Virology Lectures 2020 #12: Infection Basics

[@peppigue]

Thanks to everyone who looks up proper info like this! We're all in this together, and every person who acquires more scientific knowledge about anything contributes to our collective prosperity.

[@proton8741]

Very true. knowledge and health care have to become back free for all people. It's crazy that in US students must debt himself for studying.

[@valerijamakarenko1714]

@@proton8741 Easier said than done. Professors also need to eat, and the governments have got a whole bunch of other stuff to invest into (not that I wouldn't like to study for free, tho).

[@proton8741]

@ Valerija Makarenko "governments have got a whole bunch of other stuff to invest into" Yes, compare military budgets, waste on ICBMs that now had to be destroy for START treaty. It's a policy choice to keep health and knowledge free and budget priority. European and Scandinavian countries do it. It's time to change the paradigme . COVID-19 crisis have showed importance of public health and state role to support private sector

[@yahya89able]

This channel is priceless, this gentleman knows what he is saying , amazing stuff hats off .

[@twothumbs6145]

These lectures are pure gold. The slides, explanations, pace, and thoughtful commentary are amazing. I’d put this professor in the top 1%. Thank you, sir, for posting these for everyone to enjoy and learn from.

[@markdezuba]

I am an insurance agent in Colorado. I am inquisitive and I came across your lectures. I very much appreciate your presentations. So much mis information and poor public policy decisions are affecting many people. I wish the politicians would listen to your lectures before making public policy edicts. I believe I had the corona virus however my body did it’s immunological job and I was back to normal in two days.

[@rbkuwar]

I am big fan of prof. Racaniello. He is an excellent teacher . I took virology in my college around 20 years ago and now I am going to update my knowledge of virology.

[@wyattpershing5232]

Thank you for the content you post! I found your page five minutes ago and I’m so glad someone as knowledgeable as you puts information out there for people like me to find. PLEASE keep up the good work, you have no idea the positive impact you are making on this world. 🙏🏻

[@questella]

Thank you for each and every one of these! 💗🥂

[@mateusvitorino]

The best explanation os mortality and fatality! Thanks

[@kedarpol9271]

Transposons is one way of triggering off viruses in evolution ... Can u give a link for more information on other sources

[@persemprenapoli10]

thank you, sir, you are my mentor!

[@doncrownover2519]

"Soap and Water" more effective than alcohol. I heard this from another study also.

[@sohaabdelmwgodabdelazeem1455]

I need to ask a question When we can say the word infection or disease is it when we see the symptoms or just when the virous enter the body? Actually I need an answer for this question ...can viroses cause infection or disease during there incubation periods? and if they do I want some examples..please

[@MicrobeTV]

The correct way to say it, is viruses cause an infection, or infect a host, and that infection may lead to disease. The incubation period by definition is the period when the virus is reproducing in the host, but there are no symptoms of disease.

[@shougatabose4013]

Sir, In the lecture you said, CoV-2 is transmitted during incubation period. Its not transmitted during disease?

[@everybot-it]

In R0 calculation: what is the difference between c and d?

[@rhuiden4086]

thought the research shows that asymptomatic spread is extremely rare?

[@John-hj6ed]

I think what you define as the definition of Incidence is really prevalence (actual number of cases at a point in time). Incidence is the rate at which the infections are occurring...

[@MrOzzyCam]

Professor Racaniello, wouldn't it be fair to say that to derive a more accurate case fatality ratio that we should look at factoring the lag time between the number of cases you have, to the time it takes for a fatal outcome to get a more accurate figure? If say with cases of COVID 19, it takes 3 to 6 weeks from case detection to a fatal outcome but you are adding 400 to 800 cases in a day as South Korea was, that you will get a skewing effect, giving an apparently lower CFR, than you actually have, especially with South Korea's highly effective drive through testing and screening protocol? If you therefore calculate today's accumulated cases against today's accumulated fatalities, you are seeing many cases that will die or recover much later. Case in point, currently South Korea has 7869 cases against 66 deaths, giving a current CFR of 0.83%, if they have found all their cases, which they haven't but assume they did, they still have 7,470 active cases and 54 serious/critical cases, wouldn't we have to wait for those cases to either resolve by recovering or dying before we could calculate an accurate case fatality ratio? I have noticed since their case detection numbers have slowed that the CFR has gone up considerably over time as fatalities from older cases have caught up. I do understand that there are going to be a percentage of asymptomatic cases that haven't been detected, that make the CFR look higher than it is too.

[@MrOzzyCam]

If I may ask another quick question. You explained the first dip between passive viremia and primary viremia as being due to it being cleared in the liver but what causes the second dip between the primary viremia and secondary viremia in your chart? @40:00

[@MrOzzyCam]

Source for South Korea current case numbers www.worldometers.info/coronavirus/country/south-korea/

[@nazishmoosakhan7132]

Why lymph let go of virus into the blood instead of stopping there?

[@jauntyj3257]

What is the connection between viruses and exosomes?

[@labonyoutube5010]

Greetings Dr. Can you update us about covd19 please? There are lots of misleading information on the internet. Thank you

[@tmlavenz]

kzbin.info/www/bejne/eIvIXmp4h7GNqqs

[@juanzalamea1753]

hi thanks for the video, is bogotá Colombia not Columbia ( seasonal chart of polivirus)

[@valtermariopereirajunior8799]

No hay una versión en español? =(

[@nazishmoosakhan7132]

Will you plz upload lecture on why virus can to be killed easily?

[@everybot-it]

There are seasons in the tropics. They have the so called "rainy season".

[@profmarcelomoreno8284]

Thanks, prof!

[@medicalmicrobiology7917]

Very helpful Sir!!!

[@racanet62]

Here are some definitions from Gordis´Epidemiology 5Th Ed, that could be useful to explain this concepts in future lectures: “The incidence rate of a disease is defined as the number of new cases of a disease that occur during a specified period of time in a population at risk for developing the disease.The critical element in defining incidence rate is NEW cases of disease. Incidence rate is a measure of events-the disease is identified in a person who develops the disease and did not have the disease previously. Because the incidence rate is a measure of events (i.e., transition from a non-diseased to a diseased state), the incidence rate is a measure of risk Prevalence is defined as the number of affected persons present in the population at a specific time divided by the number of persons in the population at that time, that is, what proportion of the population is affected by the disease at that time? For example, if we are interested in knowing the prevalence of arthritis in a certain community on a certain date, we might visit every household in that community and, using interviews or physical examinations, determine how many people have arthritis on that day. This number becomes the numerator for prevalence. The denominator is the population in the community on that date. What is the difference between incidence and prevalence? Prevalence can be viewed as a snapshot or a slice through the population at a point in time at which we determine who has the disease and who does not. But in so doing, we are not determining when the disease developed. Some individuals may have developed arthritis yesterday, some last week, some last year, and some 10 or 20 years ago. Thus, when we survey a community to estimate the prevalence of a disease, we generally do not take into account the duration of the disease. Consequently, the numerator of prevalence includes a mix of people with different durations of disease, and as a result we do not have a measure of risk. If we wish to measure risk, we must use incidence, because in contrast to prevalence, it includes only new cases or events and a specified time period during which those events occurred.”

[@alfredcam9362]

what if climate which by definition changes, does not increase temperature by 2100? Which I am sure is the least of everyone here's worry...

[@Artbyevelyn]

This lecture was made right before the country was closed due to COVID-19, then delta variant and now new one omicron 🙄

[@FishTankEnjoyer]

So are we all going to die or not?

[@MicrobeTV]

Of course not. Depending on the country between 0.4% - 4% will die and that is only because of limitations in health care systems. Such has been happening in Italy where they will soon run out of ICU beds.

[@johnmatrix7003]

Nope.

[@traiandanciu8139]

@@MicrobeTV of fear may be But when ?

[@vkoptchev]

CFR should not be fatalities over infected, but fatalities over (deceased + cured). It is a logical fallacy to include Infected patients with no outcome in the denominator.

[@abdullabakoush2138]

thanks

[@sunving]

Thanks Doctor

[@munirulhassan8774]

Thanks sir

[@larsd1174]

Great lectures! But I still haven't understand how a virus can have a driving force if it's dead.

[@caribou893]

Thank you

[@dvonpache]

Let me fill you in Professor, re the shedding via aerosols(the smallest ones with the least of mass, aka floaters) as demonstrated in the Gusedheit-II experiment that you rushed over similarly they used to rush over the question or deny the probability whether infected mosquitos are vectors or cariers of HIV back in the late 80's - 90's. SARS-CoV-2 is roughly 1/10 the size of common smoke particle. So, as we can easily smell smoke from as far as miles at times, well, what then could prevent us from contracting it via simply respiring or ocular mucus membranes particularly from a source with a high viral load and/or infection manifestation? And, PLEASE, don't say again that there hasn't been much studies on this or, that we don't know or, that it is impossible, all, without due proof and/or researched justification and thank you.

[@megancombs6276]

Thanks, Professor! I appreciate your informative and interesting videos, especially while I'm stuck at home because of this community health crisis. I'm learning so much about viruses! I have feedback/Qs. 1) Could you possibly include more definitions/vocab recap for us totally non-experts tuning in at home? You provide a lot of helpful definitions, I'm asking if you could repeat them more frequently. 2) Why are so many of the medical textbook illustrations primarily depictions of white people? I think these should be updated to reflect our diversely populated world and counteract the idea of white peoples as the default or norm. Thanks again for sharing these lectures. :)

[@megancombs6276]

Also, I love the Socratic questions for recall. I'd love to see even more of these if possible.

[@megancombs6276]

One more question--do iatrogenic and nosocomial transmission apply to the healthcare workers getting infected themselves or just the patients? Is there a different term for this? I would imagine that our nurses, doctors, and all hospital staff are at greater risk for infection, especially when PPE supplies are insufficient as the reports I've been reading have mentioned.

[@SB9P4]

How viruses know that needs cells to duplicate? Big question

[@r3g4rds]

Knowledge isnt a requirement for viral replication... a series of linked mechanisms allow viruses to do this. The are programmed by their DNA to produce the machinery that supports their existence, just like higher organisms.

[@mobiuscoreindustries]

diffrent surface markers. viruses tend to prefer some type of cells to duplicate, and the receptors on their surface act as "keys" that allow the virus to enter a cell. For covid we lack accurate data about what cells are infected, and what cells potentially hold the virus as reservoir, as is likely to be the case considering there is a non trivial number of people suriving the intial infection, but getting infected again and dying in very short time. problem is that china has been spoofing the numbers since day one, south koreah has not entered the stage where they can no longer handle all the patients, and iran, japan and italy have not been monitoring their cases, as such we aren't getting numbers from them. Data from chineese scientists and the international comunity has also been clashing as many details considering the geneome of the virus have been incompatible between what china says and what the limited international samples have been saying

[@sjdjjdaaasd3772]

virus does not know anything! it is not sentient and as dead as a rock. viruses that happen to enter cell and replicate live, and those who did not enter cells cease to exist

[@megancombs6276]

@@sjdjjdaaasd3772 That's what the viruses want you to think man!

[@johnmatrix7003]

Still here. Baffled but OK. Went to the Docs - refused to do Covid-19 test. MMM...

[@allthatsheiz]

Who else is here to learn about what we are up against with SARS 2 /coronavirus 🤚🏾

[@djalitanaful]

thank you

[@dantegaliber6246]

Thanks