15

Unvaccinated members of a population contribute to the susceptibility of the rest of the population to disease, especially vulnerable people who cannot be vaccinated. This fact is true whether or not infectious individuals are asymptomatic for a long time or a short time. Many (if not most) infectious diseases are contagious before symptoms clearly manifest ...


11

This is a really interesting question, because it really isn't as easy as people being a bit more susceptible in the winter. There's no definitive answer yet. Influenza Seasonality: Underlying Causes and Modeling Theories says: In temperate climates, flu infections at whatever level of intensity are characterized by a flu season. In these areas, the ...


11

Covid-19 is the result of a zoonotic outbreak from bats to an intermediate ( and unidentified host ) thence to humans. It is thought that bats don't suffer the disease themselves as they carry low levels of virus but the intermediate host modifies the virus, and amplifies it so that it vastly increases the amount of virus that can shed into the environment ...


9

Hands play a major role especially in the transmission of blood-borne, fecal, and respiratory tract viruses. Hand washing after use of bathroom aims at preventing the transmission of pathogens, which rely on faecal-oral transmission, such as rotavirus, noroviruses, enteroviruses in some cases hepatitis A virus (1). It prevents those pathogens from reaching ...


8

It seems to me that you are looking for solid risk numbers, which I am afraid might not be available. This is just a summary of the basic facts that play into this likelihood. For example, what is the likelihood when the partner is asymptomatic vs symptomatic So-called "asymptomatic shedding", when the virus can be transmitted despite the carrier not ...


7

This is an excellent question. Let us give an example of a procedure that some humans really need to be exposed to - and that is Radiation Therapy. Radiation therapy is usually given to cancer patients to destroy a tumor. Technically, there are two methods of giving radiation to a patient for therapeutic purposes - External and Internal radiation ...


7

Mostly it depends on the cause of the pneumonia. Pneumonia is the name for infection or inflammation of the lungs. It can be primary or secondary. A good example of the difference is pneumonia caused by the influenza virus. Influenza affects the lungs directly. That's a primary pneumonia, and yes, this is contagious, as the air one coughs out contains ...


7

Urine is not sterile, not while in the bladder and certainly not when it comes out. Contrary to dogma that urine is sterile in the absence of a clinical urinary tract infection (UTI); our research team and others have recently shown the existence of a urinary microbiota in individuals with and without lower urinary tract symptoms From "Bacteria isolated ...


7

Here's an article that I found helpful, to understand why washing hands with soap is so helpful, and how it helps (Pall Thordarson is a professor of chemistry at the University of New South Wales, Sydney): Why does soap work so well on the Sars-CoV-2, the coronavirus and indeed most viruses? The short story: because the virus is a self-assembled ...


6

Assuming that we are talking about the risk of having intercourse one time under the conditions you described, and assuming you do not know if your male partner had an STD, and provided your partner used a latex or polyurethane condom labeled as protective against disease, the risk of contracting HIV, gonorrhea, chlamydia, and trichomoniasis quite low (it is ...


6

What should I take care of while sleeping with another woman to protect her against AIDS? Get tested and go see you doctor. CDC.gov: No HIV test can detect HIV immediately after infection. If you think you’ve been exposed to HIV, talk to your health care provider as soon as possible. It takes 3-12 weeks after initial exposure for testing to be able ...


6

You picked an interesting virus (and illness) to ask about. There are still a lot of studies being conducted and many of the answers aren't in. A bit of background. Epstein-Barr virus (EBV - the virus that causes infectious mononucleosis) is a member of the herpesvirus family, very "successful" viruses in that most of the world's population are infected (...


6

This is a very good and important question, not only for you but for other people as well. As people have said in the comments, YES it can be potentially dangerous to have unprotected sexual encounters with her without having tested for STDs first. Even if she's had unprotected sex with only ONE person, she would've been at risk for an STD. As long as she ...


6

Yes, it does. According to the CDC, this is how surfaces should be disinfected: Surfaces Wear disposable gloves when cleaning and disinfecting surfaces. Gloves should be discarded after each cleaning. If reusable gloves are used, those gloves should be dedicated for cleaning and disinfection of surfaces for COVID-19 and should not be used for ...


6

People don't just act in response to official orders. People react to the perception of danger, and by the time various official responses were announced, they were already taking measures to prevent the spread of COVID-19 (some more effective than others). For example, look at the mobility data for New York: By the time the lockdown started on March 22, ...


5

The yeast (fungus) that causes thrush or yeast infection in both men and women are of the genus Candida. These fungi can be found as normal flora on skin however outgrowth results in yeast infection. Candida albicans, which is most likely the strain of thrush you saw on the lady, can be transmitted by both sex and oral sex. Most likely your mucosal immune ...


5

Positively, no. HIV is not spread by mosquitoes. You cannot contract any disease from swallowing a mosquito. Here, is a very large list of all the things that you could have caught :) If you were bitten.


5

Yes, you can contract it, but it is very unlikely. The chickenpox vaccine is a live (attenuated) vaccine, meaning that it was weakened. People who get chickenpox vaccines can spread the vaccine-strain varicella-zoster-virus to others. However, this happens very rarely. Source: CDC In a 10 year study of Varivax (the Merck vaccine), this happened in ...


5

This answer covers herpes, with both HSV1 (usually appearing and transmitted orally) and HSV2 (usually called genital herpes). So-called "asymptomatic shedding", when the virus can be transmitted despite the carrier not showing any sores, is unfortunately very common in both herpes types. An in my opinion good article is Asymptomatic Shedding of Herpes ...


5

It's quite easy to be infected with HIV and not know it. HIV is notoriously stealthy, often producing no symptoms for months or even years, and in the meantime the person can transmit the disease. That scenario describes a large percentage of the people who have transmitted the disease. Then there are the people who don't even know it exists, much less how ...


5

Your back-of-the-envelope calculations seem to be off in estimating the extent of viral load reduction in a treated versus untreated person as well as the risk of transmission for unprotected, untreated sex (5% is much higher than any other number I have seen). Obviously the viral load is not zero because then they wouldn't be HIV positive is not ...


5

Yes, the virus can be made un-harmful by soap and water. From the Economist: The outer proteins sit athwart a membrane provided by the cell in which the virion was created. This membrane, made of lipids, breaks up when it encounters soap and water, which is why hand-washing is such a valuable barrier to infection. This should give you enough key ...


5

This question may a bit too broad (e.g. there are some separate questions about Covid-19 and food) but on the topic of transmission in an office-like setting there have been some studies/reports, some more systematic/formal than others. I know of a study in South Korea in an office building, call center more precisely, (this has received widespread press ...


4

Yes, rabies is most definitely contagious. The most common route of infection is from the bite of an infected animal, which introduces virus-laden saliva to the victim. It's also possible, though much less likely, to be exposed to infective saliva in the eyes, nose and mouth. The CDC claims that a person-to-person transmission of the virus via bite is ...


4

The hepatitis B virus has been found in semen, salivia, and vaginal secretions (as well as in blood, of course). The risk of transmission is lower for oral sex than it is for vaginal or anal sex, but it is not zero. For oral sex with an infected man on the receiving end, a condom is recommended. As for giving oral sex, a dental dam can be used. To reduce ...


4

First, it is unlikely that the fecal matter was in fact pathogen-laden, but as a general statement should be treated as such. Further pathogens that would be in fecal mater are mostly transmitted through the fecal-oral route. That's why on an individual case you have little to worry about without any symptoms, but as a general case we wouldn't recommend ...


4

Yes, E. coli is definitely contagious through direct contact. In fact your girlfriend's pyelonephritis could have come from you after sexual intercourse. The general mechanism for this would be that you had the pathogenic E. coli on your penis, and then it traveled up her urethra to the kidney. This is why there is a recommendation for women to urinate ...


4

In short, the answer (regarding diseases) is yes. Anytime you deal with blood or other bodily fluid, you risk catching a variety of diseases. The risk is compounded if you are not wearing proper protective equipment, washing your hands after handling them and covering breaks in skin before handling. Here is a list of the diseases you could end up with as ...


4

There are arguments made that handshakes in healthcare settings are not safe; for example see Sklansky et al 2014. Some of the issues increasing the risk include noncompliance with hand-washing protocols (by both healthcare workers and patients) and pathogens that are less susceptible to hand sanitizers. A fist bump with a glove coated in E coli ...


4

There are three possibilities when someone is coughing on the bus: they don't have Coronavirus -- or even a virus at all. I coughed a lot when my lungs were full of tumours. Some people cough when their asthma is acting up. This is by far the most common case. they do have Coronavirus and are not wearing a mask. You are more than 2 metres away from them. ...


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