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.

"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.

The effects of gaffkaemia infection include lethargy (typically seen as a drooping tail), anorexia and a pink colour on the ventral side of the abdomen, which gives the disease its alternative common name of red tail disease. When lobsters are moribund, they may lie on their sides, and frequently lose appendages. The effects of gaffkaemia are slowed by low temperatures, such that death can occur within two days of infection at , but can take over 60 days at .

As few as five bacteria can lead to clinical disease. When they enter the host, the bacteria colonise the heart and hepatopancreas. They may be engulfed by phagocytosis into the lobster's blood cells, but continue to survive within the blood cells, feeding on the cytoplasm. The lobster's blood cell count drops, and the infection develops into septicaemia. The stores of glycogen in the hepatopancreas become depleted, concentrations of glucose and lactic acid in the blood drop, and concentrations of adenosine triphosphate in muscles also fall. In a severe infection, the ability of the lobster's blood pigment haemocyanin to carry oxygen may be reduced by up to 50%.

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

Dutch elm disease (DED) is caused by a member of the sac fungi (Ascomycota) affecting elm trees, and is spread by elm bark beetles. Although believed to be originally native to Asia, the disease was accidentally introduced into America and Europe, where it has devastated native populations of elms that did not have resistance to the disease. It has also reached New Zealand. The name "Dutch elm disease" refers to its identification in 1921 and later in the Netherlands by Dutch phytopathologists Bea Schwarz and Christine Buisman who both worked with Professor Johanna Westerdijk. The disease affects species in the genera "Ulmus" and "Zelkova", therefore it is not specific to the Dutch elm hybrid.

The causative agents of DED are ascomycete microfungi. Three species are now recognized:

- "Ophiostoma ulmi", which afflicted Europe from 1910, reaching North America on imported timber in 1928.

- "Ophiostoma himal-ulmi", a species endemic to the western Himalaya.

- "Ophiostoma novo-ulmi", an extremely virulent species from Japan which was first described in Europe and North America in the 1940s and has devastated elms in both continents since the late 1960s.

DED is spread in North America by three species of bark beetles (Family: Curculionidae, Subfamily: Scolytinae):

- The native elm bark beetle, "Hylurgopinus rufipes".

- The European elm bark beetle, "Scolytus multistriatus".

- The banded elm bark beetle, "Scolytus schevyrewi".

In Europe, while "S. multistriatus" still acts as a vector for infection, it is much less effective than the large elm bark beetle, "S. scolytus". "H. rufipes" can be a vector for the disease, but is inefficient compared to the other vectors. "S. schevyrewi" was found in 2003 in Colorado and Utah.

Other reported DED vectors include "Scolytus sulcifrons", "S. pygmaeus", "S. laevis", "Pteleobius vittatus" and "Р. kraatzi". Other elm bark beetle species are also likely vectors.

Afro-textured hair is the natural hair texture of certain populations in Africa, the African diaspora, Australia and Asia, which has not been altered by hot combs, flat irons or chemicals (through perming, relaxation or other straightening methods). Each strand of this hair type grows in a tiny, spring-like helix shape. The overall effect is such that, compared to straight, wavy or curly hair, afro-textured hair appears denser.

Exotic ungulate encephalopathy is a transmissible spongiform encephalopathy (TSE), or prion disease, identified in infected organs of zoo animals. This subgroup of the TSEs in captive animals was identified in zoo animals in Great Britain including species of greater kudu, nyala, gemsbok, the common eland, Arabian and Scimitar Oryx, an Ankole-Watusi cow, and an American bison. Studies indicate that transmission likely occurred via the consumption of feed supplemented with meat and bone meal, although some animals died after the British ban on ground offal in animal feed. All animals died during the 1990s, with the last death occurring in 1998.

In many post-Columbian, Western societies, adjectives such as "wooly", "kinky", "nappy", or "spiralled" have frequently been used to describe natural afro-textured hair. More recently, however, it has become common in some circles to apply numerical grading systems to human hair types.

One popular version of these systems classifies afro-textured hair as 'type 4' (straight hair is type 1, wavy type 2, and curly is type 3, with the letters A, B, and C used to indicate the degree of coil variation within each type), with the subcategory of type 4C being most exemplary of this hair type (Walker, 1997). However, afro-textured hair is often difficult to categorize because of the many different variations among individuals. Those variations include pattern (mainly tight coils), pattern size (watch spring to chalk), density (sparse to dense), strand diameter (fine, medium, coarse), and feel (cottony, wooly, spongy).

The chart below is the most commonly used chart to help determine hair types:

Foals appear normal immediately after birth. JEB affects tissues including mucous membranes, so one of the first signs is blistering of the gingiva and tongue after the first attempt at nursing. Within the next few days, the foal develops lesions all over the body, especially over pressure points. The proteins affected by the gene mutations are also present in the hooves, causing hooves to slough.

Other symptoms that occur in JEB:

- Corneal lesions

- Dental dysplasia

- Depression

- Oral ulcers

- Suppressed appetite

- Incisors present at birth

JEB has documented in Belgian drafts, American Cream Draft, Breton drafts, Comtois, and American Saddlebreds. Of these horses, 12% of Belgians and 4% of Saddlebreds are thought to carry the disorder.

Focal infection theory is the historical concept that many chronic diseases, including systemic and common ones, are caused by focal infections. In present medical consensus, a focal infection is a localized infection, often asymptomatic, that causes disease elsewhere in the host, but focal infections are fairly infrequent and limited to fairly uncommon diseases. (Distant injury is focal infection's key principle, whereas in ordinary infectious disease, the infection itself is systemic, as in measles, or the initially infected site is readily identifiable and invasion progresses contiguously, as in gangrene.) Focal infection theory, rather, so explained virtually all diseases, including arthritis, atherosclerosis, cancer, and mental illnesses.

An ancient concept that took modern form around 1900, focal infection theory was widely accepted in medicine by the 1920s. In the theory, the "focus of infection" might lead to secondary infections at sites particularly susceptible to such microbial species or toxin. Commonly alleged foci were diverse—appendix, urinary bladder, gall bladder, kidney, liver, prostate, and nasal sinuses—but most commonly were oral. Besides dental decay and infected tonsils, both dental restorations and especially endodontically treated teeth were blamed as foci. The putative "oral sepsis" was countered by tonsillectomies and tooth extractions, including of endodontically treated teeth and even of apparently healthy teeth, newly popular approaches—sometimes leaving individuals toothless—to treat or prevent diverse diseases.

Drawing severe criticism in the 1930s, focal infection theory—whose popularity zealously exceeded consensus evidence—was discredited in the 1940s by research attacks that drew overwhelming consensus of this sweeping theory's falsity. Thereupon, dental restorations and endodontic therapy became again favored. Untreated endodontic "disease" retained mainstream recognition as fostering systemic disease. But only alternative medicine and later biological dentistry continued highlighting sites of dental treatment—still endodontic therapy, but, more recently, also dental implant, and even tooth extraction, too—as foci of infection causing chronic and systemic diseases. In mainstream dentistry and medicine, the primary recognition of focal infection is endocarditis, if oral bacteria enter blood and infect the heart, perhaps its valves.

Entering the 21st century, scientific evidence supporting general relevance of focal infections remained slim, yet evolved understandings of disease mechanisms had established a third possible mechanism—altogether, metastasis of infection, metastatic toxic injury, and, as recently revealed, metastatic immunologic injury—that might occur simultaneously and even interact. Meanwhile, focal infection theory has gained renewed attention, as dental infections apparently are widespread and significant contributors to systemic diseases, although mainstream attention is on ordinary periodontal disease, not on hypotheses of stealth infections via dental "treatment". Despite some doubts renewed in the 1990s by conventional dentistry's critics, dentistry scholars maintain that endodontic therapy can be performed without creating focal infections.

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.

A lallation (also called cambia-letras or troca-letra, "letter changer", in Latin American countries) is an imperfect enunciation of the letter "L", in which it sounds like "R" (or vice versa), as frequently found in infantile speech.

The speech pattern has been particularly associated with the use of the Portuguese, Spanish and English languages by Chinese, Korean, and Japanese people. The use of lallation has thus been a common feature of Western stereotypes of East Asian people. It is also common among English-speakers in parts of East Africa.

Among the indigenous peoples of Latin America, in which this illness is most common, susto may be conceptualized as a case of spirit attack. Symptoms of susto are thought to include nervousness, anorexia, insomnia, listlessness, fever, depression, and diarrhea.

Hemoglobin J is an abnormal hemoglobin, an alpha globin gene variant and present in various geographic locations. It was first reported in a black American family in 1956. Later on reported from Indonsia, India, and other parts of the world. Hemoglobin J reported from Meerut India shows the mutation of 120th Alanine to Glutamic acid on alpha chain. Hemoglobin J was also reported from Chhattisgarh, Central India as revealed by Lingojwar and coworkers in 2016.

AP is characterized by itchy, inflamed papules, nodules, and plaques on the skin. Lesions typically appear hours or days after exposure of the skin to UV light, and follow a general pattern of sun-exposed areas. The face, neck, arms, hands, and legs are often affected, although lesions sometimes appear on skin that is covered by clothing and thus not exposed to UV light, thus making AP somewhat difficult to diagnose.

AP is a chronic disease, and symptoms usually worsen in the spring and summer as the day lengthens and exposure to sunlight increases.

Symptoms range in severity from mild to disabling.

Symptoms are common, but vague and non-specific for the condition. The most common are feeling tired, "brain fog" (short-term memory problems, difficulty concentrating), gastrointestinal problems, headaches, and muscle pain.

A partial list of other symptoms patients have attributed to MCS include: difficulty breathing, pains in the throat, chest, or abdominal region, skin irritation, headaches, neurological symptoms (nerve pain, pins and needles feelings, weakness, trembling, restless leg syndrome), tendonitis, seizures, visual disturbances (blurring, halo effect, inability to focus), anxiety, panic and/or anger, sleep disturbance, suppression of immune system, digestive difficulties, nausea, indigestion/heartburn, vomiting, diarrhea, joint pains, vertigo/dizziness, abnormally acute sense of smell (hyperosmia), sensitivity to natural plant fragrance or natural pine terpenes, dry mouth, dry eyes, and an overactive bladder.

Susto may be a culturally dependent variation of the symptoms of panic attack, distinct from anxiety and depressive disorders.

Rabies is a viral disease that exists in Haiti and throughout the world. It often causes fatal inflammation of the brain in humans and other mammals, such as dogs and mongooses in Haiti. The term "rabies" is derived from a Latin word that means "to rage"; rabid animals sometimes appear to be angry. Early symptoms can include fever and tingling at the site of exposure, followed by one or more of the following symptoms: violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness. Once symptoms appear, death is nearly always the outcome. The time period between contracting the disease and showing symptoms is usually one to three months; however, this time period can vary from less than a week to more than a year. The time between contraction and the onset of symptoms is dependent on the distance the virus must travel to reach the central nervous system.

Haiti is one of five remaining countries in the Americas where canine rabies is still a problem. It has the highest rate of human rabies deaths in the western hemisphere with an estimated two deaths each week. Only about seven deaths are reported to health authorities each year due to poor surveillance, limitations in diagnostic capacity, and lack of awareness and education about the disease among Haitians.

Actinic prurigo is a rare sunlight-induced, pruritic, papular or nodular skin eruption. Some medical experts use the term "actinic prurigo" to denote a rare photodermatosis that develops in childhood and is chronic and persistent; this rare photodermatosis, associated with the human leukocyte antigen HLA-DR4, is often called "Familial polymorphous light eruption of American Indians" or "Hereditary polymorphous light eruption of American Indians" but some experts consider it to be a variant of the syndrome known as polymorphous light eruption (PMLE). Some experts use the term "actinic prurigo" for Hutchinson's summer prurigo (aka "hydroa aestivale") and several other photodermatoses that might, or might not, be distinct clinical entities.

Ryan Higa (born June 6, 1990), also known by his YouTube username nigahiga (), is an American comedian, YouTube personality, and actor. He is known for his comedy videos on YouTube, which have been viewed over 3 billion times. Higa's YouTube channel, nigahiga, was the most subscribed channel on YouTube for 677 consecutive days from 2009–2011, longer than any other channel besides PewDiePie. , he has over 20 million subscribers, making his channel the 21st most subscribed on YouTube.

Multiple chemical sensitivity (MCS), also known as idiopathic environmental intolerances (IEI), is a disputed chronic condition characterized by symptoms that the affected person attributes to low-level exposures to commonly used chemicals. Symptoms are typically vague and non-specific. They may include fatigue, headaches, nausea, and dizziness.

Commonly attributed substances include scented products, pesticides, plastics, synthetic fabrics, smoke, petroleum products, and paint fumes.

Although the symptoms themselves are real, and can be disabling, MCS is not recognized as an organic, chemical-caused illness by the World Health Organization, American Medical Association, or any of several other professional medical organizations. Blinded clinical trials show that people with MCS react as often and as strongly to placebos as they do to chemical stimuli; the existence and severity of symptoms is related to perception that a chemical stimulus is present. Some attribute the symptoms to depression, somatoform disorders, or anxiety disorders.

Bowen–Conradi syndrome (BCS or BWCNS) is a disease in humans that can affect children. The disease is due to an autosomal recessive abnormality of the "EMG1" gene, which plays a role in small ribosomal subunit (SSU) assembly. The preponderance of diagnoses has been in North American Hutterite children, but BWCNS can affect other population groups.

BWCNS is a ribosomopathy. A D86G mutation of "EMG1" destroys an EcoRV restriction endonuclease site in the most highly conserved region of the protein.

Skeletal dysmorphology is seen and severe prenatal and postnatal growth failure usually leads to death by one year of age.