Free Biology NEET Video Lectures for Human Health And Disease

00:00:45 Hello friends, I am Shubhangi Rhodgi PGT Bio KV number one AFS Hinden and I welcome you to the session number one on the class on chapter 8 human health and diseases. Health is a topic which is of concern to everybody not necessarily only biology students and since time immemorial people have been trying to find out answers related to the questions on health. There were great thinkers like hypocrites who have done a lot of work in this field. Earlier it was believed that health is a result of a balance between certain body fluids

00:01:25 that is the humors. It was thought that there are four different humors. The yellow bile, black bile, film and the blood. Each of these represent a particular element of the nature. And it was believed that it is the balance between these four uh humors or the body fluids that results in good health. And if there is any kind of imbalance between these uh body fluids, it will result in bad health. For example, it was thought that persons with black bile will have hot personalities and would have

00:02:03 fevers. Later with advents in the science, particularly in the field of biology, many different discoveries were made and new beliefs were formed. William Harvey discovered blood circulation. Here is his pic. and he demonstrated that normal body temperatures are present in persons with black bile. So good human hypothesis of health was thus discarded. Now biology has progressed a lot and we have come to know much about health. It is now known that mind affects health. How? Well, our brain exerts control on our immune

00:02:46 system through the neural system and the endocrine system and it is this immune system that guards our health. So we can safely say that our mind affects our health. After knowing so much about health, can we now describe or define what is health? Well, according to the World Health Organization, WH, it has been stated that health is a state of complete physical, mental and social well-being and not merely the absence of any disease or infirmity. Now, please pay attention on the words here. It very

00:03:27 clearly says that health is a state of complete total physical, mental and social well-being. not only the absence of any disease. Why these words have been incorporated in this definition? Well, we just discussed that our mind affects our health and about social aspect. Well, we know that human beings are social animals. We cannot live in isolation. Anybody who is healthy displays wellness in all these aspects. Think about any person who is habitual of say stealing or picks up fights very easily, does not gel along with people

00:04:16 regularly and or obsessed with thoughts of sex all the time. He may or may not have other infirmities or symptoms of so-called diseases. But yet would we call him fit or healthy? No. Because for being healthy means to be completely physical, mental and socially wellbeing and not only be free from any infirmity. Moving ahead, why is this health being healthy so important? Well, if you are healthy, it will lead to more efficiency at work, more productivity leading to the prosperity and increased longevity. It also leads to reduction in

00:05:04 infant and maternal mortality. For any government, development of a healthy society is very important and all the governments have the health and development of healthy society in their topmost priority agendas because a healthy nation only can be a happy and prosperous nation. Now that we know that what is the importance of being healthy, let us discuss the factors that affect the health. You must have some idea about the factors that affect health. Let us discuss them and try to enumerate them. The first and foremost factor that

00:05:46 comes to mind is our lifestyle. When we talk about lifestyle, we include the food and water that we consume, exercise that we do or don't do, and our habits. habits like washing hands before taking food, not washing them, sleeping in late regularly or having a love for junk food. All these habits are going to affect our health. The second factor that affects our health is the infections. Infections impair our health very badly. And thirdly, our genetic composition. Our genetic makeup decides whether or not we

00:06:32 are going to fall sick easily, whether we are susceptible or more resistant towards different kinds of genes, whether we can escape the infection quickly or not. This all is determined by our genetic composition. Now having a look at the factors that affect health, let us see how can we achieve good health. Obviously if we know the factors we can try to control the factors to achieve the good health. Let us begin with the lifestyle. In lifestyle we studied about the food and the water we consumed. So

00:07:11 obviously if we take balanced diet if we take uh clean drinking water in adequate amounts we can pave way for a good health. Similarly, doing regular physical exercises, aerobic exercises or yoga can impart good health. And talking about the habits, habits of maintaining proper personal and social hygiene and also having proper awareness about the diseases and the ways to prevent it can cause a lot of difference and help us to achieve good health. Talking about infections, how can we control the

00:07:52 infections? How can we prevent them? Well, the first and foremost thing is to maintain good personal and social hygiene. And the second thing is to have proper vaccination. Vaccination does a lot to prevent many different diseases. Then we should also ensure that we dispose of our waste properly and control the growth of vectors which spread the infectious pathogens. Government has been uh undertaking many programs and many schemes are being run in order to prevent infection amongst us like pulse polio program nirmal bharat

00:08:32 swatch bharat aban all these schemes are aimed to increase awareness and lead towards a healthy society but the most important thing that we can do is to maintain proper personal and social hygiene to stay away from infections. The last factor that we studied was genetic composition. Well, there are genetic disorders which may affect a person and if there is knowledge about these disorders, they can be treated in the embryionic stages. They can be checked during the embryionic stages through different therapies like gene therapy.

00:09:18 Now having decided what is health, how health is important for us, let us try to define disease. What is a disease? Well, a disease can be defined as any condition that impairs the normal functioning of the body. It may affect one or many organs or systems of the body. And a disease is always characterized by various signs and symptoms. Let us discuss the types of diseases. Diseases can be broadly classified as infectious or non-infectious. Infectious as the name suggests are those diseases which can be

00:10:01 transmitted from one person to another while the non-infectious uh diseases are those which cannot be transmitted. These are deficiency diseases, genetic disorders or physiological disorders. Deficiency diseases arise because of deficiency of any nutrient in our food like uh you have studied about night blindness, berry berry, scurvy, ricketetts all of these are deficiency diseases. Then talking about genetic diseases, genetic diseases may arise because of chromosomal aberrations or they can be under

00:10:38 mandelian disorders like uh Turner syndrome or cickle cell anemia. Then there are phys uh physiological disorders like diabetes, amma or hypertension. Talking about infectious diseases, as I said earlier, these are those diseases which can be transmitted from person to person and these diseases are caused by pathogens. Now, what are pathogens? Well, as I just said that infectious diseases are caused by pathogens, we can just reframe our words to say that pathogens are the disease-causing organisms.

00:11:20 Most parasites are pathogens. Parasites are those organisms which have started living inside the host body and they derive their nutrition from the host body itself. In this process they also can harm the host body and when they start harming the host body we say that these parasites are pathogens. Now living inside the host body is not an easy task and these pathogens have come to be variously adapted to survive and multiply inside the host body. Some of their adaptations are like they may have

00:12:00 hooks for attachment. Some might have developed uh strategies to survive the pH of the gut. They show a very high reproductive potential and they have ability to evade imological responses of the host. And with all such adaptations, the pathogens attack the host body and cause the disease. So what can be the common characteristics of the pathogens? We have discussed a bit about pathogens and we will try to uh enumerate their common characteristics. As I just said, pathogens are those organisms which

00:12:44 cause infectious diseases and they can be transmitted easily from one person to another. How are they transmitted? This transmission can be through air, water, food, direct or indirect contact or through vectors. Now the pathogens can be broadly classified into five different categories. Out of these four are cellular that is living and one is ascellular. The four different categories of paras uh pathogens are helmans like tapeworms then protozoa fungi and procariots like bacteria. So all these different types of organisms

00:13:29 can be pathogen on humans. Similarly, some viruses can also cause diseases in humans. What happens when pathogen enters the body? Here is a uh figure that shows what happens when pathogen enters our body. First of all, when the pathogen enters, it starts multiplying and increasing its number. This period is known as the incubation period. At this time, the body does not show any symptoms. It is the time between the infection and the onset of the symptoms. Once the pathogen has multiplied and reached enormous number its presence

00:14:18 starts affecting the body and the symptoms of the disease start appearing. It is the time when we say that illness has occurred and it is the time when body also starts recognizing the presence of the pathogen and tries to eliminate it by various methods like inflammation. What is inflammation? Inflammation is a process in which in order to eliminate a pathogen the body creates many different responses because of which uh we can see the redness, swelling or hotness and even the pain in that particular area. All these

00:14:59 strategies are a part of the program to eliminate the pathogen out of the body and but during this time when the illness is there the immune response is now not yet fully responded. It is just trying to identify the pathogen and trying to get rid of it but it is not very effective at this time. The last phase is the decline and recovery phase where the immune responses are at the peak. Now by this time the body or the medical treatment that was given overpowers the pathogen and the growth of the pathogen declines and now the

00:15:40 body starts repairing the damages. Let us try to look at this uh cycle of events more closely. Suppose I try to draw a graph. A graph between time and number of pathogens. When a pathogen gains entry in the body, its numbers are very low and initially it takes time to grow in number and multiply. During this time the body has not yet sensed the presence of the pathogen. The pathogen is multiplying freely in the body and the symptoms have not yet appeared. This phase is known as the incubation phase.

00:16:40 That was the first phase we talked about. Now as the number of pathogen keeps of on increasing in our body, our body starts showing the symptoms of the disease. The immune responses start somewhere here. When the illness has onset, the illness has set in the body and the immune system starts as the number of pathogen is increasing the immune responses are also increasing. There comes a time when the pathogen number reaches a peak. By this time the immune responses have also started and now the number of pathogen starts to

00:17:25 decline. Why? because our immune system is overpowering the growth of the pathogens. Now uh if we try to draw the response of immune system on the same graph we can show that when the immune response reaches the peak the pathogen reaches the its least level. So this graph shows the incubation period, the period of illness and the period of decline and recovery. Okay, moving ahead. Let us now discuss some modes of transmission of infectious diseases. This is a picture given in one of the older NCERTT books and it shows the

00:18:23 various routes by which the infectious diseases can be transmitted from an infected person to a healthy person. It can be through direct contact which can be physical or sexual or by the indirect contact when a healthy person comes in contact with the articles used or touched by an infected person. The infectious diseases can also be transmitted through food and water. Contaminated food and water are one of the biggest sources of infection. Then there are some in airborne microbes which are present in

00:19:02 the uh droplets exhaled by the infectious person and when this air is taken in or inhaled by the healthy person he or she gets sick. Some infectious agents are also transmitted by various carriers like house flies or vectors like mosquitoes. So these are the different routes by which uh infectious diseases are transmitted by direct contact by indirect contact by food and water by air or by car carriers and vectors. Having said so, we have till now discussed general aspects of being healthy and disease. We have tried to

00:19:49 define the disease and the pathogens as well. We have seen some general characteristics of pathogens, the modes of their transmission and also tried to study a few ways by which we can prevent the onset of infectious diseases. Now let us study some common diseases in humans. Now there are some infectious diseases which affect a large part of population in India and these books uh these uh diseases have been included in your book. But the problem with such detailed study on diseases is that it becomes a bit tough to memorize all the

00:20:30 names and terms given under different headings. There are about seven or eight diseases that had been discussed in your book and in order to make their study easy, we will try to categorize these diseases into five main categories. So the diseases that you are going to study can be catei categorized according to the pathogen that causes these diseases. So these diseases can be caused by bacteria or by virus. Some diseases can be caused by protozoa or helmans or some diseases can be fungal. If we categorize the diseases like this

00:21:30 in this order, our study will become a bit easier. So first of all, under the bacterial diseases head, we will study about two diseases typhoid and pneumonia. See when you develop a habit of tabulating things like that or making flowcharts while studying and making your notes you will find that remembering things and grasping things becomes easier for you in this manner. So let us study about typhoid. Typhoid is a very dangerous disease and it is caused by the bacteria salmonella typhide which is transmitted through

00:22:18 contaminated food and water. Now this disease is very difficult to be fought off by the immune system because this bacteria salmonella typhi can live inside the host cells. So the immune system gets puzzled how to kill its own cells. The diagnosis is through the viral test. The vital test is a antigen antibbody uh relation uh linking test and it uh finds out the antibodies present in the blood. The symptoms are onset after 6 to 30 days of exposure that is this much is the incubation period of this bacteria inside the body.

00:23:01 Major symptoms are fever, rash, weakness, abdominal pain, constipation or headaches. Now in serious untreated cases even the bubble can become perforated and if left untreated this disease can be fatal. Also when we talk about typhoid a classic case of typhoid Mary also comes to mention she was Mary melon and she was the first asymptomatic carrier of typhoid fever. What is the meaning of asytomatic carrier? That means the bacteria salmon type was present inside her bo body. But since her immune system was so developed that

00:23:48 the bacteria kept at such levels that she never actually had the symptoms of the typhoid fever. So she never actually knew that she is carrying the bacteria of typhoid fever in her body and she was a cook. So she uh whenever she uh worked as cook people got affected and infected by trifoid. She was presumed to have infected about 51 people over the course of her career as cook. Eventually she was confined so that other people can be prevented from getting the disease uh by coming in contact with her contaminated

00:24:31 food preparations. The next disease that we are going to study is pneumonia. Now pneumonia is a term which is given to the inflammation of alvoli of the lungs and following this inflammation the alvoli get filled with the water or fluids. Now do you know what are alvoli? Alvoli are small balloons shaped structures present inside the skin uh lungs. They have very thin walls. Why? Because they serve for the exchange of gases between the lungs and the blood capillaries. Now they have very thin walls and their function is

00:25:15 exchange of gases through diffusion. What would happen if these elvoli get filled with some fluid? What will happen? Well, obviously their capacity to exchange the gases will dramatically be reduced. This is what that happens in the pneumonia. Now, pneumonia is a disease that can be caused by any number of factors. It can be caused by bacteria, fungi and even viruses. But for our course of study we will study uh talk about the pneumonia caused by bacteria hemophilus influenza or streptococcus pneumoni. I will once

00:25:58 again repeat that there are many different pathogens that can cause pneumonia but here we are talking about hemop hemophilus influenza and streptoccus pneumoni as I said that they lead to inflammation of the elvoli and they get filled with the fluid mode of transmission is the inhalation of droplets from infected person or by indirect contact and the common symptoms are cough fever shortness ness of breath, shaking chills and because of low supply of oxygen, gray to purplish skin color because the blood is poorly

00:26:38 oxygenated. Just I told you why the diagnosis can be made by the chest x-rays, physical exam, blood test or by the analysis of sputum or bronoscopy. Now there are many diseases which can be caused by the bacteria in the humans. Here you can see a list of different diseases. Some of these diseases were lethal in the past. Some are still lethal. Some can be uh controlled while others can't. Some can be transmitted uh through sexual intercourse. Some can be controlled by vaccination while others

00:27:21 are treated by antibiotics. Talking about antibiotics, do you know what are antibiotics? You must all have uh undergone this experience or have might have heard that somebody got ill or sick and the doctor prescribed a few antibiotics and told them to uh take these antibiotics for a particular given course of time and these antibiotics get rid of the ailment. So if you have such experience you can very well easily say that antibiotics are those chemicals which can kill certain microbes which cause diseases in

00:28:02 us. So let us try to define antibiotics. They are the antimicrobial drugs used in treatment and prevention of bacterial infections. Uh they may either kill or inhibit the growth of the bacteria. You know how antibiotics were discovered? Alexender Fleming was working in his laboratory and he saw that in the cultures where penicylium was growing the bacteria could not grow. So he observed that something must be there which is being produced by the penicylium fungi and it is not allowing the other bacteria to grow. Later on it

00:28:45 was these substances that were not allowing the bacteria to grow were identified as antibiotics and antibiotics have uh revolution revolutionalized the way we treat different diseases uh along with vaccination and antibiotics. Now we can control many different diseases which were not under control in the past. But one thing to remember is that antibiotics are not effective against viruses. We cannot use antibiotics to kill viruses. Do you know why? Well, I just told you that uh antibiotics kill

00:29:28 or inhibit the growth of bacteria. How? They may tear their cell wall or digest them and uh impair their machinery for reproduction. But viruses they use our cellular machinery for their reproduction for their protein synthesis. So how can antibiotics kill the viruses? They are not at all effective against viruses. There is a question on the effectiveness and the proper use of antibiotics. It is being thought whether antibiotics are boon or bane. There are some side effects of using antibiotics

00:30:09 but most side effects are not very serious though really some may cause allergies severe allergies. The problem with the antibiotics is that they can kill off the normal defense bacteria of our body. In different parts of our body a lot of different microbes and bacteria are living and they are living in symbiotic associations. They help us in many ways. For example, the gut bacteria that is present in the gut, it produces vitamin B12 also. Now, these bacteria are beneficial for us because they also

00:30:48 do not allow other pathogens to come and live inside our body. Why? Because they offer severe competition. Think about a metro coach or a bus fully occupied by the people. uh will other people be able to enter that bus or the coach? No, because it is all uh already overpop populated by the people inside the coach. Similar situation happens that uh there are normal symbiotic bacteria growing inside our body inside our gut and they do not allow other invading pathogens to come and grow inside our

00:31:27 body. But when we take antibiotics without proper prescription, without proper knowledge, what we are doing? We are also killing that beneficial bacteria which was up till now protecting us. Now that we have killed that bacteria, the metro coach or the bus that we were talking about as analogy has got free. Now any pathogen can enter our body and infect us. So antibiotics can kill off normal defense bacteria and this may then allow thrush or other bad bacteria or fungi to grow. Another um bad thing that happens when

00:32:11 you take antibiotics without proper consultation is the development of antibiotic resistant bacteria. How does this happen? Does antibiotics uh confer resistant to the bacteria? How can they do so? We are saying that antibiotics kill the bacteria. How can they make them resistant? Well, the answer lies in the proper understanding of evolution. Uh let us say that there are some bacteria inside our body and they are harming us. Now we know that all these bacteria can be genetically dissimilar. So a few of

00:32:56 them might be carrying an antibiotic resistant gene. I'm showing a antibiotic resistant gene with this orange color. Okay, antibiotic resistance gene. Okay. So uh let us see once again. There were certain bacteria growing inside our body and infecting us causing some disease and a few of them might be carrying an antibiotic resistance gene. Now you happen to take an antibiotic. What will happen? All the bacteria that did not have antibiotic resistance gene will die sooner or later. But the one carrying the

00:33:46 antibiotic resistance gene will survive. Now what has happened here? The competition has eliminated. It has become the lone survivor. It has now all the resources for itself. What will happen? It will now reproduce, grow and multiply in number very quickly because it has now got ample resources for itself. And soon we will have a population of bacteria which all have one or the other antibiotic resistance gene. And now if we take the same antibiotic again for the same infection, will it be effective? No. Why? Because now all

00:34:37 these bacterias are carrying the antibiotic resistant gene. This is how antibiotic resistance develops in the different strains of bacteria. And this is why we say that antibiotics should never be overconumed or should uh be consumed only under proper prescription from the doctors otherwise the antibiotic resistant bacteria can develop very quickly. Talking about the antibiotic resistance just as the way I have taught you now uh meticuline resistance stafylocus orius bacteria has developed and this bacteria

00:35:18 is very difficult to control. If any bacteria develops antibiotic resistance, how will we control it? How will we treat the disease that is caused by such bacteria? It becomes very difficult. So what you can do? How can you help to control this antibiotic resistance? Well, always take care of these points when you are taking the antibiotics. Always take them in the correct way and never take the antibiotics without prescription. Never take antibiotics prescribed from somewhere else. Why? because the

00:35:57 bacteria affecting you and the bacteria that was affecting the other person might be different. So never uh exchange the antibiotics or never take the antibiotics without any prescription. Also never skip doses and always take the entire course of antibiotics as directed by your doctor. Now what may happen? You took antibiotics for a certain period of time and you started feeling well. the symptoms started fading away and you feel now you are good to go but the bacteria is not properly killed. uh its

00:36:35 population might have reduced but it might might not be uh totally eliminated from the system and if you stop taking the antibiotic now chances are that this the leftover bacteria will develop fast and it might develop an antibiotic resistance also this always discard the leftover medicine and the best way is to get vaccinated if vaccines are available will get yourself vaccinated so that you don't have to rely on the antibiotics for your treatments. And last but not the least, never take an antibiotic for a viral

00:37:19 infection because the viruses cannot be killed by the antibiotic. And the antibiotic which will enter your body when you have taken it for a viral infection, what will it do? it will go harm the beneficial bacteria or help in production of antibiotic resistant bacteria. So never take antibiotics for any viral infection. This is all about antibiotics. And now let us proceed towards the viral infections. Under viral infections, we will discuss the common cold. Common cold is one of the most common disease that infects almost

00:37:57 all of us throughout our lives. It is caused by pathogens and the problem is that there are more than 200 different types of pathogens viruses which can cause common cold and rhino virus is the most prevalent of them. Other viruses that cause common cold are corona virus, adino virus, respiratory cynical virus or parinfluenza virus. Now our immune response is not very effective against common cold. Why? because new cold viruses constantly develop and the body never builds up resistant against all of

00:38:33 them. Okay. The symptoms you all know the symptoms of common cold nasal, stuffiness, scratchy throat, sneezing, horarsseness, cough, watery eyes etc. All these are the symptoms of the common cold. How can the cold be transmitted? Well, it can be transmitted through airborne droplets. When you inhale the droplets of a person who is sneezing or coughing or touching the viral infected surfaces actually the problem is the first thing that direct contact with the secretions can also cause the disease

00:39:11 and the cold virus can also live on the objects for several hours and can thus be acquired from contact with these objects. If you touch a thing that has previously been touched by a person who had flu or common cold, chances are that the virus which was still living on that surface will be taken up by you also and you can also get the flu. Inhaling the airborne viruses after individual sneeze or cuff I shown it through this figure. This can also lead to transmission of the common cold virus. Now people often

00:39:50 confuse influenza with cold. Influenza is caused by the influenza virus and common cold is generally caused by the rhino virus. These two have all together different shapes. The symptoms of influenza and common cold may be similar but influenza is a severe illness while the common cold is somewhat milder. How can common cold be prevented? This is one of the diseases that can easily be prevented if we take care of our habits and our personal hygiene. If you uh use tissue every time you sneeze and

00:40:32 cough and throw this tissue in the waste bins, chances are that you will reduce the chances of spread of the uh flu. Wash your hands with soap and water regularly or use alcohol- based sanitizers. If you are sick, if you have flu-l like symptoms, visit your doctor. Don't touch your eyes or nose. And uh please stay at home confined in isolation so that you don't spread the flu to others also. And if you meet somebody who has flu then try to avoid direct contact with that person as much as possible. This is how the common cold

00:41:15 can be prevented. Let us now move on to the protozone diseases. One of the scariest uh protozone diseases is the malaria and the other one is amabic dentry or the amiosis. Malaria. Do you know what are the causes of malaria? Malaria is caused by the pathogen plasmodium. Many species of plasmodium are known and falsiparam is the most dangerous one. The malaria caused by this species can sometimes be fatal also. Here there is a picture of blood smear showing malarial uh pathogen growing inside the RBCs.

00:42:00 This pathogen is uh spread by the vector female anal fleas mosquito. Before going into the details of the question, I have one question for you. Uh if a mosquito bites you someday, can you just by looking at it from the far off, can you tell whether it is male mosquito or female mosquito? Can you tell that? Will you be able to answer just by having one simple look at the morphology of that particular mosquito? Can you tell whether it is male mosquito or female? Well, yes you can because mostly you are bitten by the female mosquitoes

00:42:42 which require the human blood meal for the development of their eggs. The male mosquitoes take food from the plant sap generally. So talking about the enofles mosquito 30 to 40 species of enofles mosquito can transmit plasmodium. The female lays about 30 to 150 eggs every 2 three days and the human blood is needed to nourish these eggs only. Now the particular feature of of this mosquito is that they start biting by late evening and the peak of the biting activity is at midnight and early hours of the morning. Why is this

00:43:22 information important? Because if you know these patterns, you can avoid being bitten by this mosquito. Let us now discuss the life cycle of the plasmodium. The plasmodium um requires two hosts for completing its life cycle. Let us begin with the infectious form, the sporosoid. The sporosoids are present inside the mosquito. This diagram has been taken from your NCERTT books. You can see this diagram there also. So the when the mosquito bites a healthy person, the sporosoids enter his blood through the bite of the mosquito and

00:44:06 then these sporzoids reach the liver. Here they reproduce inside the liver and grow in number and finally they come out and attack our RBCs. Now they grow and multiply inside RBCs also and when they burst open they release a toxin known as hemosone. This hemosone toxin is responsible for production of chills and fevers that are characteristic symptoms of the malaria. When the uh parasite is inside the RBCS only it develops its sexual stages which are now known as gamtoytes. So there are fe male and

00:44:49 female uh stages formed. They travel inside the blood in these forms only. Now if another mosquito happens to bite this person, what will happen? These sexual stages will be taken up by the mosquito along with the blood meal. Once the uh sexual stages or the gamos gamitoyes reach the intestine of the mosquito fertilization takes place there and again sporosites are formed. These sporosoids move to the salivory gland of the mosquito and stay there so that whenever this mosquito bites another healthy person these sporosoids can be

00:45:33 transmitted uh through the bite into that healthy person. So the points to remember here are that the sporosoid is the infectious form. Gamito is the sexual stage and fertilization takes place inside the mosquito's intestine and sporosites are stored in the saliva salivory glands of the mosquito. The symptoms of the malaria are very characteristic and it infects almost all of the body. It affects almost all of the body. And here is a picture a diagrammatic uh view of RBC's uh which carry the

00:46:14 plasmodium. How can you prevent uh being bitten from the mosquito? There are two methods. You have to look for get preventing the bite when you are inside the house and when you are outside the house you have to look for the ways by which you can prevent the breeding of the uh vector that is you control the vector population. So let us first see what we can do in our houses. Remember I told you that the mosquito starts biting late uh evening and the biting activity is at the peak during midnight. So what

00:46:49 can we do inside our homes? When we sleep, we use mosquito nets or we use insect repellence. However useful or harmful they are that is uh matter or topic of debate but to some extent they do protect us from the mosquito bites. Most effective will be to keep the windows closed especially during the evening hours. If we do these things, we can prevent the bite inside our house. Talking about outside, we can do many things to control the vector population. We can do fumigation or we can spray various um chemicals on the standing

00:47:33 stagnant water chemicals like petrol or kerosen oil uh so that the mosquito larve do not get proper oxygen and they die. And one of the biocontrol methods which is very effective is release of gambusia fish in the stagnant water bodies. These gambusia fish are very small and they feed specifically on the mosquito larve. So if there are large uh bodies of stagnant water, standing water, these fish can be introduced in those water bodies and they will eat of the mosquito larve and ultimately the vector population will decline. This is

00:48:16 how we can control the vector of um mosquitoes. We can control the mosquitoes. The next disease that we are talking uh about is amibiasis. It is caused by ant amiba histoica. This uh pathogen is carried by house flies from places to places. What happens that the parasite lives in the intestine and it is passed on the outside with the fecal matter. When the housely sits on the fecal matter and then later it sits on the food or water that you are going to consume the parasite or the pathogen will gain an

00:48:57 entry inside your body also. So contaminated food and water are the main sources of infection and the symptoms are constipation, pain, cramps, stool with excess mucus and blood clots. How can you prevent uh this disease? by ensuring that you do not consume food and water that has been contaminated. How can you do so? Well, you can keep your food items covered so that the uh housefly do not get to sit on it and avoid uh eating cut fruits and salads and different food preparations from the vendors who do not keep their

00:49:40 food items covered. And also you should try to avoid the entrance of uh house flies in your homes also by keeping the surroundings clean. It does not mean that you just clean your home and throw the garbage outside next to your home on the streets. This will not control the house flies. They will come and sit on the garbage and then come back to your house and spread the diseases. Next topic is the diseases caused by helmans. Here we will discuss ascarasis and filarasis. Ascariasis is caused by

00:50:19 the round worms. Here is a picture of round worms. This is the male round worm which is smaller as compared to the female round worm. And here you can see the characteristic curve of the tail. This helps us to identify the male from the female. They live in the intestine and their eggs are excreted along with the fecal matter. So here al also the infection is acquired through contaminated food and water. The symptoms are internal bleeding, muscular pain, blockage of intestinal passage, fever and anemia. These are this is a

00:50:56 very dangerous disease and it harms a lot of people especially children and it can be prevented only by using simple methods like uh habit of washing hands every time before you take meal like by inculcating the habit of keeping the food items covered and these diseases can also be treated by uh tablets. which are available in the pharmacies at very low cost. The only thing required is proper awareness and inculcation of good habits which pertain to good personal hygiene and social hygiene as well. The next disease is phariais. It

00:51:46 is caused by the pathogen which brought andia malai. This is a microscopic uh pathogen and it is carried by the vector uh female mosquitoes like ulix and anofl and this lives in the lymphatic vessels of our body and the symptoms of this disease uh range from simple u pain and discomfort to al elephantiasis. The symptoms of alenfantesis are severe deformity of lower body, limbs and even genitalia. The skin may become thicker and may cause the pain also. The last disease that we are going to study is a

00:52:36 fungal disease that is a ringorm. Ringworm can be caused by a variety of fungi like microsporum, tririccoyon or epidermopyon and it is generally acquired from soil but can also be transmitted by use of articles of the infected person. The symptoms are presence of dry scaly lesions and intense itching and they generally occur in skin force, groin, toes and they also can occur on nails and scalp. So this was all about the various diseases which are very common amongst the Indian population and a thorough awareness is

00:53:20 required to prevent these diseases. I hope that today's session has helped you to understand the basic logic behind the spread of infections and uh you can understand how important uh is the inculcation of good habits proper uh maintenance of proper personal hygiene and social hygiene is important for prevention of various diseases. I have brought some questions for you to think over like what are the various adaptations of pathogens that help them to survive in the host body. You remember we discussed some uh

00:54:02 adaptations in the beginning of the session. Please try to list them. The second question that you should look for answer is what are the common modes of transmission of pathogen? Next, how can vectorbone infections be controlled? Fourth question that you should try to find out the answer is how important is the maintenance of personal and social hygiene for prevention of diseases. Lastly, our habits can save us from many diseases. Please try to justify this statement with examples. Thank you.