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.

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.

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.

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.

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.

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%.

Fungal meningitis refers to meningitis caused by a fungal infection.

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).

American tick bite fever (also known as ""Rickettsia parkeri" infection") is a condition that may be characterized by a rash of maculopapules.

Vietnamese tuberculosis refers to certain forms of chronic melioidosis that look clinically very similar to tuberculosis. It is derived from the clinical appearance of the disease in American soldiers returning from the Vietnam War.

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.

Sarcoidosis is a disease of unknown cause characterized by non-necrotizing ("non-caseating") granulomas in multiple organs and body sites, most commonly the lungs and lymph nodes within the chest cavity. Other common sites of involvement include the liver, spleen, skin and eyes. The granulomas of sarcoidosis are similar to the granulomas of tuberculosis and other infectious granulomatous diseases. However, in most cases of sarcoidosis, the granulomas do not contain necrosis and are surrounded by concentric scar tissue (fibrosis). Sarcoid granulomas often contain star-shaped structures termed asteroid bodies or lamellar structures termed Schaumann bodies. However, these structures are not specific for sarcoidosis. Sarcoid granulomas can resolve spontaneously without complications or heal with residual scarring. In the lungs, this scarring can cause a condition known as pulmonary fibrosis that impairs breathing. In the heart, it can lead to rhythm disturbances, heart failure, and even death.

Mediastinal fibrosis most common cause is idiopathic mediastinal fibrosis; less commonly histoplasmosis tuberculosis or unknown. It is characterized by invasive, calcified fibrosis centered on lymph nodes that block major vessels and airways. In Europe, this disease is exceptionally rare. More cases are seen

in USA where the disease may often be associated with histoplasmosis.

This syndrome is characterized by an increased susceptibility to disseminated nontuberculous mycobacterial infections, viral infections, especially with human papillomaviruses, and fungal infections, primarily histoplasmosis, and molds. There is profound monocytopenia, B lymphocytopenia and NK lymphocytopenia. Patients have an increased chance of developing malignancies, including: myelodysplasia/leukemia vulvar carcinoma, metastatic melanoma, cervical carcinoma, Bowen disease of the vulva, and multiple Epstein-Barr virus(+) leiomyosarcoma. Patients may also develop pulmonary alveolar proteinosis without mutations in the granulocyte-macrophage colony-stimulating factor receptor or anti-granulocyte-macrophage colony-stimulating factor autoantibodies. Last, patients may develop autoimmune phenomena, including lupus like syndromes, primary biliary cirrhosis or aggressive multiple sclerosis.

Of the 26, now 28, patients probably afflicted by this syndrome, 48% died of causes ranging from cancer to myelodysplasia with a mean age at death of 34.7 years and median age of 36.5 years.

MonoMAC is a rare autosomal dominant syndrome associated with monocytopenia, B and NK cell lymphopenia and mycobacterial, fungal and viral infections. It was first described by Vihn and colleagues in 2010 and is associated with myelodysplasia, cytogenetic abnormalities, pulmonary alveolar proteinosis and myeloid leukemias. Multiple mutations in the GATA2 are considered to be responsible for this syndrome.

American foulbrood (AFB, "Histolysis infectiosa perniciosa larvae apium", "Pestis americana larvae apium"), caused by the spore-forming "Paenibacillus larvae" ssp. "larvae" (formerly classified as "Bacillus larvae"), is the most widespread and destructive of the bee brood diseases.

The most detailed study on the frequency, onset, and duration of MVD clinical signs and symptoms was performed during the 1998–2000 mixed MARV/RAVV disease outbreak. A maculopapular rash, petechiae, purpura, ecchymoses, and hematomas (especially around needle injection sites) are typical hemorrhagic manifestations. However, contrary to popular belief, hemorrhage does not lead to hypovolemia and is not the cause of death (total blood loss is minimal except during labor). Instead, death occurs due to multiple organ dysfunction syndrome (MODS) due to fluid redistribution, hypotension, disseminated intravascular coagulation, and focal tissue necroses.

Clinical phases of Marburg Hemorrhagic Fever's presentation are described below. Note that phases overlap due to variability between cases.

1. Incubation: 2–21 days, averaging 5–9 days.

2. Generalization Phase: Day 1 up to Day 5 from onset of clinical symptoms. MHF presents with a high fever (~40˚C) and a sudden, severe headache, with accompanying chills, fatigue, nausea, vomiting, diarrhea, pharyngitis, maculopapular rash, abdominal pain, conjunctivitis, & malaise.

3. Early Organ Phase: Day 5 up to Day 13. Symptoms include prostration, dyspnea, edema, conjunctival injection, viral exanthema, and CNS symptoms, including encephalitis, confusion, delirium, apathy, and aggression. Hemorrhagic symptoms typically occur late and herald the end of the early organ phase, leading either to eventual recovery or worsening & death. Symptoms include bloody stools, ecchymoses, blood leakage from venipuncture sites, mucosal & visceral hemorrhaging, and possibly hematemesis.

4. Late Organ Phase: Day 13 up to Day 21+. Symptoms bifurcate into two constellations for survivors & fatal cases. Survivors will enter a convalescence phase, experiencing myalgia, fibromyalgia, hepatitis, asthenia, ocular symptoms, & psychosis. Fatal cases continue to deteriorate, experiencing continued fever, obtundation, coma, convulsions, diffuse coagulopathy, metabolic disturbances, shock and death, with death typically occurring between Days 8 and 16.

Affected individuals typically develop symptoms including high fevers, shaking, chills, fatigue, headaches, vomiting, and general illness within 48 hours of the initial infection. The erythematous skin lesion enlarges rapidly and has a sharply demarcated, raised edge. It appears as a red, swollen, warm, and painful rash, similar in consistency to an orange peel. More severe infections can result in vesicles (pox or insect bite-like marks), blisters, and petechiae (small purple or red spots), with possible skin necrosis (death). Lymph nodes may be swollen, and lymphedema may occur. Occasionally, a red streak extending to the lymph node can be seen.

The infection may occur on any part of the skin, including the face, arms, fingers, legs, and toes; it tends to favour the extremities. Fat tissue and facial areas, typically around the eyes, ears, and cheeks, are most susceptible to infection. Repeated infection of the extremities can lead to chronic swelling (lymphangitis).

Gaffkaemia (gaffkemia in American English) is a bacterial disease of lobsters, caused by the Gram-positive lactic acid bacterium Aerococcus viridans" var. "homari.

"Paenibacillus larvae" is a rod-shaped bacterium, which is visible only under a high power microscope. Larvae up to 3 days old become infected by ingesting spores that are present in their food. Young larvae less than 24 hours old are most susceptible to infection. Spores germinate in the gut of the larva and the vegetative form of the bacteria begins to grow, taking its nourishment from the larva. Spores will not germinate in larvae over 3 days old. Infected larvae normally die after their cell is sealed. The vegetative form of the bacterium will die but not before it produces many millions of spores. Each dead larva may contain as many as 100 million spores. This disease only affects the bee larvae but is highly infectious and deadly to bee brood. Infected larvae darken and die.

Parasitic infestations, stings, and bites in humans are caused by several groups of organisms belonging to the following phyla: Annelida, Arthropoda, Bryozoa, Chordata, Cnidaria, Cyanobacteria, Echinodermata, Nemathelminthes, Platyhelminthes, and Protozoa.

- "Acanthamoeba" infection

- Amebiasis cutis

- Ant sting

- Arachnidism

- Baker's itch

- "Balamuthia" infection

- Bedbug infestation (bedbug bite, cimicosis)

- Bee and wasp stings

- Blister beetle dermatitis

- Bombardier beetle burn

- Bristleworm sting

- Centipede bite

- Cheyletiella dermatitis

- Chigger bite

- Coolie itch

- Copra itch

- Coral dermatitis

- Creeping eruption (cutaneous larva migrans)

- Cutaneous leishmaniasis (Aleppo boil, Baghdad boil, bay sore, Biskra button, Chiclero ulcer, Delhi boil, Kandahar sore, Lahore sore, leishmaniasis tropica, oriental sore, "pian bois, uta")

- "Cysticercosis" cutis

- Demodex mite bite

- Dogger Bank itch

- Dracunculiasis (dracontiasis, guinea worm disease, Medina worm)

- Echinococcosis (hydatid disease)

- Elephantiasis tropica (elephantiasis arabum)

- Elephant skin

- Enterobiasis (oxyuriasis, pinworm infection, seatworm infection)

- "Erisipela de la costa"

- Feather pillow dermatitis

- Funnel web spider bite

- Gamasoidosis

- Gnathostomiasis (larva migrans profundus)

- Grain itch (barley itch, mattress itch, prairie itch, straw itch)

- Grocer's itch

- Head lice infestation (cooties, pediculosis capitis)

- Hookworm disease (ancylostomiasis, ground itch, necatoriasis, uncinariasis)

- Human trypanosomiasis

- Hydroid dermatitis

- Irukandji syndrome

- Jellyfish dermatitis

- Ked itch

- Larva currens

- Latrodectism (widow spider bite)

- Leech bite

- Leopard skin

- Lepidopterism (Caripito itch, caterpillar dermatitis, moth dermatitis)

- Lizard bite

- Lizard skin

- Loaiasis (Calabar swelling, fugitive swelling, "loa loa", tropical swelling)

- Loxoscelism (brown recluse spider bite, necrotic cutaneous loxoscelism)

- "Mal morando"

- Millipede burn

- Mosquito bite

- Mucocutaneous leishmaniasis (espundia, leishmaniasis americana)

- Myiasis

- Nairobi fly dermatitis (Kenya fly dermatitis, Nairobi eye)

- Nematode dermatitis

- Norwegian scabies (crusted scabies)

- Onchocerciasis

- Ophthalmia nodosa

- Paederus dermatitis

- Pediculosis corporis (pediculosis vestimenti, Vagabond's disease)

- Pediculosis pubis (crabs, phthirus pubis, pthirus pubis, pubic lice)

- Pneumocystosis (often classified as fungal)

- Portuguese man-of-war dermatitis

- Post-kala-azar dermal leishmaniasis (post-kala-azar dermatosis)

- Protothecosis

- Pulicosis (flea bites)

- Reduviid bite

- Scabies (itch mite infestation, seven-year itch)

- Scorpion sting

- Sea anemone dermatitis

- Seabather's eruption (sea lice)

- Sea urchin injury

- Seaweed dermatitis

- Snake bite

- Sowda

- Sparganosis

- Spider bite

- Stingray injury

- Swimmer's itch (cercarial dermatitis, schistosome cercarial dermatitis)

- Tarantula bite

- Tick bite

- Toxoplasmosis

- Trichinosis

- Trichomoniasis

- Tungiasis ("bicho de pie", chigoe flea bite, jigger bite, "nigua, pique")

- Visceral leishmaniasis (dumdum fever, "kala-azar")

- Visceral schistosomiasis (bilharziasis)

- Viscerotropic leishmaniasis

- Wheat warehouse itch

Many conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. The two main types of human skin are: glabrous skin, the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, the hairs occur in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis. The superficial papillary dermis with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and ground substance. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow). Diagnosis of many conditions often also requires a skin biopsy which yields histologic information that can be correlated with the clinical presentation and any laboratory data.

Hand–Schüller–Christian disease is associated with multifocal Langerhans cell histiocytosis.

It is associated with a triad of exophthalmos, lytic bone lesions (often in the skull), and diabetes insipidus (from pituitary stalk infiltration).

It is named for the US-American pediatrician Alfred Hand Jr, the Austrian neurologist and radiologist Arthur Schüller, and the US-American internist Henry Asbury Christian, who described it in 1893, 1915/16 and 1919