Hi there, I'm Mrs. Kemp, and welcome to today's lesson all about fungal and protist diseases in humans.

This fits into the health and disease topic.

So our learning outcome for today is I can describe examples of common fungal and protist diseases in humans, how they are spread, and ways to reduce the spread.

As we go through the slide deck, we'll be using lots of new key terms. They're here for you now, and if you'd like to read those in more detail, please do pause the video.

We've got three learning cycles for today.

We've got pathogenic fungi, pathogenic protists, and interaction between malaria and sickle cell trait.

Of course we'll be beginning with the fungi.

So what do you think the world would look like without any fungi in it? Have a little moment to think about that.

So fungi are really important to us.

They're actually decomposers, so what they do is they break down dead and decaying material in our ecosystem.

They also recycle lots of nutrients, such as nitrogen, and without them we'd have a really big buildup of waste.

We'd also get like lots of other organisms not being able to survive because of the fact that they no longer have those nutrients available to them.

Fungi actually fit into the domain of eukaryotes.

This means that they have a nucleus and other organelles.

We can see on that image there that we've got a nucleus.

We've also got mitochondria there, which is another type of organelle.

Some fungi are pathogens, and that's because they can cause communicable diseases.

A communicable disease is one that can be passed from organism to organisms. Communicable diseases can be passed in different ways, such as in bodily fluids like blood, or saliva, or even vomit, and also it can pass in contaminated food or water and potentially by touching another organism that actually has that disease.

Okay, onto our first check of the day then.

This is true or false.

Some fungi are pathogens because they can cause non-communicable diseases.

Is that true or is that false? Can you justify your answer? a, fungi can be spread from organism to organism.

b, fungi cannot be spread from organism to organism.

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

Okay, did you realise that that was false? And that's because fungi can be spread from organism to organism.

Excellent.

Really well done.

So an example of a disease that is caused by fungi is athlete's foot.

Now many of you may actually recognise athlete's foot because it's really, really common.

And the types of symptoms that you might have then is maybe itchy white patches on your toes, a red rash around your toes, or dry and cracked flaky skin that you can see in that image there.

And we often can contract that by actually touching contaminated surfaces or even the infected skin of somebody else, okay? We can see a changing room there that you might find in a swimming baths or a gym.

People are walking around barefoot, and any areas where their foot has touched, if they have athlete's foot, somebody else could then come past, put their foot on it, and they would then contract that infection.

It can be treated with an antifungal cream or spray that you can get from the pharmacist, and you should try to make sure that your feet are really clean and dry.

So if you've done some kind of sporting activity, for example, afterwards, really important to have a shower and make sure that you really clean in between your toes and make sure that you dry that surface off.

In order to stop the spread then of athlete's foot, we should try not to share towels or socks with other people, especially if we know they have athlete's foot.

We should also try not to walk around barefoot in communal areas, such as in those locker rooms that we saw earlier on or in swimming pools or showers.

And just putting something like a slider or a flip flop on would make sure that you have a barrier there between you and the infected surface, and so therefore you're less likely to contract athlete's foot.

Onto our first check then here, which is which type of pathogen causes athlete's foot? a, bacteria, b, fungi, or c, virus.

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

Okay, did you realise that was fungi? Excellent.

Well done.

Okay, onto our first task of the day then.

Please get your worksheet out so you can record your answers on there.

Could you design a poster to display on a wall of a gym changing room giving advice on how athlete's foot is spread, and how to reduce the spread, and also how it can be treated.

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

Okay, so how can athlete's foot be spread? So athlete's foot is spread by touching infected skin or contaminated surfaces, for example, wet floors that have been walked on by someone with athlete's foot.

How to reduce the spread.

Do not share towels or socks with other people.

Wear flip flops or water shoes when walking around communal areas like changing rooms and when using the shower.

Treatment.

Mainly an antifungal cream or spray then, but also try to keep your feet clean and dry.

If you need to add a little bit more onto your poster, please do that now.

So onto pathogenic protists.

You may not have heard of protists before, but actually protists are also eukaryotes, okay? They are microorganisms, so we need to use a microscope to be able to see them, but they do have a nucleus and other organelles.

We can see an example there of euglena, and we can see that it's got that darker spot within it, and that is where the nucleus is found.

There are actually four kingdoms within the eukaryotes.

We are a eukaryote, so we fit into the animal kingdom there, and then we've got the plant kingdom, the fungi, and also the protists.

So all of these will definitely have a nucleus containing the genetic information for the cell.

Amoeba and euglena are both examples, and the one on the left there we can see is the euglena, and they can be found in freshwater and saltwater habitats, and especially ones that are rich in nutrients.

Euglena are actually able to photosynthesize, so they have chloroplasts in order to use the light to make their own food.

We've got amoeba there on the other side, and they are found in freshwater ponds and lakes as well as saltwater environments.

Okay, which kingdom do protists belong to? a, plants, b, bacteria or c, eukaryota? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get c, eukaryota? Excellent.

Really well done.

So protists can also be pathogens, okay, so they can also cause communicable diseases that can be passed from organism to organism.

An example of one that we need to know about is malaria, and this is caused by the protist Plasmodium.

Now, Plasmodium is passed via a vector.

A vector is an organism that is passing a disease from one organism to another.

People sometimes get confused and they think that the mosquito, the vector, is actually the thing that causes the disease, but it's not.

It is the Plasmodium, which is a type of protist, that is passed from organism to organism via the mosquito.

So the mosquito is the vector.

So we call that mosquito the vector, and it will transmit the pathogen from one organism to another.

The malaria is often found in tropical areas.

We can see some examples there on the world map, but it tends to be in areas of Africa and also Asia, okay? These areas have really hot damp climates where the mosquito really likes to live and breed, and so therefore you're more likely to get lots of mosquitoes in that area, and they are the type of mosquitoes that are able to carry that Plasmodium.

So the main symptoms of malaria are things like high temperature, sweats and chills, headaches, feeling sleepy, sickness, muscle pains, and actually if you experience any of these symptoms when travelling to areas that have malaria, it is in fact an emergency and should be treated very quickly.

So you should try and go and get help straight away.

If left untreated, malaria can cause death in people.

The best way to help yourself from malaria is actually if you're travelling to an area that is high risk, then you should try to prevent yourself from getting that.

One way is that you can take an anti-malarial drug before visiting, but also during, and sometimes after.

Use an insect repellent to make sure that we stop that mosquito from being attracted to us and biting us.

Sleep under a mosquito net.

You may have seen those before, and you can carry those with you.

Making sure that you wear long sleeves and also trousers when walking around to prevent the mosquito being able to get at your skin.

So other ways that populations may look to actually control malaria is to basically control the population of mosquitoes, and we can do that by spraying different areas with insecticides.

So an insecticide is a chemical that will kill insects.

We can vaccinate children against malaria, and also we can reduce the number of places where mosquitoes can breed.

So making sure that any sort of stagnant water pools are drained where we've got lots of people living in those areas because actually that's where the mosquitoes are going to be able to breed.

We wouldn't want to have say puddles or big buckets of waters and things outside people's houses.

Okay, onto another check then.

Which pathogen causes malaria? a, mosquito, b, malaria virus, or c, Plasmodium? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get that c, plasmodium? Excellent.

Well done.

Remember the mosquito is a vector and not the pathogen.

Okay, onto our next task of the day then.

This is B.

Again, you can record this on your worksheet.

A person is travelling to an area that has high numbers of malaria.

Number one, what symptoms of malaria should the traveller be aware of? Number two, what advice would you give to them before they travel? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get the symptoms should be high temperature, headaches, feeling sleepy, sickness, and also muscle pain? Advice then.

Take an anti-malarial drug before and during your visit, use an insect repellent on your skin, sleep under a mosquito net, and wear long sleeves and trousers.

Excellent.

Well done.

Onto our final learning cycle of the day then.

This is interaction between malaria and sickle cell trait.

So the malaria pathogen itself, Plasmodium, as we know it lives in humans and also in mosquitoes.

Because of that, it's got a really complicated lifecycle, but essentially if we start with it being in the mosquito, the mosquito bites a person and passes that Plasmodium into their blood.

From the blood, the Plasmodium makes its way to the liver and then makes its way back to red blood cells.

At this point then the plasmodium can infect red blood cells, and this is where a person would then be showing signs and symptoms of malaria.

And all of those symptoms that we discussed earlier they would be experiencing.

We can see in that image there that actually the red blood cell has taken on a sort of like prickly structure, and we know that that one has been infected by malaria.

Okay, so what's sickle cell, and what does that have to do with malaria? Well, sickle cell anaemia is a condition where a person's red blood cells become misshapen, so they're not that normal lovely disc shape.

Where we've got the gene of a person that normally makes the red blood cells, then actually somebody has got a mutation, which is just a single base mutation on the DNA.

It causes a different version of that gene.

That's known as an allele.

In sickle cell allele, one base has been substituted for another, okay, so swapped for another one, and this leads to different versions of a protein being made, and this affects the shape of the red blood cells.

The different form of the protein leads to a change in the shape of the red blood cells.

So we've got a sickle shape.

This is what we find in people when they have that mutation, and they may have some of the normal cells, so we can see the bi-concave shape of a normal red blood cell, and then we've got some of those sickle shaped cells.

Why is that a problem then? Well, actually they can carry less oxygen around the body for respiration, and they can also block arteries because they're spiky and so they sort of get hooked up together preventing blood flow, all right? Remember, blood will be taking glucose and oxygen as fuel for respiration to all of the different cells around the body.

Now, the Plasmodium process then causes malaria is less able to actually penetrate those sickle shaped red blood cells.

All right, so you kind of get a benefit from having some sickle shaped red blood cells because the mosquito can still bite the person, the person can still get that Plasmodium, but then the Plasmodium can't make its way into the red blood cell, therefore stopping its lifecycle and preventing that person from getting malaria.

Okay, which is the sickle shaped red blood cell? a, b, or c? I'll give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you get c? Excellent.

Well done.

So if an individual inherits one sickle cell allele from one parent, okay, so obviously when you inherit genes, all right, you'll get a version from the sperm that made you and a version from the egg that made you.

If only one of those alleles is sickle cell, okay, then you get something called sickle cell trait.

This is not the full disease, okay? You've only got a smaller number of those sickle shaped red blood cells, and actually that provides protection against malaria, and so therefore they don't show any signs and symptoms of sickle cell, but they actually have a level of protection against malaria.

The sickle cell mutation then has actually led to a survival advantage in different parts of the world where there are high numbers of malaria cases, such as in Africa, and we can see this map here of the prevalence of malaria is concentrated in that particular areas where it's black.

And then we've got the prevalence, so how many numbers of cases of sickle cell we have in the same map of Africa.

And it's really concentrated around the areas where we find malaria.

So it's actually providing a survival advantage.

So people are surviving more if they have one of those sickle cell trait alleles.

And so therefore they're more likely to survive, and they're more likely to be able to breed and pass that allele onto the next generation as part of evolution.

However, there is a downside to this.

That actually if a person inherits two copies of sickle cell allele, they will actually suffer the full sickle cell disease, okay, or we can abbreviate that to SCD.

It's a really, really fatal disease, and actually 50 to 90% of children with sickle cell disease will die before their fifth birthday.

So this is not something to be taken lightly, and it is a very, very dangerous inherited condition.

And in fact, unlike having sickle cell trait, if you have sickle cell disease because as part of the disease you have a weakened immune system, you're actually more at risk of dying from malaria than if you didn't have either alleles.

Okay, true or false? When individuals have one copy of the sickle cell allele they have a survival advantage against malaria.

Can you justify your answer? a, having one copy of the sickle cell allele means they don't have sickle cell anaemia, or b, the protist that causes malaria cannot penetrate the sickle shaped cell as easily.

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

Okay, did you get that as true? Excellent.

Well done.

And that's because the protist that causes malaria cannot penetrate the sickle shaped cell as easily.

Well done.

Onto our final task of the day then.

So please get your worksheet out so you can record your answer on there.

Explain why parts of the world that have a high incidence of malaria have more people living with sickle cell trait.

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 look at what you could have written then.

So the malaria pathogen, Plasmodium, spends part of its lifecycle in red blood cells where it reproduces.

When individuals inherit one allele of sickle cell, they develop sickle cell trait where some of their red blood cells are sickle shaped.

The Plasmodium is not able to penetrate the sickle shaped cells as easily and cannot reproduce and make the person ill.

Therefore, people with sickle cell trait are more likely to survive and able to pass on their alleles to the next generation.

Over time, this leads to more people with sickle cell trait in areas where malaria is present.

Okay, I hope you got all those points down, but do feel free to add a little bit more into your answer if you need.

So onto our final summary of the day then.

So fungi are decomposers that recycle nutrients, such as nitrogen, in an ecosystem.

There are pathogenic fungi that cause communicable diseases, such as athlete's foot.

Athlete's foot can be spread from person to person through touch or contact with contaminated surfaces.

Malaria is caused by a protist.

Protists are eukaryotic cells.

Malaria is passed from person to person via a vector, the mosquito.

People who have sickle cell trait only have one allele of sickle cell.

They have a natural survival advantage to malaria, and we see higher numbers of sickle cell disease in areas with high cases of malaria.

This has been a really enjoyable lesson today.

I hope you've enjoyed it too.

I hope to see you again soon.

Bye.