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.

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.

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 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.

In China, traditional treatment based on the causes suggested by cultural beliefs are administrated to the patient. Praying to gods and asking Taoist priests to perform exorcism is common. If a fox spirit is believed to be involved, people may hit gongs or beat the person to drive it out. The person will receive a yang- or yin-augmenting Chinese medicine potion, usually including herbs, pilose antler (stag of deer) or deer tail, and tiger penis, deer penis, or fur seal penis. Other foods for therapy are pepper soup, ginger soup and liquor.

According to Balaratnasingam and Janca, “mass hysteria is to date a poorly understood condition. Little certainty exists regarding its” cause.

Besides the difficulties common to all research involving the social sciences, including a lack of opportunity for controlled experiments, mass sociogenic illness presents special difficulties to researchers in this field. Balaratnasingam and Janca report that the methods for “diagnosis of mass hysteria remains contentious. According to Timothy Jones of the Tennessee Department of Public Health, the effects resulting from MPI “can be difficult to differentiate from [those of] bioterrorism, rapidly spreading infection or acute toxic exposure.”

These troubles result from the residual diagnosis of MPI. Singer, of the Uniformed Schools of Medicine, puts the problems with such a diagnosis thus:

“[y]ou find a group of people getting sick, you investigate, you measure everything you can measure . . . and when you still can't find any physical reason, you say 'well, there's nothing else here, so let's call it a case of MPI.'” There is a lack of logic in an argument that proceeds: “There isn't anything, so it must be MPI.” It precludes the notion that an organic factor could have been overlooked. Nevertheless, running an extensive number of tests extends the probability of false positives.

British psychiatrist Simon Wesseley distinguishes between two forms of MPI:

- mass anxiety hysteria “consists of episodes of acute anxiety, occurring mainly in schoolchildren. Prior tension is absent and the rapid spread is by visual contact.”

- mass motor hysteria “consists of abnormalities in motor behaviour. It occurs in any age group and prior tension is present. Initial cases can be identified and the spread is gradual. . . . [T]he outbreak may be prolonged.”

While his definition is sometimes adhered to, others such as Ali-Gombe et al. of the University of Maiduguri, Nigeria contest Wesseley's definition and describe outbreaks with qualities of both mass motor hysteria and mass anxiety hysteria.

An evolutionary psychology explanation for this disorder, as well as for conversion disorder more generally, is that the symptom may have been evolutionarily advantageous during warfare. A non-combatant with these symptoms signals non-verbally, possibly to someone speaking a different language, that she or he is not dangerous as a combatant and also may be carrying some form of dangerous infectious disease. This can explain that conversion disorder may develop following a threatening situation, that there may be a group effect with many people simultaneously developing similar symptoms, and the gender difference in prevalence.

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.

When the Malays were asked why they thought that women were more likely to suffer from latah, they responded with the cultural explanation that women have less 'semangat' or soul substance. They also said women are simply easier to tease than men, and coupling these two together: latah becomes more readily observable and developed throughout recurrent provocation in women than in men. This also accounts for the higher prevalence of latah in lower status persons, as they are more vulnerable to abuse than others. The Malay also believe women are more susceptible because they lose more blood than men, through menstruation. Some Malay believe that excess tickling of a child will predispose them to latah later in life.

In historical culture-bound cases, reassurance and talks on sexual anatomy are given. Patients are treated with psychotherapy distributed according to symptoms and to etiologically significant points in the past. Prognosis appears to be better in cases with a previously functional personality, a short history and low frequency of attacks, and a relatively uncomplicated sexual life.

For sporadic Western cases, careful diagnostic workup including searching for underlying sexual conflict is common. The choice of psychotherapeutic treatment is based on the psychiatric pathology found.

The onset of Latah is often associated with stress. In a study done by Tanner and Chamberland in 2001, a significant number of research participants had experienced a life stressor (such as a child or husband dying) just before becoming latah. Additionally, a large number of participants from many research studies have reported strange dreams occurring just before the onset of latah. These dreams usually had a sexual element to them, often involving penises or enlarged penises. According to Tanner and Chamberland, perhaps the dreams, although with variation, indicate some sort of dysfunction in a specific anatomical area. Exploring this further might lead to more insights as to the cause and/or cure of latah.

Osborne (2001) states that latah is a possible emotional outlet in a stifling culture. Winzeler’s believes that latah is less demeaning for women than it is for men, and that women actually have more freedom in society because they are not held to as strict of standards as men are. He argues that as men age, they become more concerned with personal dignity and poise while women become less so. Because of this, women feel more freedom to engage in latah behavior, while men do not.

The infection is treated with antibiotics. Intravenous fluids and oxygen may be needed to stabilize the patient. There is a significant disparity between the untreated mortality and treated mortality rates: 10-60% untreated versus close to 0% treated with antibiotics within 8 days of initial infection. Tetracycline, Chloramphenicol, and doxycycline are commonly used. Infection can also be prevented by vaccination.

Some of the simplest methods of prevention and treatment focus on preventing infestation of body lice. Complete change of clothing, washing the infested clothing in hot water, and in some cases also treating recently used bedsheets all help to prevent typhus by removing potentially infected lice. Clothes also left unworn and unwashed for 7 days also cause both lice and their eggs to die, as they have no access to their human host. Another form of lice prevention requires dusting infested clothing with a powder consisting of 10% DDT, 1% malathion, or 1% permethrin, which kill lice and their eggs.

As of 2017 there is no commercially available vaccine. A vaccine has been in development for scrub typhus known as the scrub typhus vaccine.

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 American Public Health Association recommends treatment based upon clinical findings and before culturing confirms the diagnosis. Without treatment, death may occur in 10 to 60 percent of patients with epidemic typhus, with patients over age 60 having the highest risk of death. In the antibiotic era, death is uncommon if doxycycline is given. In one study of 60 hospitalized patients with epidemic typhus, no patient died when given doxycycline or chloramphenicol. Some patients also may need oxygen and intravenous (IV) fluids.

Katagelasticism is a psychological condition in which a person excessively enjoys laughing at others (coined by Christian F. Hempelmann and Sean Harrigan from ("katagelastēs"), Ancient Greek for “mocker”). Katagelasticists actively seek and establish situations in which they can laugh at others (at the expense of these people). There is a broad variety of things that katagelasticists would do—starting from harmless pranks or word plays to truly embarrassing and even harmful, mean-spirited jokes. They would be of the opinion that laughing at others is part of the daily life and if others do not like being laughed at, they should just fight back. For the katagelasticists it is fun laughing at others and there is almost nothing that might hinder them from doing so. For them, some people even might provoke getting laughed at (and surely deserve being laughed at). This condition often makes it difficult for sufferers to gain and maintain acquaintances and romantic partners.

Coxsackie B virus is spread by contact and epidemics usually occur during warm weather in temperate regions and at any time in the tropics.

The illness lasts about a week and is rarely fatal. Treatment includes the administration of nonsteroidal anti-inflammatory agents or the application of heat to the affected muscles. Relapses during the weeks following the initial episode are a characteristic feature of this disease.

There is no vaccine for SARS to date. Isolation and quarantine remain the most effective means to prevent the spread of SARS. Other preventative measures include:

- Handwashing

- Disinfection of surfaces for fomites

- Wearing a surgical mask

- Avoiding contact with bodily fluids

- Washing the personal items of someone with SARS in hot, soapy water (eating utensils, dishes, bedding, etc.)

- Keeping children with symptoms home from school

Many public health interventions were taken to help control the spread of the disease; which is mainly spread through respiratory droplets in the air. These interventions included earlier detection of the disease, isolation of people who are infected, droplet and contact precautions, and the use of personal protective equipment (PPE); including masks and isolation gowns. A screening process was also put in place at airports to monitor air travel to and from affected countries. Although no cases have been identified since 2004, the CDC is still working to make federal and local rapid response guidelines and recommendations in the event of a reappearance of the virus.

The first academic paper to investigate this phenomenon was published in 2009. Along with gelotophobia and gelotophilia it can be measured through a questionnaire that consists of 45 questions (the PhoPhiKat-45; the PhoPhiKat-30 is a short form that consists of 30 items). This is a reliable and valid instrument that has been used in a variety of studies. The questionnaire is also online for a free self-assessment in an English form at gelotophobia.org and in a German form here.

Gelotophobia, gelotophilia, and katagelasticism describe three different stances towards laughter and laughing at. Empirical studies with the PhoPhiKat-45 show that, of course, people can not at the same time fear and like being laughed at (i.e., be gelotophobes and gelotophiles at the same time). However, there is at least a subgroup of gelotophobes that enjoys laughing at others, despite knowing how harmful this can be. Finally, gelotophilia and katagelasticism are positively related; i.e., those who enjoy being laughed at might also enjoy laughing at others.

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.

have been proposed among "possible causes" of the disease. For instance, the above-mentioned declaration produced by the April 2013 International Conference which took place in San Salvador said that:

The nature of multifactorial problems is, that the observed disease can be caused from regionally different sets of risk factors, e.g. agrochemicals and heavy metals are ubiquitous in endemic and non-endemic areas, feature proteinuria, or have not been related previously to CKD but only to acute kidney injury. Mesoamerican volcanic soils, for instance, are rich in arsenic and cadmium (e.g. CKDu miners).

Encephalitis lethargica or Nellysa disease is an atypical form of encephalitis. Also known as "sleeping sickness" or "sleepy sickness" (distinct from tsetse fly-transmitted sleeping sickness), it was first described in 1917 by the neurologist Constantin von Economo and the pathologist Jean-René Cruchet.

The disease attacks the brain, leaving some victims in a statue-like condition, speechless and motionless. Between 1915 and 1926, an epidemic of encephalitis lethargica spread around the world. Nearly five million people were affected, a third of whom died in the acute stages. Many of those who survived never returned to their pre-existing "aliveness".They would be conscious and aware – yet not fully awake; they would sit motionless and speechless all day in their chairs, totally lacking energy, impetus, initiative, motive, appetite, affect or desire; they registered what went on about them without active attention, and with profound indifference. They neither conveyed nor felt the feeling of life; they were as insubstantial as ghosts, and as passive as zombies.No recurrence of the epidemic has since been reported, though isolated cases continue to occur.

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.

Antibiotics are ineffective, as SARS is a viral disease. Treatment of SARS is largely supportive with antipyretics, supplemental oxygen and mechanical ventilation as needed.

People with SARS must be isolated, preferably in negative pressure rooms, with complete barrier nursing precautions taken for any necessary contact with these patients.

Some of the more serious damage caused by SARS may be due to the body's own immune system reacting in what is known as cytokine storm.

As of 2017, there is no cure or protective vaccine for SARS that has been shown to be both safe and effective in humans. The identification and development of novel vaccines and medicines to treat SARS is a priority for governments and public health agencies around the world. MassBiologics, a non-profit organization engaged in the discovery, development and manufacturing of biologic therapies, is cooperating with researchers at NIH and the CDC developed a monoclonal antibody therapy that demonstrated efficacy in animal models.

The disease may remain manageable, but in more severe cases, lymph nodes in the neck may swell, and breathing and swallowing are more difficult. People in this stage should seek immediate medical attention, as obstruction in the throat may require intubation or a tracheotomy. Abnormal cardiac rhythms can occur early in the course of the illness or weeks later, and can lead to heart failure. Diphtheria can also cause paralysis in the eye, neck, throat, or respiratory muscles. Patients with severe cases are put in a hospital intensive care unit and given a diphtheria antitoxin. Since antitoxin does not neutralize toxin that is already bound to tissues, delaying its administration is associated with an increase in mortality risk. Therefore, the decision to administer diphtheria antitoxin is based on clinical diagnosis, and should not await laboratory confirmation.

Antibiotics have not been demonstrated to affect healing of local infection in diphtheria patients treated with antitoxin. Antibiotics are used in patients or carriers to eradicate "C. diphtheriae" and prevent its transmission to others. The Centers for Disease Control and Prevention recommends either:

- Metronidazole

- Erythromycin is given (orally or by injection) for 14 days (40 mg/kg per day with a maximum of 2 g/d), or

- Procaine penicillin G is given intramuscularly for 14 days (300,000 U/d for patients weighing 10 kg); patients with allergies to penicillin G or erythromycin can use rifampin or clindamycin.

In cases that progress beyond a throat infection, diphtheria toxin spreads through the blood and can lead to potentially life-threatening complications that affect other organs, such as the heart and kidneys. Damage to the heart caused by the toxin affects the heart's ability to pump blood or the kidneys' ability to clear wastes. It can also cause nerve damage, eventually leading to paralysis. About 40% to 50% of those left untreated can die.