Hi there, I'm Mrs. Kern and welcome to today's lesson all about bacterial and viral diseases in humans.

In particular, we're going to be talking about salmonella and influenza.

Now, our main outcome for today is I can describe examples of common bacterial and viral diseases in humans, how they are spread, and ways to reduce the spread.

Here are some of the key terms that we'll be learning about today, and if you would like to read these in more detail, please do pause the video now.

However, do rest assured that I will be going through each one of these as we move through the lesson.

We have three learning cycles for today.

We've got pathogens, pathogenic bacteria, and pathogenic viruses.

Of course, we'll be starting with pathogens.

So actually, what is a pathogen? A pathogen is a virus bacterium or any other microorganism that causes a communicable disease.

These are some of the examples then like virus, bacteria, fungi, and protists.

However, not every example of these will be a pathogen.

Some of them don't cause disease and they live within us or around us without causing any trouble.

They can also infect plants as well as animals, and in fact, bacteria can become infected with viruses as well.

Pathogens then, why they are causing communicable diseases, is because they can be spread from one organism to another and they'll go from an infected organism into a healthy one.

Usually, that will be within the same species, so usually it would go from a human to a human.

However, sometimes it can jump from one type of animal into another.

So for example, from a bird into a human.

These are some of the different ways that diseases can be spread: in bodily fluids then, so things like a blood, saliva, mucus and semen, but also in waste products, so things like faeces or even potentially vomit, in contaminated food or water, and also just by touching one person to the next, or even objects that people that have been infected had have also touched.

Okay, onto our first check of the day then.

So pathogens are microorganisms that cause disease.

Is that true or is that false? Can you justify your answer? A, not all microorganisms cause disease.

B, all microorganisms cause disease.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, that's true.

But not all microorganisms do cause disease.

Only the pathogens.

Excellent, really well done.

Okay, so not all microorganisms are pathogens.

Let's think about this in a little bit more detail.

Millions of bacteria actually live in our digestive system and we call that our gut flora.

This is actually a really good thing for us and they don't really cause us any problems normally.

And they live inside our gut and they do really important things such as help us to digest our food that maybe we're not able to digest ourselves.

So they'll break down larger molecules into smaller molecules so that they can be absorbed.

We also use bacteria and things like food and medicine.

Okay, so some bacteria and other types of microorganisms might produce medicines for us, and also they make wonderful food products such as yoghourts and cheeses.

Okay, which substances do bacteria help to make? A, apples? B, medicine? C, wood? Or D, yoghourt? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get medicine, B, and yoghourt, D? Excellent, really well done.

Okay, onto our first task of the day then, and I would like you to get your worksheets out so that you can record your answer on there.

So number one, what is a pathogen? Number two, name two types of pathogen.

And number three, describe how micro, or how some microorganisms can be useful.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, shall we go through the answers of those then? So number one, a pathogen is a microorganism that causes a disease.

Number two, any two from bacteria, fungi, virus, or protists.

Number three, our gut flora is made up of millions of bacteria.

These can help us digest food that we cannot digest by ourselves.

We also use microorganisms to produce medicine and foods such as yoghourt and cheese.

Okay, hope you've got all those down.

If not, please do add a little bit more onto your answer.

Well done.

Onto our second learning cycle of today then, looking at pathogenic bacteria.

So bacteria are a type of cell known as prokaryotes, which means they have no nucleus.

Plants and animals are part of the eukaryotes, but the bacteria are much more simple and that's why they're classed in a different way.

Here's an example of a bacterial cell, and we can see that it has a circular loop of DNA that is just free within the cytoplasm and not contained within a nucleus.

Now, bacteria are able to produce things called toxins, and toxins are a poison that is able to damage our living tissue and make us feel ill.

They are chemicals, and we can see that in that image there, that bacterial cell has produced a type of toxin that's being released from its cell.

Salmonella then is a genus of bacteria, that's its classification, that can cause food poisoning.

Now, you may have had food poisoning before.

It's not always caused by salmonella, but this is one example.

Salmonella is often found in faeces or infected animals, and it is spread when food or water becomes contaminated with salmonella.

This can happen in many different parts of the kind of process of getting chicken or food to our table.

So for example, could happen in the farm where one infected organism spreads the disease to another.

It could happen in the abattoir, so where that chicken or animal is slaughtered.

In the processing plant, if there is some salmonella there, it can be passed from one food to another.

Or essentially also in the kitchen, if you are cooking or preparing for chicken, you might have that salmonella on your hands and then you can actually spread it to other types or other, yeah, types of food, and other things that you have in your kitchen.

So onto our next check, which type of pathogen is salmonella? Is it A, bacteria? B, protists? Or C, fungi? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, that's bacteria.

Okay, we got that one right? Excellent, well done.

Okay, so when people ingest that contaminated food, they will also become infected themselves.

And the types of symptoms that you will experience when you have food poisoning, things like vomiting, so being sick, having really bad stomach cramps, diarrhoea, a high temperature.

Usually in a healthy person, these symptoms will pass within the week.

Only in very small number of cases then could this become quite serious, especially in people that are very young or very old.

In those cases, 'cause it is a bacterial infection, you could potentially be given some antibiotics.

So how can we prevent the spread? One way is that poultry, so things like chicken and any kind of bird, they could be vaccinated against salmonella.

Making sure that when you are in your own kitchen, but also if you are working in the farm or abattoirs, then you are making sure that you're following basic hygiene standards.

So things like washing your hands.

Also make sure that your food is cooked thoroughly, so make sure that all the way through, it's really, really hot.

Now you can do that by cutting open the food and having a look, or you could use a thermometer where you pop it into the food to make sure that it is cooked.

How is salmonella spread then? A, bodily fluids? B, contaminated food or drink? Or C, touch.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get B, contaminated food or drink? Excellent, well done.

Okay, onto our next task of the day.

This is task B.

Again, you can record this on your worksheet.

So number one, describe some of the symptoms of salmonella.

Number two, explain why you cannot catch salmonella by standing close to someone with the infection.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, so the symptoms of salmonella.

Did you get vomiting, stomach cramps, diarrhoea, and a high temperature? You cannot catch that by standing next to someone, and that's because salmonella is spread through contaminated food and drink that needs to be ingested.

Salmonella is not spread through bodily fluids that may become airborne.

I hope you got all those down, but again, you can add to your answer if you wish.

Okay then, onto our third and final learning cycle of today.

Pathogenic viruses.

So you may not realise this, but actually viruses are not alive.

They're actually acellular, they're not made of cells.

And they also don't carry out all of the seven different life processes without other cells being there.

So for example, viruses have to have a cell, a host cell, in order to be able to replicate.

How they do that then is that the virus enters the host cell.

We can see in that little image, there are virus entering the cell.

It then gets into the host's DNA, and it makes sure that the host is then able to replicate the virus for it.

It then gets packaged up, okay, by the cell into a new viral particle, of which it can then burst out of the cell causing damage to the host.

So that is how it makes people feel poorly or other organisms poorly when they get infected by the virus.

Similar to other pathogens then, viruses can spend a long time outside of that host and actually then still be viable and still be able to cause disease.

So that means that it could be on a surface that somebody has touched for a long period of time.

And then when another person comes along and touches that, they could still become infected by it.

They're also able to lay dormant in cells for long periods of time.

So things like HIV, the first initial symptoms, of sort of cold and flu-like symptoms may arise in the initial stages of the infection, but then that virus can hide inside the host cells for up to 10 years before actually then showing the full-blown infection.

This can be a problem because then actually you are unaware that you've got that disease and it may mean that you spread that to other people unknowingly.

Okay, two students were discussing whether the viruses are alive.

Who do you think has the best answer? Laura, "I think viruses are alive because they are made of cells." Sophia, "I don't think viruses are alive because they cannot replicate on their own." I'll give you a moment to think about it, but if you need more time, please pause the video.

Did you think that Sophia has the best description of that then? So I don't think viruses are alive because they cannot replicate on their own.

Excellent, well done.

Can we match up each type of pathogen with how they actually cause damage to the host? We've got bacteria and virus, burst outta the host cells once replicated or produces toxins.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Did you match bacteria to produces toxins and virus to burst outta the host cells once replicated? Well done.

Okay, let's have a little look at an example then.

So this one is influenza or often called the flu.

It is a communicable disease 'cause it can be spread from organism to organism and it's caused by the influenza virus.

The types of symptoms that you might experience then are high temperature, aching body, cough, sore throat, and also exhaustion.

People with influenza really do suffer quite badly.

It does make people feel a lot more poorly than say the common cold, even though the symptoms are similar.

The influenza virus then can be spread when a person coughs or sneezes.

We can see in that image what is happening when that person is sneezing.

There is a big plume of mucus droplets that go out into the air.

And within those mucus droplets then, there are many, many, many of those virus particles and they can then be breathed in by somebody else and they would then become infected with influenza.

Some people are much more vulnerable to influenza then, such as the very old and the very young.

So we mentioned that actually people can experience much worse symptoms and with the common cold.

So if people are also quite vulnerable, then they would have much more severe symptoms that can lead to them being very poorly for a long time.

Most people would just need to take some rest, save some time off school, and actually have some paracetamol or ibuprofen to help bring their temperature to a normal temperature.

If you want to stop the spread of influenza then, just make sure that you are following basic hygiene rules that we've mentioned previously.

So things like washing your hands.

When you cough or you sneeze, you do that into a tissue and then put that in the bin.

And also isolate yourselves from other people, so staying home from work or school so that you are not spreading that virus around to other people.

The best way to prevent flu is actually through a vaccination.

And actually, that is because the influenza virus actually is able to mutate very, very quickly and become a new strain.

And so actually, people can often, even if they've had the flu previously, not have the same level of immunity to it when it comes out the following year.

And so we need to have a new vaccine each year to make sure that people are covered in their immunity to the new strains that have evolved.

Remember that we talked about the fact that some people are more vulnerable, so the very old or they're very young, and actually the NHS recommends that some of these groups actually get the vaccine each year.

It might also be that you've got asthma and you might also fall into that category as well where the NHS is recommending you to have the vaccine.

Let's think about how a vaccine actually stops the spread of disease through a population then.

So if none of the population is vaccinated, then a disease would spread really quickly and easily through a population.

We can see that little green sad face there.

That is a person that has been infected.

The pink people that have also got a sad face, they are unvaccinated.

And so if a person comes into contact with an infected person that is unvaccinated, they would very easily get that disease.

If, however, we've got some people in the population, those are the people that have the smiley blue faces and they come into contact with the infected person, then the disease can still spread to the unvaccinated people, but actually the people that are vaccinated are not going to get that disease and therefore they are going to stay well.

If most of the population are vaccinated then, it's very difficult for a virus to spread from person to person, and that means that even the people that are not vaccinated actually still don't get that disease.

Okay, onto another check then.

Which is the best way to stop the spread of influenza? A, coughing into a tissue? B, getting vaccinated? C, washing hands? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get getting vaccinated? Excellent, well done.

Onto our final task of the day then.

This is task C.

Again, you can record this on your worksheet.

Number one, explain why influenza is a communicable disease.

Number two, what are the symptoms of influenza? And number three, describe how we can prevent the spread of influenza.

I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, let's have a little look at what we could have included then.

So number one, the flu is caused by a virus, and can spread from organism to organism.

If a person coughs or sneezes, the virus will be present in the droplets of mucus, which can then be inhaled by someone else.

Number two, the symptoms are high temperature, aching body, cough, sore throat, and exhaustion.

Number three, how we can prevent the spread then? People should follow basic hygiene rules such as washing hands regularly, coughing or sneezing into a tissue and throwing it away.

People should not attend work or school if they have the flu.

Vulnerable people such as the very young or old should be vaccinated.

I hope you've got all those down, but if you want to add a little bit more to your answer, please do that now.

Onto our final summary then before we finish.

So our key learning points for today are some microorganisms or pathogens and cause communicable diseases.

Some microorganisms do not cause disease such as the ones that live in our small intestines.

Pathogenic bacteria produce toxins of damaged tissue, living tissue, and cause disease.

Salmonella is a type of bacteria that causes food poisoning.

It is spread through contaminated food or drink.

Viruses invade cells to reproduce where they cause damage to cells.

Influenza is a viral infection that is spread through droplets of mucus containing the virus being breathed in by another person.

I've really enjoyed today's lesson.

I hope you have, too.

Hope to see you again soon.

Thank you, bye.