Understanding Human Health and Disease
Health is the state of overall well-being encompassing physical, mental, and social aspects, maintained through a balanced diet, exercise, shelter, sleep, and good hygiene. Disease is a disorder affecting the body or mind, leading to a departure from good health, manifested as acute or chronic conditions. Diseases can be physical or infectious, caused by pathogens that can be transmitted. Examples include influenza, which is a viral respiratory infection with severe symptoms and global impact.
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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
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 diagnosed by a doctor analysing the symptoms (physical and mental signs).
Acute disease Sudden and rapid onset Symptoms disappear quickly E.g. influenza Chronic disease Long term Symptoms lasting months or years E.g. Tuberculosis
Physical disease Results from permanent or temporary damage to the body
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.
Examples: Influenza ('flu) Influenza ('flu) 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 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 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.
Chickenpox Measles
Water or food borne Salmonella Salmonellosis is an infection with a bacteria called Salmonella. Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness Cholera 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 Typhoid fever is contracted when people eat food or drink water that has been infected with Salmonella typhi 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 Paratyphoid fever shows similar symptoms, but tends to be milder and the case-fatality rate is much lower.
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? 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? 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? 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 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: 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.
Syphilis 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 3 - 8 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.
Clinical Tetanus 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
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.
Global Statistics 40% of the world's population is at risk 300-500 million new cases/year 1.5-2.7 million deaths/year Malaria is endemic to over 100 countries and territories More than 90% of all cases are in sub-Saharan Africa
Non-infectious diseases Diseases that are not caused by pathogens
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
Serious mental diseases include: Creutzfelt-Jacob disease (CJD) Destroyed brain tissue resulting in spongy appearance Infection with prion protein Results in loss of co-ordination and mental derangement Fatal
GENETIC CJD Genetic CJD is a very rare illness. In this form, CJD is caused by an inherited abnormal gene. The illness is therefore not "caught" in any way and there is no causal relationship between this form and BSE. In most cases, the illness is known within the family because of the family history. Occasionally, genetic cases are seen in which no previous family history is identified. The definitive test in relation to genetic CJD is a blood test in order that the gene can be analysed to see whether there is any genetic abnormality. The United Kingdom has a population of around 58 million and there are only a few deaths due to genetic CJD in a year. IATROGENIC CJD Iatrogenic CJD is also very rare. This is CJD which has been accidentally transmitted during the course of medical or surgical procedures. The most important example of this in the United Kingdom relates to CJD transmitted via Human Growth Hormone treatment in childhood. There are only a few deaths per year due to iatrogenic CJD in the United Kingdom. The diagnosis is usually clear from the history of a relevant medical or surgical treatment in the past. SPORADIC CJD Sporadic CJD is numerically the most common form of CJD. It is not confined to the United Kingdom and, indeed, has been found in every country in the world where it has been looked for. In general, it affects about one person per million of the population. There are therefore some fifty to sixty deaths per year due to sporadic CJD in the United Kingdom. Similar figures are seen in other countries such as Australia, Canada and the USA. The cause of sporadic CJD remains uncertain. However, the most favoured current theory suggests that the normal prion protein in the brain undergoes a spontaneous change to the abnormal form, thereby resulting in disease. If this theory is correct (and it has not been proven at this point) then the disease arises simply as a chance event inside the brain. On this basis, it would not be "caught" in any way. VARIANT CJD Variant CJD was first reported in 1996. At this point in time, the CJD Surveillance Unit has not seen any cases of variant CJD with symptoms that began before 1994. Aside from 6 cases in France, one case in Ireland, one case in Italy and one case in the USA, variant CJD has been confined to the United Kingdom. The current view on variant CJD is that it has resulted from transmission of infection from BSE in cattle to humans via infectivity in food.
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
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), LSD (acid), amphetamines (speed), and cannabis (hash, marijuana, pot, ganja, skunk, dope, spliffs, joints) seems to bring on schizophrenia.
In manic depressive illness, sufferers experience mood swings that are far beyond what most people ever experience in the course of their lives. These mood swings may be low, as in depression, or high, as in periods when we might feel very elated. These high periods are known as manic phases. Many sufferers have both high and low phases, but some will only experience either depression or mania. A more technical term used to describe this illness is bipolar affective disorder . This leaflet will describe both aspects of the disorder, the particular problems they present, ways of coping with them and the range of treatments available. It is a serious condition but, with the right treatment, it is possible to live one s life without too much interference.
Schizophrenia and manic depression Usually occurs in young people May not be apparent for some year owing to subtleties And periods of perceptible good health Clinical changes: - changes in blood flow in brain - imbalances in secretion of neurotransmitters in brain. Treatment drugs to mimic or inhibit neurotransmitters
Deficiency disease Associated with malnutrition
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 1519-22 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: 1.quart of apple juice daily 2.25 drops of elixir vitriol (sulfuric acid and aromatics) 3.two spoonfuls of vinegar three times a day 4.concoction of herbs and spices 5.half-pint of sea water daily 6.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.
night blindness 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. Folk medicine has long recognized the role of the ingestion of liver in alleviating the condition, but it was not until the first quarter of the 20th cent. that vitamin A was identified as the crucial element. Treatment of night blindness consists of the oral or intravenous administration of vitamin A.
Rickets legs with rickets knee closeup legs in a child with rickets closeup of right knee
Examples of deficiency diseases Scurvy vitamin C Night blindness vitamin A Rickets vitamin D Iron deficiency anaemia
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.
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.
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
Hydrologists estimate that when the amount of fresh water per person in a country drops below 1,700 cubic meters a year the country is facing water stress.
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
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