The Dancing Plague (or Dance Epidemic) of 1518 was a case of dancing mania that occurred in Strasbourg, Alsace, (then part of the Holy Roman Empire) in July 1518. Around 400 people took to dancing for days without rest and, over the period of about one month, some of those affected collapsed or even died of heart attack, stroke, or exhaustion.

The Tanganyika laughter epidemic of 1962 was an outbreak of mass hysteriaor mass psychogenic illness (MPI)rumored to have occurred in or near the village of Kashasha on the western coast of Lake Victoria in the modern nation of Tanzania (formerly Tanganyika) near the border of Uganda.

Dancing mania (also known as dancing plague, choreomania, St John's Dance and, historically, St. Vitus's Dance) was a social phenomenon that occurred primarily in mainland Europe between the 14th and 17th centuries. It involved groups of people dancing erratically, sometimes thousands at a time. The mania affected men, women, and children who danced until they collapsed from exhaustion. One of the first major outbreaks was in Aachen, in the Holy Roman Empire, in 1374, and it quickly spread throughout Europe; one particularly notable outbreak occurred in Strasbourg in 1518, also in the Holy Roman Empire.

Affecting thousands of people across several centuries, dancing mania was not an isolated event, and was well documented in contemporary reports. It was nevertheless poorly understood, and remedies were based on guesswork. Generally, musicians accompanied dancers, to help ward off the mania, but this tactic sometimes backfired by encouraging more to join in. There is no consensus among modern-day scholars as to the cause of dancing mania.

The several theories proposed range from religious cults being behind the processions to people dancing to relieve themselves of stress and put the poverty of the period out of their minds. It is, however, thought to have been a mass psychogenic illness in which the occurrence of similar physical symptoms, with no known physical cause, affect a large or small group of people as a form of social influence.

Mass psychogenic illness (MPI), also called mass sociogenic illness or just sociogenic illness, is "the rapid spread of illness signs and symptoms affecting members of a cohesive group, originating from a nervous system disturbance involving excitation, loss, or alteration of function, whereby physical complaints that are exhibited unconsciously have no corresponding organic" cause. MPI is distinct from other collective delusions, also included under the blanket terms of mass hysteria, in that MPI causes symptoms of disease, though there is no organic cause.

There is a clear preponderance of female victims. The DSM-IV-TR does not have specific diagnosis for this condition but the text describing conversion disorder states that "In 'epidemic hysteria', shared symptoms develop in a circumscribed group of people following 'exposure' to a common precipitant."

The outbreak began in July 1518 when a woman, Mrs. Troffea, began to dance fervently in a street in Strasbourg. This lasted somewhere between four and six days. Within a week, 34 others had joined, and within a month, there were around 400 dancers, predominantly female. Some of these people would die from heart attacks, strokes, or exhaustion. One report indicates that for a period, the plague killed around fifteen people per day.

Historical documents, including "physician notes, cathedral sermons, local and regional chronicles, and even notes issued by the Strasbourg city council" are clear that the victims danced. It is not known why these people danced, some even to their deaths.

As the dancing plague worsened, concerned nobles sought the advice of local physicians, who ruled out astrological and supernatural causes, instead announcing that the plague was a "natural disease" caused by "hot blood". However, instead of prescribing bleeding, authorities encouraged more dancing, in part by opening two guildhalls and a grain market, and even constructing a wooden stage. The authorities did this because they believed that the dancers would recover only if they danced continuously night and day. To increase the effectiveness of the cure, authorities even paid for musicians to keep the afflicted moving.

Historian John Waller stated that a marathon runner could not have lasted the intense workout that these men and women did hundreds of years ago.

Millie McCoy and Christine McCoy (July 11, 1851 – October 8, 1912) were American conjoined twins who went by the stage names "The Carolina Twins", "The Two-Headed Nightingale" and "The Eighth Wonder of the World". The Twins traveled throughout the world performing song and dance for entertainment.

In the 1890s, an epizootic of the rinderpest virus struck Africa, considered to be "the most devastating epidemic to hit southern Africa in the late nineteenth century". It killed more than 5.2 million cattle south of the Zambezi, as well as domestic oxen, sheep, and goats, and wild populations of buffalo, giraffe, and wildebeest. This led to starvation resulting in the death of an estimated third of the human population of Ethiopia and two-thirds of the Maasai people of Tanzania.

Tarantism is a form of hysteric behaviour, popularly believed to result from the bite of the wolf spider "Lycosa tarantula" (distinct from the broad class of spiders also called tarantulas).

A better candidate cause is "Latrodectus tredecimguttatus", commonly known as the Mediterranean black widow or steppe spider, although no link between such bites and the behaviour of tarantism has ever been demonstrated. However, the term historically is used to refer to a dancing mania - characteristic of southern Italy - which likely had little to do with spider bites. The tarantella dance supposedly evolved from this therapy.

The virus is thought to have been introduced into Eritrea in 1887 by Indian cattle brought by the Italians for their campaign against Somalia. It spread throughout the Horn of Africa, and crossed the Zambezi in March of 1896.

Qualities of MPI outbreaks often include:

- symptoms that have no plausible organic basis;

- symptoms that are transient and benign;

- symptoms with rapid onset and recovery;

- occurrence in a segregated group;

- the presence of extraordinary anxiety;

- symptoms that are spread via sight, sound or oral communication;

- a spread that moves down the age scale, beginning with older or higher-status people;

- a preponderance of female participants

Also, the illness may recur after the initial outbreak.

Most patients report acute anxiety attacks due to perceived genital retraction and/or genital shrinkage, despite a lack of any objectively visible biological changes in the genitalia that are longstanding. "Longstanding" refers to changes that are sustained over a significant period and do not appear reversible, unlike the effect of cold temperatures on some genital regions that cause retraction. These changes may trigger a koro attack when observed, although the effects of cold temperatures are objectively reversible. According to literature, episodes usually last several hours, though the duration may be as long as two days. There are cases in which koro symptoms persist for years in a chronic state, indicating a potential co-morbidity with body dysmorphic disorder. In addition to retraction, other symptoms include a perception of alteration of penis shape and loss of penile muscle tone. In cases when sufferers have no perception of retraction, some patients may complain of genital paraesthesia or genital shortening. Among females, the cardinal symptom is nipple retraction in the breast, generally into the breast as a whole.

Psychological components of koro anxiety include fear of impending death, penile dissolution and loss of sexual power. Feelings of impending death along with retraction and perceived spermatorrhea has a strong cultural link with Chinese traditional beliefs. This is demonstrated by the fact that Asians generally believe koro symptoms are fatal, unlike most patients in the West. Other ideational themes are intra-abdominal organ shrinkage, sex change to female or eunuch, non-specific physical danger, urinary obstruction, sterility, impending madness, spirit possession and a feeling of being bewitched.

Extremely anxious sufferers and their family members may resort to physical methods to prevent the believed retraction of the penis. A man may perform manual or mechanical penile traction, or "anchoring" by a loop of string or some clamping device. Similarly, a woman may be seen grabbing her own breast, pulling her nipple, or even having iron pins inserted into the nipple. Physical injury may occur from these attempts. These forceful attempts often lead to injuries, even death.

Koro is a culture-specific syndrome delusional disorder in which an individual has an overpowering belief that one's genitalia are retracting and will disappear, despite the lack of any true longstanding changes to the genitals. Koro is also known as shrinking penis, and it is listed in the "Diagnostic and Statistical Manual of Mental Disorders". The syndrome occurs worldwide, and mass hysteria of genital-shrinkage anxiety has a history in Africa, Asia, and Europe. In the United States and Europe, the syndrome is commonly known as genital retraction syndrome. The condition can be diagnosed through psychological assessment along with physical examination to rule out genuine disorders of the genitalia that could be causing true retraction.

Melancholia (from , '), also lugubriousness, from the Latin "lugere", to mourn; moroseness, from the Latin "morosus", self-willed, fastidious habit; wistfulness, from old English "wist": intent, or saturnine, was a concept in ancient and pre-modern medicine. Melancholy was one of the four temperaments matching the four humours. In the 19th century, "melancholia" could be physical as well as mental, and melancholic conditions were classified as such by their common cause rather than by their properties.

The outbreaks of dancing mania varied, and several characteristics of it have been recorded. Generally occurring in times of hardship, up to tens of thousands of people would appear to dance for hours, days, weeks, and even months.

Women have often been portrayed in modern literature as the usual participants in dancing mania, although contemporary sources suggest otherwise. Whether the dancing was spontaneous, or an organised event, is also debated. What is certain, however, is that dancers seemed to be in a state of unconsciousness, and unable to control themselves.

In his research into social phenomena, author Robert Bartholomew notes that contemporary sources record that participants often did not reside where the dancing took place. Such people would travel from place to place, and others would join them along the way. With them they brought customs and behaviour that were strange to the local people. Bartholomew describes how dancers wore "strange, colorful attire" and "held wooden sticks".

Robert Marks, in his study of hypnotism, notes that some decorated their hair with garlands. However, not all outbreaks involved foreigners, and not all were particularly calm. Bartholomew notes that some "paraded around naked" and made "obscene gestures". Some even had sexual intercourse. Others acted like animals, and jumped, hopped and leaped about.

They hardly stopped, and some danced until they broke their ribs and subsequently died. Throughout, dancers screamed, laughed, or cried, and some sang. Bartholomew also notes that observers of dancing mania were sometimes treated violently if they refused to join in. Participants demonstrated odd reactions to the colour red; in "A History of Madness in Sixteenth-Century Germany", Midelfort notes they "could not perceive the color red at all", and Bartholomew reports "it was said that dancers could not stand... the color red, often becoming violent on seeing [it]".

Bartholomew also notes that dancers "could not stand pointed shoes", and that dancers enjoyed their feet being hit. Throughout, those affected by dancing mania suffered from a variety of ailments, including chest pains, convulsions, hallucinations, hyperventilation, epileptic fits, and visions. In the end, most simply dropped down, overwhelmed with exhaustion. Midelfort, however, describes how some ended up in a state of ecstasy. Typically, the mania was contagious but it often struck small groups, such as families and individuals.

Lucio Godina (March 8, 1908 – November 24, 1936) and Simplicio Godina (March 8, 1908 - December 8, 1936) were pygopagus conjoined twins from the island of Samar in the Philippines.

At the age of 21 they married Natividad and Victorina Matos, who were identical twins. They performed in various sideshow acts, including in an orchestra on Coney Island and in dance with their wives.

After Lucio died of rheumatic fever in New York City, doctors operated to separate him from Simplicio. Simplicio survived the operation, but died shortly thereafter due to spinal meningitis.

The earliest known report of "bakanae" is from 1828; it was first described scientifically in 1898 by Japanese researcher Shotaro Hori, who showed that the causative agent was fungal.

The fungus affects rice crops in Asia, Africa, and North America. In epidemic cases yield losses may reach up to 20% or more. A 2003 publication from the International Rice Research Institute estimated that outbreaks of bakanae caused crop losses that were 20% to 50% in Japan, 15% in Thailand and 3.7% in India.

Mesoamerican nephropathy (MeN) is a currently unexplained epidemic of chronic kidney disease of unknown origin (CKDu), prevalent in the Pacific Ocean coastal low lands of the Mesoamerican region, including southern Mexico, Guatemala, El Salvador, Nicaragua, Honduras and Costa Rica. In rural areas of Nicaragua the disease is colloquially called creatinina.

This CKD epidemic in Central America spans along a nearly 1000 kilometer stretch of the Pacific coast. In El Salvador and Nicaragua alone, the reported number of men dying from this painful disease has risen five-fold in the last 20 years, although some researchers believe hidden cases have always been there and this increment in official data could be partially due to the recent increase in reports and improved case search, pushed by the growing social and political interest in the disease. In El Salvador, the disease has become the second leading cause of death among adult men, and according to a recent editorial, it has been estimated that this largely unknown epidemic has caused the premature death of at least 20,000 men in the region. Science Magazine reports: "In El Salvador alone, PAHO's latest figures say CKD of all causes kills at least 2,500 people in the country each year".

The people affected by the epidemic are mainly young and middle-aged male laborers in the agricultural sector, particularly sugarcane workers. The disease has also been found to be prevalent in other occupations with a high risk of heat stress, implying strenuous work (miners, construction, port and transportation workers) in the high temperatures of the coastlands. The epidemic appears to affect particular Pacific coastal regions of Nicaragua, El Salvador, Costa Rica, and Guatemala.

Boanthropy is a psychological disorder in which a human believes himself or herself to be a bovine.

Epidemic typhus is a form of typhus so named because the disease often causes epidemics following wars and natural disasters. The causative organism is "Rickettsia prowazekii", transmitted by the human body louse ("Pediculus humanus humanus").

The cause of MeN is unclear, but it is certainly not explained by conventional causes such as diabetes mellitus or hypertension. Many risk factors have been proposed but to date, the causes of the disease remain uncertain and controversial.

The laughter epidemic began on January 30, 1962, at a mission-run boarding school for girls in Kashasha. The laughter started with three girls and spread haphazardly throughout the school, affecting 95 of the 159 pupils, aged 12–18. Symptoms lasted from a few hours to 16 days in those affected. The teaching staff were not affected but reported that students were unable to concentrate on their lessons. The school was forced to close down on March 18, 1962.

After the school was closed and the students were sent home, the epidemic spread to Nshamba, a village that was home to several of the girls. In April and May, 217 people had laughing attacks in the village, most of them being school children and young adults. The Kashasha school was reopened on May 21, only to be closed again at the end of June. In June, the laughing epidemic spread to Ramashenye girls’ middle school, near Bukoba, affecting 48 girls.

The school from which the epidemic sprang was sued; the children and parents transmitted it to the surrounding area. Other schools, Kashasha itself, and another village, comprising thousands of people, were all affected to some degree. Six to eighteen months after it started, the phenomenon died off. The following symptoms were reported on an equally massive scale as the reports of the laughter itself: pain, fainting, flatulence, respiratory problems, rashes, attacks of crying, and random screaming. In total 14 schools were shut down and 1000 people were affected.

Symptoms include severe headache, a sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, delirium and death. A rash begins on the chest about five days after the fever appears, and spreads to the trunk and extremities. A symptom common to all forms of typhus is a fever which may reach 39 °C (102 °F).

Brill-Zinsser disease, first described by Nathan Brill in 1913 at Mount Sinai Hospital in New York City, is a mild form of epidemic typhus which recurs in someone after a long period of latency (similar to the relationship between chickenpox and shingles). This recurrence often occurs in times of relative immunosuppression, which is often in the context of malnutrition and other illnesses. In combination with poor sanitation and hygiene which leads to a greater density of lice, this reactivation is why typhus forms epidemics in times of social chaos and upheaval.

The following signs and symptoms refer to epidemic typhus as it is the most important of the typhus group of diseases.

Signs and symptoms begin with sudden onset of fever, and other flu-like symptoms about one to two weeks after being infected. Five to nine days after the symptoms have started, a rash typically begins on the trunk and spreads to the extremities. This rash eventually spreads over most of the body, sparing the face, palms, and soles. Signs of meningoencephalitis begin with the rash and continue into the second or third weeks. Other signs of meningoencephalitis include sensitivity to light (photophobia), altered mental status (delirium), or coma. Untreated cases are often fatal.

Alvinolagnia or belly fetish or stomach fetish is a partialism in which an individual is sexually attracted to the stomach or belly.

Multiple diseases include the word "typhus" in their description. Types include: