The several forms of the infection are:

- Skin/subcutaneous tissue disease is a septic phlegmon that develops classically in the hand and forearm after a cat bite. Inflammatory signs are very rapid to develop; in 1 or 2 hours, edema, severe pain, and serosanguineous exudate appear. Fever, moderate or very high, can be seen, along with vomiting, headache, and diarrhea. Lymphangitis is common. Complications are possible, in the form of septic arthritis, osteitis, or evolution to chronicity.

- Sepsis is very rare, but can be as fulminant as septicaemic plague, with high fever, rigors, and vomiting, followed by shock and coagulopathy.

- Pneumonia disease is also rare and appears in patients with some chronic pulmonary pathology. It usually presents as bilateral consolidating pneumonia, sometimes very severe.

- Zoonosis, pasteurellosis can be transmitted to humans through cats.

Other locations are possible, such as septic arthritis, meningitis, and acute endocarditis, but are very rare.

Diagnosis is made with isolation of "Pasteurella multocida" in a normally sterile site (blood, pus, or cerebrospinal fluid).

The acute stage of the disease, occurring most often in the spring and summer, begins one to three weeks after infection and lasts for two to four weeks. Clinical signs include a fever, petechiae, bleeding disorders, vasculitis, lymphadenopathy, discharge from the nose and eyes, and edema of the legs and scrotum. There are no outward signs of the subclinical phase. Clinical signs of the chronic phase include weight loss, pale gums due to anemia, bleeding due to thrombocytopenia, vasculitis, lymphadenopathy, dyspnea, coughing, polyuria, polydipsia, lameness, ophthalmic diseases such as retinal hemorrhage and anterior uveitis, and neurological disease. Dogs that are severely affected can die from this disease.

Although people can get ehrlichiosis, dogs do not transmit the bacteria to humans; rather, ticks pass on the "ehrlichia" organism. Clinical signs of human ehrlichiosis include fever, headache, eye pain, and gastrointestinal upset. It is quite similar to Rocky Mountain spotted fever, but rash is not seen in patients.

A rickettsiosis is a disease caused by intracellular bacteria. It has been predicted that global warming may lead to greater incidence.

The secondary stage most often occurs 10–30 days later, but can present up to six months later. The infection spreads to the lymph nodes through lymphatic drainage pathways. The most frequent presenting clinical manifestation of LGV among males whose primary exposure was genital is unilateral (in 2/3 of cases) lymphadenitis and lymphangitis, often with tender inguinal and/or femoral lymphadenopathy because of the drainage pathway for their likely infected areas. Lymphangitis of the dorsal penis may also occur and resembles a string or cord. If the route was anal sex the infected person may experience lymphadenitis and lymphangitis noted above. They may instead develop proctitis, inflammation limited to the rectum (the distal 10–12 cm) that may be associated with anorectal pain, tenesmus, and rectal discharge, or proctocolitis, inflammation of the colonic mucosa extending to 12 cm above the anus and associated with symptoms of proctitis plus diarrhea or abdominal cramps.

In addition, symptoms may include inflammatory involvement of the perirectal or perianal lymphatic tissues. In females, cervicitis, perimetritis, or salpingitis may occur as well as lymphangitis and lymphadenitis in deeper nodes. Because of lymphatic drainage pathways, some patients develop an abdominal mass which seldom suppurates, and 20–30% develop inguinal lymphadenopathy. Systemic signs which can appear include fever, decreased appetite, and malaise. Diagnosis is more difficult in women and men who have sex with men (MSM) who may not have the inguinal symptoms.

Over the course of the disease, lymph nodes enlarge, as may occur in any infection of the same areas as well. Enlarged nodes are called buboes. Buboes are commonly painful. Nodes commonly become inflamed, thinning and fixation of the overlying skin. These changes may progress to necrosis, fluctuant and suppurative lymph nodes, abscesses, fistulas, strictures, and sinus tracts. During the infection and when it subsides and healing takes place, fibrosis may occur. This can result in varying degrees of lymphatic obstruction, chronic edema, and strictures. These late stages characterised by fibrosis and edema are also known as the third stage of LGV and are mainly permanent.

LGV may begin as a self-limited painless genital ulcer that occurs at the contact site 3–12 days after infection. Women rarely notice a primary infection because the initial ulceration where the organism penetrates the mucosal layer is often located out of sight, in the vaginal wall. In men fewer than 1/3 of those infected notice the first signs of LGV. This primary stage heals in a few days. Erythema nodosum occurs in 10% of cases.

Rickettsioses can be divided into a spotted fever group (SPG) and typhus group (TG).

In the past, rickettsioses were considered to be caused by species of Rickettsia. However, scrub typhus is still considered a rickettsiosis, even though the causative organism has been reclassified from "Rickettsia tsutsugamushi" to "Orientia tsutsugamushi".

Examples of rickettsioses include typhus, both endemic and epidemic, Rocky Mountain spotted fever, and Rickettsialpox.

Organisms involved include Rickettsia parkeri.

Many new causative organisms have been identified in the last few decades.

Most are in the genus Rickettsia, but scrub typhus is in the genus Orientia.

Diagnosis is achieved most commonly by serologic testing of the blood for the presence of antibodies against the ehrlichia organism. Many veterinarians routinely test for the disease, especially in enzootic areas. During the acute phase of infection, the test can be falsely negative because the body will not have had time to make antibodies to the infection. As such, the test should be repeated. A PCR (polymerase chain reaction) test can be performed during this stage to detect genetic material of the bacteria. The PCR test is more likely to yield a negative result during the subclinical and chronic disease phases. In addition, blood tests may show abnormalities in the numbers of red blood cells, white blood cells, and most commonly platelets, if the disease is present. Uncommonly, a diagnosis can be made by looking under a microscope at a blood smear for the presence of the "ehrlichia" morulae, which sometimes can be seen as intracytoplasmic inclusion bodies within a white blood cell.

External abscesses are the most common form of pigeon fever seen in horses. Abscesses develop on the body, usually in the pectoral region and along the ventral midline of the abdomen. However, abscesses can also develop on other areas of the body such as the prepuce, mammary gland, triceps, limbs and head. The fatality rate for this form infection is very low. The abscess is often drained once it has matured.

This is the least common form of pigeon fever seen in horses. It is characterized by severe limb swelling and cellulitis in one or both hind limbs and can lead to lameness, fever, lethargy and loss of appetite. Antimicrobial and anti-inflammatory treatments are required to prevent further complications such as limb edema, prolonged or recurrent infection, lameness, weakness and weight loss.

Lymphangitis is an inflammation or an infection of the lymphatic channels that occurs as a result of infection at a site distal to the channel. The most common cause of lymphangitis in humans is "Streptococcus pyogenes" (Group A strep), although it can also be caused by the fungus "Sporothrix schenckii". Lymphangitis is sometimes mistakenly called "blood poisoning". In reality, "blood poisoning" is synonymous with "sepsis".

Signs and symptoms include a deep reddening of the skin, warmth, lymphadenitis (inflammation of a lymphatic gland), and a raised border around the affected area. The person may also have chills and a high fever along with moderate pain and swelling. A person with lymphangitis should be hospitalized and closely monitored by medical professionals.

Lymphangitis is the inflammation of the lymphatic vessels and channels. This is characterized by certain inflammatory conditions of the skin caused by bacterial infections. Thin red lines may be observed running along the course of the lymphatic vessels in the affected area, accompanied by painful enlargement of the nearby lymph nodes.

When the inferior limbs are affected, the redness of the skin runs over the great saphenous vein location and confusion can be made with a thrombophlebitis.

Chronic lymphangitis is a cutaneous condition that is the result of recurrent bouts of acute bacterial lymphangitis.

Porocephaliasis is a condition associated with species in the closely related genera "Porocephalus" and "Armillifer". (The term "pentastomiasis" encompasses all diseases of Pentastomida, which includes Porocephaliasis and Linguatulosis.)

Porocephaliasis is associated with contact with snakes. (This is in contrast with Linguatulosis, which is associated with contact with dogs or wolves.)

It has been reported from Africa, Malaysia and the Middle East. Its occurrence has been rare in Europe and North America where it has been found in immigrants and travelers.

Lymphadenopathy of the axillary lymph nodes can be defined as solid nodes measuring more than 15 mm without fatty hilum. Axillary lymph nodes may be normal up to 30 mm if consisting largely of fat.

It is prevalent in parts of Africa and Asia where eating snake meat is common. In Africa it has also been associated with groups who use the snake as a totem. Unlike linguatuliasis, humans are only ever an accidental intermediate host for "Armillifer", i.e. the larvae establish themselves in the visceral organs causing human visceral pentastomiasis, but adults do not occur in the human respiratory system. After a while the larvae die within the host and sometimes calcify, leaving characteristic crescent-shaped structures seen in X-ray. In extreme cases a heavy parasite burden can have serious medical consequences and can even be fatal.

An eschar (; Greek: "eschara") is a slough or piece of dead tissue that is cast off from the surface of the skin, particularly after a burn injury, but also seen in gangrene, ulcer, fungal infections, necrotizing spider bite wounds, spotted fevers and exposure to cutaneous anthrax. The term "eschar" is not interchangeable with "scab". An eschar contains necrotic tissue, whereas a scab is composed of dried blood and exudate.

Black eschars are most commonly attributed to anthrax, which may be contracted through herd animal exposure, but can also be obtained from "Pasteurella multocida" exposure in cats and rabbits. A newly identified human rickettsial infection, "R. parkeri" rickettsiosis, can be differentiated from Rocky Mountain spotted fever by the presence of an eschar at the site of inoculation.

Eschar is sometimes called a "black wound" because the wound is covered with thick, dry, black necrotic tissue.

Eschar may be allowed to slough off naturally, or it may require surgical removal (debridement) to prevent infection, especially in immunocompromised patients (e.g. if a skin graft is to be conducted).

If eschar is on a limb, it is important to assess peripheral pulses of the affected limb to make sure blood and lymphatic circulation is not compromised. If circulation is compromised, an escharotomy, or surgical incision through the eschar, may be indicated.

Lymph node enlargement is recognized as a common sign of infectious, autoimmune, or malignant disease. Examples may include:

- Reactive: acute infection ("e.g.," bacterial, or viral), or chronic infections (tuberculous lymphadenitis, cat-scratch disease).

- The most distinctive sign of bubonic plague is extreme swelling of one or more lymph nodes that bulge out of the skin as "buboes." The buboes often become necrotic and may even rupture.

- Infectious mononucleosis is an acute viral infection caused by Epstein-Barr virus and may be characterized by a marked enlargement of the cervical lymph nodes.

- It is also a sign of cutaneous anthrax and Human African trypanosomiasis

- Toxoplasmosis, a parasitic disease, gives a generalized lymphadenopathy ("Piringer-Kuchinka lymphadenopathy").

- Plasma cell variant of Castleman's disease - associated with HHV-8 infection and HIV infection

- Mesenteric lymphadenitis after viral systemic infection (particularly in the GALT in the appendix) can commonly present like appendicitis.

Less common infectious causes of lymphadenopathy may include bacterial infections such as cat scratch disease, tularemia, brucellosis, or prevotella.

- Tumoral:

- Primary: Hodgkin lymphoma and non-Hodgkin lymphoma give lymphadenopathy in all or a few lymph nodes.

- Secondary: metastasis, Virchow's Node, neuroblastoma, and chronic lymphocytic leukemia.

- Autoimmune: systemic lupus erythematosus and rheumatoid arthritis may have a generalized lymphadenopathy.

- Immunocompromised: AIDS. Generalized lymphadenopathy is an early sign of infection with human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS). "Lymphadenopathy syndrome" has been used to describe the first symptomatic stage of HIV progression, preceding a diagnosis of AIDS.

- Bites from certain venomous snakes such as the pit viper

- Unknown: Kikuchi disease, progressive transformation of germinal centers, sarcoidosis, hyaline-vascular variant of Castleman's disease, Rosai-Dorfman disease, Kawasaki disease, Kimura disease

Lymphadenitis, the swelling of the lymph nodes, is a commonly recognized symptom of many diseases. An early manifestation of filariasis, lymphadenitis more frequently occurs in the inguinal area during "B. malayi" infection and can occur before the worms mature.

Lymphangitis is the inflammation of the lymphatic vessels in response to infection. It occurs early in the course of infection in response to worm development, molting, death, or bacterial and fungal infection. The affected lymphatic vessel becomes distended and tender, and the overlying skin becomes erythemous and hot. Abscess formation and ulceration of the affected lymph node occasionally occurs during "B. malayi infection", more readily than in Bancroftian filariasis. Remnants of adult worms can sometimes be found in the ulcer drainage.

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).

Erysipelas is an acute infection typically with a skin rash, usually on any of the legs and toes, face, arms, and fingers. It is an infection of the upper dermis and superficial lymphatics, usually caused by beta-hemolytic group A "Streptococcus" bacteria on scratches or otherwise infected areas. Erysipelas is more superficial than cellulitis, and is typically more raised and demarcated. The term is from Greek ἐρυσίπελας, meaning "red skin".

Elephantiasis is a symptom of a variety of diseases, where parts of a person's body swell to massive proportions.

Some conditions that have this symptom include:

- Elephantiasis nostras, due to longstanding chronic lymphangitis

- Elephantiasis tropica or lymphatic filariasis, caused by a number of parasitic worms, particularly "Wuchereria bancrofti". More than 120 million people, mostly in Africa and Southeast Asia, are affected.

- Nonfilarial elephantiasis or podoconiosis, an immune disease affecting the lymph vessels

- Elephantiasis, Grade 3 lymphedema which may occur in people with breast cancer.

- Genital elephantiasis, end result of lymphogranuloma venereum

- Proteus syndrome, the genetic disorder of the so-called Elephant Man.

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.

Elephantiasis nostras is a cutaneous condition, a final hypertrophic fibrosis following longstanding chronic lymphangitis.

TNF receptor associated periodic syndrome presents with the following signs and symptoms:

- Episodic fever

- Erythrocyte sedimentation rate(increased)

- Pericarditis

- Splenomegaly

- Uveitis

- Vertigo

An escharotic is a substance that causes tissue to die and slough off. Examples include acids, alkalis, carbon dioxide, metallic salts and sanguinarine, as well as certain medicines like imiquimod. Escharotics known as black salves, containing ingredients such as zinc chloride and sanguinarine containing bloodroot extracts, were traditionally used in herbal medicine as topical treatments for localised skin cancers, but often cause scarring and can potentially cause serious injury and disfigurement. Consequently, escharotic salves are very strictly regulated in most western countries and while some prescription medicines are available with this effect, unauthorized sales are illegal. Some prosecutions have been pursued over unlicensed sales of escharotic products such as Cansema.