1. HUMAN HEALTH AND DISEASE

2. Objectives Define health and disease Explain acute and chronic disease
State different categories of diseases
With specific examples

3. Human Health and Disease
What is health?
‘The state of complete physical, mental and social well-being’
To sustain a healthy lifestyle person needs:
A balanced and varied diet
·  Take exercise
·  Proper shelter
·   Enough sleep
Good hygiene will reduce the likelihood of infection

4. What is disease?
Disease is a disorder or malfunction of the mind
or body, which leads to a departure from good health.
Can be a disorder of a specific tissue or organ due to a
single cause. E.g. malaria.
May have many causes.
Often referred to as multifactorial. E.g. heart disease.
Disease is diagnosed by a doctor analysing
the symptoms (physical and mental signs).

5. Acute disease
Sudden and rapid onset
Symptoms disappear quickly
E.g. influenza
Chronic disease
Long term
Symptoms lasting months or years
E.g. Tuberculosis

6. Categories of diseases

7. Results from permanent or temporary damage
Physical disease
Results from permanent or temporary damage
to the body

8. Infectious diseases
Organisms that cause disease inside the human body are
called pathogens
Bacteria and Viruses are the best know pathogens.
Fungi, protists and parasites can also cause disease
Diseases are said to be infectious or communicable if
pathogens can be passed from one person to another.

9. Examples: Influenza ('flu) Symptoms Causes
Influenza is a virus which causes a severe form of respiratory tract infection with generalised bodily symptoms. It spreads around the world in epidemics and is responsible for much ill health as well as many deaths.
Symptoms
If you start to develop cold symptoms but starting more rapidly and rather more violently, with higher fever and severe aches and pains, often in the back and muscles, then you may well be developing influenza. This may be associated with severe headache, cough, and, as a result of the fever, intermittent sweating and shivering. Sometimes there is a gastrointestinal element, with vomiting and/or diarrhoea.
Many people think they have had "flu" when all that they have suffered is a bad cold. When you have influenza you will know the difference. Most people will find it impossible to leave their bed and feel terrible.
The worst symptoms usually last for three to five days, and then should begin to improve. It is common to need two to three weeks off work as there is considerable debility left after the feverish illness is over. Do not be surprised to be quite depressed, this is a natural after-effect of the condition.
Influenza makes everyone feel terrible, but most people recover. It does however have a small, but significant mortality, especially in the very young, the very old, and those with poor immunity.
Causes
Influenza is caused by a virus which attacks our body cells resulting in various manifestations depending on the strain of the virus.
New mutations of the virus arise all the time and unfortunately immunity against one strain (which is conferred by exposure or immunisation) does not protect against other strains. In the era of rapid air transport the world wide spread of a new type of influenza can be extremely fast.

10. Water or food borne Cholera Typhoid
Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. The infection is often mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.
Typhoid
Typhoid fever is contracted when people eat food or drink water that has been infected with Salmonella typhi. It is recognized by the sudden onset of sustained fever, severe headache, nausea and severe loss of appetite. It is sometimes accompanied by hoarse cough and constipation or diarrhoea. Case-fatality rates of 10% can be reduced to less than 1% with appropriate antibiotic therapy. Paratyphoid fever shows similar symptoms, but tends to be milder and the case-fatality rate is much lower.

11. Sexually transmitted Gonorrhoea
This is caused by bacteria and can affect the vagina, cervix, urethra, rectum or even the throat.
How could I get it? Gonorrhoea can be passed on through: · vaginal sex - where the man puts his penis in the woman's vagina · anal sex - where the penis is put into the rectum · oral sex - where partners lick or suck each others sexual parts.
Can I get it from toilet seats or towels? You cannot it get it from toilet seats or swimming pools or by sharing cups and towels.
How do I know if I have it? You may not know - that is the problem with gonorrhoea. And sometimes other sexually transmissible infections can hide the symptoms of gonorrhoea. Most women notice nothing at all until the infection has spread from the cervix. Some may notice: · an unusual discharge · pain or discomfort when passing water · sore throat. Men may notice: · white or yellow discharge oozing from the tip of the penis. This is enough to stain the under pants. · pain or discomfort urinating · itching or discharge from the anus · sore throat
There may be no symptoms in both men and women. In women, it can not be picked up from cervical smear.

12. Syphilis This is caused by the bacteria called Treponema pallidum which is spread mainly by sexual intercourse, but can be passed on to your baby if are pregnant. If you are pregnant, in this country you would have had this test during your antenatal visit to the hospital. It usually starts as a painless sore and may be any where in the private part, areas of contact during sex as (the mouth, anus) or in women on the neck of the womb. If left untreated it usually heals in weeks. This is called primary syphilis. About 8 to 10 weeks after the sore has healed, you feel unwell with flu-like illness and develop skin rashes. Sometimes what looks like warts occur around the genitals and the peri-anal areas. This could occur over period sometimes lasting up to 2 years.. This period is known as secondary syphilis. Again it may clear without any treatment. It then lurks in the body and is only found when blood test are done for it and in others this may go on to cause problems with the joints, heart and brain. This period is what we call tertiary syphilis.

13. Progression of disease
·         Clinical Tetanus
Spores deposited in tissue - wound, burn, ulcer, compound fracture, operative wounds, drug injection - tetanus neonatorum: infection of umbilical stump - necrotic tissue (poor blood supply, anoxia) needed - mixed infections, foreign bodies also contribute - 10 year latency reported
Progression of disease

14. Malaria
Malaria infects an estimated 300 million people, and is spread by mosquitoes, transfusions, and shared hypodermic needles. Control of mosquito populations has led to declines in malaria in many areas. Infected individuals can be treayted with a variety of medicines. However, some of the sporozoans that cause malaria heve developed immunity to some of the more commonly employed medicines.

15. Non-infectious diseases
Diseases that are not caused by pathogens

16. Mental diseases
A disease that affects a person’s mind
Thoughts, emotions, memory and personal and social behaviour
May have physical symptoms.
Example of a mild condition is claustrophobia

17. Alzheimer’s disease

18. Degeneration of certain groups of brain cells
that usually secrete acetylcholine (neurotransmitter)
Symptoms:
progressive degeneration of memory
General decline in all mental faculties - dementia
Common in older people
Can occur in younger age groups - genetic

19. How common is it. Schizophrenia affects one in every hundred people
How common is it? Schizophrenia affects one in every hundred people. This is about the same for many different places and peoples across the world. It seems to be more common in city areas.
Who does it affect? Schizophrenia affects men and women equally. It rarely starts before the age of 15, but can develop at any time after this. Men with schizophrenia usually notice the first signs in their late teens or early twenties. Women are often first affected a little later, in their twenties or thirties
We don’t yet know for sure what causes schizophrenia. It is likely to be a combination of several different factors, which may be different for different people.
Genes
Brain Damage New ways of producing pictures of the brain show that some people with schizophrenia have larger spaces in the brain than people who don't suffer from the illness.
Stress
Street Drugs and Alcohol Sometimes, the use of street drugs like ecstasy (e), cannabis (hash, marijuana, pot, ganja, skunk, dope, spliffs, joints) seems to bring on schizophrenia.

20. Schizophrenia
Usually occurs in young people
Clinical changes:
- changes in blood flow in brain
- imbalances in secretion of
neurotransmitters in brain.
Treatment – drugs to mimic or inhibit
neurotransmitters

21. Deficiency disease
Associated with malnutrition

22. Scurvy
In 1747 as the HMS Salisbury sailed from England to the Plymouth Colony, the ship's physician, James Lind, performed a simple experiment to determine what might be effective as a cure for scurvy. Scurvy was described as early as 1500 BC in the Ebers papyrus and other descriptions appeared in Greek and Roman writings. It struck the crew of Magellan's around the world journey in and a British report in 1600 indicated that in the previous 20 years some 10,000 mariners had been destroyed by the disease.
On May 20, 1747, Lind divided his 12 ill men into six groups of two each. All 12 shared a common diet for breakfast, lunch and dinner but each group received a different supplement as follows:
quart of apple juice daily
25 drops of elixir vitriol (sulfuric acid and aromatics)
two spoonfuls of vinegar three times a day
concoction of herbs and spices
half-pint of sea water daily
two oranges and one lemon daily
The two men who ate the oranges and lemon recovered immediately. One was fit for duty in six days and the other was also well in six days and was appointed as nurse to all the others. The two men who drank apple cider improved but were not well enough to work. None of the others showed any improvement.
Mr. Lind concluded that something in the citrus fruit was counteracting the cause of the scurvy disease so he gave citrus fruits to all the other men and observed that all were cured of the disease.

23. night blindness
inability to see normally in subdued light. It is usually a result of vitamin A deficiency. The rod cells, one of two light-sensitive areas of the retina of the eye, are impaired in their capacity to produce a chemical compound called rhodopsin, or visual purple, that is necessary for the perception of objects in dim light. Consequently, the visual threshold, or the minimum intensity of light necessary for sight, is greatly increased. Treatment of night blindness consists of the oral or intravenous administration of vitamin A.

24. legs in a child with rickets
closeup of right knee

25. Examples of deficiency diseases
Scurvy – vitamin C
Night blindness – vitamin A
Rickets – vitamin D
Iron deficiency anaemia

26. Degenerative diseases
Usually associated with ageing
A gradual loss of function in one or several organs
or tissues can occur (associated with a progressive
destruction of specialised cells) in youth or middle age
Reasons for this loss of function:
- Immune system attack its own cells
- Deficiency in childhood which leads to
degeneration later in life.

27. Muscular Dystrophy
What is muscular dystrophy? Muscular dystrophy (MD) is a broad term that describes a genetic (inherited) disorder of the muscles. Muscular dystrophy causes the muscles in the body to become very weak. The muscles break down and are replaced with fatty deposits over time.
Other health problems commonly associated with muscular dystrophy include the following:
heart problems
scoliosis (a condition that causes the back bones to curve)
obesity
The most common form of muscular dystrophy is called Duchenne’s muscular dystrophy (DMD). Duchenne’s muscular dystrophy usually affects only males. It occurs in one out of 3,500 live male births. Muscular dystrophy rarely affects girls, but when it does, the condition is normally not as severe.

28. Types of degenerative diseases
Skeletal muscle and nervous system
Examples: muscular dystrophy, multiple sclerosis,
motor neurone and Alzheimer’s
Cardiovascular
Examples: coronary heart disease and stroke
Cancers

29. Social diseases

30. Social factors
Factors affecting disease:
Standard of housing – overcrowding/unhygienic
Environmental factors such as levels of pollution and
Purity of water supply
Lack of food – deficiency diseases
Excess of food – diseases associated with obesity
And cardiovascular disease
Occupation
Exposure and/or abuse of drugs