Contagious & Infectious

Contagious (pronounced kuhn-tey-juhs)

(1) Capable of being transmitted by bodily contact with an infected person or object.

(2) Carrying or spreading a contagious disease; bearing contagion, as a person or animal with an infectious disease that is contagious.

(3) Tending to spread from person to person.

1350–1400: From the Middle English, from the Old French contagieus (which endures in Modern French as contagieux), from the Late Latin contāgiōsus, the construct being contāgi(ō) (contagion) (a touching, contact," often in a bad sense, "a contact with something physically or morally unclean, contagion") + -ōsus (from the Old Latin -ōsos from -ōnt-to-s  from -o-wont-to-s, the last form being a combination of two primitive Indo-European suffixes (-went- & -wont- and -to-); the suffix -ōsus was added to a noun to form an adjective indicating an abundance of that noun, much as -εις (-eis) operated in Ancient Greek).  The Latin contingere (to touch) came from an assimilated form of com (with, together) + tangere (to touch) from the primitive Indo-European tag- (to touch, handle).  Originally a technical word purely used in medicine, the figurative sense in which it could be applied to anything apt to spread from one to another (rumors etc) dates from the 1650s.  Contagious is an adjective, contagion, contagionist, contagionism, contagiousness & contagosity are nouns and contagiously is an adverb; the most common noun plural is contagions.

Infectious (pronounced in-fek-shuhs)

(1) Communicable by infection, as from one person to another or from one part of the body to another.

(2) Causing or communicating infection (of a disease) caused by pathogenic microorganism or agent, such as bacteria, viruses, or protozoa.

(3) Tending to spread from one to another.

(4) In international law, capable of contaminating with illegality; exposing to seizure or forfeiture.

(5) Diseased (wholly obsolete).

1535–1545: A compound from Middle English, the construct being infect From Middle French infect, from Latin infectivus & infectus (from the Proto-Italic enfaktos (the construct being in- (not) + factus perfect passive participle of faciō (do, make)), perfect passive participle of inficere & inficiō (dye, taint) + -ious (an alternative spelling of -ous, from the Middle English -ous, borrowed from the Old French -ous and -eux, from the Latin -ōsus (full, full of) and a doublet of -ose in unstressed position; the suffix was used to form adjectives from nouns, to denote possession or presence of a quality in any degree, commonly in abundance).  The sense of "catching diseases, having the quality of spreading from person to person, communicable by infection" dates from the 1540s which by the early seventeenth century had spread to emotions, actions et al; earlier in the same sense were infectious, common by the late fifteenth century and infective from a hundred-odd years earlier.  The most novel adaptation of the word was the sense of "captivating", noted first in the 1650s.  Disinfectant (agent used for destroying the germs of infectious diseases) dates from 1837 from the French désinfectant (1816), noun use of present participle of désinfecter, or else from the adjective in English (by 1827) in the sense of "serving to disinfect".  Infectious is an adjective, infection, infectionist, infectionism, infector & infectiousness are nouns and infectiously is an adverb; the most common noun plural is infections.  

Sort of interchangeable

Increasing the risk of contagion: Lindsay Lohan sneezing.

Except for specialists such as virologists or epidemiologists, contagious and infectious can probably be used interchangeably although, when used in the figurative sense, many style guides suggest contagious should be used if referring to something undesirable whereas infectious should be preferred if speaking of the pleasantly irresistible quality of something.  There’s no etymological basis for this; it’s just a convention of use.  Something contagious is a thing which can be transmitted from one living being to another through direct or indirect contact.  Although infectious is also used to describe the process, it has a slightly different meaning in that it refers to diseases caused by infectious agents (such as or SARS-CoV-2 which causes COVID-19) not normally present in the body.  While the notion of contagiousness dates at least from Antiquity, the idea of infectious diseases is more modern, arising only after the publication of the germ theory of disease, not proposed until the late nineteenth century.  Contagious and infectious are also used to refer to people who have communicable diseases at a stage at which transmission to others is likely.

Reducing the risk of contagion: Lindsay Lohan in facemask (although the twin one-way, non-return valves of these masks limit their effectiveness in reducing the risk of infecting others).

For those in the relevant professions however, the difference between the two is significant.  “Infectious” is a description a disease-causing agent’s (typically a virus, bacterium or parasite) ability to enter, survive, and multiply in a host organism; by definition any infectious disease is caused by the presence and activity of such agents.  The best-known infectious diseases include the various strains of influenza (commonly clipped to “the flu”), tuberculosis (TB), malaria, hepatitis, AIDS (HIV the agent) and of course COVID-19 (Sars-COV-2 the agent).  “Contagious” refers to the ability of a disease to spread from one host (such as a bacterium, human or other animal) to another through a variety of vectors including (1) direct contact (shaking hands, kissing, sexual contact (these sometimes sequential)), (2) indirect contact (such as touching a door knob contaminated with the infectious agent using one’s hand which then introduces the agent to the system via the eyes, nose or mouth), (3) airborne transmission (usually by breathing in droplets when an infected person in close vicinity coughs or sneezes) or (4) through a third party (such as animal scratch or bite).

A contagious disease is a sub-set of infectious diseases which can (some more easily than others) be transmitted from one host to another.  Examples of contagious diseases include measles, chickenpox (and other –pox types), COVID-19 and most commonly, the endemic common cold.  While all contagious diseases are infectious, not all infectious diseases are necessarily contagious; tetanus is an infectious disease caused by the bacterium Clostridium tetani, but it is not contagious from host to host.

Quarantine

Quarantine (pronounced kwawr-uhn-teen or kwor-uhn-teen)

(1) In historic English common law, the period of 40 days during which a widow was entitled to remain in her deceased husband's home while any dower is collected and returned.

(2) A strict isolation imposed to prevent the spread of disease and (by extension), any rigorous measure of isolation, regardless of the reason.

(3) A period, originally 40 days (the historic understanding of the maximum known incubation period of disease) of detention or isolation imposed upon ships, persons, animals, or plants on arrival at a port or place, when suspected of carrying some infectious or contagious disease; a record system kept by port health authorities in order to monitor and prevent the spread of contagious diseases.  The origin was in measures taken in 1448 in Venice's lazaret to avoid renewed outbreaks of the bubonic plague.

(4) In historic French law, a 40-day period imposed by the king upon warring nobles during which they were forbidden from exacting revenge or to continue warfare.

(5) A place where such isolation is enforced (a lazaret).

(6) In international relations, a blockade of trade, suspension of diplomatic relations, or other action whereby one country seeks to isolate another.

(7) In computing, a place where files suspected of harboring a computer virus or other harmful code are stored in a way preventing infection of other files or machines; the process of such an isolation.

(8) To withhold a portion of a welfare payment from a person or group of people (Australia).

(9) To quarantine someone or something.

1600–1610: From the Middle English quarentine (period a ship suspected of carrying contagious disease is kept in isolation), from the Norman quarenteine, from the French quarenteine, from the Italian quarantina, a variant of quarantena, originally from the upper Italian (Venetian) dialect as quaranta giorni (space of forty days, group of forty), from quaranta (forty) from the Medieval Latin quarentīna (period of forty days; Lent), from the Classical Latin quadrāgintā (four tens, forty) and related to quattuor (four), from the primitive Indo-European root kwetwer (four).  The difference between quarantine and isolation is one of context; while people might for many reasons be isolated, quarantine is a public health measure to deal with those exposed to or at risk of having been infected by a communicable disease, the duration of the quarantine being sufficient to ensure any risk of spreading the infection has passed.  The name is from the Venetian policy (first enforced as the 30 day edict trentino in 1377) of keeping ships from plague-stricken countries waiting off its port for forty days to ensure no latent cases remained aboard.  The extended sense of "any period of forced isolation" dates from the 1670s.  A doublet of carene and quadragene.

In the context the L'Ancien Régime (pre-revolutionary France), it was a calque of the French quarantaine, following the edicts of Louis IX (and formalized by the quarantaine du Roi (1704) of Louis XIV which was a mechanism of quieting squabbling nobles).  Quarantine was introduced to international relations as a euphemism for "blockade" in 1937 because the Roosevelt administration was (1) conscious of public reaction to the effects on civilians of the Royal Navy’s blockade of Imperial Germany during World War I (1914-1918) and (2) legal advice that a “blockade” of a non-belligerent was, under international law, probably an act of war.  The use was revived by the Kennedy administration during the Cuban Missile Crisis (October 1962).  The verb meaning "put under quarantine" came quickly to be used in any sense including figuratively (to isolate, as by authority) dates from 1804.  Predating the use in public health, in early sixteenth century English common law, the quarentine was the period of 40 days during which a widow was entitled to remain in her dead husband's home while any dower is collected and returned.  The alternative spellings quarentine, quarantin, quaranteen, quarantain, quarantaine, quarrentine, quarantene, quarentene, quarentyne, querentyne are all obsolete except in historic references).  While not of necessity entirely synonymous, detention, sequester, separation, seclusion, segregation, sequestration, lazaretto, segregate, confine, separate, seclude, insulate, restrict, detach & cordon, are at least vaguely similar.  Quarantine is a noun & verb, quarantiner is a noun, quarantinable is an adjective and quarantined & quarantining are verbs & adjectives.

In scripture, the number 40 often occurs although Biblical scholars, always anxious to dismiss musings from numerologists, new age practitioners and crystal-wearing basket weavers, reject the notion it has any special meaning beyond the idea of a “period of trial or struggle”, memorably expressed in the phrase “forty days and forty nights”.  In the Old Testament, when God destroyed the earth in the Great Flood, he delivered rain for 40 days and 40 nights (Genesis 7:12).  After killing the Egyptian, Moses fled to Midian where he spent 40 years in the desert tending flocks (Acts 7:30) and subsequently he stood on Mount Sinai for 40 days and 40 nights (Exodus 24:18) and then interceded on Israel’s behalf for 40 days and 40 nights (Deuteronomy 9:18, 25).  In Deuteronomy 25:3, the maximum number of lashes a man could receive as punishment for a crime was set at 40.  The Israelite spies took 40 days to spy out Canaan (Numbers 13:25), the Israelites wandered for 40 years (Deuteronomy 8:2-5) and before Samson’s deliverance, Israel served the Philistines for 40 years (Judges 13:1).  Goliath taunted Saul’s army for 40 days before David arrived to slay him (1 Samuel 17:16) and when Elijah fled from Jezebel, he traveled 40 days and 40 nights to Mt. Horeb (1 Kings 19:8).  The number 40 also appears in the prophecies of Ezekiel (4:6; 29:11-13) and Jonah (3:4).  In the New Testament, the quarentyne was the desert in which Christ fasted and was tempted for for 40 days and 40 nights (Matthew 4:2) and there were 40 days between Jesus’ resurrection and ascension (Acts 1:3).  Presumably, this influenced Western medicine because it was long (and still by some) recommended that women should for 40 days rest after childbirth.

Plague, the Venetians and Quarantino

The Plague of Justinian arrived in Byzantine capital of Constantinople in 541, brought from recently conquered Egypt across the Mediterranean by plague-ridden fleas in the fur of rats on ships bringing loot from the war.  From the imperial capital it spread across Europe, Asia, North Africa and Arabia, killing an estimated thirty to fifty million, perhaps a quarter the inhabitants of the eastern Mediterranean.  Plague never really went away, localized outbreaks happening periodically unit it returned as a pandemic some eight-hundred years later; the Black Death, which hit Europe in 1347, claimed some two-hundred million in just four years and demographically, Europe would not for centuries recover from the Black Death.

There was at the time little scientific understanding of contagion but it became clear it was related to proximity so officials in Venetian-controlled port city of Ragusa (now Dubrovnik in Croatia) resolved to keep newly arrived sailors in isolation until it was apparent they were healthy.  Initially, the sailors were confined to their ships for thirty days, formalized in a 1377 Venetian law as a trentino (thirty days), which radically reduced the transmission rate and by 1448, the Venetians had increased the forced isolation to forty days (quarantine), which, given bubonic plague’s thirty-seven day cycle from infection to death, was an example of a practical scientific experiment.  The word soon entered Middle English as quarantine (already in use in common law as a measure of certain rights accruing to a widow), the origin of the modern word and practice of quarantine.  The English had many opportunities to practice quarentine.  In the three-hundred odd years between 1348 and 1665, London suffered some forty outbreaks, about once a generation (or every twenty years), the significance of this pattern something which modern epidemiologists would later understand.  Quarentine laws were introduced in the early sixteenth century and proved effective, reducing the historic medieval death-rates to about twenty percent.

Eggs à la Lohan

In self-imposed quarantine in March 2020, Lindsay Lohan was apparently inspired by a widely shared motivational poem by Kitty O’Meara (on the internet dubbed the "poet laureate of the pandemic") which included the fragment:

And the people stayed home.  And read books, and listened, and rested, and exercised, and made art, and played games, and learned new ways of being, and were still.  And listened more deeply.  Some meditated, some prayed, some danced.  Some met their shadows.  And the people began to think differently.

One of Lindsay Lohan's recommendations for a time of quarantine was to take the time to cook, posting a photograph of Eggs à la Lohan, a tasty looking omelet.  The poem also contained the words:

And the people healed.  And, in the absence of people living in ignorant, dangerous, mindless, and heartless ways, the earth began to heal.  And when the danger passed, and the people joined together again, they grieved their losses, and made new choices, and dreamed new images, and created new ways to live and heal the earth fully, as they had been healed.

Unfortunately, viewed from early 2023, it would seem Ms O'Meara's hopes quarantine might have left us kinder, gentler and more thoughtful may not have be realized.  It may be Mr Putin didn’t read poem and just ate omelet. 

Isolation

Isolation (pronounced ahy-suh-ley-shuhn)

(1) An act or instance of isolating; the state of being isolated.

(2) In medicine, the complete separation from others of a person suffering from contagious or infectious disease; quarantine.

(3) In diplomacy, the separation, as a deliberate choice by government, of a nation from other nations by nonparticipation in or withdrawal from international relations and institutions.

(4) In psychoanalysis, a process whereby an idea or memory is divested of its emotional component.

(5) In social psychology, the failure of an individual to maintain contact with others or genuine communication where interaction with others persists.

(6) In linguistics and other fields, to consider matters without regard to context.

(7) In chemistry, obtaining an element from one of its compounds, or of a compound from a mixture

(8) In computing, a database property that determines when and how changes made in one transaction are visible to other concurrent transactions.

1830s: A compound word, isolate + -ion.  A modern English borrowing from the French isolé (placed on an island (thus away from other people)).  Isolé was derived from the Italian isolato, past participle of isolare, the root of which was the Latin insulātus & insulātes (made into an island), from insula (island).  From circa 1740, English at first used the French isolé (rendered as isole) which appeared also as isole'd in the 1750s, isolate the verb emerging in the 1830s; isolated the past participle.  Isolation is now the most familiar form, the suffix –ion is from the Latin -iō (genitive -iōnis), appended to a perfect passive participle to form a noun of action.  Words with similar meanings, often varying by context, includes solitude, desolation, confinement, segregation, remoteness, privacy, quarantine, sequestration, aloofness, detachment, withdrawal, exile, aloneness, concealment, retreat, hiding, reclusion, monkhood, and seclusiveness.

Isolation, Social Phobia and Social Anxiety Disorder

As long ago as 400 BC, Greek physician Hippocrates (circa 460–c 370 BC) noted there were people who sought social isolation, describing them as those who "love darkness as life" adding, in a hint at later understandings of mental illness, they tended also to "think every man observes them."  Such folk doubtless pre-dated antiquity, being always part of organized societies but it wasn’t until the late nineteenth century when psychiatry emerged as a distinct field that the particular human condition came to be known as social phobia or social neurosis, then thought of as a descriptor of extremely shy patients who sought isolation by choice.

Desolate: an emo in isolation.

Despite the increasing medicalization of the spectrum of the human condition, it wasn’t until 1968, in the second edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-II), that social isolation was described as a specific phobia of social situations or excessive fear of being observed or scrutinized by others but at this point the definition of social phobia was very narrow.  With the release in 1980 of the DSM-III, social phobia was included as an official psychiatric diagnosis although it restricted the criteria, noting those who sought social isolation did so because of a fear of “performance situations” and did not include fears of less formal encounters such as casual conversations.  Those with such broad fears were instead to be diagnosed with “avoidant personality disorder” which, for technical reasons defined within the DSM-III, could not be co-diagnosed as social phobia, an attitude reflecting the editors’ view that phobias and neuroses needed specifically to be codified rather than acknowledging there existed in some a “general anxiety” disorder.  This neglect was addressed in the 1987 revision to the DSM-III (DSM-III-R) which changed the diagnostic criteria, making it possible to diagnose social phobia and avoidant personality disorder in the same patient.  In this revision, the term "generalized social phobia" was introduced.

DSM-IV was published in 1994 and the term “social anxiety disorder” (SAD) replaced social phobia, this reflecting how broad and generalized fears are in the condition although the diagnostic criteria differed only slightly from those in the DSM-III-R.  The DSM-IV position remains essentially current; the modifications in the DSM-5 (2013) not substantively changing the diagnosis, altering little more than the wording of the time frame although the emphasis on recognizing whether the experience of anxiety is unreasonable or excessive was shifted from patient to clinician.