Mud fever, also known as scratches or pastern dermatitis, is a group of diseases of horses causing irritation and dermatitis in the lower limbs of horses. Often caused by a mixture of bacteria, typically "Dermatophilus congolensis", and "Staphylococcus spp", mud fever can also be caused by fungal organisms (dermatophytes). Photosensitization, chorioptic mange mites, contact dermatitis and other conditions also contribute to some cases. This condition is also known as "dew poisoning," "grease heel," or "greasy heel".

Mud fever affects most horses and ponies during winter and early spring, resulting in painful sores and scabs, which in severe cases can make a horse lame. Mud fever most commonly affects the pastern and heel area but can also affect the upper leg, the belly, and in some cases the neck area (also known as Rain Scald). Non-pigmented skin tends to be more severely affected.

Mud fever is a chronic but progressive dermatitis. It affects all breeds of horses, but it is most common in heavy draft horses like the Clydesdales. It often starts as a small red ulceration of the skin in the plantar pastern region of the legs. The lesions then grow and develop scaling with the formation of a crust, hair loss, edema, oozing and the release of a malodorous exudate. Skin fissures and papillomatous lesions can develop in chronic cases.

There are two different manifestations of rainscald: the winter form, which is more severe due to the longer coat of the horse, and the summer form, which is less severe. Horses are usually affected on the back, head, and neck, where insects commonly bite, and the legs, which are commonly infected if the horse is kept in moist footing. Initially, the horse will display a matted coat and bumps which will then progress to crusty scabs and lesions. The animal may also be itchy and display signs of discomfort.

Rainscald (also known as "dermatophilosis", "rain rot" and "streptothricosis") is a common skin disease in horses that is caused by the bacterium "Dermatophilus congolensis". This is the same organism that causes Mud fever in horses. This disease is very common in cows, sheep and goats and is also found occasionally in cats, dogs, and humans. D. congolensis is a gram-positive bacterium that is thought to originate from the soil. It commonly causes disease in moist tropical areas, but can also be found in wet northern environments. Moisture and high temperatures facilitate the dispersal and penetration of zoospores into the skin, contributing to the spread of the disease.

Ticks, biting flies, and contact with other infected animals also causes the spread of rainscald. Once in the skin, the bacteria cause inflammation of the skin as well as the typical symptoms associated with rainscald.

"Trench foot " is a medical condition caused by prolonged exposure of the feet to damp, unsanitary, and cold conditions. The use of the word "trench" in the name of this condition is a reference to trench warfare, mainly associated with World War I. Affected feet may become numb, affected by erythrosis (turning red) or cyanosis (turning blue) as a result of poor vascular supply, and feet may begin to have a decaying odour due to the possibility of the early stages of necrosis setting in. As the condition worsens, feet may also begin to swell. Advanced trench foot often involves blisters and open sores, which lead to fungal infections; this is sometimes called tropical ulcer (jungle rot).

If left untreated, trench foot usually results in gangrene, which can cause the need for amputation. If trench foot is treated properly, complete recovery is normal, though it is marked by severe short-term pain when feeling returns. As with other cold-related injuries, trench foot leaves sufferers more susceptible to it in the future.

"Tropical immersion foot" (also known as "Paddy foot", and "Paddy-field foot") is a skin condition of the feet seen after continuous immersion of the feet in water or mud of temperature above 22 degrees Celsius (roughly 72 degrees Fahrenheit ) for two to ten days.

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.

Pigeon fever is a disease of horses, also known as dryland distemper or equine distemper, caused by the Gram-positive bacteria "Corynebacterium pseudotuberculosis" biovar "equi". Infected horses commonly have swelling in the chest area, making it look similar to a 'pigeon chest'. This disease is common in dry areas. Pigeon Fever is sometimes confused for Strangles, another infection that causes abscesses.

It resembles bacterial sepsis and can occur after initiation of antibacterials, such as mild silver protein, penicillin or tetracycline, for the treatment of louse-borne relapsing fever (80–90% of patients) and in tick-borne relapsing fever (30–40%). It usually manifests within a few hours of the first dose of antibiotic as fever, chills, rigor, hypotension, headache, tachycardia, hyperventilation, vasodilation with flushing, myalgia (muscle pain), exacerbation of skin lesions and anxiety. The intensity of the reaction indicates the severity of inflammation. Reaction commonly occurs within two hours of drug administration, but is usually self-limiting. It is observed in 50% of patients with primary syphilis and about 90% of patients with secondary syphilis.

Symptoms are different for every person depending on the type of rat-bite fever with which the person is infected. Both spirillary and streptobacillary rat-bite fever have a few individual symptoms, although most symptoms are shared. Streptobacillosis is most commonly found in the United States and spirillary rat-bite fever is generally diagnosed in patients in Africa. Rat-bite symptoms are visually seen in most cases and include inflammation around the open sore. A rash can also spread around the area and appear red or purple. Other symptoms associated with streptobacillary rat-bite fever include chills, fever, vomiting, headaches, and muscle aches. Joints can also become painfully swollen and pain can be experienced in the back. Skin irritations such as ulcers or inflammation can develop on the hands and feet. Wounds heal slowly, so symptoms possibly come and go over the course of a few months.

Symptoms associated with spirillary rat-bite fever include issues with the lymph nodes, which often swell or become inflamed as a reaction to the infection. The most common locations of lymph node swelling are in the neck, groin, and underarm. Symptoms generally appear within 2 to 10 days of exposure to the infected animal. It begins with the fever and progresses to the rash on the hands and feet within 2 to 4 days. Rash appears all over the body with this form, but rarely causes joint pain.

A Jarisch–Herxheimer reaction () is a reaction to endotoxin-like products released by the death of harmful microorganisms within the body during antibiotic treatment. Efficacious antimicrobial therapy results in lysis (destruction) of bacterial cell membranes, and in the consequent release into the bloodstream of bacterial toxins, resulting in a systemic inflammatory response.

Jarisch–Herxheimer reactions are usually not life-threatening.

In the subgroup of patients where an inoculating event was noted, the mean incubation period of acute melioidosis was 9 days (range 1–21 days). Patients with latent melioidosis may be symptom-free for decades; the longest period between presumed exposure and clinical presentation is 62 years. The potential for prolonged incubation was recognized in US servicemen involved in the Vietnam War, and was referred to as the "Vietnam time-bomb". A wide spectrum of severity exists; in chronic presentations, symptoms may last months, but fulminant infection, particularly associated with near-drowning, may present with severe symptoms over hours.

Symptoms usually appear 2 to 4 weeks after exposure. There are four general types of infection including localized, pulmonary, blood-borne, or disseminated throughout the body. The type and location of the infection usually determines which symptoms appear first as well as which symptoms are more prominent.

Patients with melioidosis usually present with fever. Pain or other symptoms may be suggestive of a clinical focus, which is found in around 75% of patients. Such symptoms include cough or pleuritic chest pain suggestive of pneumonia, bone or joint pain suggestive of osteomyelitis or septic arthritis, or cellulitis. Intra-abdominal infection (including liver and/or splenic abscesses, or prostatic abscesses) do not usually present with focal pain, and imaging of these organs using ultrasound or computed tomography should be performed routinely. In one series of 214 patients, 27.6% had abscesses in the liver or spleen (95% confidence interval, 22.0% to 33.9%). "B. pseudomallei" abscesses may have a characteristic "honeycomb" or "swiss cheese" architecture (hypoechoic, multiseptate, multiloculate) on CT.

Regional variations in disease presentation are seen: parotid abscesses characteristically occur in Thai children, but this presentation has been described only once in Australia. Conversely, prostatic abscesses are found in up to 20% of Australian males, but are rarely described elsewhere. An encephalomyelitis syndrome is recognised in northern Australia.

Patients with melioidosis usually have risk factors for disease, such as diabetes, thalassemia, hazardous alcohol use, or renal disease, and frequently give a history of occupational or recreational exposure to mud or pooled surface water. However, otherwise healthy patients, including children, may also get melioidosis.

In up to 25% of patients, no focus of infection is found and the diagnosis is usually made on blood cultures or throat swab. Melioidosis is said to be able to affect any organ in the body except the heart valves (endocarditis). Although meningitis has been described secondary to ruptured brain abscesses, primary meningitis has not been described. Less common manifestations include intravascular infection, lymph node abscesses (1.2–2.2%), pyopericardium and myocarditis, mediastinal infection, and thyroid and scrotal abscesses and ocular infection.

The streptobacillosis form of rat-bite fever is known by the alternative names Haverhill fever and epidemic arthritic erythema. It is a severe disease caused by "Streptobacillus moniliformis", transmitted either by rat bite or ingestion of contaminated products (Haverhill fever). After an incubation period of 2–10 days, Haverhill fever begins with high prostrating fevers, rigors (shivering), headache, and polyarthralgia (joint pain). Soon, an exanthem (widespread rash) appears, either maculopapular (flat red with bumps) or petechial (red or purple spots) and arthritis of large joints can be seen. The organism can be cultivated in blood or articular fluid. The disease can be fatal if untreated in 20% of cases due to malignant endocarditis, meningoencephalitis, or septic shock. Treatment is with penicillin, tetracycline, or doxycycline.

Chronic melioidosis is usually defined by a duration of symptoms greater than two months and occurs in about 10% of patients. The clinical presentation of chronic melioidosis is protean and includes such presentations as chronic skin infections, chronic lung nodule, and pneumonia. In particular, chronic melioidosis closely mimics tuberculosis, and has sometimes been called "Vietnamese tuberculosis".

Patients can develop two clinical phases: an acute septic phase and a chronic eruptive phase associated with skin lesions. In the acute phase (also known as Oroya fever or "fiebre de la Oroya"), "B. bacilliformis" infection is a sudden, potentially life-threatening infection associated with high fever and decreased levels of circulating red blood cells (i.e., hemolytic anemia)and transient immunosuppression. "B. bacilliformis" is considered the most deadly species to date, with a death rate of up to 90% during the acute phase, which typically lasts two to four weeks. Peripheral blood smears show anisomacrocytosis with many bacilli adherent to red blood cells. Thrombocytopenia is also seen and can be very severe. Neurologic manifestations (neurobartonellosis) are altered mental status, agitation, or even coma, ataxia, spinal meningitis, or paralysis. It is seen in 20% of patients with acute infection, in which the prognosis is very guarded with an about 50% mortality. The most feared complication is overwhelming infection mainly by Enterobacteriaceae, particularly "Salmonella" (both "S. typhi" and " S. "non-"typhi", as well as reactivation of toxoplasmosis and other opportunistic infections .

The chronic manifestation consists of a benign skin eruption with raised, reddish-purple nodules (angiomatous tumours). The bacterium can be seen microscopically, if a skin biopsy is silver stained (the Warthin–Starry method).

The signs and symptoms are generally flu-like. They include fever, chills, nausea, headache, fatigue, muscle aches, joint pains, lack of appetite, shortness of breath, pneumonia, chest pain, change in blood pressure, and coughing. A sweet or metallic taste in the mouth may also be reported, along with a dry or irritated throat which may lead to hoarseness. Symptoms of a more severe metal toxicity may also include a burning sensation in the body, shock, no urine output, collapse, convulsions, shortness of breath, yellow eyes or yellow skin, rash, vomiting, watery or bloody diarrhea or low or high blood pressure, which require prompt medical attention. Flu-like symptoms normally disappear within 24 to 48 hours. Full recovery often requires one to three weeks.

"B. henselae" is the etiologic agent for peliosis hepatis, which is defined as a vascular proliferation of sinusoid hepatic capillaries resulting in blood-filled spaces in the liver in HIV patients and organ transplant recipients. Peliosis hepatis can be associated with peliosis of the spleen, as well as bacillary angiomatosis of the skin in HIV patients.

Filicollis anatis is an endoparasite in the Polymorphidae family of thorny-headed worms. Adults have been found to occur in waterbirds such as ducks, where they cause a condition known as filicollosis. Larval stages occur in invertebrate hosts such as crayfish.

A study in the Chernihiv region of Ukraine found that "F. anatis" infected ducks throughout their grazing period, but not in the winter; it also found that the parasite's eggs could remain viable throughout the winter when buried in mud under natural conditions.

Acanthocephalans such as "F. anatis" form capsules in their intermediate arthropod hosts to protect the developing larvae from the host immune system. "F. anatis" forms its capsules primarily by secreting material during the initial (acanthellar) stage after infecting the intermediate host.

Metal fume fever, also known as brass founders' ague, brass shakes, zinc shakes, galvie flu, metal dust fever, Welding Shivers, or Monday morning fever, is an illness primarily caused by exposure to chemicals such as zinc oxide (ZnO), aluminum oxide (AlO), or magnesium oxide (MgO) which are produced as byproducts in the fumes that result when certain metals are heated. Other common sources are fuming silver, gold, platinum, chromium (from stainless steel), nickel, arsenic, manganese, beryllium, cadmium, cobalt, lead, selenium, and zinc.

Welders are commonly exposed to the substances that cause metal fume fever from the base metal, plating, or filler. Brazing and soldering can also cause metal poisoning due to exposure to lead, zinc, copper, or cadmium. In extreme cases, cadmium (present in some older silver solder alloys) can cause loss of consciousness.

Onset of symptoms begins one to nine days following exposure (with an average of five). Initial symptoms include changes in taste and smell, headache, fever, nausea, vomiting, back pain, and a stiff neck. Secondary symptoms are also meningitis-like including confusion, hallucinations, lack of attention, ataxia, cramp and seizures. After the start of symptoms, the disease progresses rapidly over three to seven days, with death usually occurring anywhere from seven to fourteen days later, although it can take longer. In 2013, a man in Taiwan died twenty-five days after being infected by "Naegleria fowleri".

It affects healthy children or young adults who have recently been exposed to bodies of fresh water. Some people have presented with a clinical triad of edematous brain lesions, immune suppression, and fever.

Symptoms arise 4–12 hours after exposure to an organic dust, and generally last from one to five days. Common generalised symptoms include fever over 38 °C, chills, myalgia and malaise. The most frequent respiratory symptoms are dyspnea and a dry cough, while a wheeze may be present less commonly. Headache, rhinitis, conjunctivitis and keratitis can also be present, and skin irritation may occur in those handling grain.

Respiratory function may worsen to the point where hypoxia occurs, and damage to the airways may lead to non-cardiogenic pulmonary edema one to three days post exposure.

Laboratory investigations may show a raised white cell (and specifically neutrophil) count, while a chest X-ray is often normal or shows minimal interstitial infiltration.

Hay fever was relatively uncommon in Japan until the early 1960s. Shortly after World War II, reforestation policies resulted in large forests of cryptomeria and Japanese cypress trees, which were an important resource for the construction industry. As these trees matured, they started to produce large amounts of pollen. Peak production of pollen occurs in trees of 30 years and older. As the Japanese economy developed in the 1970s and 1980s, cheaper imported building materials decreased the demand for cryptomeria and Japanese cypress materials. This resulted in increasing forest density and aging trees, further contributing to pollen production and thus, hay fever. In 1970, about 50% of cryptomeria were more than 10 years old, and just 25% were more than 20 years old. By 2000, almost 85% of cryptomeria were over 20 years old, and more than 60% of trees were over 30 years old. This cryptomeria aging trend has continued since then, and though cryptomeria forest acreage has hardly increased since 1980, pollen production has continued to increase. Furthermore, urbanization of land in Japan led to increasing coverage of soft soil and grass land by concrete and asphalt. Pollen settling on such hard surfaces can easily be swept up again by winds to recirculate and contribute to hay fever. As a result, approximately 25 million people (about 20% of the population) currently suffer from this type of seasonal hay fever in Japan.

The palate may appear gray or white and contain many papules or nodules that are slightly elevated with red dots in their center. These red dots represent the ducts of minor salivary glands which have become inflamed by heat. The condition is painless. If a denture is normally worn while smoking, then the mucosa underneath the denture appears unaffected by the condition. In severe cases, the mucosa may show fissuring and develop a "dried lake bed" appearance. Other changes associated with tobacco use may be evident such as brown or black extrinsic staining of teeth from tar and other components of tobacco smoke.

The clinical signs of milk fever can be divided into three distinct stages:

Stage 1: Cows are mobile but show signs of hypersensitivity and excitability such as restlessness, tremors, ear twitching, head bobbing and mild ataxia. If not treated, symptoms usually progress to stage 2.

Stage 2: Cows can no longer stand and present in sternal recumbency. Tachycardia, weakened heart contraction and peripheral pulses. Cows appear dull, have dry muzzles, cold extremities and a lower than normal body temperature. Smooth muscle paralysis can cause bloat, and the inability to urinate or defecate. Cows often tuck their heads into their flanks.

Stage 3: Lateral recumbency, muscle flaccidity, unresponsiveness to stimuli, and loss of consciousness progressing to coma. Heart rate can approach 120 bpm, with peripheral pulses becoming undetectable. If untreated, progression will continue to death.

Organic dust toxic syndrome (ODTS) is a potentially severe flu-like syndrome originally described in farmers, mushroom workers, bird breeders and other persons occupationally exposed to dusty conditions.