If one is in good health they are:
- able to carry out normal mental and physical tasks
- well fed with a balanced diet
- usually happy with a positive outlook
- suitably housed with proper sanitation
- well integrated into society
- free from diseases
What is disease?
- Disease is a departure from good health caused by malfunction of the mind or body
- symptoms can be physical, mental or social
- those caused by living organisms are called infectious diseases - usually physical
Parasites and Pathogens
- Parasites
- Live on (external) or in (internal) another living thing (host)
- they cause harm to the host by taking nutrients
- they may live all or part of their life on the host
- they can overburden the host and make it more susceptible to secondary infections
- Pathogens
- this is an organism that causes disease
- they live by taking nutrition from their host and cause damage in the process
- includes a wife range of bacteria, fungi, protoctist and viruses
- Bacteria - cholera
- caused by bacterium Vibrio cholerae
- it is a water-borne disease and spreads through contaminated water, food or shell fish
- they act on the walls of the small intestine causing diarrhoea, dehydration and weakness.
- Tuberculosis
- aka TB is an infectious disease that can affect any part of the body although it is usually found n the lungs as these are the first site of infection
- it kills approx 2 million people each year - more than any other infectious disease
- tuberculosis is caued by one of two species of rod shaped bacteria
- Mycobacterium tuberculosis
- Mycobacterium bovis
- Fungi - Athletes foot and ringworm
- Caused by Tinea fungus
- many different species that causes these diseases
- they live in the skin
- cause redness and severe irritation
- Viruses - TMV and HIV
- TMV - tobacco mosaic virus - affects plants
- HIV - human immunodeficiency virus - affects humans
- also more common diseases such as colds and flu.
- take over the cells genetic machinery and organelles to allow it to reproduce
- Protosctist
- Amoeboid dysentery
- Malaria
- enter cells and feed on the contents as they grow
TRANSMISSION OF DISEASE
For a micro-organism to be considered a pathogen they must
- travel from one host to another
- gain entry to the host's tissues
- reproduce
- resist the defences of the host
- cause damage to the host's tissues
Forms of transmission
- by the means of a vector (carrier)
- by physical contact
- by droplet infection
- Malaria
- caused by eukaryotic Plasmodium
- Plasmodium falciparum is the most common
- spreads by the female Anopheles mosquito
- these feed on blood
- the parasite lives in the red blood cells and feed on the haemoglobin
- HIV/AIDs
- The HIV virus enters the body and may remain inactive
- This is known as being HIV positive
- once active, the virus attacks and destroys T helper cells in the immune system
- these cells help to prevent infection
- their destruction reduces the person's ability to resist infection
- EFFECT
- you are unable to defend yourself against any pathogen that enters your body
- these are known as opportunistic infections
- it is the effect of these that eventually kills as person with HIV
- AIDS stands for acquired immune deficiency syndrome
- Transmission
- Exchange of bodily fluids such as blood-to-blood contact
- unprotected sex
- unscreened blood transfusions
- use of unsterislised surical equipment
- sharing hypodermic needles
- accidents such as 'needle-stick'
- across the placenta or during childbirth
- from mother to baby during breast feeding
- Tuberculosis (TB)
- TB is an infectious disease that can affect any part of the body although it is usually found in the lungs as these are the first site of infection
- Pulmonary tuberculosis is spread through the air by droplets containing the bacteria, released into the air when infected individuals cough, sneeze or even talk.
- normally takes close contact with an infected person over a period of time rather than a causal meeting in the street to transmit the bacteria
- Symptoms (droplet infection)
- the symptoms of pulmonary tuberculosis initially include a persistent cough, tiredness, and loss of appetite that leads to weight loss.
- As the disease develops, fever and coughing up of blood may occur
- Risks
- some groups are at greater risks of contracting TB than others.
- people who are in close contact with infected individuals over long period e.g. living and sleeping in overcrowded conditions
- work or reside in long term care facilities where relatively large numbers of people live close together e.g. old people's home, care homes, hospital or prisons
- people from countries where TB is common
- have reduced immunity such as
- the very young or very old
- those with AIDS
- people with other medical conditions that make the body less able to resist disease e.g. diabetes, or lung disease such as silicosis
- those undergoing treatment wit immunosuppressant drugs eg. following a transplant surgery
- the malnourished
- alcoholics or injecting drug-users
- the homeless
The World Health Organisation (WHO)
- WHO states that good health is a human riht
- poor health causes a lot of suffering
- Ill health has an economic cost as a result of medical provision and loss of productivity
- worldwide, many peopl have no access to the basic requirements for good health
- contributing factors
- poverty
- lack of proper shelter
- lack of purified water
- poor nutrition
- poor hygiene
- lack of government investment
- poor/inadequate education on disease, it causes and transmission
- civil unrest or warfare
- Malaria
- kills around 3 million people peryear
- about 300 million are affected worldwide
- it is limited to were the vector (Anopheles mosquito) can survive
- 90% of sufferers live in sub-Saharan Africa
- It is difficult to control
- mosquito
- resistant to insecticides/pesticides/chemicals used for control
- build up in food chains/kill predators
- breeds quickly/very common/lays many eggs
- breeds in small bodies of water/inaccessible places
- especially in rainy seasons
- difficult drain/spray/cover
- difficult to encourage everyone to use netswide range of increasing because of climate change
- rests and hides in houses
- Plasmodium
- side effects of (e.g. anti-malarial) drugs/people don't take drugs long enough (think they are well but not)
- many strains and species
- resistant to drugs
- inside red blood cells or liver cells
- antigen concealment
- dormant/in body for a long time/symptomless carriers/long incubation
- different stages in life cycle in the body
- no vaccine/difficult to develop vaccine
- people lose immunity if malaria is eradicated
- HIV/AIDS
- Spreading in pandemic proportions (is an epidemic of infectious disease that is spreading through human populations across a large region)
- 45 million people living with HIV/AIDS at the end of 2005 (>half in sub-Saharan Africa)
- 5 million newly infected each year
- at the end of 2006 30 million died as result of HIV/AIDS related disease
- Epidemiology
- = patterns in the occurrence of the disease in the human population
- it identifies the cause of a disease
- the risk factors associated with the disease
- determines the incidence of a disease
- determines the prevalence of the disease as well as the mortality and morbidity
- study how quickly it's spreading
- identify countries/part of population at risk
- identify a disease as endemic, epidemic or pandemic
- ENDEMIC: always present in a population
- EPIDEMIC: spreading rapidly to a lot of people over a large area
- PANDEMIC: a worldwide epidemic
- they target education programmes at people at most risks
- target advertisements to raise the awareness
- target screening programmes to identify individuals at risk
- provide specialist healthcare in certain areas
- provide vaccination programme for the major disease
- targeting research to find cures for the major disease
