Wikipedia:Reference desk/Archives/Science/2020 March 21

= March 21 =

Immune system questions.
If we moved into a low-bacteria environment, does that make our immune system weaker to bacteria? Like, does our immune system lose their resistance to bacteria? I ask this because I know this is the case for allergies. I happen to be cat-allergic, got my 1st cat at age 12. Took only 2 days with some allergies. Then lived and cuddled with the same cat for 6 years. 18, went to college for a year, came back, immediately allergic to my cat. Red eye, running nose, and in a 3-week period was not enough to recover. That my immune system was stronger at age 12 than age 18 is standard. Years later expose to cat for lesser periods, can still fight it off, but will lose allergic-resistance to cats if not exposed for some time. But that's not my q. My q is about bacteria. Supposed someone moved into an apartment and bleaches the walls, floors, and doorknobs. Stores toothbrush in hydrogen-peroxide water solution, mouthwashes every day, hand sanitizers. Does that make their immune system weaker to bacteria so if they leave the environment and venture onto the public?

So as a 2nd question, is our body's immune system to bacteria, separate to the immune system to allergies? Meaning, 1 can have a strong immune system to bacteria but weak to allergies, or strong to allergies but weak to bacteria? Supposedly a person hit with chicken-pox becomes immune to it for life (or at least a good 50 years). I also happen to be motion-sickness naturally, and can temporarily be immune to that. If I read while in car, feel sick to throw up, then can read in car the next day. However, if I don't read in car for a year, I have to restart that resistance. But does that mean humans have to constantly be exposed to all kinds of bacteria in order to stay immune from them? 67.175.224.138 (talk) 11:49, 21 March 2020 (UTC).


 * See: Allergy, Hygiene hypothesis and Immune tolerance. Allergies are the result of the immune system malfunctioning and becoming being hypersensitive to harmless substances in the environment. The Hygiene hypothesis suggests that this may be the result of the immune system not being challenged enough in early life. Motion sickness is nothing to do with the immune system. Presumably your system of balance becomes habituated to the motion of a car the more often you experience it. Richerman  (talk) 19:55, 21 March 2020 (UTC)
 * People can become habituated to a particular cause of Motion sickness (there are several) on a temporary basis without this habituation becoming permanent. Horatio Nelson notoriously suffered from seasickness for several days every time he embarked after a period onshore, throughout his life. {The poster formerly known as 87.81.230.195} 90.197.27.39 (talk) 10:45, 22 March 2020 (UTC)

Anyways, I didn't ask about immune system immunity to viruses cuz I already know the answer. I happen to explore sewers. Got sick from the norovirus and rotavirus floating in the moist air, got gastroenteritis. Then when recovered, go right back into the tunnels because got immune to them. 4 years later, got sick again, but maybe 75% as bad. Asked a microbiology professor, why is that? Did I lose my immunity? The answer is viruses change over time. But what I don't know is if bacteria changes over time. If it does, then I imagine it's good to stay in a regular-bacterial environment. Now if viruses stays the same for 20 years, can your immunity stay the same? No way to test. But if bacterial stays the same for 20 years, do we lose immunity to it if we leave their environment for some time and come back? Just like my cat allergies, or motion-sickness. 67.175.224.138 (talk) 18:07, 23 March 2020 (UTC).

Mixing soap and bleach
Mixing bleach with a cleaning stuff can be dangerous. Is it safe to mix soap and bleach? This is ordinary soap like soap bar. Soap I use is made by village people from olive oil cut into blocks. Also, if I add bleach to soapy water like % 0,2 solution will be better disinfecting surfaces? Thanks Hevesli (talk) 20:31, 21 March 2020 (UTC)
 * Since the pH can vary, and the presence of ammonia compounds is unknown, it would be prudent not to mix bleach with bar soap. There are several sources warning against mixing bleach with other cleaners, including dish soap (e.g.).  It would be better to clean with soap, then use a bleach solution as a rinse to disinfect. 2606:A000:1126:28D:D137:5FBD:51AA:C141 (talk) 21:17, 21 March 2020 (UTC)


 * Don't mix hypochlorite bleaches with acids - it releases chlorine, which is an irritant, maybe toxic in quantity, has even been fatal. Soaps are alkaline, not acidic, so this is OK.
 * But I'd still ask why?   As a general principle here, do one thing, and do it well.  You don't need to soap-and-bleach, just use soap. Andy Dingley (talk) 00:05, 22 March 2020 (UTC)
 * Although ammonia is basic, mixing bleach with ammonia produces toxic and potentially deadly chloramine vapours. Ammonia can be used in soap production. If someone makes a calculation error (or uses the amounts that are proper when using pure olive oil but uses olive pomace instead), the finished product may still contain some (chemically active) ammonia. I am fairly certain, though, that the smell would give this away, and certainly if the smell is not masked by perfume, as it is unlikely to be in rurally home-produced soap. So if the soap has no pungent smell, there is no real risk. Chloramine vapours give off the familiar "chlorine smell" of swimming pools, so that should also be a warning to open the windows. Regular soap does not kill bacteria; at best it washes them away. By itself, a cocktail that both cleans (acts as a surfactant) and kills microorganisms is a good idea. It is the basis of antibacterial soaps, which add an antibacterial ingredient to liquid soap. --Lambiam 09:23, 22 March 2020 (UTC)
 * You might as well argue that if someone made "soap" with metallic sodium instead of the hydroxide, that would be a bad idea to mix with hypochlorite bleaches! A failed "soap" with free ammonia at the end isn't soap, it's chemical waste. Andy Dingley (talk) 11:48, 22 March 2020 (UTC)

Germany, Netherlands and COVID-19
In 2019–20 coronavirus pandemic article I read for Germany 22.213 cases with 84 deaths is % 0,38. But for Netherlands 3.640 cases with 137 deaths is % 3,8. So is 10 times more! How can this be understood, please? Hevesli (talk) 20:57, 21 March 2020 (UTC)
 * We won't know until the pandemic has run its course. ←Baseball Bugs What's up, Doc? carrots→ 21:00, 21 March 2020 (UTC)
 * We can figure out a lot of things about the universe while it goes on, and the same is true for the current pandemic. With respect to the original question, there are at least educated guesses. The German Robert Koch Institute maintains that in German, the ratio of detected/reported cases to undetected cases is rather low, i.e. a large fraction of all cases are known. More severe cases are, usually, detected and reported everywhere. So if Germany detects more of the mild cases, the fraction of deaths seems to be lower. Another possible (and communicated) reason is that Germany has a decent health care system, and in particular has a lot more ICU beds with respirators per population than most other countries. --Stephan Schulz (talk) 21:27, 21 March 2020 (UTC)
 * Netherland has a decent health care system too and no shortage of IC beds (not yet, at least). But in Netherland only the patients sick enough to require hospitalisation are consistently tested, others are considered suspected Covid-19 patients and requested to quarantine themselves, but not counted. Another factor may be that Dutch doctors often don't treat patients if they consider the probability of success negligible (where surviving in a vegetative state isn't considered success). This means that the hopeless patients are not sent to IC and may die a few days sooner, which, given the exponential growth of the epidemic, leads to an apparent increase in death rate. (Don't worry, if the patient (or his relatives) insist on treatment, the doctors will do what they can.) PiusImpavidus (talk) 11:32, 22 March 2020 (UTC)
 * There is an article about this (with some speculation as to the reasons) here: https://www.theguardian.com/world/2020/mar/22/germany-low-coronavirus-mortality-rate-puzzles-experts Iapetus (talk) 10:13, 23 March 2020 (UTC)
 * If you can understand German, there also is a good YouTube video by Harald Lesch (a professor of Physics an LMU in Munich and one of the better known science communicators in Germany). There is some overlap with the Guardian article, in particular the sampling bias. In Germany, with early testing, many of the identified carriers are young and fit people returning from Skiing, and their circles. In Italy, testing was primarily driven by people presenting with a serious illness. I don't know how this compares the the Netherlands, though. --Stephan Schulz (talk) 16:49, 23 March 2020 (UTC)

CT scan coronavirus diagnosis
Chess grandmaster Irina Krush (in NYC area, I believe) reported:
 * So I went to the ER (not the most pleasant experience, there were people around with a cough so severe I was really concerned I could catch the virus there). Anyway, the CT scan showed "early coronavirus" and pneumonia in both lungs. I was also given the actual test, which only came back today (positive). I spent a couple days in the hospital, I guess mostly under observation as there wasn't much that needed to be done for me...they did test my blood for oxygenation and found it was fine. So now I am home...taking the hydroxychloroquine tablets.

She is recovering at home now and seems to be doing ok. I thought it was interesting that she is being treated with hydroxychloroquine which I thought was still in clinical trials. I also had never heard of CT scan as a diagnosis for virus. Is that a thing? Thanks. 2601:648:8202:96B0:386A:A40C:EBB1:ACC0 (talk) 23:56, 21 March 2020 (UTC)
 * About hydroxychloroquine, aren't you the same person who asked where replies extensively discussed such off label usage? In any case, I'm not sure if there is anything to add that wasn't already mentioned there.  On the other issues, our Coronavirus disease 2019 and the more specific COVID-19 testing article has a fair amount of info on CT testing. As it sort of indicates, despite one limited early study claiming the ability to distinguish SARS-CoV-2 infections from other forms of pneumonia, this isn't well accepted. Therefore AFAIK, most health authorities would not label such a case as confirmed case absence of laboratory (RT-PCR at this stage) confirmation. See e.g. the WHO's definitions  or this NZ one [//www.health.govt.nz/system/files/documents/pages/case-definition-of-covid-19-infection-14-march.pdf]. I think this even applies to the Chinese CDC but I'm unsure.  However the CT scan results probably combined with other symptoms may be enough to indicate laboratory testing depending on the health authority or doctor involved, maybe even without exposure to a known case. And those especially when combined with exposure to a confirmed case may be enough for a probable case if laboratory testing either could not be performed or was inconclusive and other possible causes have been ruled out. This isn't unique to COVID-19 see e.g. this for MERS [//www.who.int/csr/disease/coronavirus_infections/mers-interim-case-definition.pdf] but as far back as SARS there was the same thing.  BTW, I would urge very strong caution from reading too much into that paper on CT scan results. The paper itself mentions limitations at the end. More generally, it's doubtful there were CT scans of people with mild symptoms.  Nil Einne (talk) 03:31, 22 March 2020 (UTC)
 * Thanks, and yes that was me the other day. This question was mostly about the CT scan and thanks for the info about it.  Yes I understood about off-label hydroxychloroquine but still found it interesting that it's being prescribed in "retail" medicine (CityMD) already.  Those places are usually rather behind the curve. 2601:648:8202:96B0:386A:A40C:EBB1:ACC0 (talk) 05:28, 22 March 2020 (UTC)
 * Numerous health authorities have warned against using hydroxychloroquine for COVID-19 outside of clinical trials except potentially as a drug of last resort in people given extensive treatment who still appear likely to die. Drugs are not benign harmless things that can never cause adverse effects. Unfortunately doctors don't always follow "best practices". There is no U.S. law against off-label prescriptions, and the drug is already available for other conditions, so nothing prevents a doctor from prescribing it for COVID-19. Indeed, there have even been reports of dentists prescribing it for themselves or others to stockpile it, which has lead to a shortage. People don't always act rationally when they panic. (Note that some off-label uses of drugs are widely accepted based on evidence; this is not presently one of them.) --47.146.63.87 (talk) 05:42, 25 March 2020 (UTC)