Visually, lesions (as pictured) are often present, most commonly on the face.

Eczema herpeticum is a rare but severe disseminated infection that generally occurs at sites of skin damage produced by, for example, atopic dermatitis, burns, long term usage of topical steroids or eczema. It is also known as Kaposi varicelliform eruption, Pustulosis varioliformis acute and Kaposi-Juliusberg dermatitis.

Some sources reserve the term "eczema herpeticum" when the cause is due to human herpes simplex virus, and the term "Kaposi varicelliform eruption" to describe the general presentation without specifying the virus.

This condition is most commonly caused by herpes simplex virus type 1 or 2, but may also be caused by coxsackievirus A16, or vaccinia virus. It appears as numerous umbilicated vesicles superimposed on healing atopic dermatitis. it is often accompanied by fever and lymphadenopathy. Eczema herpeticum can be life-threatening in babies.

Paracoccidioidomycosis (PCM) (also known as "Brazilian blastomycosis," "South American blastomycosis,","Lutz-Splendore-de Almeida disease" and "paracoccidioidal granuloma") is a fungal infection caused by the fungus "Paracoccidioides brasiliensis". Sometimes called "South American blastomycosis", paracoccidioidomycosis is caused by a different fungus than that which causes blastomycosis.

Blastomycosis manifests as a primary lung infection in about 70% of cases. The onset is relatively slow and symptoms are suggestive of pneumonia, often leading to initial treatment with antibacterials. Occasionally, if a lesion is seen on X-ray in a cigarette smoker, the disease may be misdiagnosed as carcinoma, leading to swift excision of the pulmonary lobe involved. Upper lung lobes are involved somewhat more frequently than lower lobes. If untreated, many cases progress over a period of months to years to become disseminated blastomycosis. In these cases, the large Blastomyces yeast cells translocate from the lungs and are trapped in capillary beds elsewhere in the body, where they cause lesions. The skin is the most common organ affected, being the site of lesions in approximately 60% of cases. The signature image of blastomycosis in textbooks is the indolent, verrucous or ulcerated dermal lesion seen in disseminated disease. Osteomyelitis is also common (12–60% of cases). Other recurring sites of dissemination are the genitourinary tract (kidney, prostate, epididymis; collectively ca. 25% of cases) and the brain (3–10% of cases).

An uncommon but very dangerous type of primary blastomycosis manifests as acute respiratory distress syndrome (ARDS); for example, this was seen in 9 of 72 blastomycosis cases studied in northeast Tennessee. Such cases may follow massive exposure, e.g., during brush clearing operations. The fatality rate in the ARDS cases in the Tennessee study was 89%, while in non-ARDS cases of pulmonary blastomycosis, the fatality rate was 10%.

African histoplasmosis is an infection caused by "Histoplasma duboisii". Disease has been most often reported in Uganda, Nigeria, Zaire and Senegal. In human disease it manifests differently than histoplasmosis (caused by "Histoplasma capsulatum"), most often involving the skin and bones and rarely involving the lungs.

Dermatophytids are fungus-free disseminated skin lesions resulting from induced sensitization in patients with ringworm infections.

The most common dermatophytid is an inflammation in the hands resulting from a fungus infection of the feet. Dermatophytids normally disappear when the primary ringworm infection is treated.

Dermatophytids may resemble erythema nodosum.

Gonococcemia (also known as "Arthritis–dermatosis syndrome" and "Disseminated gonococcal infection") is a condition characterized by a hemorrhagic vesiculopustular eruption, bouts of fever, and arthralgia or actual arthritis of one or several joints.

It's characterized by a triad of symptoms: migratory polyarthritis, tenosynovitis, and dermatitis (pustular skin lesions).

A localized disease is an infectious or neoplastic process that originates in and is confined to one organ system or general area in the body, such as a sprained ankle, a boil on the hand, an abscess of finger.

A localized cancer that has not extended beyond the margins of the organ involved can also be described as localized disease, while cancers that extend into other tissues are described as invasive. Tumors that are non-hematologic in origin but extend into the bloodstream or lymphatic system are known as metastatic.

Localized diseases are contrasted with disseminated diseases and systemic diseases.

Some diseases are capable of changing from local to disseminated diseases. Pneumonia, for example, is generally confined to one or both lungs but can become disseminated through sepsis, in which the microbe responsible for the pneumonia "seeds" the bloodstream or lymphatic system and is transported to distant sites in the body. When that occurs, the process is no longer described as a localized disease, but rather as a disseminated disease.

Pneumocystis infection in the lungs is usually not associated with granulomas, but rare cases are well documented to cause granulomatous inflammation. The diagnosis is established by finding Pneumocystis yeasts within the granulomas on lung biopsies.

"Listeria monocytogenes" infection in infants can cause potentially fatal disseminated granulomas, called granulomatosis infantiseptica, following "in utero" infection.

This infection affects multiple organs, including the eyes, brain, lung, and liver, and can be fatal.

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.

An estimated 60% of people infected with the fungi responsible for coccidioidomycosis have minimal to no symptoms, while 40% will have a range of possible clinical symptoms. Of those who do develop symptoms, the primary infection is most often respiratory, with symptoms resembling bronchitis or pneumonia that resolve over a matter of a few weeks. In endemic regions, coccidioidomycosis is responsible for 20% of cases of community-acquired pneumonia. Notable coccidioidomycosis signs and symptoms include a profound feeling of tiredness, fever, cough, headaches, rash, muscle pain, and joint pain. Fatigue can persist for many months after initial infection. The classic triad of coccidioidomycosis known as "desert rheumatism" includes the combination of fever, joint pains, and erythema nodosum.

Nearly 3% to 5% of infected individuals do not recover from the initial acute infection and develop a chronic infection. This can take the form of chronic lung infection or widespread disseminated infection (affecting the tissues lining the brain, soft tissues, joints, and bone). Chronic infection is responsible for most of the morbidity and mortality. Chronic fibrocavitary disease is manifested by cough, sputum, fevers, night sweats and weight loss. Osteomyelitis, including involvement of the spine, and meningitis which may occur months to years after initial infection. Severe lung disease may develop in HIV-infected persons.

Papular mucinosis is chronic and may be progressive. The dermal layer of the skin breaks out into small and solid bumps, usually conical in shape and measured from 2 to 4 mm or sometimes flat-topped papules. Unlike pustules, these bumps do not contain pus. Instead they contain mucin, a substance of mucus, the body's natural and protective lubricant found in saliva and epithelial cells in lungs and the sensitive part of the nose. They usually come in clusters such as linear arrays. Less frequently, urticarial, nodular, or sometimes annular lesions may be appreciated. The dorsal aspect of the hands, face, elbows, and extensor portions of the extremities are most frequently affected. Mucosal lesions are absent. The coalescence of papules on the face, particularly on the glabella, results in longitudinal folding and gives the appearance of a leonine facies.

In scleromyxedema, symptoms can occur on larger part of the body. Erythema and scleroderma-like induration occurs on the skin. In addition, the mobility of the lips, hands, arms, and legs is reduced. Proximal myopathy, inflammatory polyarthritis, central nervous system symptoms, esophageal aperistalsis, and hoarseness are among the notable systemic symptoms. If viscera is involved, the disease will be fatal. The dermatoneuro syndrome is a rare neurological complication of the disease presenting with fever, seizures and altered mental status.