Wikipedia:Reference desk/Archives/Science/2017 June 15

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June 15

Why just after getting scabies is needed to wash the clothes in hot water?

Why just after getting scabies is needed to wash the clothes in hot water? We don't see this instruction for people who have gonorrhea or chlamydia for example. What is the reason for that? Do these bacteria cannot exist outside of the body on clothes? Could they not be in a Endospore forms? 93.126.88.30 (talk) 06:57, 15 June 2017 (UTC)

You need to read our article on Scabies. The cause is not a virus or bacterium, it's a tiny mite, so it and any eggs are killed by hot water. Dbfirs 07:37, 15 June 2017 (UTC)

Venereal disease is by definition not going to be transmitted by touching discarded clothing - otherwise, it wouldn't be defined as a venereal disease! Wnt (talk) 14:38, 15 June 2017 (UTC)

Did you read our article?

Scabies is contagious and can be contracted through prolonged physical contact with an infested person.[24] This includes sexual intercourse, although a majority of cases are acquired through other forms of skin-to-skin contact. Less commonly, scabies infestation can happen through the sharing of clothes, towels, and bedding, but this is not a major mode of transmission; individual mites can only survive for two to three days, at most, away from human skin at room temperature.[25][26]

So simple touching? Maybe not but prolonged contact can, but isn't a common mode of transmission. Still the risk is high enough that washing bedding and clothing used within the past 3 days is recommended. BTW, as this part makes clear, scabies is an STI, but sexual transmission isn't the most common form of transmission. Nil Einne (talk) 15:14, 15 June 2017 (UTC)

Hmmmm, according to our article there's a difference between sexually transmitted infection which is potentially also non-sexual, and sexually transmitted disease that is more restrictively defined. I assumed "venereal disease" was the equivalent of the latter but our article makes it sound like the former; admittedly that term is outdated now. If someone's feeling more energetic at the moment they could tease out those definitions in more detail for the article... Wnt (talk) 16:57, 15 June 2017 (UTC)

What article? The sexually transmitted infection article seems clear and supports my understanding, the term sexually transmitted disease is not generally used nowadays as it's unclear if it refers solely to sexually transmitted infections when they manifest as diseases or is a synonym for sexually transmitted infection and there's no general need to restrict to sexually transmitted infections when they manifest as diseases; therefore the term sexually transmitted infection is generally preferred. In other words the term sexually transmitted disease is ill-defined and not necessarily different from sexually transmitted infection. (However the term STD is still used a lot, but I think you'll find investigating these uses that many of them are using it as a synonym for STI. And yes it's often useful to differentiate between the infections and diseases themselves, e.g. a HIV infection vs HIV/AIDS, but that's a different point.)

This has come, at least partly from the recognition that there tend to be significantly more sexually transmitted infections than are presented as a disease (whether because they never manifested as a disease or because they symptoms were missed or simply ignored/kept secret). And with modern medicine, many tests are for sexually transmitted infections rather than only attempting to detect what may be called disease. The term venereal disease coming from before this happened and AFAIK having been largely abandoned before this happened is even more ill-defined. In any case, none of these really deal with whether scabies is or isn't an STI/STD.

Our article also mentions "sexually transmissible disease" as any disease which can be spread via sexual contact and suggests that the term STI is restricted to infections where sexual transmission is the primary vector and even goes as far as to suggest STI is used when the probability of transmission by means other than sexual contact (not taking into account things like sharing needles and blood transfusions) is negligible. But the terms "sexually transmissible disease" or "sexually transmissible infection" still seem to be a lot less commonly used. (Since I can't work out how to combine plural and singular, I won't give proper results but Google Scholar suggests transmitted has several 10ks for disease/s and infection/s but less than 10k for transmissible again for both disease/s and infection/s.)

And scabies is classified as a sexually transmitted infection both in the STI article and Template:STD and STI. This source [1] claims that "Scabies in adults frequently is sexually acquired, although scabies in children usually is not" but neither of the sources used really seem to say that to me that I noticed [2] [3]. (One simply recommends treatment of all close contacts including sexual contacts, the other something similar and "Scabies is considered to be a sexually transmitted disease, therefore, patients should undergo routine examination for sexually transmitted infection.") I did find another non reliable source that claims it's the most common form of transmission among sexually active young adults [4] but it provides no citations and I couldn't find any RS that mentions this.

But in any case, I'm not convinced this is the reason why it's generally considered an sexually transmitted infection. Despite what our article claims, sexually transmitted infection does seem to commonly include infections where sexual transmission is a common but not necessarily most common mode of transmission. This likely depends on the audience, for patients and their doctors, treating scabies as an STI makes sense since it's something sexually active people may need to consider (especially as barrier methods may be relatively ineffective at preventing transmission). And if someone does have an infection it may be worth testing for other STIs (which seems to be that that source is saying) as well as providing general advice on STIs. Contacting all recent sexual partners (depending on the precise infection) may also make sense. For an epidemiologist studying the spread of scabies, knowing that it's sexually transmissible is important but in many case treating it as an STI in modelling the spread would be a mistake.

This also suggests why even adding terms like "sexually transmissible infection" or disease is an imperfect solution, since something like meningitis may be sexually transmissible but I'm not sure how common it is they are usefully treated as STIs. (Although it's possible this may change [5]. Also with some sexually transmissible infections which aren't generally considered sexually transmitted it may sometimes be possible to guess whether it was likely sexually transmitted by the area of infection. In addition, factors like notification of sexual partners probably depend more on the risk of sexual transmission rather than whether you can to consider it an STI. But it's a moot point if any sexual partner would already be considered at sufficient risk which admitedly does apply to scabies if transmission is understood.)

Anyway while this isn't the place to discuss article content, I don't personally see much point trying to spend much time clarifying what venereal disease means in our article. But it might be helpful to check if definition of STI mention in our article really fits with how it's used.

Nil Einne (talk) 04:35, 16 June 2017 (UTC)

BTW while researching the answer above, I noticed that one of the sources [6] says

Studies done by K. Mellanby showed that only two new cases of scabies (1 %) resulted from 63 experiments using underwear and blankets from heavily infested patients [9]. Moreover, none of the 25 experiments using blankets alone resulted in transmission of scabies [9].

so it seems the risk is actually probably very low. Still at least in the developed world, the cost-benefit may still support cleaning the material rather than risk further spread.

Nil Einne (talk) 04:35, 16 June 2017 (UTC)

Digsilent

Is there any body who has digsilent 2017? I wanna run a simulation via this software but my laptop, neither my friends', doesn't support the latest version. Unfortunately the task which I need is not available in the earlier versions. I'll be really glad if some one could help me. (It just takes few minutes).Freshman404^Talk 17:51, 15 June 2017 (UTC)