A disease is a particular abnormal condition, a disorder of a structure or function, that affects part or all of an organism.

A pathogen (= "infectious agent") is anything that can produce disease. For example, a virus_, bacterium_, protozoan_, prion_, viroid_, or fungus_.

The study of disease is called pathology.

Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in defined populations.

Epidemiology, literally meaning "the study of what is upon the people", is derived from Greek epi, meaning 'upon, among', demos, meaning 'people, district', and logos, meaning 'study, word, discourse', suggesting that it applies only to human populations.

Disease can be acute or chronic.


1   Cause

Diseases can be caused by pathogens or by inheriting abnormal genes.

2   Examples

2.1   Herpes

See, there are two types of Herpes: HSV-1 and HSV-2. HSV-1 usually causes breakouts around the mouth — we just call them cold sores or fever blisters. Over 80% of the population has HSV-1, although at any given time almost none of us have a breakout. HSV-2 causes breakouts around the genitals.14 The majority of people never get breakouts or get such minor breakouts that they don’t even realize that it’s herpes. My friend who has had a breakout said that he originally thought his was just a bug bite. It wasn’t until a second one showed up that he decided to get it checked out. It’s been over three years and he hasn’t had another breakout since. He’s also in a monogamous relationship and his girlfriend has never had a breakout.

Herpes never goes away, but it’s relatively harmless. In fact, even if you do get breakouts, most people stop getting them after a couple years. And if you’re one of the unlucky few who actually does get bad break outs, you can take medication to suppress them. So there. Not worried about herpes anymore… After all, I probably already have it, and so do many of you.

2.2   HIV

HIV is no longer the death warrant it once was. Don’t get me wrong, contracting it would be awful and surely life-altering. But you would live. I just hope you have good health insurance. As of 2011, the life expectancy of someone who contracts HIV is 40 years from the day they contract it. When in doubt, just look at Magic Johnson.

There are some demographics which are far more likely to catch HIV than others, primarily gay men and drug users. 80% of all HIV cases come from gay men or drug addicts who use dirty needles. When it comes to vaginal sex, it’s almost impossible for a man to catch it from a woman, while a woman can catch it from a man. But anal sex seems to be the big culprit here.

Also, I hate to say it, but HIV positive cases are predominantly lower income classes. African-Americans account disproportionately for 42% of all HIV cases in the US. The disease practically doesn’t exist in Western Europe at this point.

The symptoms of HIV are flu-like symptoms a couple weeks after contracting it. From there your immune system slowly shuts down over the period of years. There are a lot of therapies and treatments available and most people who contract it are able to live functional, mostly normal lives, assuming they get the proper medical care. So the news on the HIV front over the past few decades has actually been mostly good.

2.3   Prion-disease

Prion disease has a case-fatality rate of 100%. That's not an estimate or approximation and it's not rounded up. They are also untreatable.

There are only five well studied prion diseases (because of their rarity). Two are exclusively heritable: fatal-familial insomnia and Gerstmann–Sträussler–Scheinker syndrome. One, Kuru, is transmitted via cannibalism.

The incubation times are extremely long. Some estimates for Kuru go up to 20-50 years.

The most prevalent form of prion disease in humans is new variant Creutzfeldt–Jakob disease (nvCJD) or Human Mad Cow which has a lag of about 10 years based on CDC data. It is transmitted by eating tainted beef products. Let me stress that this is extremely rare: there have been 3 confirmed cases in the United States.

It is extremely unlikely that Soylent is a vector for prion disease, especially since it's been vegan since version 1.2 and never contained beef as an ingredient. Even if it somehow contained tainted beef, given that it's been available for less than 3 years, it's extremely unlikely that any cases of nvCJD (of which there have only a few in the last decade) or any other cases of prion disease were caused by Soylent.

3   Spread


Public Health systems are prepared to deal with short-term outbreaks that last for weeks, like an outbreak of meningitis. They do not have the capacity to sustain for outbreaks that last for months. Other solutions will have to be found.


Public Health systems are prepared to deal with short-term outbreaks that last for weeks, like an outbreak of meningitis. They do not have the capacity to sustain for outbreaks that last for months. Other solutions will have to be found.

3.1   Social distancing

Social distancing ...

3.2   Epidemic

An epidemic (= "outbreak") is the rapid spread of disease to a large number of people within a short period of time.

The term epidemic derives from a word form attributed to Homer's Odyssey, which later took its medical meaning from the Epidemics, a treatise by Hippocrates.

Thucydides' description of the Plague of Athens is considered one of the earliest accounts of a disease epidemic.

4   History

The Greek physician Hippocrates, known as the father of medicine,[5][6] sought a logic to sickness; he is the first person known to have examined the relationships between the occurrence of disease and environmental influences

The distinction between "epidemic" and "endemic" was first drawn by Hippocrates,[3] to distinguish between diseases that are "visited upon" a population (epidemic) from those that "reside within" a population (endemic).

4.1   Miasma theory

Miasma theory held that diseases such as cholera, chlamydia infection, or the Black Death were caused by a miasma, a noxious form of "bad air" emanating from rotting organic matter

4.2   Germ Theory

The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease.

Basic forms of germ theory were proposed in the late Middle Ages by Girolamo Fracastoro in 1546 and expanded upon by Marcus von Plenciz in 1762. However, such views were held in disdain in Europe, where Galen's miasma theory remained dominant among scientists and doctors.

The Italian scholar and physician Girolamo Fracastoro proposed in 1546 in his book De Contagione et Contagiosis Morbis that epidemic diseases are caused by transferable seed-like entities (seminaria morbi) that transmit infection by direct or indirect contact, or even without contact over long distances.

By the early nineteenth century, smallpox vaccination was commonplace in Europe, though doctors were unaware of how it worked or how to extend the principle to other diseases.

Italian physician Francesco Redi provided early evidence against spontaneous generation. He devised an experiment in 1668 in which he used three jars. He placed a meatloaf and egg in each of the three jars. He had one of the jars open, another one tightly sealed, and the last one covered with gauze. After a few days, he observed that the meatloaf in the open jar was covered with maggots, and the jar covered with gauze had maggots on the surface of the gauze. However, the tightly sealed jar had no maggots inside or outside it. He also noticed that the maggots were found only on surfaces that were accessible by flies. From this he concluded that spontaneous generation is not a plausible theory.

Spontaneous generation refers to an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms. The theory of spontaneous generation held that living creatures could arise from nonliving matter and that such processes were commonplace and regular. For instance, it was hypothesized that certain forms such as fleas could arise from inanimate matter such as dust, or that maggots could arise from dead flesh.

The doctrine of spontaneous generation was coherently synthesized by Aristotle who compiled and expanded the work of earlier natural philosophers and the various ancient explanations for the appearance of organisms, and was taken as scientific fact for two millennia.

Though challenged in the 17th and 18th centuries by the experiments of Francesco Redi and Lazzaro Spallanzani, spontaneous generation was not disproved until the work of Louis Pasteur and John Tyndall in the mid-19th century.