Frequently asymptomatic. Gastrointestinal system symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Löffler's syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas as well as larva currens. Eosinophilia is generally present.

Strongyloidiasis can become chronic and then become completely asymptomatic.

Strongyloides infection occurs in five forms. On acquiring the infection, there may be respiratory symptoms (Löffler's syndrome). The infection may then become chronic with mainly digestive symptoms. On reinfection (when larvae migrate through the body), there may be respiratory, skin and digestive symptoms. Finally, the hyperinfection syndrome causes symptoms in many organ systems, including the central nervous system.

The infection causes a red, intensely pruritic (itchy) eruption. The itching can become very painful and if scratched may allow a secondary bacterial infection to develop. Cutaneous larva migrans usually heals spontaneously over weeks to months and has been known to last as long as one year. However, the severity of the symptoms usually causes those infected to seek medical treatment before spontaneous resolution occurs. Following proper treatment, migration of the larvae within the skin is halted and relief of the associated itching can occur in less than 48 hours (reported for thiabendazole).

This is separate from the similar cutaneous larva currens which is caused by "Strongyloides". Larva currens is also a cause of migratory pruritic eruptions but is marked by 1) migratory speed on the order of inches per hour 2) perianal involvement due to autoinfection from stool and 3) a wide band of urticaria.

Cutaneous larva migrans (abbreviated CLM) is a skin disease in humans, caused by the larvae of various nematode parasites of the hookworm family (Ancylostomatidae). The most common species causing this disease in the Americas is "Ancylostoma braziliense". These parasites live in the intestines of dogs, cats, and wild animals and should not be confused with other members of the hookworm family for which humans are definitive hosts, namely "Ancylostoma duodenale" and "Necator americanus".

Colloquially called creeping eruption due to its presentation, the disease is also somewhat ambiguously known as "ground itch" or (in some parts of the Southern USA) "sandworms", as the larvae like to live in sandy soil. Another vernacular name is plumber's itch. The medical term CLM literally means "wandering larvae in the skin".

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

Mucocutaneous leishmaniasis is an especially disturbing form of cutaneous leishmaniasis, because it produces destructive and disfiguring lesions of the face. It is most often caused by "Leishmania braziliensis", but cases caused by "L. aethiopica" have also been described.

Mucocutaneous leishmaniasis is very difficult to treat. Treatment involves the use of pentavalent antimonial compounds, which are highly toxic (common side effects include thrombophlebitis, pancreatitis, cardiotoxicity and hepatotoxicity) and not very effective. For example, in one study, despite treatment with high doses of sodium stibogluconate for 28 days, only 30% of patients remained disease-free at 12 months follow-up. Even in those patients who achieve an apparent cure, as many as 19% will relapse. Several drug combinations with immunomodulators have been tested, for example, a combination of pentoxifylline (inhibitor of TNF-α) and a pentavalent antimonial at a high dose for 30 days in a small-scale (23 patients) randomised placebo-controlled study from Brazil achieved cure rates of 90% and reduced time to cure, a result that should be interpreted cautiously in light of inherent limitations of small-scale studies. In an earlier small-scale (12 patients) study, addition of imiquimod showed promising results which need yet to be confirmed in larger trials.

Post-kala-azar dermal leishmaniasis (PKDL) is a recurrence of kala-azar that may appear on the skin of affected individuals months and up to 20 years after being partially treated, untreated or even in those considered adequately treated. In Sudan, they can be demonstrated in up to 60% of treated cases. They manifest as hypopigmented skin lesions (such as macules, papules, nodules), or facial redness. Though any organism causing kala-azar can lead to PKDL, it is commonly associated with "Leishmania donovani" which gives different disease patterns in India and Sudan. In the Indian variant, nodules enlarge with time and form plaques but rarely ulcerate, but nodules from the African variety often ulcerate as they progress. Nerve involvement is common in African variety but rare in Indian subcontinent. Histology demonstrates a mixture of chronic inflammatory cells; there can be macrophage or epitheloid granuloma. Parasite concentration is not consistent among studies, perhaps reflecting low sensitivity of diagnostic methods used in earlier entries.

Current approach to diagnosis involves 1. demonstration of parasite by microscopy, "in vitro" culture or animal inoculation; 2. immunodiagnosis of parasite antigen; 3. detection of parasite DNA in tissue. Newer PCR based tools have higher sensitivity and specificity. Emergence of PKDL has been reported in HIV affected individuals and may become a problem in future.

Sodium stibogluconate alone or in combination with rifampicin is used for the treatment of PKDL for a long course of up to 4 months. Compliance can be an issue for such a long course.

Because the TVC's entry point usually is the site of a trauma, wound or puncture in the skin (during an autopsy, for example), the most frequent site for the wart are the hands. But it can occur anywhere in the skin, such as in the sole of the feet, in the anus, and, in the case of children from developing countries, in the buttocks and knees. This is because children from countries of high incidence of tuberculosis can contract the lesion after contact with tuberculous sputum, by walking barefoot, sitting or playing on the ground.

When recent, the skin lesion has the outside appearance of a wart or verruca, thus it can be confused with other kinds of warts. It evolves to an annular red-brown plaque with time, with central healing and gradual expansion in the periphery. In this phase, it can be confused with fungal infections such as blastomycosis and chromoblastomycosis.

Tuberculosis verrucosa cutis (also known as "lupus verrucosus", "prosector's wart", and "warty tuberculosis") is a rash of small, red papular nodules in the skin that may appear 2–4 weeks after inoculation by "Mycobacterium tuberculosis" in a previously infected and immunocompetent individual.

It is so called because it was a common occupational disease of prosectors, the preparers of dissections and autopsies. Reinfection by tuberculosis via the skin, therefore, can result from accidental exposure to human tuberculous tissue in physicians, pathologists and laboratory workers; or to tissues of other infected animals, in veterinarians, butchers, etc. Other names given to this form of skin tuberculosis are anatomist's wart and verruca necrogenica (literally, generated by corpses).

TVC is one of the many forms of cutaneous tuberculosis, such as the tuberculous chancre (which results from the inoculation in people without immunity), and the reactivation cutaneous tuberculosis (the most common form, which appears in previously infected patients). Other forms of cutaneous tuberculosis are: lupus vulgaris, scrofuloderma, lichen scrofulosorum, erythema induratum and the papulonecrotic tuberculid.

It was described by René Laennec in 1826.

The symptoms of leishmaniasis are skin sores which erupt weeks to months after the person is bitten by infected sand flies.

Leishmaniasis may be divided into the following types:

- Cutaneous leishmaniasis is the most common form, which causes an open sore at the bite sites, which heals in a few months to a year and half, leaving an unpleasant-looking scar. Diffuse cutaneous leishmaniasis produces widespread skin lesions which resemble leprosy, and may not heal on its own.

- Mucocutaneous leishmaniasis causes both skin and mucosal ulcers with damage primarily of the nose and mouth.

- Visceral leishmaniasis or "kala-azar" ('black fever') is the most serious form, and is potentially fatal if untreated. Other consequences, which can occur a few months to years after infection, include fever, damage to the spleen and liver, and anemia.

Leishmaniasis is considered one of the classic causes of a markedly enlarged (and therefore palpable) spleen; the organ, which is not normally felt during examination of the abdomen, may even become larger than the liver in severe cases.

The disease usually affects the lower legs or scrotum. The swelling is accompanied by rough nodules or wart-like plaques on the skin. If the disease is not treated, it eventually results in pain and immobility.

Although elephantiasis nostras resembles the elephantiasis caused by helminths, it is not a filarial disease. Instead, it is a complication of chronic lymphedema. Both elephantiasis nostras and filarial elephantiasis are characterized by impaired lymphatic drainage, which results in excess fluid accumulation.

The Mazzotti reaction, first described in 1948, is a symptom complex seen in patients after undergoing treatment of onchocerciasis with the medication diethylcarbamazine (DEC). Mazzotti reactions can be life-threatening, and are characterized by fever, urticaria, swollen and tender lymph nodes, tachycardia, hypotension, arthralgias, oedema, and abdominal pain that occur within seven days of treatment of microfilariasis. The Mazzotti reaction correlates with intensity of infection; however, there are probably multiple infection intensity-dependent mechanisms responsible for mediating this complex reaction.

The phenomenon is so common when DEC is used for the treatment of onchocerciasis that this drug is the basis of a skin patch test used to confirm that diagnosis. The drug patch is placed on the skin, and if the patient is infected with the microfilaria of "O. volvulus", localized pruritus and urticaria are seen at the application site.

A case of the Mazzotti reaction has been reported after presumptive treatment of schistosomiasis and strongyloidiasis with ivermectin, praziquantel and albendazole. The patient had complete resolution of symptoms after intravenous therapy with methylprednisolone.

Leishmaniasis is a disease caused by parasites of the "Leishmania" type. It is spread by the bite of certain types of sandflies. The disease can present in three main ways: cutaneous, mucocutaneous, or visceral leishmaniasis. The cutaneous form presents with skin ulcers, while the mucocutaneous form presents with ulcers of the skin, mouth, and nose, and the visceral form starts with skin ulcers and then later presents with fever, low red blood cells, and enlarged spleen and liver.

Infections in humans are caused by more than 20 species of "Leishmania". Risk factors include poverty, malnutrition, deforestation, and urbanization. All three types can be diagnosed by seeing the parasites under the microscope. Additionally, visceral disease can be diagnosed by blood tests.

Leishmaniasis can be partly prevented by sleeping under nets treated with insecticide. Other measures include spraying insecticides to kill sandflies and treating people with the disease early to prevent further spread. The treatment needed is determined by where the disease is acquired, the species of "Leishmania", and the type of infection. Some possible medications used for visceral disease include liposomal amphotericin B, a combination of pentavalent antimonials and paromomycin, and miltefosine. For cutaneous disease, paromomycin, fluconazole, or pentamidine may be effective.

About 4 to 12 million people are currently infected in some 98 countries. About 2 million new cases and between 20 and 50 thousand deaths occur each year. About 200 million people in Asia, Africa, South and Central America, and southern Europe live in areas where the disease is common. The World Health Organization has obtained discounts on some medications to treat the disease. It is classified as a neglected tropical disease. The disease may occur in a number of other animals, including dogs and rodents.

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.

Ulcerative sarcoidosis is a cutaneous condition affecting roughly 5% of people with sarcoidosis.

Annular sarcoidosis is a cutaneous condition characterized by papular skin lesions arranged in annular

patterns, usually with a red-brown hue.

Morpheaform sarcoidosis is a very rare cutaneous condition characterized by specific cutaneous skin lesions of sarcoidosis accompanied by substantial fibrosis, simulating morphea.

Erythrodermic sarcoidosis is a cutaneous condition and very rare form of sarcoidosis.

Hypopigmented sarcoidosis is a cutaneous condition characterized by areas of hypopigmented skin. It is usually diagnosed in darkly pigmented races and may be the earliest sign of sarcoidosis.

Papular sarcoid is a cutaneous condition characterized by papules, which are the most common morphology of cutaneous sarcoidosis.

Ichthyosiform sarcoidosis is a cutaneous condition resembling ichthyosis vulgaris or acquired ichthyosis, with fine scaling usually on the distal extremities, by caused by sarcoidosis.

This condition is characterized by:

- a diffuse infiltration of all the skin which never transforms into nodule

- a complete alopecia of eyebrows and eyelashes and body hair

- an anhydrotic and dysesthesic zones of the skin

- a peculiar type of lepra reaction named Lucio's phenomenon or necrotic erythema

Lucio's phenomenon consists of well-shaped erythematous spots which later become necrotic with scabs, ulcerations and scars. These lesion usually on the lower extremities and may be extensive They are frequently painful. Rarely it may be fatal.

A canine vector-borne disease (CVBD) is one of "a group of globally distributed and rapidly spreading illnesses that are caused by a range of pathogens transmitted by arthropods including ticks, fleas, mosquitoes and phlebotomine sandflies." CVBDs are important in the fields of veterinary medicine, animal welfare, and public health. Some CVBDs are of zoonotic concern.

Many CVBD infect humans as well as companion animals. Some CVBD are fatal; most can only be controlled, not cured. Therefore, infection should be avoided by preventing arthropod vectors from feeding on the blood of their preferred hosts. While it is well known that arthropods transmit bacteria and protozoa during blood feeds, viruses are also becoming recognized as another group of transmitted pathogens of both animals and humans.

Some "canine vector-borne pathogens of major zoonotic concern" are distributed worldwide, while others are localized by continent. Listed by vector, some such pathogens and their associated diseases are the following:

- Phlebotomine sandflies (Psychodidae): "Leishmania amazonensis", "L. colombiensis", and "L. infantum" cause visceral leishmaniasis (see also canine leishmaniasis). "L. braziliensis" causes mucocutaneous leishmaniasis. "L. tropica" causes cutaneous leishmaniasis. "L. peruviana" and "L. major" cause localized cutaneous leishmaniasis.

- Triatomine bugs (Reduviidae): "Trypanosoma cruzi" causes trypanosomiasis (Chagas disease).

- Ticks (Ixodidae): "Babesia canis" subspecies ("Babesia canis canis", "B. canis vogeli", "B. canis rossi", and "B. canis gibsoni" cause babesiosis. "Ehrlichia canis" and "E. chaffeensis" cause monocytic ehrlichiosis. "Anaplasma phagocytophilum" causes granulocytic anaplasmosis. "Borrelia burgdorferi" causes Lyme disease. "Rickettsia rickettsii" causes Rocky Mountain spotted fever. "Rickettsia conorii" causes Mediterranean spotted fever.

- Mosquitoes (Culicidae): "Dirofilaria immitis" and "D. repens" cause dirofilariasis.

The diffuse leprosy of Lucio and Latapí, also known as diffuse lepromatous leprosy or "pretty leprosy" is a clinical variety of lepromatous leprosy. It was first described by Lucio and Alvarado in 1852 and re-identified by Latapí in 1936. It is common in Mexico (23% leprosy cases) and in Costa Rica and very rare in other countries.

Although a clear understanding of the various skin lesions in IgG4-related disease is a work in progress, skin lesions have been classified into subtypes based on documented cases:

- Angiolymphoid hyperplasia with eosinophilia (or lesions that mimic it) and cutaneous pseudolymphoma

- Cutaneous plasmacytosis

- Eyelid swelling (as part of Mikulicz's disease)

- Psoriasis-like eruptions

- Unspecified maculopapular or erythematous eruptions

- Hypergammaglobulinemic purpura and urticarial vasculitis

- Impaired blood supply to fingers or toes, leading to Raynaud's phenomenon or gangrene

Note:

In addition, Wells syndrome has also been reported in a case of IgG4-related disease.

In most cases skin lesions do not cause symptoms, however itching, burning, or pain may occur.

Frequently reported symptoms include mild fever, muscle pain, joint pain, or an overall feeling of discomfort. Additional symptoms depend on the cause of the vasculitis and if other organ systems are involved. For example, if the vasculitis is a manifestation of Henoch-Schönlein purpura, individuals may also experience abdominal pain or blood in the urine.

Initially red to pink, flat spots (formally, "macules") and raised bumps (formally, "papules") may be seen on the skin.

Once fully developed, the classic appearance is "non-blanching, palpable purpura". This appears as deep red to purple spots that feel raised to the touch. Purpura refers to the red-purple discolored spots, while palpable implies that these spots can be felt as raised from the surrounding skin. Additionally, when gently pressed, the color does not fade to a lighter color ("non-blanching"). The red-purple color of the lesions is due to the inflammation in the blood vessels causing red blood cells to escape into the dermis skin layer.

Small fluid-filled blisters (or "vesicles"), pus-filled bumps resembling a pimple (or "pustules"), or shallow ulcers may also develop but are less common.

The location of skin lesions varies but are most commonly found symmetrically below the waist, primarily on the buttocks and legs. Other distributions include localized areas on the upper body or over several areas of the body.

With treatment, the lesions typically resolve in weeks to months and leave behind flat spots that are darker than the surrounding skin. (see "Postinflammatory hyperpigmentation" on "Hyperpigmentation")

A portion of cases may be persistent or recurrent. This tends to occur when the vasculitis is associated with chronic conditions such as connective tissue diseases.

Non-mycosis fungoides CD30− cutaneous large T-cell lymphoma is a cutaneous condition that usually presents as solitary or generalized plaques, nodules, or tumors of short duration.