HEALTH AND IMMUNITY BIOLOGY FORM ONE NOTES

 

THE CONCEPTS OF HEALTH AND IMMUNITY
Health is a state of physical, mental and social well-being. It involves more than just the
absence of disease. 

A truly health person not only feels good physically but also has a realistic outlook on life and gets along well with other people.

Elements of physical health

Nutrition:
A balanced diet provides all the food substances needed by the body for healthy growth and development

Exercise

Exercises help to keep the body healthy and fit. Vigorous exercises strengthen muscles and improve the function of the circulatory and respiratory systems. Physical fitness benefits both physical and mental health and helps the body withstand stress.

Rest and sleep

Help to overcome fatigue and restore energy to the body. Everyone needs rest and sleepiest and relaxation are as important as sleep. After strenuous work or exercise a person may need a period of total rest.

Cleanliness

Cleanliness prevents the growth of bacteria and other germs that can cause diseases. A regular bath or shower keeps the body free from dirt and odour. It also helps to prevent skin infections.

Medical and dental care

Regular checkups by dentists and physicians play an important role in safeguarding health. Doctors recommend that people seek medical care at the first sign of illness. Early care can result in quicker cures and lower medical costs.

Avoiding risk behaviours

Careful observation over a range of lifestyle factors indicates that positive changes can bring about a corresponding change in health status Risk behaviours that need to be avoided include:

Smoking

cigarette smoking increases respiratory diseases such as bronchitis and increases the risk of death from lung cancer and heart attack.

 

Alcoholism: heavy, long-term drinking has several effects on the body. It affects the nervous system, causes liver disease (cirrhosis), etc;

 

Drug abuse: drugs can cause addiction, long-term harmful effects, disruption of normal life and some can lead to death.

MENTAL HEALTH
Mental health is as important as physical health and to a great extend depends on it.

Elements of mental health

Emotional development
Experiences during childhood strongly influence a person’s mental health throughout life. Children remain dependent for many years. At this period they learn certain guidelines for relating to other people. 

Thus children develop the knowledge necessary to deal with difficult situations in life. This knowledge helps them maintain good mental health throughout life.

Emotional development does not end when a person reaches adulthood. An individual's mental health continues to change from time to time. These changes result from daily circumstances that cause either pleasure or pain to the person.

Handling stress
Stress handling is essential for avoiding both mental and physical illness. Feelings of stress are the body’s response to any threatening or unfamiliar situation. 

Causes of stress include the following:

• Most severe stress may result from divorce or the loss of a job.
• Stress can also occur even in pleasant situations such as: Watching a football game,
• Waiting for a lovely one to return from a trip, etc.

If not handled properly stress can lead to

• Physical or emotional illness
• High blood pressure
• Stomach ulcers

No one can avoid stress but certain things that can be done to lessen it include:

• Regular exercises and sufficient sleep strengthens the body's resistance to stress
• Relax by resting
• Taking a walk
• Meditating
• Working with hobby

Social relationships
Close personal relationships with friends and relatives provide opportunities for
communication, sharing and emotional growth. Such relationships also provide strength
and support for dealing with challenging situations or personal problems.

IMPORTANCE OF GOOD HEALTH

• Enables people to enjoy life and have the opportunity to achieve their goals.
• Sets someone free from attack by diseases.
• Enables people to work effectively and efficiently.
• Good health helps people to participate in social issues.
• Enables mothers to deliver healthy babies.
• Raises the family economy which in turn ensures peace and security within the family and the surrounding community.

TYPES OF BODY IMMUNITY AND THEIR IMPORTANCE
Immunity is the ability of the body to resist certain diseases and poisons. Immunity can also be defined as the ability of the body to defend itself against infectious agents, foreign cells and even abnormal cells such as cancer cells

The scientific study of the immune system is called immunology.

Immune system
The immune system comprises a group of cells, molecules and tissues that help defend against disease and other harmful invaders. The invaders include disease-causing organisms (pathogens) such as bacteria, fungi, protozoa, viruses and worms. 

A key feature of the immune system is its ability to destroy foreign organisms, leaving the body’s own health tissues alone.
The immune system consists of white blood cells, lymph nodes, spleen, liver and bone
marrow.

TYPES OF IMMUNITY
Basically, there are two types of immunity
Natural immunity
Artificial immunity

NATURAL IMMUNITY
Natural immunity is that which an individual is born with. Natural immunity can be divided into categories, namely:

• Natural active immunity
• Natural passive immunity

Natural active immunity: This immunity develops in a body after a natural infection. After
infection, antibodies are produced in the body. 

The antibodies normally reside in the blood or in other parts of the body. The body can make more antibodies whenever the pathogen tries to attack the body again.

Natural passive immunity: This type of immunity is achieved during the development of the foetus where antibodies pass from the mother to the foetus through the placenta or through the mother’s milk after the baby is born. 

The antibodies disappear from the infant a few months after birth.

ARTIFICIAL IMMUNITY
Artificial immunity is that which an individual acquires during his/her lifetime.

There are two types of artificial immunity

• Artificial active immunity
• Artificial passive immunity

Artificial active immunity
This is immunity introduced in the body by immunization. Immunization is the process of introducing a vaccine into the body of an animal in order to increase its ability to produce antibodies. These antibodies protect the person if he/she is exposed to the actual disease.

Most vaccines contain disease-causing bacteria or viruses that have been killed. Others consist of live germs but in a weakened form or attenuated. Toxoid vaccines are made from poisons produced by disease-causing organisms. 

These poisons are chemically treated so that they provide immunity without causing disease.

Some vaccines are made from parts of disease-causing organisms. Vaccines have been developed against many diseases such as chicken pox, diphtheria, influenza, measles, meningitis, mumps, pneumonia, poliomyelitis, cholera, rabies, rubella (German measles), tetanus, whooping cough and yellow fever. Vaccines can be taken through, injection, rubbing or the mouth (orally).

Artificial passive immunity
This type of immunity involves the injection of serum into the body of an organism.
The serum contains antibodies that have been formed in another person or animal. 

It provides immediate protection from infection and lasts for weeks or months and after that period there are no antibodies left in the body and therefore no immunity.

FACTORS WHICH AFFECT BODY IMMUNITY
Factors which may lead to low body immunity

• Alcohol and other toxic drugs.
• Lack of immunization.
• Lack of a properly balanced diet.
• Inability of the body to produce antibodies and white blood cells.
• Pathogens of HIV (Human Immunodeficiency Virus)

INFECTIONS AND DISEASES
Infection is the invasion of disease-causing microorganisms into the body. The disease is the disturbance of the normal state of the body. 

It is a disordered state of an organ or organism. Infections normally lead to diseases.

CLASSIFICATION OF DISEASES
Diseases are classified as:

• Infectious (communicable) diseases
• Non-infectious (non-communicable) diseases

Infectious (communicable) diseases
These are diseases which can be transmitted from one person to another person. Communicable diseases are normally caused by micro-organisms like viruses, bacteria, fungi and protozoa, etc

Examples of infectious diseases include malaria, typhoid, tuberculosis, cholera, gonorrhoea, syphilis, ebola, AIDS, chlamydia, etc.

Many of the infectious diseases are transmitted by way of:

• Droplet of liquid
• Air
• Food or water
• Sexual intercourse
• Touch or contact e.g. ringworm
• An intermediate organism called a vector e.g. malaria by mosquito and bubonic plague by rat flea.
• Diseases causing micro-organisms can enter the body through the mouth, nose, skin, vagina, anus, penis, ears, eyes and open wounds.

Infectious diseases can be:
Epidemic disease - a disease that affects a larger number of people in a short period of time in a region for example, cholera, meningitis, bubonic plague, rift valley fever (RVF), tuberculosis.

Pandemic disease - a communicable disease which is widespread over a country continent or the whole world, for example, HIV/AIDS, etc.

Endemic disease - a communicable disease which occurs in an area continuously, for example, bilharzia, sexually transmitted diseases (STDs), malaria (an endemic disease in tropical regions) and cholera (endemic in Asia).

Non- infectious (non-communicable) diseases
These are diseases which cannot be transmitted from one person to another.

Examples of non-communicable diseases include:
Environmental diseases e.g. Lung cancer Asbestosis Asthma Coronary (heart) diseases Alcoholism

Deficiency diseases
These diseases are due to a lack of certain nutrients in the diet.

They may be due to a lack of one of the main food groups e.g.:

• Kwashiorkor: lack of protein
• Marasmus: lack of both carbohydrate and proteins
• Night blindness: lack of Vitamin A
• Beriberi: lack of Vitamin B1
• Scurvy: lack of Vitamin C
• Rickets: lack of Vitamin D, calcium, and phosphorous
• Anaemia: lack of iron
• Goitre: lack of iodine
• Excessive bleeding (haemophilia): lack of Vitamin K

Genetic and congenital disorders e.g.

• Colour blindness
• Haemophilia
• Sickle cell anaemia
• Albinism
• Down’s syndrome
• Klinefelter’s syndrome
• Turner's syndrome

Ageing and degenerative diseases e.g.

• Long-sightedness due to weakening of eye muscles
• Arteriosclerosis (hardening of arteries)
• Arthritis – ageing of joint and bone tissues
• Mental illness e.g.
• Schizophrenia
• Senile dementia
• Depression

Hormonal diseases e.g.

• Diabetes mellitus
• Diabetes inspidus
• Cretinism

COMMON INFECTIONS AND DISEASES
Common Infections and Diseases include the following:

• CHOLERA
• MALARIA
• TYPHOID
• TUBERCULOSIS (T.B)
• MENINGITIS
• AMOEBIC DYSENTRY (AMOBIASIS)
• PLAGUE
• TRYPANOSOMIASIS (SLEEPING SICKNESS)
• BILHARZIA (SCHISTOSOMIASIS)
• ATHLETE’S FOOT
• GONORRHOEA
• SYPHILIS
• CLAMYDIA
• GENITAL HERPES
• GENITAL WARTS
• HEPATITIS B
• TRICHOMONIASIS
• CANDIDIASIS

THE CAUSES, SYMPTOMS, MODE OF TRANSMISSION AND EFFECTS OF COMMON INFECTIONS AND DISEASES

CHOLERA

Cause:

It is caused by a bacterium known as Vibrio cholerae

Symptoms

• Severe watery diarrhoea and vomiting
• Body weakness
• Fast and weak pulse
• Low blood pressure
• Wrinkled skin and sunken eyes due to dehydration
• Rapid loss of weight

Transmission

• Cholera is transmitted through:
• Food or water-borne material contaminated with faeces from an infected person
• Handling of contaminated objects
• Vectors e.g. flies moving from human faeces to food.

Prevention of Cholera

• Wash hands after visiting the toilet or latrine
• Food should be well-cooked and drinking water should be boiled and well filtered
• Hands should be washed before and after eating
• Food should be well covered
• Utensils should be washed thoroughly
• Maintain general environmental cleanliness

Control of Cholera

• The infected person should be isolated
• Special precautions should be taken when handling the infected person
• Vaccination is possible

Treatment
The disease can be treated by using antibiotics such as tetracycline, chloramphenicol
Administering rehydration salt solutions

Effects

• May lead to death
• Extra medical expenses
• Failure to perform daily activities

MALARIA

Cause:
Malaria is caused by a protozoan called plasmodium.

Signs and symptoms

• High fever. Fever may be continuous, irregular or twice daily.
• Vomiting
• Lack of appetite
• General body weakness
• Joint pains

Transmission
Malaria is transmitted by a female anopheles mosquito. The mosquito sucks blood containing plasmodium from the infected person and introduces them into the body of a healthy person. 

In rare cases, malaria can be transmitted through blood transfusion from the infected person to a healthy person.

Prevention and control of malaria

• Spraying insecticides to destroy adult mosquitoes
• Introducing fish eating mosquitoes into stagnant water e.g. Gambusia that feed on
• mosquito larvae.
• Draining stagnant water to remove the breeding sites for mosquitoes
• Use of mosquito nets to prevent mosquitoes from biting people
• Screening the windows with mosquito-proof wire-mesh to prevent entry of mosquitoes
• in the house through the windows.
• Wear long-sleeved shirts and trousers to prevent mosquito bites.
• Mosquito larvae and pupa can be killed by spraying oil into stagnant water that cannot be drained.
• Taking regular weekly doses of preventive drugs to kill parasites on entry.
• Cutting bushes around the houses to destroy shelter for mosquitoes
• Using mosquito repellents to flee away the mosquitoes

Treatment of Malaria
Anti-malarial drugs can be used to treat the disease e.g. quinine, fansider, mefloquine, chloroquine, etc.

Effects of Malaria
Can cause death

• This can lead to mental confusion in the case of cerebral malaria
• Paralysis and unconsciousness
• Drowsiness
• Anaemia
• Miscarriage
• Inability to participate in economic activities
• Increased medical expenses

TYPHOID
Cause:

It is caused by a bacterium known as Salmonella typhus. The bacteria damage the intestinal wall and other parts of the body like gall bladder, spleen and bone marrow.

Signs and symptoms

• Mild fever
• Slight abdominal pains
• Diarrhoea
• Vomiting
• Ulceration and rupture of the intestine

Transmission
The disease is spread through

• Contaminated water and food
• Handling of contaminated objects
• Vectors of the disease e.g. houseflies

Prevention and control of Typhoid

• Wash hands after visiting the toilet
• Food and water must be protected from dust and flies
• Wash hands before and after eating
• Drink boiled water and eat properly cooked food; fruits should be washed thoroughly before being eaten.
• Vaccination can also help to control the disease

Treatment:
The disease can be treated by using antibiotics such as tetracycline, chloramphenicol, etc.

Effects

• Can cause death
• May cause ulcers and finally rupture of the intestine
• Enlarged spleen

TUBERCULOSIS (T.B)

Cause:
T.B is caused by a bacterium called Mycobacterium tuberculosis. The bacteria can attack the lungs or any part of the body and destroy tissues.

Signs and symptoms

• Loss of weight
• Coughing
• Fever
• Chest pain
• Blood in the sputum

Transmission

• Through droplet infection
• Through drinking milk from infected cattle
• T.B is common in overcrowded areas with poor sanitation
• Appropriate Preventive and Control Measures for Common Infections and Diseases

Prevention and control of T.B

• Elimination of the conditions under which TB thrives e.g. overcrowding, poverty level
• living and inadequate nutrition.
• Observing general personal hygiene, especially when coughing and sneezing.
• Early BCG (Bacillus Calmette-Guérin) VaccineThe Vaccine may be used for either of two
• reasons:(i) Protecting newly-born babies or children at particular risk of infection.(ii)
• Immunization of young persons or at risk groups in the community.
• Keeping children, in particular, away from risk situations.
• The use of sterilized milk and pasteurized dairy products
• Contact tracing so that risk to others may be minimized

Treatment:

Antibiotics such as streptomycin can be used to cure the disease.

Effects of T.B

• Causes a number of deaths.
• Abscess full of pus may form near the lump in the spine.
• Shortening and thickening of the chest in case of TB of the spine.

SEXUALLY TRANSMITTED INFECTIONS (STIS) AND SEXUALLY TRANSMITTED
DISEASES(STDS)

Cause
Is caused by HIV (Human Immunodeficiency Virus).The Virus attack the body's immune system weakening it and making it more susceptible to infections and some cancers.

It is important to realize that, infection with the HIV virus does not necessarily result in AIDS. As with other diseases, some people remain symptomless and are said to be carriers.

TYPES OF HIV VIRUSES
There are two major types of HIV Viruses, HIV 1 and HIV 2.

HIV 1 is the most predominant virus and it is more easily transmitted while HIV 2 occurs in a small number of people in West Africa, Angola, Mozambique and some parts of India. It is less virulent.

Where in the body can you find HIV viruses? 

The virus in the body can be found in the following body fluids: blood, semen, vaginal fluid, tears, saliva and urine and breast milk. It is observed that semen, blood and vaginal fluids are more infectious.

SIGNS AND SYMPTOMS OF AIDS
A person infected with HIV may start to show signs of illness from a few weeks to many years. The infected individual may experience the following signs and symptoms:

• Tremendous loss of weight
• Persistent fever
• Chest pain
• Diarrhoea for no obvious cause
• Coughing for more than one month
• Shortness of breath getting worse over several weeks
• Itchy skin rashes
• Thrush in the mouth and throat
• Loss of hair

TRANSMISSION
AIDS can be transmitted through any of the following ways:

• Sexual intercourse with an infected person
• Transmission from the mother to the baby during pregnancy, birth or breastfeeding.
• Sharing sharp objects with infected people e.g. sharing needles, razor blades, tooth
• brushes etc.

AIDS-RELATED COMPLEX
The infected person may exhibit a variety of conditions. Common bacterial, fungal and viral infections attack the victim. These are known as opportunistic infections. They include diseases like pneumonia, T.B, meningitis, candidiasis, cancer e.g. Kaposi’s sarcoma, etc.

PREVENTION OF HIV/AIDS
Use the ABC method to prevent the disease: A-Abstain from sex B- Be faithful to your only partner C- use Condoms. This means that you are advised to abstain completely from sexual intercourse. 

If you can't then have one faithful partner and if this seems to be difficult then use condoms.
Avoid sharing sharp tools with the infected individuals

Blood transfusion should be done prior to HIV screening

Pregnant mothers should attend clinic so that they get treatment that will prevent HIV
transmission from the mother to the baby.

Avoid all the risk behaviours, situations and practices that may enhance HIV transmission. The risk behaviours include drug abuse, prostitution, rape, anal sex, oral sex, alcoholism, unsafe sex, roaming in bars, guest house, etc.

MANAGEMENT OF STIS AND HIV/AIDS
Ways of Avoiding Risky Situations, Risky Behaviours and Practices

• Risky behaviours can be avoided by:
• Practising safe sex
• Applying non- penetrative sex e.g. kissing, hugging, etc.
• Delaying technique e.g. I’m required at home just now lets meet tomorrow
• Discouraging/negative words e.g. I’m HIV positive
• Discouraging peer pressure
• Engaging in sports and games which distract one’s mind from concentrating to sex.
• Showing a sense of dislike to express the way you are by wearing T-shirts, caps with
• various messages e.g. ‘say no to sex’, ‘practice safe sex’, ‘Mimi nimepima wewe je?’, ‘AIDS kills’ etc

PREVENTION OF HIV/AIDS

• Avoid sexual intercourse. It is possible to live a healthy normal life without having sexual intercourse.
• Use a condom correctly every time you have vaginal sex. It is often hard to be sure that your partner is truly faithful and unaffected.
• Avoid multiple partners. Don’t have more than one sexual partner.
• Avoid alcohol and drug abuse as they affect your decision making ability thus leading you to unsafe sex.
• Avoid sharing needles and other skin piercing tools. Needles can be contaminated and HIV can survive in a syringe for a month or longer.
• Avoid contracting other STIs because they increase the chances of HIV and AIDS infection. For those who have been infected, they must get proper treatment from a qualified medical practitioner.
• Avoid risky behaviours such as going to night clubs, negative peer pressure and taking alcohol or drug abuse. These might put you in danger of being infected.

Prevent mother-to-child transmission by:

• counselling and treating the mother;
• using caesarean section as a mode of delivery;
• use of alternative feeding (milk) instead of breastfeeding; and
• not sharing breast milk.
• Prevent transmission through organ and tissue transplants by screening both the donor and the patient.

Prevent minor injuries which might lead to infection. This can be achieved through:

• use of gloves;
• use of sterile instruments;
• avoiding direct contact with contaminated body fluids;
• proper handling of contaminated human waste;
• decontaminating soiled surfaces and lined.

Effective treatment of the infected through:

(a) administering anti-retroviral therapy; and

(b) prompt treatment of opportunistic infections.

CARE AND SUPPORT OF PEOPLE LIVING WITH HIV/AIDS (PLWHA)
The importance of care and support to people living with HIV/AIDS (PLWHA) includes the following:

• It enables them to prolong their lives in case they are administered with ARVs.
• It reduces the fear of death.
• It enables them to perform their daily activities without fear.
• It reduces depression and self-dislike.

Necessary Care and Support Services Provided to PLWHA in the Family, Community and at School
People who are infected with HIV need care and support from their friends, families and the community, especially when they are ill. Friends and family members sometimes worry that they might be infected when caring for a person with HIV.

HIV cannot be passed on by touching, hugging, coughing, or sharing eating utensils. It is possible for people who are infected with HIV to live long healthy lives. 

You can help those who are infected by:
showing love, respect and support;
knowing the facts about HIV/AIDS and talking openly about the disease;

• helping to reduce stress and stressful situations;
• helping to provide balanced and nutritious meals;
• seeking support from family and friends as well as from other people who are HIV-positive;
• encouraging them to live with hope;
• encouraging them to be active. 
• Do not stop them from doing things they like; spend time with the sick person. For example help them to prepare their meals, clean their rooms, make their beds and take them for a walk if they can walk. Encourage family and friends to do this too;
• encouraging them to get treatment if they are sick. Most infections are easily treated and cured, even if a person is HIV positive.
• Cleaning their houses, utensils, clothes, etc.;
• trying to relieve any pain the person may be feeling, for example by administering painkillers; and treating them with respect and dignity making them as comfortable as possible.

Precautions to be taken when handling PLWHA and STIs
There may be situations where you need to clean up body fluids or blood from someone infected with HIV. Do not touch body fluids such as blood, stool and urine with your bare hands. 

It is important to use rubber or plastic gloves or other barriers such as plastic bags or thick cloth to prevent direct contact. Make sure that you have these easily available at all times.

• Wash the gloves or plastic bags in hot water every time you have used them. 
• Keep clothes and bedding with blood, diarrhoea or body fluids away from other washings.
• Wash the bedding and clothes with soap. Hang them where there is plenty of sunshine and air circulation to dry well.
• Do not share toothbrushes, razors, skin-piecing instruments, or needles
• Cover your wounds with a clean and sterile bandage. Buy disposable gloves so that once used they are discarded.
• Dispose off properly the vomits or bandages used when dressing wounds.
• Learn about the ways HIV can and cannot be transmitted. 
• Talk to your friends and family. 
• Contact your local clinic for more information

The Effects of Discrimination and Stigma to People Living with HIV/AIDS to the
Individual, Family and Society

HIV-related stigma and discrimination exist worldwide, although they manifest themselves differently across countries, communities, religious groups and individuals.

Possible consequences of HIV-related stigma could be:

• loss of income and livelihood
• loss of marriage and childbearing options
• poor care within the health sector
• withdrawal of caregiver at home
• loss of hope and feelings of worthlessness
• loss of reputation