 Hello everyone, let's continue our classes on causation of disease. So in this session I will be covering about germ theory, epidemological triad multifactorial causation and web of causation. The other few things like natural history, risk factors and spectrum of disease should be covered in future classes. So I spoke of disease we had covered in detail. So there were a lot of theories present before the germ theory, how the disease is caused, all those theories were supernatural theory, theory of humus, humus means a bad production of body, theory of contagion, theory of miasma, miasma is nothing but the bad air which causing disease and theory of spontaneous generation. All these theories were conspiracy theories with not much without any scientific evidences. So one of the first theory with scientific evidences was germ theory. So it was started when French bacteriologist, we know Louis Pasteur, he found out the presence of bacteria in air and he advanced the theory of spontaneous generation. Then after that period Robert Koch came into the limelight of bacteriology. So it is known as golden era of bacteriology. He found out the anthrax, cosplay, some bacteria. After that many bacteria were discovered, gonococcus, typhus, cholera, diphtheria. So at that point of time when germ theory was there, people believed that or it was believed that a particular agent entering into man and causing a disease mostly microbes. So Robert Koch postulated a theory that is germ theory is completely emphasizing on the presence of microbes in producing a disease. So he with a scientific background, he inoculated bacterias and produced infections. So he had evidences. So this postulates where a specific microorganism is always associated with a given disease because a disease is always caused by a microorganism and it can be isolated from a disease animal and it can also be grown in a laboratory and the grown new micro can cause and can transfer to healthy animal and again it can be isolated from the animal. So these were the course postulates, it is a part of germ theory but the theory had a limitation because it was unable to explain why some people suffer the disease after exposed to micro organism, not all because not everyone is getting the micro organisms is not producing symptoms or not producing disease that is tubercula, parcellae. So that is a bacteria of tuberculosis. So this was the main problem because some people carry the bacteria as carrier state without producing any symptoms. So this lead to the formation of the second concept that is epidemiological triad because the tuberculosis was not able to explain by the theory, germ theory and course postulates because even after having presence of microbes all the people are not producing symptoms or not having any disease. So the germ theory was rejected and the second one for the next theory that is epidemiological or ecological triad theory came into existence because it need to be an interaction of agent, environment and host or the imbalance of these three factors can cause a disease like tuberculosis. Okay, so the epidemiological triad there should be an imbalance between these three factors. Agent means our tuberculous parcellae, environment means the environment which where the person is living and host is the immunity factors or the host factors. So all these factors has to be compiled for this disease to be happen. So before the germ theory was explaining only this part of the epidemiological triad, now we have to concentrate on environmental and host factors. So agent is something which is coming from outside. It can be biological, mechanical, nutrition like deficiency or physical or chemical agent and host factors it depends upon the genetics, age, gender, is literacy level, is income, lifestyle, immunity, everything has a contributing factor for the disease. And the environment it is depend upon the customs, if follows, psychological factors, biological factors and physical factors. So all these three factors that is environment and agent and host factors has a role in producing a disease that is epidemiological triad. So the equilibrium should be lost or the equilibrium should be disrupted for the disease to be happen. So this model explains that some persons do not suffer from the disease even though they have a pathogen which was not able to explain by the germ theory. But the problem arises when it is not applicable for non-infectious and chronic diseases like coronary and diseases, mental illness and such diseases where the disease is caused by multiple factors. So this has to lead to the next theory or next concept as is multifactorial causation of disease that is a disease is caused by many factors. So it was first introduced by Galen in 130-150 AD, it was very ago. Then in Pittenkofer of Germany also introduced this theory during this era of 19th century but it was overshadowed by the germ theory because that was the golden era of bacteriology because all these factors like social, economic, culture and psychological factors has to be there for a disease to be produced. So otherwise the disease will not happen especially the chronic type and the lifestyle diseases because it is factors which are factors like poverty, illiteracy, ignorance and poor living conditions, overcrowding all will contribute to the disease. So tuberculosis is not just due to bacteria, it is also due to poverty, overcrowding and malnutrition. So the modern diseases are the diseases of civilization like limb, cancer, diabetes, coronary heart disease, mental illness are mainly due to the multiple factors or the multifactorial causation. Also we know that for example excess of fat intake and smoking lack of physical exercise obesity are all involved in pathogens of coronary heart disease, we just cannot point out a single factor. All factors have its contribution in producing this disease. So that is the multifactorial disease. It is also considered a broad aspect of epitomulgical triad because we can put all these factors into epitomulgical factors like causative factors and non-mental cultural other factors and the post factors. It is a different version of the same epitomulgical triad that is about the multifactorial causation. And the last one is web of causation, a little more complicated concept because this model of disease suggested by MacMohan and Puck and this model is basically suited for chronic diseases because the same diseases which we were explaining multifactorial, this is little more advanced. So this is like a lot of factors which has intricate relationship between each other and we cannot just point out a one factor or two factor because all factors are interrelated and giving a complex relationship and producing the disease. We can just take an example of myocardial infraction. So basic factors are changes in lifestyles, smoking and stress. Stress is causing emotional disturbance which is ultimately releasing hypertension and it causes walls of artery changes and it gives coronary inclusion. Same times aging also cause hypertension at the same time changes in lifestyle, lot of food habit, obesity it also results in hypertension and obesity also results in hyperlipidemia that results in atherosclerosis that also goes to the coronary inclusion. So all these factors are interrelated we just cannot put these factors into a triangle shape. So it is just like a web of all factors which is interrelated and causing the disease. So this is what exactly nowadays we are following in the chronic diseases or lifestyle diseases other than multifactorial disease position. This is almost like multifactorial but the interrelation is more specific in this way. So today's session we will be seeing about iceberg phenomenon. So in the cover pic I have put a picture of a iceberg which caused destruction of the unsinkable ship Titanic. So that's the idea of iceberg. So why the ship sank because the captain of the ship didn't see the underwater portion of this iceberg. He was just seeing the above water level and he tried to turn the ship but what happened was the lower ducks hit with the underwater portion of iceberg and it sank. So that's the idea of iceberg phenomena. So let's apply this idea into disease. So in today's class I will be talking about iceberg phenomena and disease. So as we know iceberg is a piece of ice that is broken off from snow. The main point is just one ninth volume of an iceberg is seen above the water. So that means the majority the 90% of the iceberg is below the water. So we'll apply the iceberg phenomena into concept of causation. So we have a lot of concepts that is epidermological, triad, multifactorial, natural history of disease, web of causation, risk factors, spectrum of disease. So today's session will be covering just iceberg of disease. So all these sessions will be covered in future classes. So let's see what is iceberg of disease. So it is just a metaphor which says that every health problem as a non case and unknown case. So if we take a population, if we take a country, we're checking any particular disease, let's take a diabetes or let's say cardiac disease, there is a very small portion which is very visible. The non cases, the people who are diagnosed with the diabetes people are taking treatment or people who are taking insulin or under other medications. And there's a lot of majority, they are not diagnosed. They are just there in the society, they are around us just being undiagnosed. That is the concept of iceberg, majority of the people are undiagnosed, very few are diagnosed. So we'll just go into detail of iceberg. The floating tip of an iceberg represents the clinical cases, that is a non case, what the physician sees, the non cases because they might express some symptoms. So they go to the clinician and they diagnosed as a diabetes. The submerged portion that is the vast portion represents a hidden mass of disease, that is they are not showing any symptoms, so they are not being diagnosed. They might be diagnosed accidentally when they go for checkup for any other, clean blood checkup or any other thing. That time they'll come to the tip of iceberg, otherwise they'll be submerged because they are pre-symptomatic most of the time and they are undiagnosed cases or the carriers of community, that is submerged portion. So let's take the example of coronavirus, more we screen the patients, more the cases we get because majority are still being undiagnosed or act as a carrier in our society. So the more tests we do, the more cases we get. The what we are seeing now is just the tip of an iceberg, the majority of the cases are submerged. So more actively we do screening, more cases and the tip of the iceberg will be more and more visible. So the water line represents a demarcation between apparent and unapparent cases, that is clinical and undiagnosed cases. And patient who are at the tip of iceberg are more likely to have very severe health problems because more and more it goes to the tip. The severity and the mobility are more and more it is going on a higher fashion and as we go down to the iceberg, the patient becoming more and more healthy, okay. But they will be gradient of disease. So just see the, let's break down this iceberg, you can see the tip, disease diagnosed and controlled and this water level diagnosed but it is uncontrolled. They know that they have disease but they are not on medication and whatever is below the water line is undiagnosed or wrongly diagnosed. Some may have the risk factors, some may are exposed to lot of diabetic prone food items and majority that is free of risk factors this part. So that's what I was saying, as you go to the tip of the iceberg, you have a lot of problems when you go down, you are more likely to be healthy, okay. So the block one and two corresponds to the iceberg, these two are icebergs and this is a submerged portion. So underwater is unidentified cases, they are very different from identified cases because the spectrum and natural history is very different and symptoms and progression since it is related the undiagnosed cases are likely to be less severe, okay. So that's the idea of iceberg, it is not very crucial thing, it is identifying the undiagnosed cases from a population, that is it basically stress the emphasis the screening part of a disease because it is not very contagious diseases mostly hidden, it will be mostly chronic or lifestyle diseases. So when we do more screening and we get more diseases, we can reduce the morbidity of that particular disease, okay. So let's see the scenario of caries, so we know what is caries, so this is a caries iceberg, so this tip of this caries, these two blocks are the diagnosed caries, okay. So this is lesions which involved into a pulp and this is the little severe cases and these are caries involved to enamel and this is just beginning lesions and they are subclinical lesions are free of caries. So these are we are treating these people because these people are coming to dentist or for a dental treatment, these people are having diseases but they are not coming to dentist or for a dental treatment because of their unawareness or they are not producing any symptoms. So this is case of dental caries iceberg. So our idea is the clinician or a researcher or a health sector people what we need to do is we have to bring more and more cases from the underwater to tip of the iceberg so they can get a treatment. So as early we find the disease at the bottom level they will not go to the severe state because anyway when the disease is coming from this to this to this they will turn up to the clinician or a dentist. So our idea is to detect the cases as early as possible so we can give them a better prognosis. So this is about the treatment part. So early we diagnose the disease that is part of screening the better will be the prognosis. So here we can do preventive care but this part of the preventive care is not possible. So if we diagnose the patient here by help of screening we can do preventive treatment rather than it's just like a piton fish seal and so fluoride instead of big rations and other part therapy. So if we see the predominant it is iceberg. So we know that the iceberg what the patients are coming with symptoms just like using tooth or the tooth elongation where the bone support is lost. So our idea is to conduct more and more radiographs and other clinical aids and find out the gingeral recession bleeding gums and pocket cases so that they get better prognosis. They diagnosed at the very early stages of disease so get a better prognosis so they don't eventually turn up to the tip of the disease we have to pick them up underwater and cure the treatment so that they don't turn up here. So this is automatically patients with symptoms so we need to find out people without symptoms by active screening and give them better treatment to get a prognosis. So similarly in oral cancer people turn up only with symptoms just like chewing problems or difficulty in swallowing or other tongue problems. So we need to do aspiration biopsy and other procedures and find out the cancers at early stages and active screening will find out the underwater diseases. I mean the asymptomatic or diseases which is not having a very severe severity. So that's the idea of iceberg phenomena. The iceberg phenomena is all about detecting the underwater diseases or the asymptomatic diseases by active screening. So a clinician cannot do active screening it is epidemiologist or other community medicine people or community dentists or community doctors they can go to the public and do active screening they can do examination on apparent healthy people and find out the disease because not all cases will show symptoms some will not show symptoms and they produce symptoms at very late stage of the disease. So we need to do active screening on the apparent healthy people and find out the cases before they actually show symptoms. So we can reduce the mobility of such cases and such patients. So that's the idea of iceberg phenomena. So I'll come up with the other concept of causation in my next classes. So thank you. Our session on concept of causation. So so far we have covered germ theory, epilomological triad, multifactorial causation, web of causation and iceberg of disease. So the remaining portions that is natural history of disease, risk factors and spectrum of disease. Okay, so these three topics will be covered into today's session. So let's move on to the natural history of disease. So natural history of disease is nothing but suppose what happens when a pathogen enters our body that is before the stage that is pre pathogenesis state that is when we are exposed to a place where there are chances of pathogen entry and to a state where the pathogen can cause its full on effect to our body. So in definition, we can say that a disease evolves over time from the earliest stage of its pre pathogenesis phase to its termination. Okay, so when it has shows is full effect that is this pathogen has shows is full effect. It results in either recovery, disability or death. Usually in absence of treatment or prevention, we are not doing anything. Suppose we are not doing anything to prevent that pathogen control of pathogen. What will be the course of this pathogen action? How do this pathogen react or present in our body? So that is natural history of disease. Usually when pathogen enters the symptoms arise, we go to doctor or we take treatment and it will be cured or with maybe some disability will be there. So what if we are not doing any prevention or any treatment? So it might end up recovery, disability or death. So that is a natural history of any disease. So the process begins like when we are going to a place or when we are at a risk of getting an infection. Suppose we are going to a slum where the epidemic of cholera is around or in the air, I mean the water. So we are exposed to this cholera bacteria and we are having a high chance of getting this bacteria through water or any other way. But we have not yet shown this pathogen entry, the way for pathogen entry. The pathogen is still outside the body. So that is pre-pathogenesis phase but any moment this pathogen can enter and once it enter it starts the pathogenesis phase because pathogen enters body and it starts replicating and it shows its effect. So that is pathogenesis and pre-pathogenesis phase. So if there is no medical intervention what happens is as I told there will be either disability or death or there will be recovery. The body immune system itself shows recovery. You will fight against the pathogen and the body will be recovered. So what happens is the pathogen exposure we are going in a place where we get exposed, pathogen enters the host body, it results in disease, there is no intervention, it may end up either death, disability or recovery. So this process is known as natural history of disease, there is no intervention here. So usually natural history of disease can be studied in a cohort study. So we know cohort study is a prospective or future looking study. It studies, study starts with a disease free person and it goes and over a future period of time the person develops a disease. So the best way to study natural history of disease is cohort study. But since we know it is very laborious and it is costly, so mostly it is done by other methods like cross sectional and retrospective like case control study. But best way is always cohort study because we can understand that how the disease shows its clear effect because when we start the study there is no disease. So over the period we will be knowing very clearly how the disease shows its effect. But if you are doing a retrospective study the disease has already done its all effect on the people or the particular person. So we will be asking questions and trying to find out what would have done. So it is not very accurate as we get the information during a cohort study. So what physician sees in clinic is just an episode of natural history of disease. So we go to a doctor when we get symptoms, we get fever, when we get headache or when we have a feeling when we feel tiredness or fatigue or such symptoms we go to the physician or a doctor. So that is just part of or just an episode of natural history of disease. So natural history of disease can be studied only by an epidemiologist. So a clinician or a doctor cannot study the natural history of disease, it should be studied by an epidemiologist how it starts, how it goes and what are the symptoms it shows and how it finishes its course by recovery, disability or death. So we can divide the natural history of disease as pre-pathogenic and pathogenic. Pre-pathogenic is before the pathogen enters the body but we are at a risk of getting the pathogen. Once the pathogen enters our body, pathogenic phase starts. So pre-pathogenic says as I mentioned earlier we are at a condition where the disease or where the pathogen can enter our body at any time but it is not yet entered. So that is the pre-pathogenesis phase, many communicable land and communicable disease. Land disease like cholera or food poisoning, we are at a position where any time we can get the pathogen. Like we are going to a restaurant where the food poisoning has been reported. Any moment we get the pathogen, we are at an area where the cholera has been reported. We get any moment the disease and the pathogen enters our body. So that is pre-pathogenesis phase because pathogen hasn't entered our body. So I am exposed to the risk of the disease because there is a risk of disease in all these places. So we are at a risk of disease but we are not infected with the pathogen. So next phase is pathogenic phase. When the pathogen or organism enters our body, when this closed sodium bottle that is a food poison causing bacteria or vibrio cholera enters our body, the pathogenic phase starts. It shows symptoms. It can be clinical or subclinical because we know many people with coronavirus it's not showing any symptoms but they are under pathogenic phase. We are all, now since it is a pandemic we are all living in pre-pathogenesis phase because everywhere there is a case present. We may get the disease from any person. So we are all under pre-pathogenic phase. There is only a case for such pandemic diseases. Once it enters it becomes pathogenesis. So clinical or subclinical let it be but it is a pathogenic phase. So the pathogenic phase decides basically the fate of the disease, how it ended up with outcome can be recovery, disability or death. So we can summarize the natural history of disease by this picture. This is a course of this pathogen, how it shows its effect on our body and these two phases one is pre-pathogenesis phase and this is pathogenesis phase. So we are living in an area where any time the pathogen can enter our body that is pre-pathogenesis phase. We are living in a slum or we are going to a restaurant that is pre-pathogenesis phase. This particular organism enters our body, the pathogenesis phase starts. Once it starts it might be asymptomatic or it is symptomatic. If it is symptomatic we will go to a doctor or a physician and we will get it diagnosed. So diagnosis can be done only at clinical stage. A symptomatic stage diagnosis is very difficult. So it may end up death, disability or recovery because we are not doing any treatment here. This is just a natural history of disease. This diagnosis is possible under clinical stage because the patient will show symptoms. So that is all about natural history of disease, how a disease progresses without any medical treatment or any intervention or any prevention. How it goes and how it shows its full effect on the as the death, disability or recovery. So studying natural history of disease is very much important in prevention of disease. So natural history of disease is over. Next is the spectrum of disease. This is almost like our natural history. So it says that it is a graphic representation. So you can see that we know spectrum of color when a light enters the prism. It radiates many colors or that's why we got this name spectrum of disease. So spectrum of disease it's a graphic representation of variations in the manifestation of disease. So one disease can present various outcome. Sometimes a particular disease might be asymptomatic in a particular person, it might be symptomatic but very mild stage. Sometimes it will be in a moderate stage. Sometimes same disease can be very fatal for that next person. So various manifestations are present for the same disease. So that is all about spectrum of disease, a healthy person, a particular disease showing various manifestations. So at one end that is this end, the person is having positive health because that particular disease is not showing any problem for that particular patient. At one end of the spectrum are subclinical infections. Suppose if we take tuberculosis many of the Indian population are carious, they are not showing any symptoms. Still they are both microorganisms in their body. So they are under subclinical infection and they are not having any problems as such because positive health, better health. And the other end is death, the same disease can cause death of a person. They are very malnourished, they are living in overcrowded slum areas. The same disease can cause death of that person. So at one end it will be positive and better health and the other extreme it shows as a death. So at one end the spectrum are subclinical infection and the other end it is fatal illness. So in the middle it is having illness ranging in severity, that is mild to moderate. This area will be mild to moderate. So spectrum of disease is nothing but a disease manifestations in various people ranging from positive health to death. So next we go to the iceberg we have already covered, next we go to the risk factors. Risk factors are very much important in the present scenario because almost of the diseases which were present in the past century like cholera, that contagious diseases, other contagious diseases like smallpox, plague, all are under well control because our scientific knowledge and our medical facilities have improved to a very extent that all these contagious diseases can be well controlled, though exceptions are there like corona, pandemic. Still all the contagious diseases can be well controlled but what happens is the other side of the disease that is chronic diseases or lifestyle diseases are on an increasing fashion because due to the change in lifestyle or due to change in the food habit or certain lifestyle, the people are getting affected with many lifestyle diseases like coronary heart disease, diabetes, obesity, high cholesterol. So all these are risk factors we can say because we just cannot say, we know that tuberculosis caused by mycobacterium tuberculae. In many diseases we cannot say what causes what because in multifactorial and web of causation we have seen how the chronic diseases or lifestyle diseases are exposed to there are many factors which are intricate relationship causing the disease. So risk factors are coming into the limelight in this 21st century or the past 30, 50 years where the lifestyle of people have changed drastically. So risk factors are nothing but an attribute that significantly associated with the development of a disease that is taking smoking. So this attribute has significantly associated with causing lung cancer. So it can be called as a risk factor, anything which has a significant effect of producing something, increased probability of causing something is known as risk factor. So it can be modified by intervention or reduce the possibility of occurrence. So we can prevent your measures, we can educate the people and risk factors can be modified and it is always modifiable. Some risk factors are not modifiable like our genetic make up, our chromosomal abnormalities, our immune system, such things are not modifiable risk factors. But many risk factors like heating practices, sedentary lifestyle, the smoking, alcoholism. So such things can be modified and the outcome will be changed. So risk factors are suggestive but not absolute proof. That is the difference between our germ theory and the recent web of causation. Germ theory says this bacteria causes this disease. But in risk factors we cannot give that much assurance or absolute proof is not possible. It can give a suggestive, suggestive probability. It can cause this disease, smoking can cause lung cancer. We cannot say that smoking causes lung cancer because many people with lung cancer smoking might not be a very significant factor. Because we don't have that much evidence, a perfect 100 percentage evidence because most of these are due to the web of causation. So that is the risk factors. So risk factors are many types, modifiable and non-modifiable are the, which is coming in our daily practices and non-modifiable risk factors are also there. So risk factors are commonly associated with our lifestyle diseases. So we have covered most of the concept of causation. So I'll just, we'll just have a recap. So germ theory we covered, epidermological, triad, multifactorial, natural and web of causation. These two are coming into our chronic or lifestyle diseases. Then the natural history of disease, how the disease be presented without any intervention. It has pre-prathogenesis and pathogenesis phase. I spoke of disease, we know what is the tip and what is under water. And spectrum of disease, how the spectrum of disease showing from perfect health death and the risk factors and risk group. And risk group, we know people who follows risk factors and there will be many risk groups because if we say contagious diseases, we can say that the slim people or overcrowded people are mostly the risk group for getting that disease. People who are under smoking habit is a risk group for lung cancer or other emphysema such diseases. So there will be always risk group. And age old people will be it's for schizophrenia, Parkinson's disease. So risk groups should be taken care of well. So this is all about concept of causation. So I covered it all the various concepts, how the diseases between diseases caused from the 18th century and prior some diseases theories were there and to the very recent ones. So the present stage, we are mostly seeing this risk factors and risk groups. Risk factors are the main thing and web of causation or multifactorial causation. So the next class, I'll be covering the prevention of disease, the levels of prevention. Okay. So that's all about concept of causation. Thank you. Hello, everyone, welcome back to a new session on dentistry and more. So today we'll be covering the concept of prevention. So the last session, we had covered concept of causation. So how the disease is caused. We had covered all the theories and all the concepts. So now we'll be moving on to the concepts of prevention. How do we prevent a disease and what are the concepts available on what levels we are going to prevent a particular disease. So that we are going to see in this particular session. So just like Benjamin Franklin said, an ounce of prevention is worth a pound of cure. Always prevention is better than cure. So in our country, the third world countries or developing countries all may always keep on to the curative part rather than the preventive part. Curity part or curative medicine is always very expensive. It might break the backbone of a individual or a family. But the problem is the preventive side of medicine or preventive aspect is not much a given importance in our country. Compared to the Western countries. So prevention is always better than cure. So what is prevention prevention? We know the word itself says pre event action. It's just like stopping an action because the action of stopping something from happening. So we are going to prevent something very simple as that prevent pre event action. So we are going to prevent a certain action that might cause a disease when we apply this to our disease prevention, smoking causes lung cancer. So we are preventing an action of smoking so that it won't result in lung cancer. So let's see what are the levels of prevention. So basically we have four levels. So we prevent diseases under this four level that is primordial prevention, primary, secondary and tertiary. It depends on the complexity. If we see the disease, the disease is not it occurred here and tertiary prevention. The disease as shows is complete effect. So it is going by disease where it is. So in true sense, we can say that primordial and primary are true sense of prevention because after primary prevention, the disease already are into action. So we are just limiting the or halting the progress of this is in primordial and primary. The disease is not yet occurred. So we are preventing actually the disease. So let's move on to the primordial prevention. So primordial prevention is newly emerged concept of prevention is nothing but preventing the occurrence or preventing the occurrence of a habit or a risk factor. Just like the smoking causes lung cancer, we are educating students or we are teaching some young people that the smoking causes lung cancer so that they don't acquire this risk factor that is primordial prevention. The primary prevention is different. Primary prevention is like the particular individual or a group of people is already having the habit, but we are modifying the risk factor so that they won't get a lung cancer or they won't get a disease. Preventing the risk factor and preventing the occurrence of risk factor is different. So the primordial prevention is preventing the occurrence of a risk factor. How do we do that? By establishing a social, economic and cultural pattern so that they won't have a habit at least that is a risk factors. So that is primordial prevention. Primordial prevention is prevention in the very early stage. So we know that primordial prevention is just like this is coronary heart disease or arterial occlusion. So what we can do is we can prevent the intake of meats. We don't take meat at all or we teach the people not to use meat or red meat. Controlling the red meat is primary prevention whereas abstinence, complete removal from the diet or complete removal of the risk factor is primordial prevention. So primary prevention as I told you, the person is already having a habit or a risk factor for a particular disease. So it is by definition actions taken prior to the onset of disease. In primordial and primary disease is not yet occurred. So what are the actions we taken prior to the onset of disease which removes the possibility of that disease will never occur. Suppose a person is under smoking, he's been smoking for few months or few years. So we are going to give a tobacco cessation counseling. He has not yet developed any disease or any lung cancer or anything. So we are going to educate him, we are going to modify his habit or a risk factor so that he won't get the disease. That is primary prevention. Primordial is we are educating the people not to smoke. Primaries we are modifying the smoking habit by educating. So this is primary prevention and it will be always at the pre-pathogenesis phase of a disease. Natural history we have seen pre-pathogenesis and pathogenesis. Pre-pathogenesis, we speak the disease is not yet occurred. The pathogen is not yet entered. The risk factor is not yet entered into the body but the particular person is not yet acquired the particular risk factor. So it is always at the pre-pathogenesis phase of a disease or a health problem. So we modify it, we educate, we modify it, we promote health so that the patient will change the habit or reduce the habit or control the habit so that he won't acquire the disease. So it is all about a concept of positive health, this primary prevention. So we can just see that high serum cholesterol you know it causes coronary artisies. So we ask them to control the diet or we put them on a diet because we ask them to control his consumption of red meat or any other oily stuff. So the risk factor is controlled or modified so that he won't get the coronary artisies. So that is the primary prevention. So it is also like symptoms are preventing HRA infections and immunizations preventing diseases like polio, VCU vaccine, all the vaccination which we give to children to prevent diseases. All are primary prevention. So there are basically two types of primary prevention. Then is mass approach and high risk approach. That is one is group approach, population approach. We have to apply to a big group of people. We have to modify our decisions so that it will benefit a very large group of people. That is mass approach. High risk group strategies we have to focus on a very particularly risk groups. So population strategies directed towards the whole population irrespective of the risk level. So whole population it will apply directly to the whole population just like the ads or the health education videos we seen before the movies against tobacco. So it is applying to everyone. Every group of individual is seeing kids, adults, males, females, everyone is seeing it. So that is a population strategy just like a small level reduction in the blood pressure or a cholesterol level. It can reduce a incidence of coronary heart disease on a very large scale because we are applying it on a very big group of people. So if it has a very small effect, the outcome will be very drastic, very big outcome will be there because it is applying on a very big group of population, a big group of people. So that is a population strategy might not be very effective. But the next strategy will be effective. That is high risk strategy. We have to select the people with special risk or high risk. Example smoking cessation programs should be applied to smokers because we apply the population strategy on every people. We apply it to people, those who are not smoking. But it might not be effective. They won't take it very seriously. But when we apply it to very special group, those who are in need, that is smoking cessation should be on smokers. That is higher strategy. So population strategy and higher strategy are part of primary prevention. So next is secondary and tertiary. The disease is already occurred. Now we are going to limit the impact of this disease. That is secondary and tertiary. So secondary is just like halt the progress of a disease at a very early stage and prevent the complication. So secondary stage is just like if we take a dental caries. Dental caries is already open. We are going to restore it and to get back to its function. That is mastication. That is secondary prevention. We take dental caries primary prevention. We have to go for a fluoride therapy or a piton fish's sealants because the dental caries will not occur. Secondary prevention is like we are treating the disease. Primordial prevention is the same scenario we apply. We are teaching the students or we are educating or to each of its, or to each twice. That is primordial prevention. Can also come under primary prevention. So there is factor modification and there is factor prevention. This is different. Primordial and primary. So but the secondary prevention is we are modifying the disease impact. So we are treating the disease or we are preventing the disease at a very early stage so that it won't get complicated and result in more morbidity. So secondary prevention is most commonly it's based on the natural history of disease. If the particular disease has very long natural history, we can get the patient at a very early stage just like a cancer treatment for a cancer patient. We cast the patient at a very early stage can reduce the complications and we can save the patient. So the tertiary prevention is like we are just disability limitation. The disease has caused its full impact. The tooth dental caries has caused the tooth destruction like tooth became non vital. The ground is completely destroyed so that you can't use it for the basic masturbatory function. So what you do? You limit the disability and rehabilitate. So you do pulp capping or root canal treatment. You rehabilitate with partial danger, fixed partial injury grounds, implants or other things. So it is disability limitation and rehabilitation. Now prevention, it's not at all a prevention in sets. Since we are treating all these under different levels, this is tertiary prevention. So we can say that it is just a disability limitation and rehabilitation. It is a measures to reduce or limit the impairment and disability and minimize the suffering. So that is the tertiary prevention. Just like rehabilitation of patients with polio myelitis, strokes, we are rehabilitating with equipments and blindness, injuries. So enabling them to take part in a social life, not in a regular way. At least they can take part with the equipments or with the rehabilitative measures we provide. So that is tertiary prevention. So this is primary prevention like we are educating with signboards asking to wear helmets. So this is secondary prevention. These two are primary prevention, secondary prevention, accident has already occurred. These both are to prevent accident. So these two are two components of primary prevention that is health education and specific protection. This is secondary prevention, accident occurred, but we are taking as early as possible. And this is tertiary after the accident amputation of limb happened. So we are replacing it and we are giving rehabilitation. We are providing wheelchair or any artificial leg. So that is tertiary prevention. Social rehabilitation, vocational and medical rehabilitation. So the primary prevention is to teach them not to prevent an accident. Secondary prevention, they have accident but we take them as early as possible so that the complications will be less. Tertiary prevention, it has full on effect of complication and now we can't do anything. Now we just rehabilitate the patient. So that's all about the prevention. So primary, secondary and tertiary prevention. So primary and primordial are true sense of prevention. Secondary and tertiary are the management of the disease complications. So that's all about the levels of prevention. Next class I will come with modes of intervention. How do we apply these levels of prevention in practice? So various methods implementive measures. So that's all about levels of prevention. Thank you. Last will be on modes of intervention. So in the last sessions we had covered causes concepts of causation and then comes the concepts of prevention. So it is like a continuum. It is all goes in the same line. So when the disease is happening, it comes under concept of causation. There are various theories and how do we prevent it? So what are the preventive strategies? That is levels and concepts of prevention. And the next one is modes of intervention. So that is how do we apply this preventive strategies? That's what we are discussing today. Modes of intervention. So it is nothing but the levels of prevention. But what are the measures we take? What are the particular steps in levels of prevention? Okay. So modes of intervention basically has five steps, which is five steps, which will be into three levels of prevention. The first two steps that is health promotion and specific protection. It comes under primary prevention. The secondary prevention is early diagnosis and treatment. And the tertiary prevention is disability limitation and rehabilitation. So let's go into detail about the health promotion that is coming under primary prevention. So primordial prevention is not mentioned here. So the primary prevention, that is the truest sense of prevention. Whether the disease is not yet occurred. Okay. So let's see what is health promotion. So health promotion is just like promoting. So we need to promote health. Just like we promote our products. We promote, people promote their movies, their books, their songs. Just like we need to promote health. So health promotion is nothing but they're all together. Compiled movement of the social, health, administrative, political, and all together come into action to promote health. Not a single factor can alone do this health promotion. So it has to be a multi-sectoral or intersectoral coordination for this health promotion activities. So let's see what is in health promotion. The steps up, the activities are health education, environmental modifications, nutritional interventions, lifestyle and behavioral changes. So all of the life sectors has to be coming into the action for promoting health. So what is health education is nothing but educating people about health. Why you need to keep hygiene all the time. Why you need to get the profile access. What are the causes of this disease. And how this disease spreads so that you can prevent the disease. Why you need to wash your hands before and after food or washroom. So all these things we need to teach them so then only they can follow it. So if they know the pathogenesis, the etiology of particular disease, they can prevent the disease. So educating people about health is a part of health promotion and that comes under primary prevention. So the second part is environmental modification. Even if we keep ourselves very hygiene, very aware of the health. What if the water we drink or we get from outside is very filthy and it's containing cauliflower bacteria. So we can't help it. So the environment also should be very health promoting. So we should be able to get safe drinking water. There should be proper sanitary latrines. And there should be control of insects and rodents. And there should be a good housing facilities. So that's why I was saying it should be a multifactorial or intersectoral approach. As an individual, as a person, I cannot be always healthy if my environment, my surroundings is very filthy or it is polluted. So even if I being very conscious or very aware of the health, there is no point. So environmental modification is must that the nutritional interventions, that's why government is providing nutrients for under five age in various schemes like mid-day male scheme, ICDS schemes through Angan bodies and all this. That is to prevent certain diseases like malnourishment and protein, nutrients and vitamin deficiencies. So we give it at a very early stage so that they don't develop the disease at all. So nutritional intervention is part of health promotion. It's just like vulnerable groups. There are programs for vulnerable groups like pregnant women, lactating women, and under five age children. So food fortification, nutritional education, child feeding program, all these are coming under health promotion. The second part of health promotion is specific protection. In first part, we are doing everything in general aspect. But the second part is specific protection. We have to be very specific just like immunization. We know immunization is against polio, MMR vaccine, mums, measles, rubella, then the hepatitis vaccine, Japanese and cephalitis vaccine. So all these are particularly or specifically against a particular disease. So that is a specific protection and use of specific nutrients to prevent a specific disease. We are providing vitamin B to prevent anemia or iron and calcium tablet to prevent anemia. So such things, nutrients and cream of profile axis and protection against occupational hazards. We know we wear the helmets when we go to a work site. Protection against accidents. We promote using helmets and seat belts. Similarly, avoidance of callogens, allergens and protection from carcinogens. So it comes into health promotion also under primary prevention. And it is a part of health promotion that is specific protection. We are specifically doing works against certain diseases or certain injuries or certain accidents to prevent such accidents or diseases. So this comes under secondary prevention. That is early diagnosis and treatment. So the secondary prevention is, we cannot say that it is truest sense. Because I had mentioned in the last class that the truest prevention is primary and primordial because the diseases not yet occurred. But in secondary prevention, diseases just started or diseases going. The progress we need to halt. We need to stop the progress of disease. So as early as we need to find out the disease. So the screening of disease is very much important in this section. We should find out the disease people or the disease at very early stage so that it won't result much of the mobility. So it won't create much of the problem for people. So if it is a cancer, we need to go to population and we need to do active screening of various types of cancer so that we can find out cancers in very apparently healthy people. So that they get a better treatment at a very early stage and they'll have a very good prognosis. What if it goes a very late stage and we diagnose it at a very late stage the prognosis will be very poor. So early diagnosis and adequate or prompt treatment is a part of secondary prevention. So that is secondary prevention. It comes early diagnosis and treatment. The number three, this is part of the first one was health promotion and specific protection. It comes under primary prevention, early diagnosis and treatment. The three comes under secondary prevention. And the last part is tertiary prevention. It has two sections. One is disability limitation and rehabilitation. The tertiary prevention in the sense the disease has caused its full effect. The person is suffering. Person is disabled. If we take dental care is tooth is non vital. Tooth has lost. Tooth is not able to do amastication. People has lost a limb. People has lost eye has lost ear something like that. So we need to limit the disability. Okay. So here it is reported at very late pathogen is faced. The pathogen or the particular problem has shown as full effect. Now only available option is limiting the disability. So objective is to prevent the transition of disease from impairment to handicap. So let it not go to a stage of handicap. Okay. So handicap means a socially is not able to perform the duties. If he's a let if we lose his leg means his socially is his job is completely stopped. If he's a like surgeon he lost his fingers due to some accident. He can't do a surgery anymore. So that handicap should not happen. So it should be stopped at every transition stage that impairment to handicap. So let's take an example. We'll get an idea. This is a concept of disability. This is happens. Then there will be impairment. Then disability handicap. Let's see an example. The disease is frostbite. Okay. So when comes in contact with very low temperature. What happens is the person lost his two fingers. Okay. So frostbite is disease. Impairment is losing two fingers. So disabilities is cannot do surgery. That is his disability is not able to do the surgery happened. The handicap thing is he can't become a surgeon. So that surgeon that is missing here can't become surgeon. So that is the handicap portion of the cycle. So we need to stop it at least this stage. Let not become a socially handicap. If it's become handicap, you need to be rehabilitated with artificial processes. And you need to be accompanied with helpers. So that stage should not happen. So tertiary prevention is always aiming at disability limitation. So we need to limit the disability and let it not go to the handicap stage. So rehabilitation is nothing but we need to rehabilitate the people or the person who has suffered a severe injury or severe disease. So rehabilitation comes into many heading. It's like medical rehabilitation. We need to replace the food he has lost. Occasional rehabilitation. We need to get him a livelihood because he was an athlete. He lost his leg. So we can't do any job. So we need to give him a livelihood. We need to socially rehabilitate. So we need to get him back to his family and social relationship. Because he might have an isolated feeling. So we need to get him back to the family circle. And we need to psychologically rehabilitate. We need to get back to restore his personal dignity and his confidence. So all these comes under rehabilitation. So this is the last part. So if disability limitation is not possible, it goes to the rehabilitative phase. So rehabilitative phase is nothing but restoration of his medical, social, educational and vocational measures. So that is able to leave a highest possible level of functional with functional ability. So it has all these sectors like medical, vocational, social and psychological rehabilitation. So that's all about the modes of intervention. So we have seen health promotion, the various measures used in health promotion, that is health education, environmental modification, nutritional and behavioral changes. Next one was specific protection. We had seen it comes under immunization, protection against hazards, accidents and carcinogens. And the secondary prevention. It is early diagnosis. We need to give proper active screening and finding out the disease at a very high stage. Then the tertiary prevention. It has disability limitation. So we can see the example of disability limitation. We need to stop at this disability limit and let it not go to the handicap. So if it is not possible, then we have to rehabilitate. So rehabilitation in the sense, medical, vocational, social and psychological. Okay, that's all about the various intervention of prevention. So this is nothing but the prevention. But how do we apply the preventive measures? So we have covered the concept of disease, concept of prevention and the modes of intervention in prevention.