Diseases: Compilation of Term Papers on Diseases | Human Health | Biology

Here is a compilation of term papers on ‘Diseases’ for class 9, 10, 11 and 12. Find paragraphs, long and short term papers on ‘Diseases’ especially written for school and college students.

Term Paper on Diseases

Term Paper Contents:

1. Term Paper on the Introduction to Diseases
2. Term Paper on the Types of Diseases
3. Term Paper on the Causes of Diseases
4. Term Paper on the Organ-Specific and Tissue Specific Manifestations
5. Term Paper on the Principles of Treatment of Diseases
6. Term Paper on the Principles of Prevention of Diseases
7. Term Paper on the Viral Diseases
8. Term Paper on the Bacterial Diseases
9. Term Paper on the Protozoan Diseases
10. Term Paper on the Helminthal Diseases (Worms)
11. Term Paper on the Vaccines for the Prevention of Diseases
12. Term Paper on the Screening for Diseases

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1. Term Paper on the Introduction to Diseases:

A disease is an abnormal, pathological condition that affects a part or all of an organism. It is a medical condition associated with specific symptoms and signs. The disease can be defined as any condition that leads to discomfort, distress, health problems, due to heredity or acquired sources and agents.

It may be caused by the factors originally from an external source, such as an infectious disease, or it may be caused by internal dysfunctions, such as an autoimmune diseases. In humans, a “disease” is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, or death to the person afflicted, or similar problems for those in contact with the person. It sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviours, and variations of structure and function.

Tissues make up a physiological systems or an organ systems that carry out body functions. Each of the organ systems has specific organs as its parts, to carry out a particular function. So, the digestive system has the stomach and intestines and it helps to digest food taken in from outside the body.

When a body contracts a disease, the functioning or appearance of one or more organ or the system is changed. These changes slowly develop symptoms and signs which indicate a particular disease.

Symptoms and Signs:

These are indications from the body which tell us that something is wrong inside the body. Headache, nausea, stomach ache, cough, lose motions etc. are the symptoms that indicate that there may be a disease but does not clearly indicate the particular disease.

Signs will give a little more definite indication of the presence of a particular disease. Any objective evidence of a disease, such as blood in the stool, a skin rash is a sign – it can be recognized by the doctor, nurse, family members and the patient himself. However, stomach-ache, lower-back pain, fatigue, for example, can only be detected or sensed by the patient, others only know about it if the patient tells them.

Light Headache:

This can only be a symptom. A light headache can only be a symptom because it is only detected by the patient.

High Blood Sugar:

This can only be a sign. High blood sugar can only be a sign because the patient cannot detect it; it can only be measured in a medical laboratory

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2. Term Paper on the Types of Diseases:

i. Acute Disease:

Acute refers to the sudden onset of the disease that lasts for a short period. An acute condition is one where symptoms appear suddenly and worsen rapidly. Acute pain tells your body you’ve been hurt, say when you fall, stub a toe, burn your finger, etc.

It appears suddenly, peaks as a signal to your body to heal the injury, and wanes away as it heals before it disappears completely once the injury is healed. Similarly, acute illnesses like flu or common cold afflict a person suddenly, worsen over a short period, and then disappear.

ii. Chronic Disease:

Chronic illness means illness lasts for months, usually more than 3 months. Chronic pain, on the other hand, creeps up on the person gradually, and by the time he feels its presence, he realizes it has been there for a while.

It lasts for weeks, even months beyond the expected recovery; the pain itself is a disease and becomes a part of the person. Back pain that lasts for months and worsens over time is a good example of chronic pain.

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3. Term Paper on the Causes of Diseases:

Disease is caused by various factors but mainly by microorganisms which enter our body through unclean drinking water, improperly cooked food, unclean surroundings, personal hygiene, direct bite of an insect carrying infectious agents and improper sanitation disposal. Sometimes, for example, unclean water may not cause everybody to fall sick but a few.

This is because a few people who fell sick were already unhealthy due to improperly balanced diet. Effects can be immediate which are also called as first level of cause like viruses, bacteria and other organisms. It can also be contributory which is a secondary disease occurred due to weak health given by first level disease.

A. Infectious Diseases:

An infectious disease is the one that is caused by an organism and that can be transferred from one person to another. The transfer may be direct, where the disease-causing organisms, such as viruses or bacteria, pass directly from person to person, or it may be carried out by an intermediary (called a vector), such as a blood-sucking insect. Examples of infectious diseases are cold, influenza, chicken pox, herpes and measles.

(a) Infectious Agents:

Organisms that can cause a disease are found in a wide range of such categories of classification. A disease can be caused by viruses, bacteria, fungi, single-celled animals or protozoans and by multicellular organisms, such as worms of different kinds. The understanding of the category is an important factor in deciding treatment pattern and dose.

Bacteria:

Typhoid fever, cholera, tuberculosis and anthrax are the bacterial diseases. Taxonomically, all the bacteria are closely related to each other than to viruses and vice versa. This means that many important life processes are similar among the bacteria group but are not shared with the virus group.

As a result, drugs that block one of the life processes in one species of the group is likely to have same effect on many other species of the group. But the same drug will not block any of the life processes in a microbe that belongs to a different group.

Antibiotic:

Antibiotics block biochemical pathways important for a bacteria to survive and grow. Many bacteria, for example, make a cell-wall to protect them. The antibiotic penicillin blocks the bacterial process that builds the cell wall. As a result, the growing bacteria becomes unable to make the cell-walls and die easily.

Human cells don’t make a cell-wall anyway, so penicillin cannot have such an effect on us. Penicillin will have this effect on any bacteria that use such a process for making cell-walls. Similarly, many antibiotics work against many species of bacteria rather than simply working against one.

Virus:

Examples of diseases caused by viruses are the common cold, influenza, dengue fever and AIDS. All viruses, live inside the host cells. Viruses do not use these pathways at all, and that is the reason the antibiotics do not work against viral infections. When suffering from common cold, antibiotics does not reduce the severity or the duration of the disease.

However, if we also get a bacterial infection along with the viral cold, taking antibiotics will help against the bacterial part of the infection. Interferon’s are the chemicals released by the body against viruses which act on them and not allow them to enter the chromosome of the host.

Fungi:

Many common skin infections are caused by different kinds of fungi. Viruses, bacteria and fungi multiply very quickly, while worms multiply very slowly in comparison. Skin infections- Ring worm, Athletes foot (Aspergillus -affects lungs) etc.

Protozoan:

Protozoan microbes cause many familiar diseases, such as malaria, kala-azar (Leismania), Amoebiasis, an African sleeping sickness. We all have come across intestinal worm infections, as well as diseases like elephantiasis caused by different species of worms.

(b) Means of Spread:

1. Air Borne Diseases: Droplet Contact:

Also known as the respiratory route, it is a typical mode of transmission among many infectious agents. As air travels always and has a water or dust holding capacity. Even microbes travel and are present in the air and cause major infection factor. If an infected person coughs or sneezes on another person the microorganisms, suspended in warm, moist droplets, may enter the body through the nose, mouth or eye surfaces.

Diseases that are commonly spread by coughing or sneezing include:

i. Bacterial Meningitis

ii. Chickenpox

iii. Common cold

iv. Influenza

v. Mumps

vi. Strep throat

vii. Tuberculosis

viii. Measles

ix. Rubella

x. Whooping cough.

2. Water Borne Diseases: Faecal Oral Transmission:

More common are the indirect routes of transfer from foodstuffs or water. Infected source makes water contaminated (by people not washing their hands before preparing food, or untreated sewage being released into a drinking water supply) and the people who eat and drink them become infected. In developing countries most sewage is discharged into the environment or on cropland.

This is the typical mode of transmission for the infectious agents of:

i. Cholera

ii. Hepatitis A

iii. Polio

iv. Rotavirus

v. Salmonella

3. Sexual Transmission:

The sexual act is one of the closest physical contact two people can have with each other. As a result, there are microbial diseases such as syphilis or AIDS that are transmitted by sexual contact from one partner to the other.

However, such sexually transmitted diseases are not spread by casual physical contact, which is handshakes or hugs on sports like wrestling, or by any of the other ways in which we touch each other socially.

Other than the sexual contact, the AIDS virus can also be spread through blood-to-blood contact with the infected people or from an infected mother to her baby during pregnancy or through breast feeding.

Some diseases transmissible by the sexual route include:

i. HIV/AIDS

ii. Chlamydia

iii. Genital Warts

iv. Gonorrhoea

v. Hepatitis B

vi. Syphilis

vii. Herpes

4. Transmission by Direct Contact:

The diseases that transmit by a direct contact are called as contagious diseases. These diseases can also be transmitted by sharing a towel (where the towel is rubbed vigorously on both the bodies) or items of clothing in close contact with the body (for example, socks) if they are not washed thoroughly before reusing them. For this reason, contagious diseases often break out in schools, where towels are shared and personal items of clothing are accidentally swapped in the changing rooms.

Some diseases that are transmissible by the direct contact include:

(i) Athlete’s foot

(ii) Impetigo

(iii) Syphilis (on rare occasions, if an uninfected person touches a chancre)

(iv) Warts

5. Vector Borne Transmission:

A vector is an organism that does not cause disease itself but that transmits infection by conveying pathogens from one host to another.

Examples include mosquitoes, deer ticks, animal bites, etc.

B. Non-Infectious Diseases:

Non-infectious diseases are diseases that lack pathogens as a cause of a disease. They include genetic diseases, such as Down syndrome, haemophilia, and those that are related to lifestyle or environment, such as cardiovascular diseases, skin cancer, and deficiency diseases.

Illustration 1:

Name the factors which cause rabies?

Solution:

Most of the animals including humans can be infected and all of them can spread the disease. Dogs, rats, monkey, squirrels, raccoon, catties, wolves and bears are also the organisms prone to rabies. In India it spreads mostly through dog and monkey bites.

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4. Term Paper on the Organ-Specific and Tissue Specific Manifestations:

Different species of microbes reside on different parts of the body. In part, this selection is connected to their point of entry. If they enter from the air via the nose, they are likely to go to the lungs. This is seen in the bacteria causing tuberculosis.

If they enter through the mouth, they can stay in the gut lining like typhoid causing bacteria or they can go to the liver, like the viruses that cause jaundice. But this needn’t always be the case. An infection like HIV that comes into the body through the sexual organs will spread to lymph nodes all over the body.

Malaria-causing microbes, enter the body through a mosquito bite. These microbes enter the blood and travel to the liver, and then to the red blood cells. The virus that causes the Japanese encephalitis, or brain fever, will similarly enter through a mosquito bite. But it goes on to infect the brain.

The signs and symptoms of a disease will thus, depend on the tissue or organ which the microbe targets. If the lungs are the target, then the symptoms will be cough and breathlessness. If the liver is targeted, there will be jaundice. If the brain is the target, we will observe headaches, vomiting, fits or unconsciousness.

In addition to these tissue-specific effects of infectious disease, there will be other common effects too, as the body’s immune system is activated in response.

Inflammation:

It is a process where active immune system recruits cells in the affected tissue to kill the disease causing microbe. Swelling, pain, fever are the part of this process.

Tissue specific infestations may cause general effects. For example, HIV affects the immune system and thus affects and lowers the immunity to fight the disease. Thus, a common cold may cause pneumonia or minor stomach infection can cause diarrhoea and blood loss.

Severity of Manifestation:

It is also important to remember that the severity of the disease manifestations depends on the number of microbes in the body. If the number of microbes is very small, the disease manifestations may be minor or unnoticed.

But if the number of the same microbes is large, the disease can be severe enough to be life-threatening. The immune system is a major factor that determines the number of microbes surviving in the body.

Illustration 2:

Phagocytosis?

Solution:

WBCs or leukocytes play an important role in the defence mechanism of the body. When a foreign body or microbe enters the blood stream, leukocytes surround the microbes and engulf them. The microbes are destroyed. This process of engulfing and destroying microbes is called as phagocytosis.

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5. Term Paper on the Principles of Treatment of Diseases:

There are two ways to treat an infectious disease:

a. To Reduce the Effects of the Disease:

To reduce the symptoms, a treatment should be provided. The symptoms are usually because of the inflammation. For example, medicines can be given that bring down fever, reduce pain or loose motions. Bed rest is advised to conserve energy. This will enable the body to focus on healing.

b. To Kill the Cause of the Disease:

The microbes can be killed by using antibiotics. A particular group of microbes perform respective pathway to make a particular compound essential for them. These pathways are not followed by the human cells.

The antibiotics block such pathways which are specific to the microorganisms which ultimately results in killing the microbe. But antibiotics do not work on viruses because viruses and its products use human metabolic pathways to stay alive. There are relatively few virus-specific targets to aim at. Despite this limitation, there are now effective anti-viral drugs, for example, the drugs that keep HIV infection under control.

Illustration 3:

Why are human cells not affected by penicillin?

Solution:

Human cells don’t make a cell-wall anyway, so penicillin cannot have such an effect on us. Penicillin will have this effect on any bacteria that use such processes for making cell-walls.

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6. Term Paper on the Principles of Prevention of Diseases:

a. General Way of Prevention-Preventing Exposure:

When a person is sick, his immune system is already weak and most likely to contract diseases. Thus, prevention of the exposure is really important. For example, if an air-borne disease contracts, one must take care of the surrounding by keeping it neat, clean, less crowded. If the disease is water borne, clean drinking water should be provided and if it is vector borne then surrounding should be clean and pests or insects free.

b. Specific Way of Preventing the Infection-Vaccination:

As a general principle, we can ‘fool’ the immune system into developing a memory for a particular infection by putting something that mimics the microbe we want to vaccinate against, into the body.

This does not actually cause the disease but this would prevent any subsequent exposure from the infecting microbe by turning into actual disease. Many such vaccines are now available for preventing a whole range of infectious diseases, and provide a disease-specific means of prevention.

There are vaccines against tetanus, diphtheria, whooping cough, measles, polio and many others. These form the public health programme of childhood immunisation for preventing the infectious diseases.

Illustration 4:

Why is it not necessary to give Hepatitis-A vaccines to children?

Solution:

Some hepatitis viruses, which cause jaundice, are transmitted through water. There is a vaccine for one of them, hepatitis A, in the market. But the majority of children in many parts of India are already immune to hepatitis-A by the time they are five years old. This is because they are exposed to the virus through water.

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7. Term Paper on the Viral Diseases:

1. Jaundice (Also Known as Hepatitis):

Pathogen:

Hepatitis virus.

Mode of Transmission:

Hepatitis A is transmitted mostly by contaminated food and water while hepatitis B is transmitted by contact with infected body secretions.

Symptoms:

(i) Fever and loss of appetite

(ii) Nausea and vomiting

(iii) Yellowness of skin

(iv) Itching of skin due to bile pigments

(v) Urine deep yellow in colour

(vi) Enlarged liver

(vii) Headache and joint pains.

Prevention and Cure:

(i) Adequate bed rest.

(ii) Carbohydrate rich diet should be given to the patients. Consumption of protein and fat should be limited.

(iii) Eating hygienic food and drinking disinfected water.

2. Rabies (Also Known as Hydrophobia):

Pathogen:

Rabies virus

Mode of Transmission:

Biting of rabid dog or cat.

Symptoms:

(i) Severe headache and high fever.

(ii) Painful contraction of muscles of throat and chest.

(iii) Choking feeling and fear of death.

Prevention and Cure:

(i) Compulsory immunization of pet dogs and cats with anti-rabies vaccine.

(ii) Killing of the rabid animal if it shows excessive salivation and tries to seek isolation.

(iii) It can be treated by Pasteur treatment in which 14 injections are given one by one on each day. However, these days, five doses of anti-rabies vaccine are given at an interval of 0.3, 7, 14 and 30th day of dog bite.

3. Polio:

Pathogen:

Polio virus

Mode of Transmission:

Through food or water contaminated with stool and urine of patients.

The polio virus enters the body through food and water and reaches the intestine and from there it enters the central nervous system (the brain and the spinal cord) via blood stream and lymphatic.

In the central nervous system, the virus destroys the motor nerve cells of the spinal cord that is responsible for the muscular control. Therefore, the muscles of polio-infected person become unable to carry out the normal functions.

Symptoms:

(i) Headache and fever followed by loss of head support.

(ii) As the virus damages the brain and nerves of the spinal cord, legs become paralyzed.

(iii) Stiffness of neck and convulsions.

Prevention and Cure:

The Polio vaccine drops are given to children at certain intervals.

Pulses polio programme is a programme organized in our country to give the polio vaccine to the children. It was launched in 1995-1996 to cover all the children below the age of 3 years.

4. lnnuenza (Commonly Known as Flu):

Compared to common cold, influenza is more severe illness.

Pathogen:

Myxovirus influenza (influenza virus), which attacks our body’s cells.

Mode of Transmission:

Through air.

Symptoms:

(i) Fever

(ii) Respiratory tract infection symptoms such as cough, sore throat, running nose, headache, pain in muscles and fatigue.

Prevention and Cure:

By annual influenza vaccination.

The person suffering from influenza should drink plenty of water.

Consult the doctor immediately for the treatment.

5. Dengue:

Pathogen:

Virus

Symptoms:

(i) Sudden onset of high fever, which may last for 4-5 days.

(ii) Severe headache mostly in the forehead.

(iii) Pain in muscles, and joints. The body aches.

(iv) Pain behind the eyes which worsens with eye movement.

(v) Vomiting or nausea.

Prevention and Cure:

(i) Avoid water stagnation for more than 72 hours so that the mosquitoes do not breed there.

(ii) Prevent mosquito breeding in stored water bodies, like ponds, wells etc.  

(iii) Destroy discarded objects like old tires, bottles, etc. As they collect and store rain water.

(iv) Use mosquito repellents and full sleeved clothes to avoid the skin exposure for mosquitoes.

(v) Use mosquito nets, also during daytime.

(vi) Avoid outdoor activities during drawn or dusk when these mosquitoes are the most active.

6. Chicken Pox:

Pathogen:

Varicella virus

Modes of transmission- By contact

Symptoms:

(i) Fever, headache and loss of appetite.

(ii) Dark red-coloured rash on the back and chest which spreads on the whole body. Later, rashes change into vesicles. After few days these vesicles start drying up and scabs (crusts) are formed. These scabs start falling.

Prevention and Cure:

There are no vaccines against the chicken pox as yet.

But precautions must be taken as follows:

(i) The patient should be kept in isolation.

(ii) Clothing, utensils, etc. used by the patient should be sterilised.

(iii) Fallen scabs should be collected and burnt.

7. AIDS (Acquired Immuno Deficiency Syndrome):

The word “immune deficiency” signifies that the immune system becomes very weak. It is a disorder of the cell-mediated immune system of the body.

Lymphocytes are the main cells of the immune system i.e. T-lymphocytes and B-lymphocytes. ‘Helper T’ lymphocytes play a great role in regulating the immune system. Damages or destruction of ‘Helper’ lymphocytes leads to the development of a cellular immune’s deficiency which makes the patient prove to wide variety of infections.

Pathogen:

HIV (Human Immunodeficiency Virus)

Mode of Transmission:

(i) Sexual contact with the affected person. In India, the most common route of HIV transmission is through unprotected sex.

(ii) Using the same syringe as that of the affected person.

(iii) Transfusion of blood contaminated with the human immune deficiency virus.

(iv) From the mother to the new baby during pregnancy or during birth.

Symptoms:

(i) A type of lung disease develops (tuberculosis).

(ii) Skin cancer may be observed.

(iii) Nerves are affected

(iv) The Brain gets badly damaged with the loss of memory, loss of ability to speak and to think.

(v) Number of platelets (thrombocytes) becomes less which may cause haemorrhage.

(vi) In severe cases the patient shows swollen lymph nodes, fever and loss of weight.

After infection with HIV, a full blown (disease at its peak) AIDS patient is observed. It may be within three years if incubation period is less or may be after 10 years of infection.

Prevention and Cure:

No medicine or vaccine is known to be available against HIV infection.

Therefore, care has to be taken through the following measures:

(i) There should not be any sexual contact with the person who has HIV infection.

(ii) Use disposable syringes and needles.

(iii) Before receiving blood for transfusion, one should ensure that it has been screened for HIV.

(iv) Condom should always be used during intercourse.

(v) People should be educated about AIDS transmission.

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8. Term Paper on the Bacterial Diseases:

1. Tuberculosis:

Pathogen:

Mycobacterium tuberculosis. The bacterium release a toxin called tuberculin.

Mode of transmission- Directly by sneezing, coughing or spitting or indirectly by air-borne discharged through sputum, cough and sneeze of an infected person.

Symptoms:

(i) Persistent fever and cough.

(ii) Chest pain and breathlessness.

(iii) Sputum containing blood.

(iv) Loss of weight and weakness.

Prevention and Cure:

(i) Isolation of TB patients to avoid spread of disease.

(ii) Use of handkerchief while coughing and sneezing.

(iii) BCG (Bacillus Calmette Guerin) vaccine provides immunity.

(iv) Living rooms should be clean, neat and airy.

2. Typhoid:

Pathogen:

Salmonella typhi bacteria.

Mode of Transmission:

Through the contaminated food and water and house files.

(i) Continuous fever, headache, and slow pulse rate.

(ii) Reddish rashes appear on the upper abdomen.

(iii) Diarrhoea which becomes haemorrhagic (loss of blood)

Prevention and Cure:

(i) Proper sanitation and cleanliness should be maintained.

(ii) Proper disposal of excreta of the patient.

(iii) Antibiotics should be administered.

(iv) Disinfection of water and proper coking of food should be done.

(v) TAB-vaccine provides immunity for 3 years.

3. Cholera:

Pathogen:

Vibrio cholera (Comma shaped bacterium)

Mode of Transmission:

Through the contaminated food and water. House fly is the carrier.

Symptoms:

(i) Acute diarrhoea.

(ii) Muscular cramps.

(iii) Loss of minerals through urine.

(iv) Dehydration, which can lead to death of an individual.

Prevention and Cure:

(i) Cholera vaccination should be given.

(ii) Proper washing and cooking of food should be done.

(iii) Electrolytes (Na, K, sugar, etc.) dissolved in water should be given to the patient to check dehydration. In the market it is available as ORS (Oral Rehydration solution).

(iv) Underground disposal of excreta.

(v) Proper covering of eatables to prevent contamination.

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9. Term Paper on the Protozoan Diseases:

1. Malaria:

Pathogen:

Malarial parasite, Plasmodium

Mode of Transmission:

By the bite of a female Anopheles mosquito. Male Anopheles mosquito feed upon plant juices.

Symptoms:

(i) Headache, nausea and muscular pain.

(ii) Feeling of chill and shivering followed by fever which becomes normal along with sweating after some time.

(iii) Patient becomes weak, exhausted and anaemic.

(iv) The malaria may secondarily cause enlargement of the liver and spleen.

Prevention and Cure:

(i) Wire-gauzing of doors, windows etc. to stop/prevent the entry of the mosquitoes.

(ii) Use of mosquitoes net and mosquito repellents.

(iii) Taking care of coolers, flower pots and uncovered water containers to prevent breeding of mosquitoes.

(iv) Sprinkling of kerosene oil in ditches or other open spaces where the water gets collected.

(v) All the mosquito breeding places like ponds and ditches should be destroyed or covered.

(vi) Use of insect repellents to prevent a mosquito bite.

2. Amoebiasis (Amoebic Dysentery):

Pathogen:

Entamoeba histolytica

Mode of Transmission:

Through contaminated food and water.

Symptoms:

(i) Formation of ulcers in the intestine.

(ii) Feeling of abdominal pain and nausea.

(iii) Acute diarrhea and mucus in stool.

Prevention and Cure:

(i) Proper sanitation should be maintained.

(ii) Vegetables and fruits should be properly washed before eating.

(iii) Antibiotics may be given to the patients.

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10. Term Paper on the Helminthal Diseases (Worms):

Filariasis:

Pathogen:

Wuchereria bancrofti, filarial worm

Mode of Transmission:

Biting of mosquitoes-Aedes and Culex

Symptoms:

(i) Fever

(ii) Collection of endothelial cells and metabolites in the wall of lymph vessels.

(iii) Swelling of the legs that appear as legs of an elephant, so this disease is also called elephantiasis.

Prevention and Cure:

(i) Wire gauzing of doors, windows etc. to stop/prevent the entry of the mosquitoes.

(ii) The water collected in tanks or other articles should be properly covered to prevent breeding of the mosquitoes.

(iii) Sprinkling of kerosene oil on ponds and ditches to kill the larva.

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11.Term Paper on the Vaccines for the Prevention of Disease:

Vaccines provide active immunity against diseases by production of antibodies or sensitized lymphocytes to certain microorganisms. Vaccines sensitize B lymphocytes in the blood, which are specific for particular infecting organism. The sensitized B lymphocytes persist in blood as memory cells for varying periods, from a few months up to many years.

This establishment of ‘memory’ by the B lymphocytes forms the basis of vaccination (active immunization) against infecting organisms and the harmful toxins they produce. Following infection after vaccination, the memory cells (sensitized B lymphocytes) become activated, multiply rapidly and release proteins (immunoglobins or antibodies) that destroy the infecting organism or its toxin and prevent the disease.

Vaccines are of three types:

i. Live Attenuated Vaccines:

These consist of live virus or bacteria, which has been rendered a virulent. Immunization is generally achieved with a single dose (but three doses are required with oral poliomyelitis and oral typhoid vaccines), which provides a durable immunity.

Live vaccines should not be given to individuals with impaired immune response, whether caused by disease or as a result of radiotherapy or treatment with high doses of corticosteroids or other immunosuppressive drugs. They should not be given to those suffering from malignant conditions such as leukemia and tumours of reticuloendothelial system. HIV positive patients should not receive BCG, yellow fever and typhoid (oral) vaccines.

ii. Inactivated Vaccines:

These consist of virus or bacteria killed by heat or chemicals. They may require a primary series of injections of vaccine to produce adequate antibody response, followed by booster injections in most of the cases.

iii. Toxoids:

These are extracts of or detoxified endotoxins produced by bacteria. They are more immunogenic, if absorbed into an adjuvant (such as aluminum hydroxide) and require primary series of injections followed by booster doses.

Viral Vaccines:

MMR vaccine is a combined live measles, mumps and rubella vaccine that has replaced measles vaccine and should be given to every child, irrespective of previous measles, mumps or rubella infection. The first dose is given to children aged 12-15 months, followed by a second (booster) dose at 4-5 years of age.

MMR vaccine occasionally produces malaise, fever, a rash and parotid swelling, about 1 week after injection. MMR vaccine should not be given within 8 weeks of administration of another live vaccine by injection and in children, who are allergic to neomycin or kanamycin (MMR vaccine contains small amounts of neomycin).

If given to women, pregnancy should be avoided for 1 month (as for rubella vaccine). Poliomyelitis vaccine is of two types; oral attenuated live virus (Sabin vaccine) and injectable inactivated live virus (Salk vaccine). Oral Sabin vaccine is preferred as it avoids injections, provides a more prolonged immunity and by providing antibodies in the intestines, prevents the spread of infection.

The dose is three drops given at an interval of 1 month, starting at two months of age. Two booster doses of poliomyelitis oral vaccine are recommended the first before school entry and second before leaving school. Oral poliomyelitis vaccine should not be given, if the child has vomiting and diarrhea and in immunodeficiency disorders. Inactivated vaccine may be used, when oral (live) vaccine is contraindicated and for immunosuppressed individuals. Vaccine associated poliomyelitis is extremely rare.

Rubella vaccine is an attenuated live virus vaccine. It is indicated for sero-negative women of childbearing age. It is important to exclude pregnancy and to avoid it for 1 month thereafter, before giving the vaccine. The objective is to prevent fetal rubella infection, which can occur up to second trimester of pregnancy. Joint pain, low-grade fever and rash may occur after vaccination.

Hepatitis B vaccine contains inactivated hepatitis B virus surface antigen (HbsAg) adsorbed on aluminum hydroxide adjuvant. It is made biosynthetically using recombinant DNA technology. This vaccine is of particular importance to the health professionals, who have direct contact with blood or blood stained body fluids or with patients’ tissues, as it can be spread by infected body fluids (blood and saliva).

Immunization takes up to 6 months to confer adequate protection. Duration of immunity is not known, but it persists for at least for 2 years. A single booster dose after 5 years is recommended. Passive immunization is also possible in individuals, who get accidentally infected by using a special serum containing large amounts of antibody (hepatitis B immunoglobulin, HBIG) against the hepatitis B virus.

Rabies vaccine are of the following types:

Antirabic vaccine carbolised (simple vaccine) is a 5% suspension of brain substance containing carbolic acid fixed rabies virus. It is injected subcutaneously in the abdominal wall daily for 14 days for post dog bite prophylaxis. Vaccine associated encephalitis and neuroparalytic complications have been reported.

Purified chick embryo cells (PCEC) vaccine is inactivated rabies virus grown on chick fibroblasts. For, post exposure prophylaxis, a course of 6 injections of 1 ml is given intramuscularly in the deltoid region, on days 0, 3, 7, 14, 30 and 90. It is highly effective and is less likely to cause neuroparalytic complications.

Merieux inactivated rabies vaccine (HDC) is freeze-dried inactivated Wister rabies virus strain cultivated in human diploid cells. For post exposure prophylaxis, a course of 5 injections is giver on days 0, 3, 7, 14 and 30 in the deltoid region, as injections in the gluteal region produce poor response. This diploid vaccine is well tolerated and its use is not associated with neurological complications. Other viral vaccines for H. influenza type B, hepatitis A, yellow fever and other less common viral diseases, are available for use in special high-risk situations.

i. Bacterial Vaccines:

BCG (Bacillus Calemette Guerin) vaccine is a live attenuated strain derived from Mycobacterium bovis, which produces tuberculosis antibodies. It is given intra-dermally in the deltoid region in the newly born infants of up to 3 months.

In children between 10-14 years of age, it should be given, if tuberculin test is negative. Within 2-6 weeks, a small swelling appears at the injection site, which progresses to a papule or to a benign ulcer of about 10 mm in diameter which heals in 6-12 weeks. It is contraindicated in tuberculin positive individuals and in individuals with impaired immune response.

Whooping cough (pertussis) vaccine is a suspension of killed B. pertussis. It is usually given combined with diphtheria and tetanus vaccine (triple vaccine), starting at 2 months of age. Pertussis vaccine immunization should not be carried out in children, who have a history of severe general reactions to preceding dose.

In these children, immunization should be completed with absorbed diphtheria and tetanus vaccine. General reactions to a preceding dose, which contraindicates its continuation of subsequent immunization, include temperature of 39.5° C or more, anaphylaxis and convulsions within 72 hours. Other bacterial vaccines for immunization against cholera, meningococcal group C, typhoid and pneumococci are available for use in special high-risk situations.

ii. Toxoids:

Tetanus toxoid (Tetanus vaccine) is formalin treated exotoxin of tetanus bacilli, which stimulates the production of protective antitoxin. In general, adsorption on aluminum hydroxide, aluminum phosphate or calcium phosphate improves antigenicity.

Adsorbed Tetanus vaccine is given routinely to babies in combination with adsorbed diphtheria and pertussis vaccine. In children, the triple vaccine, not only gives protection against tetanus in childhood, but also give the basic immunity for subsequent booster doses of adsorbed tetanus vaccine at school entry and at school leaving (combined with adsorbed diphtheria vaccine) and also when a potentially tetanus contaminated injury takes place.

Tetanus vaccine is important for pregnant women (two doses during second and third trimester) and persons in older age groups for elective surgery, who may never, had a routine or complete course of earlier immunization. Apart from minor local reactions, complications are extremely rare. Diphtheria vaccine is prepared from the toxin of Coryne-bacterium diphtheria. Adsorbed diphtheria vaccine is used in combination with adsorbed tetanus vaccine for routine immunization schedule for children.

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12. Term Paper on the Screening for Diseases:

Definition and Object of Screening:

1. It is search for un-recognised disease by means of rapidly applied tests or procedures in apparently healthy persons

2. Object of screening is early detection of those diseases for which early treatment has been shown to be effective.

Purpose of Screening:

1— To detect the case

2— To carry out the research

3— To control the disease

Type and Uses of Screening: 

Types:

1— Mass screening

2— High risk screening

3— Multiphasic screening

Uses:

1— Early case detection

2— Control of diseases

3— Research purposes

4— Educational

Criteria for Screening:  

1— Health problem or disease should be of important public health problem.

2— Disease should be a latent, presymptomatic stage.

3— It should be early dis­tinguishable from norma­lity.

4— Problem should be reversible or controllable by treatment.

Measurement of Validity:

Introduction:

(a) Validity means judging the effi­ciency of the test in diagnosing the disease.

(b) By screening results positive & negatives are detected among those false true and false negative can be identified.

Specificity:

It is the ability to detect a high proportion of true positive that is to give very few false negative. Sensitivity

= True Negative/True Negative ++ False Positive × False Positive

= A/A+C × 100

Specificity:

It is the ability for correct identification of the true negative that is to give very few false positive results.

Specificity:

True Negative /True Negative + False Positive × 100

D /B+D × 100

Predictive Value:

It reflects the diagnostic power of the test. It expresses true positives as a proportion of all positive.

Predictivity:

= True Negative/ True Negative + False Positive × 100

= A/A+B × 100

Common and Important Screening Test:

Adult & Elderly:

—Cataract 

—Glaucoma

—Cancer

—Chronic bronchitis

—Tuberculosis

—Nutritional disorders

Middle Aged:

—Obesity

—Hypertension

—Diabetes mellitus

—Cancer

Pregnancy:

Anaemia

—Toxemia

—Diabetes

—VDRL test

—HIV detection

Infancy & Childhood:

—Low birth weight

—Congenital heart disease

—Visual or hearing defect

—Hypothyroidism

—Sickle cell anaemia