In our lower classes, we have observed that cells are the fundamental units of living organisms. They are made of a variety of chemical substances such as proteins, carbohydrates, fats or lipids and so on. We have also seen that each living cell is a dynamic place.
Things are always happening there. For instance, cells move from place to place. Even if a cell is not moving, in it repairing may go on. New cells are being made. In our body organs, too, various specialised activities are going on, e.g., the heart is beating to pump blood to all body parts, the lungs are breathing to exchange gases, the kidneys are filtering the blood and making the urine and brain is thinking.
All these activities of various body organs are interconnected. If kidneys, for example, stop filtering the blood, poisonous substances will accumulate in the body. Under such conditions, the brain will not be able to think properly. For all these interconnected activities, energy and raw materials are needed from outside the body. In other words, food is necessary for cell and tissue functions. Anything that prevents proper functioning of the cells and tissues will lead to a lack of proper activities of the body.
5.2 Health and its Failure
A. Significance of Health
• Health has been described as the state of complete physical, mental and social well being.
• For keeping a healthy life cycle, a person needs to have a balanced and varied diet, has to take exercise, lives in a proper shelter and takes enough sleep.
• In addition, good hygiene tend to reduce the chances of infection.
• A disease is usually due to malfunction of the body.
• A doctor is able to diagnose what a disease is by looking at the symptoms. Symptoms of a disease may be physical, mental or both.
• Our health is affected not only by unbalanced diet but also by diseases, which may be water-borne, airborne or food-borne.
• Some diseases are caused by infection through microorganisms, insects and parasites.
• Infection develops when germs/microbes (i.e., viruses) or some-pathogenic (disease-producing) organisms such as bacteria, fungi, protozoans, helminthes, nematodes, etc., enter human body.
• Personal hygiene and community hygiene help in the prevention and spreading of the causes of diseases.
• Diseases of humans are due to their wrong food habits. Large families, overcrowded houses and poverty also result in poor health.
B. Overlap of Personal and Community Issues for Health
• Our social environment therefore is an important factor in our individual health.
• If there are heaps of garbage and trash is littered here and there, or if there is open drain water lying stagnant around where we live, the possibility of poor health increases.
• Public cleanliness is also important for individual health.
• Differences between Healthy and Disease free
|1. It is a state of complete physical,mental and social well being.
2. It depends upon t he individual as well as physical and social environment.
3. A healthy person will be disease free.
4. Healthy person is energetic and able to perform as per requirement.
|1. It is a state of absence of discomfort or derangement in any part of body.
2. It is related to the individual only.
3. A disease free person can be healthy or unhealthy.
4. Performance of a disease free person depends upon environment and personal attitude.
• Good economic conditions are also required for good health.
• We require to be happy in order to be truly healthy.
• Social equality and harmonious relationships among our population are necessary for the individual health.
• Thus, we see that there is a overlap of personal and community issues for health.
C Essential conditions for good health
• Steps to ensure sanitation, i.e., clean surroundings by providing good sewage and rain water disposal systems and proper garbage disposals.
• Availability of clean drinking water.
• Availability of adequate, nutritious food.
• Social equality and harmony.
5.3 Disease and its causes
• Human health is negatively affected due to physiological malfunctioning, psychological reasons or pathogenic (disease-causing) organisms.
• Sickness, illness, ailment or disease is a disorder that affects an organism.
• Disease can be defined as an impairment (malfunctioning) of the normal state of the living organism that disturbs or modifies the performance of the vital functions and is a response to environmental factors (as malnutrition, industrial hazards or climate), to specific infective agents (as worms, protozoans, fungi, bacteria or viruses), to inherent defects of the organism (as genetic anomalies) or to combination of these factors.
5.4 SOURCES OF DISEASE
Human health is effected by various factors, causes or sources These factors are of following types:
A. Intrinsic or Internal Factors
• The disease causing factors which exist within the human body are called intrinsic factors.
• The important intrinsic factors which affect human health are the following:
(i) Malfunctioning or improper functioning of various body parts such as heart, kidney, liver, etc.;
(ii) Genetic disorder
(iii) Hormonal imbalances
(iv) Malfunctioning of immune system of body, e.g., allergy.
|Disease||Hormone involved||Level of hormone|
|1. Grave’s disease
2. Cretinism (in infants)
4. Addison’s disease
5. Diabetes mellitus
|1. Thyroid hormones
2. – do –
3. – do –
• The diseases caused by intrinsic sources are called organic or metabolic diseases.
• Some of the diseases caused by intrinsic sources or factors are:
1. Cardiac failure (Heart attack)
2. Kidney failure
6. Sickle cell anaemia
12. Allergies (e.g., asthma)
• Classification of some common human diseases
|Type of disease||Causes of disease||Example|
|1. Temporary or permanent damage to body parts.
2. Invasion of the body by other organisms (viruses, bacteria, fungi protozoans, nema todes, insects, etc.)
3. Inadequate diet
4. Defective genes passed on from parents to offspring.
5. Organs and tissues wear away and do not work so well with age.
6. Brain damage or psychological.
7. Social interact ions with family friends and strangers.
|1. Bone fracture, leprosy.
2. Typhoid, diarrhoea, malaria, hepatitis, AIDS, T.B., polio, influenza, cholera.
3. Kwa shiorkor, marasmus, scurvy, rickets, anaemia, goitre,xerophthalmia, beri-beri.
5. Arthritis, poor sight and hearing defects
6. Depression, paranoia.
B. Extrinsic or External Factors
The disease causing (pathogenic) factors which enter the human body from outside are called extrinsic factors. The important extrinsic factors which upset human health are the following:
1. Unbalanced diet or inadequate diet.
2. Disease causing microorganisms such as viruses, bacteria, fungi, protozoans, helminthes, worms, etc.;
3. Environmental pollutants;
4. Tobacco, alcohol and narcotic drugs.
• Some of the important diseases caused by extrinsic factors are:
12. Food poisoning
28. Hepatitis (Jaundice)
30. Amoebic dysentery
31. Giardiasis and
32. Skin disease (Ring worm).
(i) Disease-causing microorganisms or pathogens.
• The pathogens include viruses, bacteria, fungi, protozoans, helminths and worms, etc.
• These pathogens are transferred to the human body through air, contaminated water, food, soil, physical contact, sexual contact and animals.
(ii) Inadequate diet.
• Absence of nutritional diet makes a person unhealthy.
• Unhealthy persons are more susceptible to diseases or infections.
• Deficiency of nutrients in the diet results in number of deficiency diseases in human beings, e.g., night-blindness, beriberi, scurvy, pellagra, rickets, anaemia, goitre, rickets, osteomalacia, bleeding disease, marasmus, kwashiorkor, etc. . Unbalanced diet may cause obesity.
Protein and total
Rickets (in children)
(iii) Environment pollutants. Various environmental pollutants such as gases (e.g., oxides of carbon, oxides of nitrogen and oxides of sulphur), particulate matter, industrial chemicals, heavy metals, (e.g., mercury, lead, cadmium and arsenic), pesticides, etc., also are causes of diseases.
(iv) Tobacco, alcohol and narcotic drugs. Continuous use of tobacco, alcohol and narcotic drugs result in harmful effects leading to chronic diseases.
C. Levels of Immediate Causes
• If few babies are suffering from loose motions, we can say that the immediate cause of infection or disease is a virus. Such immediate causes of diseases are called first-level causes.
• Lack of good nourishment becomes second level cause of the disease the babies suffering from. These babies are not properly fed because they belong to poor house hold.
• Poor public services providing unclean drinking water in the region where such babies are living in society, and poverty becomes the third level cause of the disease.
• Possibly, some genetic difference in these few babies might be the reason that makes them more likely to suffer from loose motions when exposed to unclean water containing such a virus. Genetic difference or poor nourishment are contributory causes of the diseases. Contributory causes themselves do not lead to a disease.
5.5 Types of Diseases
|Infectious or Communicable Diseases||Non-Infecti ous or Non-Communicable Diseases|
|1. They are caused by attack of pathogen.
2. The diseases are brought about by extrinsic or external factors.
3. Infectious diseases can pass from diseased person to healthy person.
4. Transmission of infection occurs through direct contact or some medium (air, water, vectors).
5. Community hygiene ca n reduce the incidence of infectious diseases.
Exampl es : Cold, Cholera,
|1. They are caused by factors other than living pathogen.
2. The diseases are mostly brought by intrinsic or internal factors.
3. Non-infectious diseases cannot pass from one person to another.
4. Transmission is absent. However hereditary diseases are transmitted from parent to offspring.
5. Community hygiene is ineffective in reducing the incidence of non infectious diseases.
(i) Acute diseases: Diseases such as influenza are described as acute, because their effects come on suddenly and affect the body quickly, e.g., common cold.
(ii) Chronic diseases: Other diseases are more long-term, with the symptoms lasting for months or years. Such diseases are called chronic diseases, e.g., elephantiasis, tuberculosis.
|Acute disease||Chronic disease|
|1. These last for only short period of time.
2. These do not cause long term bad effects on human health.
3. Examples include cold, cough, typhoid, cholera, etc.
|1. These last for a long time, even as much as a life time.
2. These cause drastic long term effects on human health.
3. Examples include elephantiasis, cardiovascular diseases, tuberculosis, diabetes, arthritis, cancer, etc.
(iii) Congenital diseases.
• The diseases that are present since birth are called Congenital disease.
• These are caused due to genetic. abnormality or due to metabolic disorders or malfunctioning of any organ.
• They are permanent, generally not easily curable and may be inherited to the children.
(iv) Acquired diseases.
• Acquired diseases can be broadly classified into two types:
(a) communicable or infectious diseases;
(b) non-communicable or non-infectious diseases.
(a) Infectious diseases
• The diseases that are communicated from diseased person to healthy person they are known as infectious diseases.
• These diseases are caused by some biological agents or pathogens such as viruses, bacteria, protozoans, helminthes, nematodes and fungi.
• Infectious diseases can rapidly spread from one person to another by various means such as by physical contact, water, air, food, and insects (vectors).
(b) Non-infectious diseases
• The noninfectious diseases are restricted only to those persons who are suffering from them.
• These are not spread from infected person to healthy person.
• Non-infectious diseases may be caused from:
1. The lack of certain essential substances in our diet, e.g., proteins, vitamins, minerals (deficiency diseases);
2. General wearing out or degeneration of tissues as in old age (degenerative diseases);
3. Uncontrolled growth of tissues in any part of body (cancer);
4. Defects in the metabolic reactions (metabolic disorders); and
5. injury and damage to any part of the body by accidents.
5.6 Infectious Diseases
I. Infection Agents
• Organisms that can cause disease are called infection agents.
• It includes viruses, some are bacteria, some are fungi and some are unicellular animals, the protozoans. Some diseases are also caused by multicellular organisms such as different kinds of worms.
• Common examples of diseases caused by viruses are the common cold, influenza, dengue, fever and AIDS.
• Diseases like typhoid fever, cholera, tuberculosis and anthrax are caused by bacteria.
• Many common skin infections are caused by different kinds of fungi.
• Protozoans cause many familiar diseases such as malaria and kala-azar.
• Worms tend to cause a variety of intestinal infections and elephantiasis.
• All viruses live inside host cells, whereas bacteria very rarely do.
• Viruses, bacteria and fungi multiply very quickly, but worms multiply very slowly in comparison.
• Antibiotics commonly block biochemical pathways important for bacteria
• Therefore, most broad spectrum antibiotics work against many species of bacteria, rather than simply working against one.
• Viruses do not use these pathways at all, that is why antibiotics do not work against viral infection. For example, if we have a common cold, taking of antibiotics does not reduce the severity or duration of disease. Instead our body secrete an antiviral protein, called interferon to combat the virus of cold.
• If we get a bacterial infection along with the viral cold, then taking antibiotics will help. In that case, too, the antibiotic will work against the bacterial part of infection, not the viral infection.
Common human disease caused by infectious agents.
(a) Common cold
(c) Dengue fever
(e) Hepatitis –B
(Acquire Immuno Deficiency Syndrome)
(g) Chicken pox
(= Severe Acute Respiratory Syndrome)
(k) Small pox
(l) Swine flu (HINI)
(a) Typhoid fever
(e) Acne (Fig)
(g) Food poisoning
Athlete’s foot, Ringworm and many other skin infections
(c) Amoebic dysentery
(d) Sleeping sickness
(a) Intestinal worm infection (b) Elephantiasis
II. Means of Spread of Infectious Diseases
Infectious diseases spread from one infected person to other normal persons by a variety of method.
1. Air-borne diseases
• These diseases are caused due microbes that are spread through air
• This occurs through the little droplets thrown out by an infected person who sneezes or coughs.
• Someone standing close by can breathe in these droplets, and the microbes get chance to start a new infection
• Examples: common cold, pneumonia and tuberculosis.
2. Water-borne diseases,
• The diseases that spread through water are called Water – borne diseases.
• This occurs if the stool from someone suffering from an infectious gut disease, such as cholera or amoebiasis, gets mixed with the drinking water used by people living nearby.
• The cholera-infested bacteria will enter new hosts through the water they drink and cause disease in them.
3. Sexually-transmitted diseases.
• These diseases are caused by the pathogens that are transmitted by sexual contact from one partner to the other.
• Sexually transmitted diseases are not spread by casual physical contact.
• Casual physical contacts include handshakes, hugs, sports such as wrestling or by any of the other ways in which we touch each other socially.
• Examples: Syphilis and AIDS
4. Fomite borne diseases.
• Articles coming in contact with patients are a source of infection.
• Examples: Door handles, taps, garments, currency, utensils, crockery, etc.
5. Spread of disease through vectors.
• Vectors are carrier of a disease or infection.
• Many animals which live with us may carry diseases.
• Thus, these animals act as intermediaries or vectors.
• Mosquitoes (Anopheles) are vector of a disease, called malaria.
• In many species of mosquitoes, the females need highly nutritious food in the form of blood in order to be able to lay mature eggs.
• They feed on many warm-blooded animals including us.
Common Human Diseases transmitted by insects
|Insect vector||Diseases transmitted|
(i) Anopheles (Female)
|Malaria Fila riasis
Yellow fewer, Dengue, Filariasis
(i) House fly
(iii) Tsetse fly
|Typhoid, Diarrhoea, Dysentery, Cholera , Tuberculosis, Conjunctivitis (an eye disease) Kala-azar, oriental sore Sleeping sickness|
|3. Louse||Epidemic t yphus|
|4. Ratflea||Bubonic plague|
Thus, m eans of transmission (spread) of infectious diseases may be of two main types:
A. Direct transmission:
1. Contact with infected person (e.g., AIDS).
2. Contact with soil (e.g., Tetanus).
3. Animal bites (e.g., Rabies).
4. Transplacental (e.g., AIDS, German measles and Syphilis).
B. Indirect transmission:
1. Through vectors (e.g., Malaria).
2. Through contaminated food and water (e.g., Amoebiasis, Hepatitis, etc.).
3. Air transmitted disease (e.g., common cold, T.B., pneumonia).
4. Formite borne.
III. Symptoms of Disease
(i) Point of entry and place of infection of microbe inside human body.
• If the microbes enter from the air via the nose, they are likely to go to the lungs.
• This happens in case of bacteria which cause tuberculosis (T.B.) of lungs.
• If the microbes enter through the mouth, they can stay in the lining of the gut as do typhoid causing bacteria.
• These microbes, can also go to the liver, like the viruses that cause jaundice (Hepatitis B). However, this pattern is not followed by all microbes.
• Infection of HIV takes place via the sexual organs but it tends to spread to lymph nodes all over the body.
• Malaria-causing protozoan enters through a mosquito bite but it first goes to liver cells and then to red blood corpuscles (RBCs).
• The virus causing Japanese encephalitis, or brain fever, enter through a mosquito bite. But it goes to infect the brain.
(ii) Symptoms and signs.
• Symptoms are evidences of the presence of diseases.
• They are in the form of structural and functional changes in the body or body parts.
• They indicate that there is something wrong in the body.
• On the basis of symptoms of a disease physicians search for definite clues or signs of the disease.
• For this, they use certain instruments and even go for laboratory tests (e.g., tests in pathologist’s labs) to pinpoint the cause of the disease.
|1. They indicate the presence of disease.
2. Symptoms are collective
indication of a number of
diseases of a particular parts or organs .
|1. They provide information about the presence of particular disease.
2. They are distinct for different diseases.
• Most of these common effects of a disease depend on the fact that the immune system of the patient’s body becomes activated in response to an infection.
• An active immune system recruits many cells to the affected tissue to destroy the disease-causing (i.e., pathogenic) microbes. Such a recruitment process is called inflammation.
• Local effects of an inflammation is shown in the form of swelling and pain. General effect of an inflammation is depicted in the form of fever.
• Infection of HIV is found to have multiple dimensional effect. In case of HIV infection, the virus goes to immune system and ultimately damages its function.
• Many symptoms of HIV-AIDS infection are due to the fact that patients body can no longer fight off many minor infections that he faces every day.
• Minor gut infection can produce major diarrhoea with blood loss. Thus, it is these secondary infections that kill people suffering from the HIV-AIDS.
IV. Principle of Treatment
• There are two ways to treat an infectious disease. One is to reduce the effects of the disease and the other is to kill the cause of the disease. For the first requirement, we can provide treatment that will reduce the symptoms. The symptoms are usually because of inflammation.
• Pathogenic microbes can be killed by two common methods. One way is to use medicines that kill microbes and the other way to affect antibiotics.
1. Antibiotics are chemicals produced by mirco-organisms (mainly bacteria and fungi) which at low concentrations have the ability to inhibit or destroy pathogens. The first antibiotic was penicillin, which was developed in the 1940’s in response to the need to treat soldiers in the Second World War. There are now about 50 to 100 commercially available antibiotics.
2. Antibiotics are characterised by their range of effectiveness and their mode of action against the pathogens:
(i) Broad spectrum antibiotics kill a wide range of bacteria.
(ii) Narrow spectrum antibiotics are effective against only a few types of bacteria.
To kill a specific pathogen, you have to use a narrow spectrum antibiotics which is specific for the disease.
3. All antibiotics must have selective toxicity. This means they should kill or inhibit the growth of bacteria or fungi, but cause little or no damage to the host.
Antibiotics tend to interfere with the growth or metabolism of the pathogen in a variety of ways.
(a)Penicillin inhibits the enzymes that are involved in the formation of the bacterial cell wall. Bacteria with weak cell walls die due to leakage of the cell contents.
(b) Streptomycin binds to bacterial ribosomes, so preventing protein synthesis, including synthesis of the enzymes. The lack of protein affects bacteria metabolism and results in its death. Fortunately, bacterial ribosomes are different from human ones. So streptomycin does not interfere with the synthesis of proteins in the cells of the patient
(= host) taking the drug.
(c) Tetracyclines also work by interfering with bacterial ribosomes.
(d) Polymixines damage bacterial cell (plasma) membranes even in resting cells (spores). Penicillin.
Antibiotics tend to be used against bacterial infections more than the fungal infections. This is because fungal cells work in a similar manner to human cells. As a result, many antifungal agents are highly toxic to humans.
V. Principles of Prevention of Disease
Following three limitations are normally confronted while treating an infectious disease:
1. Once someone has a disease, its body functions are damaged and may never recover completely.
2. Treatment of a disease takes time. This means that if someone suffering from a disease, he is like to bedridden for some time, even if we give him proper treatment.
3. The person suffering from an infectious disease can serve as the source from where the infection may spread to other people.
Visualizing these difficulties, prevention of diseases is far better than their cure.
There are following two ways of prevention of diseases, one is general another is specific one.
1. General ways of prevention of infectious diseases.
Public hygiene is one basic key to the prevention of infectious diseases. Thus, in this method of prevention of diseases, following practices are adopted:
(i) For air-borne microbes, we can prevent exposure by providing living conditions that are not overcrowded.
(ii) For water-borne microbes, we can prevent exposure by providing safe drinking water.
(iii) For vector-borne infections, we can provide clean environments. Such a clean environment, for example, would not allow mosquito breeding.
2. Specific ways of prevention of infectious diseases.
Immune system and immunisation: Children escape infection of cold and cough because the immune system of their bodies is normally fighting off the microbes (pathogenic microorganisms). These cells go into action each time infecting microbes enter the body. If these cells are successful.
• The immune cells (WBCs) manage to kill off the infection long before it assumes major proportions.
• Becoming exposed to infection or be infected with an infectious microbe does not necessarily mean developing noticeable disease.
• One way of looking at severe infectious disease is that it represents failure of the immune system. The functioning of the immune system, like any other system in the body, will not be good enough if proper and sufficient nourishment and food is not available.
• Therefore, second basic principle of prevention of infectious disease is the availability of proper and sufficient food for everyone.
5.8 Immune Response
• An immune response is the way in which the body responds to invasion by a specific pathogen or antigen.
• This response involves the production of cells (lymphocytes) and chemicals (antibodies) designed to defend the body against the pathogen.
• Antigens are substances that can produce an immune response. Antigens trigger the production of antibodies (glycoproteins or immunoglobulins) by the immune system. Each type of antibodies is specific to a particular antigen and reacts with it to make it harmless.
• Cell-mediated immunity.
• Cell-mediated immunity involves T-lymphocytes and macrophages.
• Macrophages are phagocytic, i.e., they engulf and digest all types of foreign cells and viruses.
• Lymphocytes are white blood cells that recognise and react with antigens.
• They are of two types: T- lymphocytes and B-lymphocytes.
• T-lymphocytes become activated in thymus gland and may be of four types:
(i) Cytotoxic T-cells or killer cells
(ii) Helper T-cells
(iii) Memory T-cells
(iv) Suppressor T-cells.
• Antibody-mediated immunity.
This involves the production of B-lymphocytes which are activated by antigens attached to the macrophage membrane.
B-lymphocytes are of three types:
(i) Plasma B-cells: They secrete antibodies into the blood circulation.
(ii) Memory B-cells: They do not produce antibodies, but become programmed to remember a specific antigen and respond very rapidly to any subsequent infection.
(iii) Dividing B-cells: They produce more B-lymphocyte cells.
• Reaction between antibody and antigen.
It involves following three steps
1. The antibody becomes attached to the antigen at the antigen-binding site like a key in a lock.
2. This causes the antibody to change from a T-shape to a Y-shape.
3. Antibody cause the antigen to stick together, a process called agglutination which stimulates phagocytosis by neutrophils.
• Active immunity.
(i) The pathogen invades the body, which responds by stimulating the production of T-lymphocytes and B-lymphocytes and, both of which are involved in the immune response.
(ii) Memory cells are formed which provide long-term immunity to the antigen.
(iii) This type of immunity if termed as active immunity because the lymphocytes are activated by antigens present on the surface of the pathogen. Since this activation takes place during the natural course of an infection, this is called natural active immunity.
(iv) But the immune response can also be triggered artificially. This involves the injection of antigens into the body. We call this artificial active immunity, although it is more commonly referred to as vaccination.
2. Passive immunity.
It occurs when an individual becomes temporarily immune to an antigen by receiving ready-made antibodies from someone else. Passive immunity is also of two types:
(a) Natural passive immunity.
• It occurs when preformed antibodies pass naturally from mother to baby across the placenta and in breast milk.
• Immunity is only temporary since the baby’s body does not ‘know’ how to make more antibodies. But it provides the baby with protection until it develops its own immune system.
(b) Artificial passive immunity.
• It occurs when pre-formed antibodies extracted from one individual are injected into another as serum.
• This sort of immunity can provide a “quick-fix” and is given to people who have been bitten by poisonous snakes or rabid dog.
Vaccination is the administration of antigenic material (a vaccine) to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens.
Many such vaccines have infectious diseases, and provide a disease-specific means of prevention. These are vaccines against
3. Whooping cough ;
4. Measles ;
10. Mumps; etc. etc.
All these vaccines form the public health programme of childhood immunisation for preventing infectious diseases.
1. Derivation of term vaccination
Three centuries ago, an English physician Edward Jenner (1749-1823) realised that milkmaids had cowpox did not catch smallpox even during epidemics. He tried deliberately giving cowpox to people, and found that they were now resistant to the smallpox virus. This was because the smallpox virus is closely related to the cowpox virus. ‘Cow’ is ‘vacca’ in Latin, and a cowpox is ‘vaccinia’. From these roots, the word vaccination has come into our
2. How are vaccines made?
A vaccine is an antigen that is injected or swallowed. It causes the development of active immunity in the patient. The small quantities of antigen introduced into the person’s body stimulate the production of antibodies as if infected by the disease. This type of immunity is long term since the body is able to produce memory cells in the natural pathway.
Antigens are treated before being introduced to the body of the person, in order to make them relatively harmless. Most vaccines are made in one of the following ways:
(i) Killed virulent organisms
• In this case, the bacteria is killed by heat or use by chemicals, which denature its enzymes.
• So the dead pathogen will not cause the disease, but it will possess antigenic sites on its surface that will be recognised by T- and B- lymphocytes, and result in the production of antibodies in the recipient.
• There is no chance of the pathogen replicating and causing infection.
• Example: Vaccine for whooping cough-bacteria.
(ii) Live non-virulent strains
• Vaccines made in this way are often called attenuated (= weaken) vaccines.
• In such vaccines, the pathogen is deliberately weakened to ensure that it does not cause severe infection.
• Examples: Rubella, BCG vaccine used against tuberculosis and the Sabin vaccine used against poliomyelitis, which is taken orally.
(iii) Modified toxins
• In this type of vaccine, the toxoids (toxic substances) produced by the bacteria are made harmless.
• Toxoids are used to stimulate antibody production, but there is no risk of infection by the pathogen.
• Example: Vaccines used against diphtheria and tetanus.
(iv) Isolated antigen
• Sometime important antigens are separated from the microorganism, in this case by breaking up the pathogen’s structure and obtaining glycoproteins.
• The “flu vaccine” contains a mixture of antigens from various strains of influenza virus, in an attempt to combat the great variations that exists.
• This antigenic variation occurs in microorganisms that have a high mutation rate.
• Example: Influenza.
(v) Genetically engineered antigens
• In this most modern type of vaccine, restriction endonuclease enzymes are used to extract from the pathogen the genes that code for a particular antigen.
• Such genes are inserted in a harmless plasmid vector using a ligase enzyme.
• The bacterial cells then replicate to produce large amounts of antigen.
|Vaccine||Disease||Age group||Safety level|
|1. DPT-Hib||Diphtheria (Corynebacterium
diphtheriae), Tetanus, Pertussis (whooping cough) and Haemophilus influenzae type B.
|To all infants of
|90% – 99%|
|2. Hepatitis-B||Hepatitis (serum hepatitis)||All infant, children and even adult.||Not yet confirmed.|
|3. Polio||Poliomyelitis||All infants up to 5 years of age; minimum of three doses at one month interval||Nearly 100%|
|4. BCG||Tuberculosis||All children between 10 to 14 years.||Nearly 70%|
DISEASES CAUSED DUE TO INFECTION BY MICROORGANISMS
(caused by protozoan)
• Malaria is a fatal disease of human beings.
• There are about 300 million people around the world which are infected with malaria every year.
• More than 2 millions persons die annually due to malaria disease.
• Malaria is caused by a protozoan parasite Plasmodium.
• This disease spreads through the bite of an insect vector—the female Anopheles mosquito which feeds on human blood.
• Main symptoms of malaria include headache, nausea, muscular pain and high fever.
• Each malarial attack is of 6 to 10 hours duration and consists of the three stages:
1. Cold stage, i.e., feeling very cold and shivering;
2. Hot stage, i.e., high fever, faster respiration and heart beat; and
3. Sweating stage, i.e., due to profuse sweating temperature goes down to normal.
• Even after the patient is cured of malaria, the patient feels weak and becomes anaemic.
• Malaria may also secondarily cause enlargement of spleen and liver.
• Presence of malarial parasite can be checked by blood test.
SOME FACTS ABOUT MALARIA
• The name Malaria was proposed by Macculoch (1827).
• C.L.A. Laveran (1880), a French physician, discovered the Malarial parasite-Plasmodium in the blood of malaria patient. He received Nobel Prize for this discovery in 1907.
• Sir Ronald Ross (1897), a British physician, confirmed that malaria is caused by malarial parasite and mosquito is the vector. He received Nobel Prize for this discovery in 1902.
• Recently Allan Porter and his coworkers produced a genetically engineered aquatic bacteria at National Institute of Singapore. When mosquito larvae feed on these bacteria, they are killed by the toxic substance produced by these bacteria. This can prove to be an effective biological control method.
• Central Drug Research Institute (CDRI), Lucknow has developed an anti-cerebral malarial drug called-Arteether. This drug is extracted from a herbaceous plant Artemisia annua belonging to family Asteraceae.
• Malaria is an infectious disease. It spreads from infected person to healthy person (hosts) by the bite of female Anopheles mosquitoes (vectors).
• The only way to prevent malaria is to prevent mosquitoes from biting.
We can protect us from the bite of mosquitoes by following methods:
1. Wire-gauze should be used on doors and windows of our houses to prevent entry of mosquitoes.
2. Insect-repellents (e.g., Odomas) should be used to prevent mosquito-bite.
3. We should sleep under mosquito net.
4. Mosquito larvae should be killed by sprinkling kerosene oil on large-sized water bodies. Some larvivorous fishes such as Gambusia, minnows or trouts or birds (e.g., ducks) can be introduced in water bodies. These animals feed on mosquito larvae and hence larvae get killed and population of mosquitoes is checked. This is called biological control of mosquito.
5. Adult mosquitoes can be killed by spraying insecticides (e.g., BHC, malathion) on the walls of human dwellings. Insecticides are chemical poisons (toxicants), hence, regulation of mosquito population by them is called chemical control. Now another insecticide DDT is not used in the chemical control of mosquitoes, since, it persists in the environment for much longer time and cause toxicity by accumulation in the body of fishes, birds and humans through food chains.
6. The breeding grounds should be destroyed. Thus, the ditches, puddles or swamps around human dwellings should be drained or filled. We should not allow the collection of water in any uncovered container such as water tank, pot, cooler, flower pot, discarded tyres (tires) etc.
• A drug named quinine, which is extracted from the bark of Cinchona tree, is used to treat a person suffering from malaria.
• This drug kills most of the stages of malarial parasite.
• There are certain other drugs (medicines) which should be taken on the advice of doctor.
• Influenza is commonly called flu.
• It is an international disease and is caused by influenza virus (Myxovirus influenza).
• There exist three types of influenza viruses- A, B and C.
• A and B types of influenza viruses are important because these are responsible for epidemics of disease throughout the world.
• The inhaled virus attacks the epithelial cells in the mucous membrane of nose, throat and upper respiratory tract.
• Influenza is spread mainly from person to person contact and by droplet infection via sneezing, coughing or talking.
• The common symptoms of influenza disease are sudden onset of chills, discharge from the nose, sneezing, fever, headache, muscular pains, coughing, inflammation of respiratory mucosa and general weakness. Fever lasts three days in adults.
• We should try to keep away from flu patients.
• We should try to keep away from flu patients.
• There is no effective control for influenza. However, vaccines are used for the control of infection and antiviral drugs are used for cure.
• Amantadine and Rimantidine are recommended for the treatment of influenza. Rest speeds up the recovery.
5.12 Jaundice or hepatitis
• Jaundice or hepatitis is the disease of liver.
• Since liver is a very important organ in body, so its inflammation due to jaundice affects digestion adversely.
• Jaundice is caused by viral infection.
• The types are: Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, Hepatitis E or Hepatitis G.
• Except for type B which is a DNA virus, all the other are RNA viruses.
• Hepatitis is spread mostly by food and water contaminated with hepatitis virus.
(i) Hepatitis A
• Hepatitis A or infectious hepatitis by a RNA-containing virus is an acute infectious disease of liver which affects mainly children and young adults.
• Transmission of hepatitis A virus (HAV) takes place by faecal-oral route, i.e., infection of HAV takes place by ingestion of contaminated water, food or milk.
1. High temperature, headache, fatigue, general weakness, and joint pains.
2. Loss of appetite (called anorexia) with a feeling of nausea and vomiting.
3. Appearance of irritating rashes on body.
4. Dark yellow urine.
5. Light coloured stool after 3 to 10 days of infection.
For avoiding infection of hepatitis A following preventive measures should be taken.
1. Use chlorinated, boiled and ozonised water.
2. Proper cleaning of hands after handling bed and vessels of the patient.
3. Hepatitis-A vaccine should be taken to prevent the disease.
1. Application of interferon injection on the advice of the doctor will control the disease.
2. For an early cure, it is essential that patient of jaundice should take adequate rest.
3. Patient of jaundice should take high calorie diet such as juice of sugarcane, radish with gur (jaggery).
4. Consumption of protein and fat should be limited.
(ii) Hepatitis B
• Hepatitis B is also known as serum hepatitis or transfusion hepatitis (by a double-stranded DNA virus).
• This is most dangerous and widespread type of viral hepatitis. (Hepatitis B is regarded more dangerous than AIDS).
• It occurs due to infection of Hepatitis B virus (HBV).
• HBV is a blood borne DNA virus.
• The infection of HBV is transmitted by infected blood, inoculation (Inoculation means the introduction of a vaccine into a living being to give immunity), from mothers to their babies and by sexual route (through the semen, saliva, etc.).
• Main symptoms of Hepatitis B include progressive liver disease, chronic active hepatitis and hepatocellular carcinoma (i.e., malignant cancer of liver cells).
• Infection of HBV can be prevented by avoiding risky practices such as free or promiscuous sex (Promiscuous means sexual contact which is not restricted to one sexual partner), injectable drug abuse and direct or indirect contact with blood, semen and other body fluids of patients of Hepatitis B.
• Hepatitis B vaccine should be taken to prevent disease.
5.13 Rabies (Hydrophobia)
• The bite of a rabid dog (mad dog) and some other rabid mammals such as monkeys, cats or rabbits may cause rabies, which is fatal viral disease caused by a rabies virus or lyssavirus which is present in the saliva of the infected animals.
• The viruses are injected into human blood by the bite of the rabid animal.
• Disease is not expressed after infection even up to 1 to 3 months.
• The long period of incubation makes it possible for a rabies vaccination, after a bite, to develop immunity and prevent the appearance of disease.
• Rabies is characterised by severe headache, high fever, painful contraction of muscles of throat and chest (due to which there is difficulty in swallowing).
• The patient feels restless, does excessive salivation, has a chocking feeling and finds difficulty in taking in even liquid food. Since patient develops fear of water, the disease is also called hydrophobia.
• Cleaning the wound with carbolic soap and clear water immediately after the dog bite is an important preventive measure.
• Any antiseptic medicine (e.g., Savlon, Dettol) should be applied to the wound caused by dog bite. A doctor should be immediately consulted for application of anti-rabies vaccine to the patient.
• Compulsory immunization of stray dogs and cats should be done. Pet dogs should be vaccinated with anti-rabies vaccine.
• A rabid animal shows excessive salivation and tries to seek isolation after bite. Such mad animals should be killed.
• Rabies can be treated with Pasteur’s treatment (discovered by Louis Pasteur), in which a course of 14 vaccines was given.
• Currently 5 anti-rabies vaccines are prescribed at an interval of 0-3-7-14-30 day of dog bite.
• AIDS stands for Acquired Immuno Deficiency Syndrome.
• It is a fatal disease.
• The disease of AIDS is caused by retrovirus (a RNA virus) known as Human Immunodeficiency Virus (HIV) AIDS virus attacks white blood cells (WBCs) or lymphocytes (T4 helper cells) of human beings and weakens the human body’s immunity or self- defence mechanism.
• Since AIDS virus reduces the natural immunity of the human body, therefore, the patients suffering from AIDS becomes prone to many other infections or diseases.
• The patients suffering from AIDS die from other infections (called secondary infections).
• Death occurs because the patient’s body cannot resist the attack of pathogens of secondary infections since patient’s natural defence mechanism has been destroyed by AIDS virus.
Transmission. AIDS disease spreads among human beings by the following ways
• The AIDS disease usually spreads through unprotected (i.e., without the use of condom; condom is a membranous penile sheath of rubber having an anti-venereal or contraceptive function) sexual contact with an infected person carrying AIDS virus. Thus, AIDS is a sexually transmitted viral disease.
• The AIDS disease also spreads through the transfusion of blood contaminated with AIDS virus.
• The AIDS disease also spreads through the use of infected needles for injections (i.e., sharing of infected injection needles which have not been sterilised).
• An AIDS infected mother can transmit the virus to her child during pregnancy or during birth (i.e., by mother’s blood). This is called vertical transmission.
• AIDS was first detected in USA in 1981 and in India, first confirmed evidence of AIDS infection came in April 1986 from Tamil Nadu.
• The AIDS disease has spread in epidemic form in Africa and western countries. This is because of the undesirable sexual practices, polygamy and polyandry.
• Recently alarmingly increasing cases of AIDS have been reported from different parts of India.
• Swollen lymph nodes; regular fever; sweating at night and weight loss.
• AIDS virus causes severe damage to brain and may lead to loss of memory, ability to speak and of clear thinking.
Prevention and control.
• So far no medicine or vaccine has been developed to cure AIDS, so, once a person gets AIDS, he is sure to die in a short span of time. The following steps may help in controlling infection of this dreaded disease:
1. People should be educated about AIDS transmission.
2. Disposable syringes and needles should be used for injection.
3. Sexual contact with unknown people should be avoided.
4. High risk groups should refrain from donating blood.
5. Sterilised needles may be provided to drug addicts.
6. Before receiving blood for transfusion, one should ensure that it has been screened for HIV.
7. The common razor at the barber’s shop should not be used.
STRUCTURE OF HIV VIRUS
• Poliomyelitis or polio is a disease of the nervous system caused by one of the smallest known virus, called polio virus.
• The virus enters the body through the food and water and reaches the intestine and from there it enters the CNS or central nervous system (brain and spinal cord) via blood stream and lymphatic systems.
• In CNS, the virus destroys the motor nerve cells of spinal cord that are responsible for the muscular control. Therefore, the muscles of polio-infected person become unable to carry out the normal functions.
• Polio is a kind of paralysis and it affects more to the legs.
• Children between the age of 6 months and 3 years are most prone to polio infection.
• Polio is transmitted among children by the faeco-oral route and through the direct contact, dirty hands, contaminated food or milk and flies.
• Faeco-oral route of infection of a disease includes transmission of an infection via food/water that is contaminated by stool of the patient.
• The early symptoms of the polio disease are sore throat and headache.
• If the infection persists, the patient suffers from fever, vomiting, muscular pain, stiffness in the neck, tingling sensation in limbs and ultimately occurrence of paralysis.
• Complete rest and physiotherapy is helpful in the beginning of attack of polio virus.
• Exercising of legs is done to reduce the paralytic effect.
• Maintenance of hygiene by proper sanitary disposal of waste is an essential step for prevention of polio.
• Oral Polio Vaccine (OPV) is given orally to the children as per National Immunisation Schedule in our country.
• OPV is a live attenuated (diluted or weakened) viral strain taken by mouth and colonises the gut and induces immunity.
Pulse polio immunisation programme (PPIP)
• Pulse polio immunisation programme forms the largest single day public health project.
• Pulse means a dose of a substance (here polio vaccine) especially when applied over a short period of time.
• It was conducted for the first time in December 1995, in an attempt to eradicate polio from our country.
• This programme uses oral polio vaccine or OPV.
• As per the National Immunisation Schedule (NIS), a dose of 3 drops (0.5 ml) is given orally to the child, i.e., one dose each at 1.5, 2.5 and 3.5 month’s age.
• Finally, a booster dose is given at the age of 1.5 years.
• The vaccine consists of milder forms of polio viral particles.
• After oral administration, virus particles in the vaccine begin to live in the intestine of the human body and multiply.
• It leads to production of protective molecules (antibodies) in the intestine and the blood.
• The prefixed days, on which pulse polio immunisation is to be carried out throughout the country, are called National Immunisation Days (NIDS).
• The pulse polio immunization campaign seems to be a successful programme.
• Since the incidence of poliomyelitis in India has decreased dramatically, India recorded 4,791 cases of polio in 1994; 2,489 in 1997; 1600 in 2002; 225 in 2003 and 135 in 2004 (Renu Verma 2011).
Aims of Pulse Polio Immunisation Programme (PPIP)
(i) To immunise those children who are not earlier immunised or are partially immunised.
(ii) To replace the disease-causing wild virus by harmless vaccine virus in the environment.
5.16 Tuberculosis (T.B.)
• Tuberculosis was first discovered by German scientist Robert Koch in 1882. He was awarded Nobel Prize for this discovery in 1905.
• T.B. is an infectious disease which is communicated from one person to another directly or indirectly.
• Tuberculosis is also contracted from animals (e.g., cattle).
• Tuberculosis is caused by a bacterium-called Mycobacterium tuberculosis. The bacterium releases a toxin called tuberculin.
• T.B. can affect all parts of body such as lungs, lymph glands, bones, intestine, etc.
• In human beings, the infection of T.B. spreads by inhaling infected droplets released through coughing, sneezing, talking and spitting by the patient.
• The incubation period of T.B. includes a few weeks to a few years.
• The patient of tuberculosis feels sick and weak.
• There is a loss of appetite and weight.
• Typical fever pattern and night sweats are also common.
• The symptoms of T.B. vary depending on the site of the infection (disease) in the body.
There are following two specific sites of tuberculosis infection.
1. Lung or pulmonary T.B.
• The person suffered with pulmonary T.B. has continuous fever, persistent cough and produces blood stained sputum.
• There is loss of weight and weakness.
• The chest-pain and breathlessness are common features of patients of lung T.B.
• When the tuberculosis bacteria get into the lungs, they set up a local inflammation and produce an abscess.
• This usually heals up and leaves a small patch of scar tissue which shows up in X-rays photographs
• In advanced stages of tuberculosis large areas of the lungs are destroyed.
2. Lymph gland T.B.
Symptoms of T.B. of lymph gland include swelling and tenderness of lymph glands, often in the leg which may discharge secretion through the skin.
• Vigorous public health measures are the best method of prevention. Other preventive measures include isolation and proper rehabilitation of the patient. Avoidance of over-crowding, provision of good ventilation and better nutrition help to reduce the incidence of the disease.
• Immunisation with BCG or Bacillus-Calmette-Guerin vaccination prevents tuberculosis. BCG vaccine contains weakened Tuberculosis bacillus and it is injected into the skin of a person to give immunity for 3 to 5 years.
• The tuberculosis can be cured by the following six essential drugs.
1. Rifampicin (RMP);
5. Ethambutol; and
Thus, T.B. can be controlled by the use of antitubercular therapy (ATT)
• The diagnosis of tuberculosis is made on the basis of positive tuberculin test, chest X-rays, positive sputum, gastric analysis, etc
• Tuberculosis is not a hereditary disease.
• The modern treatment of tuberculosis is based on the six main factors: namely rest, diet, drugs, surgery, rehabilitation and health education.
• BCG vaccine is injected into the skin for providing considerable protection against the tuberculosis disease.
• Cholera is an acute infectious, fatal disease and is more common during overcrowded fairs, festivals and after floods.
• Sometimes cholera occurs in epidemic form (epidemic means wide and destructive in occurrence) spread over large population.
• Cholera is caused by the bacterium Vibrio cholerae.
• It is transmitted by flies, contaminated water and food.
• When sanitation is poor, it spreads rapidly.
• The incubation period of cholera is generally from a few hours to two or three days.
• When the bacteria of cholera are ingested, they multiply in the small intestine and invade its epithelial cells.
• When the bacteria die, they release toxins which irritate the intestinal lining and lead to the secretion of large amounts of water and salts.
• Watery diarrhoea (i.e., rice-water like stools) which is generally painless.
• Effortless vomiting without nausea.
• Loss of several litres of fluid from patient’s body takes place within hours. This results in dehydration, muscle cramps and weight loss.
• Great loss of mineral salts and body fluid leads to kidney failure.
• Eyes of patient become shrunken.
• Persons should be immunised by standard cholera vaccine. One dose of immunisation lasts for about six months.
• In cholera-prone areas, boiled water and cooked food should be taken.
• Careful personal hygiene and good sanitation in the community are the only certain protection against cholera.
• For preventing dehydration therapy with Oral Rehydration Solution(ORS) should be done immediately. ORS solution contains 3.5 g sodium chloride, 2.5 g sodium bicarbonate, 1.5 g potassium chloride, 20 g glucose, 40 g sucrose in one litre water. Taking small sips of ORS solution at intervals prevents dehydration of the patient.
• Immediate medical advice should be taken.
Antibiotics such as tetracycline kill the bacteria of cholera.
• Typhoid is most common infectious or communicable disease of India.
• Typhoid fever is common in humans of the 1 to 15 years age group.
• Typhoid is caused by a rod-shaped and motile bacterium, called Salmonella typhi which is commonly found in the intestine of human beings. Human infection is direct.
• Infection takes place by the oral route through ingestion of food, milk or water contaminated by contact with faecal matter of the typhoid patient.
• The bacteria spread through faecal matter by house flies.
• The symptoms of typhoid often appear 10 to 14 days after the infection.
• Headache and typhoid fever which rises maximum in the afternoon. The temperature increases each day in the first week.
• High fever in the second week. Fever gradually declines during 3rd and 4th day.
• In nutshell symptoms of typhoid include continuous fever often with delirium (disorder of the mind), slow pulse, tender and distended abdomen, diarrhoea with water-green stools and eruption of rosy spots (rash) on the body of the patient.
• Proper sanitation and disposal of faecal matter prevents infection.
• TAB-vaccination provides immunity for 3 years. (TAB vaccine contains killed typhoid bacilli and paratyphoid organisms-Salmonella paratyphiA and B).
• Typhoral oral vaccine also prevents typhoid.
There are standard drugs (e.g., Chloromycetin) which cure typhoid.
• Diarrhoeal disease form a group of intestinal infections, including food poisoning. The main symptom of all such infections is diarrhoea.
• Diarrhoea is an abnormally frequent discharge of semisolid or fluid faeces.
• Other symptoms of diarrhoeal disease include decreased appetite, nausea, vomiting, borborygmus (i.e., gurgling noise produced by movement of gas in the alimentary canal) and abdominal cramps.
• There may be blood and mucus in the stools.
• Persistent vomiting and loose stools cause dehydration and shock. Blood pressure may fall, pulse rate increases and temperature rise.
• Diarrhoea is one of the major causes of infant mortality in India.
• Infection of diarrhoea spread through contaminated food, water, drinks, hands, clothes, bed sheets and utensils.
• The causative agents of diarrhoea are mainly bacteria such as Escherichia coli, Clostridium botulinum, Shigella dysentiriae, Campylobacter jejuri and Salmonella .
• The protozoans (Entamoeba histolytica, Giardia intestinalis and Balantidium coli), some viruses (Rotavirus, Enterovirus, Adenovirus and Norwalk) and nematodes (Ascaris) also act as causative agents of diarrhoea.
• Frequent loose motions and vomiting lead to dehydration.
• Dehydration (loss of water from body tissues) which makes the patient dangerously ill in a very short time.
• Most of the infant deaths due to diarrhoea can be prevented by making sure that dehydration does not take place due to excessive loss of body fluids through stools and vomiting.
• In cases of dehydration, the patient becomes irritable, eyes appear sunken, nose is pinched and the tongue and the inner side of cheeks appear dry.
• There is sudden weight loss, weak pulse, deep breathing and fever or fits.
• Eatables should be covered to prevent their contamination.
• Fruits and vegetables should be properly washed before use.
• Proper personal hygiene is important. Hands should be washed with soap and water before eating any food.
• Stale food should not be consumed.
• Community hygiene is also important.
• Complete bed rest should be ensured till the illness is fully controlled.
• For treating diarrhoea anti-microbial drugs and anti-diarrhoeal agents should be used.
• If there is frequent vomiting, liberal amount of fluids with electrolytes should be provided orally.
• Pulp of boiled unripe banana along with required amount of salt, turmeric powder and lime is helpful in controlling the diarrhoea.
• Husk of isabgol seed (Plantago ovata) with water or curd provides relief.
• Saline drip may be given intravenously to maintain fluid and electrolytes in the body. Alternatively oral rehydration solution (ORS) may be given to the patient periodically.
• Dilute soups and dais, rice-water and butter-milk can also be given to the child to compensate the loss of water. Meanwhile, a doctor should be called in who will give some antibiotic treatment. In children, diarrhoea can be prevented by keeping clean surroundings, clean milk and feeding bottles and by following proper feeding habits. There is no vaccine for preventing diarrhoea.
5.20 Peptic Ulcers
• Peptic ulcers are painful bleeding areas in stomach and duodenum.
• Robin Warren a Perth based Australian pathologist observed in 1984 that areas of peptic ulcers contained many small curved gram negative bacterium, named Helicobacter pylori
• Barry Marshall, a young clinical fellow of Warren succeeded in culturing the bacteria (1985).
• Marshall and Warren (1985) found that amoxicillin, an antibiotic effective in killing the bacteria could also cure the peptic ulcers.
• The finding helped in changing once painful chronic and disabling condition into short duration treatable disease. For this breakthrough Marshall and Warren were awarded Nobel Prize for Physiology and Medicine in 2005.
• Anthrax is an acute infectious disease caused by a rod-shaped non-motile bacterium called Bacillus anthracis.
• This disease commonly occurs in wild and domesticated animals such as cattle, sheep, goat, horses and pigs.
• Anthrax can spread by eating under-cooked meat of infected animals.
• Human beings can also contract infection from animal products such as bones, wool, hide and bristles. B. anthracis produces an extra-cellular toxin.
• Fowls are resistant to anthrax.
Infection of anthrax can occur in following three forms:
1. Cutaneous (skin);
2. Inhalation; and
(i) Cutaneous anthrax
About 20 per cent of untreated cases of cutaneous anthrax will result in death. Cutaneous cases are rare.
(ii) Intestinal anthrax.
Its symptoms are nausea, loss of appetite, vomiting, pain and vomiting blood. It results in death of 25 per cent to 60 per cent cases.
(iii) Infection by inhalation.
Its initial symptoms may resemble a common cold leading to severe breathing problems. It ultimately results in death of patient.
• Vaccine of anthrax is found to provide 93 per cent protection against anthrax.
• Course of four subcutaneous injections of anthrax vaccine is recommended. Mild adverse reaction to the vaccine of anthrax is reported.
• Treatment should be started early to get good result. At this stage food infection should be distinguished from food poisoning.
• In food infection, food merely transfers bacteria into the body.
• In food poisoning, bacteria grow in food and release toxins.
• When such a food is taken, toxins are absorbed into the blood from the digestive tract.
• They affect the body quickly, causing gastrointestinal trouble and other effects.
Some Vital Facts about Diseases
1. Dengue fever is a viral disease whose vector is Aedes aegypti. It is a daytime biting mosquito.
2. World T.B. Day: 24th March.
3. National T.B. Control Programme was started in 1962.
4. The WHO has announced a new treatment, and management regimen-Directly Observed Treatment, Short-course (DOTS) for the control of tuberculosis (TB), also called “White plague” and for reducing the threat of multi drug resistant strains in the next decade. (Regimen = A systematized course of living, as to food, clothing, etc.).
5. The incidence of tetanus in India is about 30 to 50 per one lakh. Neonatal tetanus carries a mortality type of 90 percent.
6. Bubonic plague is commonest type of plague. It is caused by a bacterium of the genus Yersinia (Y.pestis).
7. Incidence of diarrhoeal diseases is highest in Andhra and Orissa states of India.
8. Hepatitis B is more dangerous than AIDS.
9. Malaria Day. August 20.
10. The Integrated Child Development Scheme (ICDS) offers a series of services to control nutritional problems. Health centres distribute tablets of iron and folic acid among women and children to prevent anaemia. Vitamin A is also given to children orally under various schemes.
11. WHO (World Health Organisation, 1978) has defined health to be “A state of complete physical, mental and social well being (and not merely the absence of disease or infirmity) that enables one to lead a socially and economically productive life”.
12. World AIDS day is December 1.
13. Because of weight loss of AIDS patient, this disease is also called slim disease.