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 primary method for controlling the incidence of gaffkaemia is improved hygiene. Other measures include limiting damage to the exoskeleton (preventing the bacterium's entry), reducing the water temperature, and reducing the stocking density. Antibiotics may be effective against the bacterium, but only tetracycline is currently approved by the U.S Food and Drug Administration for use in American lobsters.

Gaffkaemia is enzootic in North America, and causes little harm to wild populations of "H. americanus". In the European or common lobster, "Homarus gammarus", however, it is far more destructive. European lobsters held in the same tanks as American lobsters can be killed within days. A number of other crustacean species can be infected with "A. v." var. "homari", but do not develop severe disease. They include the shrimp "Pandalus platyceros", and the crabs "Cancer borealis", "Cancer irroratus", "Metacarcinus magister", "Libinia emarginata", "Chionoecetes opilio" and "Chaceon quinquedens". Spiny lobsters appear to be either immune or resistant to gaffkaemia.

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.

One of the biggest risks factors faced by the affected foals is susceptibility to secondary infection. Within three to eight days after birth, the foal may die from infection or is euthanized for welfare reasons.

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.

JEB also affects the human population. Symptoms are closely related to those that are seen in horses. Blisters occur over a large portion of the body and are very susceptible to agitation. There are other symptoms associated, such as alopecia (hair loss), abnormalities of fingernails and toenails, and joint deformities.

Children born with JEB may not live past the first year of age if the condition is severe enough. Other children that have a less severe case of JEB may live a normal lifespan.

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.

During the 1980s, dentist Hal Huggins, sparking severe controversy, spawned biological dentistry, which claims that conventional tooth extraction routinely leaves within the tooth socket the periodontal ligament that often becomes gangrenous, then, forming a jawbone "cavitation" seeping infectious and toxic material. Sometimes forming elsewhere in bones after injury or ischemia, jawbone cavitations are recognized as foci also in osteopathy and in alternative medicine, but conventional dentists generally conclude them to be nonexistent. Although the International Academy of Oral Medicine & Toxicology claims that the scientific evidence establishing the existence of jawbone cavitations is overwhelming, and even published in textbooks, the diagnosis and related treatment remain controversial, and allegations of quackery persist.

Huggins and many biological dentists also espouse Weston Price's findings on endodontically treated teeth routinely being foci of infection, although these dentists have been accused of quackery. Conventional belief is that microorganisms within inaccessible regions of a tooth's roots are rendered harmless once entrapped by the filling material, although little evidence supports this. A H Rogers in 1976 and E H Ehrmann in 1977 had dismissed any relation between endodontics and focal infection. At dentist George Meinig's 1994 book, "Root Canal Cover-Up Exposed", discussing researches of Rosenow and of Price, some dentistry scholars reasserted that the claims were evaluated and disproved by the 1940s. Yet Meinig was but one of at least three authors who in the early 1990s independently renewed the concern.

Boyd Haley and Curt Pendergrass found especially high levels of bacterial toxins in root-filled teeth. Although such possibility appears especially likely amid compromised immunity—as in individuals cirrhotic, asplenic, elderly, rheumatoid arthritic, or using steroid drugs—there remained a lack of carefully controlled studies definitely establishing adverse systemic effects. Conversely, some if few studies have investigated effects of systemic disease on root-canal therapy's outcomes, which tend to worsen with poor glycemic control, perhaps via impaired immune response, a factor largely ignored until recently, but now recognized as important. Still, even by 2010, "the potential association between systemic health and root canal therapy has been strongly disputed by dental governing bodies and there remains little evidence to substantiate the claims".

The traditional root-filling material is gutta-percha, whereas a new material, Biocalex, drew initial optimism even in alternative dentistry, but Biocalex-filled teeth were later reported by Boyd Haley to likewise seep toxic byproducts of anaerobic bacterial metabolism. Seeking to sterilize the tooth interior, some dentists, both alternative and conventional, have applied laser technology. Although endodontic therapy can fail and eventually often does, dentistry scholars maintain that it "can" be performed without creating focal infections. And even by 2010, molecular methods had rendered no consensus reports of bacteremia traced to asymptomatic endodontic infection. In any event, the predominant view is that shunning endodonthic therapy or routinely extracting endodontically treated teeth to treat or prevent systemic diseases remains unscientific and misguided.

With the 1950s introduction of antibiotics, attempts to explain unexplained diseases via bacterial etiology seemed all the more unlikely. By the 1970s, however, it was established that antibiotics could trigger bacteria's switch to their L phase. Eluding detection by traditional methods of medical microbiology, bacterial L forms and the similar mycoplasma—and, later, viruses—became the entities expected in the theory of focal infection. Yet until the 1980s, such researchers were scarce, largely via scarce funding for such investigations.

Despite the limited funding, research established that L forms can adhere to red blood cells and thereby disseminate from foci within internal organs such as the spleen, or from oral tissues and the intestines, especially during dysbiosis. Perhaps some of Weston Price's identified "toxins" in endodontically treated teeth were L forms, thought nonexistent by bacteriologists of his time and widely overlooked into the 21st century. Apparently, dental infections, including by uncultured or cryptic microorganisms, contribute to systemic diseases.

Clarence (2012) suggests that afro-textured hair may have initially evolved because of an adaptive need amongst humans' early hominid ancestors for protection against the intense UV radiation of the sun in Africa. With regard to the hypothesized recent African origin of modern humans, the author argues that afro-textured hair was the original hair texture of all modern humans prior to the "Out-of-Africa" migration that populated the rest of the globe. According to Clarence (2012), afro-textured hair may have been adaptive for the earliest modern humans in Africa because the relatively sparse density of such hair, combined with its elastic helix shape, results in an airy effect. The resulting increased circulation of cool air onto the scalp may have thus served to facilitate the body-temperature-regulation system of hominids while they lived on the open savannah. Afro-hair requires more moisture than straight hair and tends to shrink when dry. Instead of sticking to the neck and scalp when damp (as do straighter textures), unless completely drenched it tends to retain its basic springiness. The trait may have been retained and/or preferred among many anatomically modern populations in equatorial areas, such as Polynesians, Micronesians, Melanesians, Australoids and the Negrito, because of its contribution to enhanced comfort levels under tropical climate conditions.

Epidemiological data from three states put the prevalence of chemical sensitivity in 1999 at 16 to 33% of the general population, 2 to 6% of whom have already been diagnosed with MCS. Women complain of MCS significantly more often than men, and most patients are 30 to 50 years old at time of diagnosis.

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.

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

In various studies, about one half of the patients who seek medical treatment for symptoms of MCS meet the criteria for depressive and anxiety disorders. Because many people eliminate whole categories of food in an effort to reduce symptoms, a complete review of the patient's diet may be needed to avoid nutritional deficiencies.

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.

The cause for actinic prurigo is unknown, however researchers believe that protein in our bodies may be a cause to the condition also:

•UV-A and UV-B light seem to be the main provoking agents. This observation is supported by the fact that most patients live at high altitudes (>1000 m above sea level), and the condition improves in many patients when they move to lower altitudes. However, some patients who are affected already live at sea level.18,19,27 •Some authors are considering a food photosensitizer or a nutritional selective deficiency as a cause; however, no evidence proves this theory.27

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.

It is commonly seen with certain hair styles or braiding patterns that pull the hairline forcefully towards the vertex of the scalp, and has been reported more often in African American women (as some wear their hair tightly pulled back), in whom it can cause scarring. It has also been seen in female ballerinas, and in cultural traditions where the hair is voluntarily not cut in religious obeisance, the latter caused by progressively increasing weight of the hair itself. Traction alopecia is mechanical in cause, rather than androgenic, and treatment is typically not pharmaceutical. Management includes cessation of the chronic traction, cosmeses, with surgical restoration reserved for more severe cases.

Traction alopecia is a substantial risk in hair weaves, which can be worn either to conceal hair loss, or purely for cosmetic purposes. The former involves creating a braid around the head below the existing hairline, to which an extended-wear hairpiece, or wig, is attached. Since the hair of the braid is still growing, it requires frequent maintenance, which involves the hairpiece being removed, the natural hair braided again, and the piece snugly reattached. The tight braiding and snug hairpiece cause tension on the hair that is already at risk for falling out. Traction Alopecia is one of the most common causes of hair loss in African American women.

Sikh men are also susceptible to traction alopecia if the hair under the turban is tied too tightly for many years.

Other causes include:

- Hairstyle. Although the aforementioned style is one of the culprits, hairstyles such as dreadlocks and single (extension) braids can also have the same effect. Men and women who have suffered from traction alopecia have found that the hair loss occurs most at the hair line—primarily around the temples and the sides of their heads.

- Headgear. Compressive safety helmets worn tightly and closely to the scalp are a cause of traction alopecia. The lining of tightly fitted safety helmets like those worn for activities such as motorcycling, cycling, skiing and snowboarding are responsible for the constant rubbing and tugging of localised areas of the hair and scalp. Frequent wearers or those who use such helmets for prolonged periods seem more likely to suffer traction alopecia.

- Chemicals. A condition known as CCCA (central cicatricial centrifugal alopecia), seen almost exclusively in African American women, can cause extensive hair loss. It is caused by a combination of too much stress (traction) on the hair and the use of harsh relaxers and dyes.

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 (AP) was first described by Escalona in Mexico, in 1954.

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