Infectious or contagious?

11:50 Sep 30, 2016 

This has been quite instructive, from my point of view. In particular, I had no idea that this was yet another example of customary usage differing between US and UK English. In UK English "contagious", to me, is a more learned and less colloquial word than "infectious", though a British speaker might use it here. In the US it's apparently the other way round. And I've had to revise my understanding of "contagious", because apparently it applies not just to touching somebody's body or clothes but also to droplet contact: coughs, sneezes, breath.

So it hasn't been a waste of time for me, but I do think it's a waste of time discussing the test question that gave rise to this any further. I have heard more than enough to convince me that treating "contagious" as a wrong answer is unjustified. Possibly whoever set the question is a speaker of British English and felt that people just wouldn't say "contagious" in that situation (which is by no means entirely true). A US speaker using "contagious" correctly and idiomatically will fail the test. Whatever the reason, it's a rubbish question, and those who answered "contagious" and were marked wrong should just shrug it off and proceed.

11:13 Sep 30, 2016 

clearly, it's colloquial. why then putting the three terms that would distinct nuances in usages for different medical conditions? colloquially, surely, we will use them interchangeably, perhaps with "contagious" covering everything. medical professionals will probably be more precise when using these terms.

since this is a test, and it's colloquial, it's not likely they are talking about Lyme disease, for instance. but then again, we can only be guessing and never be sure.

11:09 Sep 30, 2016 

It seems, from the discussion and from Michael Barnett's answer, that "contagious" is used in the US, when "infectious" would be used in the UK because we use "contagious" to mean transmitted through physical contact. A person can be infected with a disease without them being infectious because they aren't yet coughing and sneezing their germs into the air around them.

Note that the test example is colloquial and not an exchange between medical professionals. It also raises the question of whether the teacher who chose the "wrong" answer learnt a different version of English from the writer of the test. (Note my rearguard struggle against the invasion of the UK by the US "different than".)

Re Charles' comment that "This sort of thing happens all the time in language tests. Answers that are not wrong are treated as wrong in order to teach a simple message, ..." That shouldn't happen, because it penalises students who have a better understanding already. However, judging by what I have heard from English parents with children in French schools, it happens more often that the teacher doesn't really understand the question and its answer(s).

10:30 Sep 30, 2016 

am I correct to assume that a flu/cold is implied as the background context, based on voice and tone? even the asker suggested that. as such, perhaps we should be looking for the typical word for cold or flu.

22:29 Sep 29, 2016 

If you haven't already checked it, the following entry may also be helpful:

https://en.oxforddictionaries.com/definition/contagious

16:32 Sep 29, 2016 

yes, sometimes it only "works" in a test, but not in real life. that's why I called it artificial context.

15:04 Sep 29, 2016 

To describe a person or animal as infectious or contagious, meaning likely to transmit the disease they are infected with, is standard usage, listed in many dictionaries, though not in all. I think it is generally accepted and I see no good reason to reject it.

14:56 Sep 29, 2016 

That's the whole point of my discussion entry below: while it is indeed a disease that is contagious, other things can be infectious, from which you might catch the desease.

14:51 Sep 29, 2016 

I think all are wrong. It is the disease a person has that is infectious, not the person. That goes for the other two options as well.

13:11 Sep 29, 2016 

If you have a language question that is "failed" by a literate native speaker, the test is wrong, and should be preserved only in the Gradgrind museum. Contagious sounds better to my ear, but infectious is also clear.

11:22 Sep 29, 2016 

in a test question.

so how can we discuss it?

but here are some points taken from dictionary.com:

1350-1400; Middle English infecten < Latin infectus (past participle of inficere to immerse in dye, discolor, taint, poison), equivalent to in- in-2+ -fec-, combining form of facere to do1, make (see fact ) + -tus past participle suffix

1350-1400; Middle English (< Middle French) < Latin contāgiōn- (stem of contāgiō) contact, infection, equivalent to con- con- + tāg- (variant stem of tangere to touch) + -iōn- -ion; cf. contact

*

based on these examples, I would say that contagious is more related to body contact and touch, while infectious can be even the air or breath close to the infected person. even if this distinction is true (which we can't confirm), how do we know if there will be any body contact upon visit (it may even be a friendly hug)?

11:18 Sep 29, 2016 

This sort of thing happens all the time in language tests. Answers that are not wrong are treated as wrong in order to teach a simple message, which in this case is "don't say contagious when you mean infectious", particularly if your native language encourages you to do so. Later on you refine this by teaching them that the "wrong" answer can be right, in particular circumstances, but usually isn't.

10:53 Sep 29, 2016 

It is simply false to say that "contagious" is wrong here. Both diseases and people (or animals) can be contagious or infectious. They're not synonyms; the difference is as Christine has said. If a person is contagious it means that he/she is liable to transmit a disease by direct contact (including contact with clothing) but not otherwise. If they are infectious, they could transmit it in their breath, for example.

In practice, I think we would usually say "infectious" in this situation, because if we are urging someone not to visit us we probably have in mind the risk of infection, not just contagion.

But what may lie behind the question, and the insistence on "infectious" as the answer, is (a) requiring people to be aware of the difference and not use them loosely as synonyms, as ordinary native speakers often do, actually, and (b) encouraging people not to say "contagious" in English just because they would say "contagioso" in Italian. In Spanish people hardly ever use "infeccioso"; they say "contagioso" even if they mean infectious, and using "contagioso" simply to mean transmissible (or liable to transmit) is not considered wrong. I suspect it may be the same in Italian

10:40 Sep 29, 2016 

The distinction is not always made in conversation, but in the example given, infectious is the only choice that sounds right to my ears.

However, contagious technically describes a disease specifically passed on by direct contact. (The organisms causing the disease cannot survive long outside the body, or are not volatile.)
Infectious diseases can be passed on in other ways, in the air, water or otherwise. The air, water, clothing, whatever is then contaminated.

Emotions and attitudes can be infectious or contagious, but that is another matter!

10:38 Sep 29, 2016 

You could make a case for saying that all three are wrong strictly speaking, but all three are possible colloquially. As you say, it's the disease we mean, not the person. But of the three strictly incorrect usage, I think there is little to choose between "infectious" and "contagious", whereas "contaminated" is rarely use, and is the sort of irony not taught to elementary student. It's a poor question altogether!

10:24 Sep 29, 2016 

In fact, all three are possible, and might well be said by everyday people without specialist medical knowledge.

'contaminated' would be humorous; we might well say "I don't want to contaminate you with my germs!" But cf. earlier uses, going back to Biblical times, of the expression 'unclean' in this same sort of context.

I think the key point is that a DISEASE can be contagious, because you can catch it — but one can't strictly say that a PERSON is contagious, since you can't catch a person! (Well, only if you run fast enough!) But in technically imprecise, everyday language, we DO say this!

'infectious', on the other hand, means 'capable of infecting' — and hence is the correct choice when talking about a person. Cf. expressions like 'infectious waste' — not waste you might catch, but waste from which you might catch something.