Heredity
is a predisposing factor when a trait inherited from a parent puts an
individual at risk for certain diseases. Cystic fibrosis, sickle cell anemia,
and Down syndrome are examples of hereditary diseases related to
genetic abnormalities
Hereditary diseases
Hereditary diseases are the result of a person’s genetic makeup.
Hereditary diseases do not always appear at birth e.g. Mild hemophilia
may go undetected until adolescence or adulthood.
Thousands of genetic diseases are identified in humans, some are fatal.
These are common ones:
1- Sickle cell anemia: A disease affecting mostly black populations
around the world. It occurs because the body produces a defective form
of hemoglobin causing red blood cells to become sickle shaped.
2- Diabetes mellitus: A disorder of carbohydrate, fat, and protein
metabolism. The disease is due primarily to insufficient insulin
production by the pancreas
3- Hemophilia: A rare bleeding disorder caused by a deficiency of
specific types of serum proteins called clotting factors. A person with
hemophilia bleeds longer following any kind of injury because the blood
does not clot normally.
4- Down syndrome: The condition is more likely to occur in children
born to parents ages 35 to 50. Infants with this condition typically have a
sloping forehead and folds of skin over the inner corners of their eyes,
and they may have heart defects.
Life style:
A way of living of individuals, families (households), and societies e.g.
smoking, alcoholism, physical exercise, nutritional habits … etc.
Smoking
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Smoking greatly increases the risk of :
lung cancer,
heart attack
chronic lung disease
stroke,
Alcoholism:
Alcohol, the ordinary name for a substance called ethyl alcohol, grain
alcohol
Side Effects:
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Confusion
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Disorientation
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Unsteady gait
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Possible hallucinations
Education
Education is associated with better health and lower level of education,
usually, leads to poorer health. Having a good education leads to better
prospects, the chance of securing a job, a better home … etc
Other classification of health determinants:
1) Biological determinants
2) Behavioural and socio-cultural conditions
3) Environment
4) socio-economic conditions
5) Health services
6) Aging of the population
7) Gender
8) Other factors
2- External determinants (Environment).
Environment is the sum total of all living and non living things that
compose the surroundings of man.
Include factors that associated with external environment in which man is
living. These are:
A- Physical environment:
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Temperature
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Humidity
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Radiation.
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Noise.
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Lighting.
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Infrastructure and health services.
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weather- related disasters such as tornados, hurricanes, and
earthquakes
B- Chemical environment:
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Insecticides and fertilizers
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Chemical gases.
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Heavy metals (Lead, Arsenic, Cadmium ...etc)
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Food additives
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Others
C- Biological environment:
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Pathogens (viruses, bacteria, parasites ... Etc).
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Animals (domestic and wild animals).
Health services
Health care is defined as “multitude of services rendered to individuals,
families or communities by the agents of the health services professions,
for the purpose of promoting, maintaining, monitoring and restoring
health”
Health services fall into two broad categories:
1- personal health services:
These include the whole range of preventive, treatment and rehabilitative
services provided for individuals.
2- public health services.
These are concerned with the control and prevention of disease in the
community, advice on public policies for health promotion, assessment of
the health care needs of the population, and planning and evaluation of
health services.
Characteristics of health care:
1- appropriateness (relevance):
Service versus need
2- comprehensiveness:
preventive + curative + promotional
3- availability: associated with ratio e.g.
- Health centre to population
- Doctors to population
4-accessibility:
- Geographic accessibility
- Economic accessibility
- Cultural accessibility
5- affordability: the service should be affordable to the individual and the
state
6- feasibility
Pathogens
(Agent factors)
A major goal of epidemiology is to assist in the prevention and control of
disease by discovering the cause of disease( the disease agent or
pathogen).
Epidemiological triad
Environment
Host
Agent
Pathogens are what we know as agent factors of disease.
Definition:Disease agent is defined as a living or non-living substance or a force the
presence or lack of which may initiate the disease process.
Classification of disease agents:1- Biological agents
2- Nutritional agents.
3- Physical agents.
4- Chemical agents
5- Social agents.
6- Mechanical agents.
7- Absence or insufficiency or excess of a factor necessary for life (as
insulin and oestrogen).
1-Biological agents:These are living agents of disease as viruses, bacteria, fungi, protozoa,
metazoa , …….etc.
The disease may be inapparent, apparent, severe or fatal.
2-Nutritional agents:These are proteins, carbohydrates, fat, vitamins, minerals and water.
Any excess or deficiency of intake of any one may lead to nutritional
disorders.
The common nutritional problems are PEM (protein energy malnutrition),
anaemia ,goiter, obesity and vitamins deficiencies.
3- Physical agents:Exposure to excessive heat, cold, pressure, radiation ,electricity
,sound……etc.
4- Chemical agents:1-Endogenous chemicals :These are chemicals produced by the body in certain conditions as urea
(ureamia), serum bilirubin (jaundice), ketones (ketosis) ,uric acid(gout)
,calcium carbonate(kidney stones)…….. etc.
2-Exogenous chemicals:These are agents from outside the human host. Examples allergens,
metals, fumes, dust, gases, insecticides……..etc.These can be acquired by
inhalation, ingestion or inoculation and may lead to certain diseases.
5- Social agents:Examples of social factors are poverty, smoking, abuse of drug and
alcohol,
unhealthy
lifestyles,
social
isolation,
maternal
deprivation……….etc.
6- Mechanical agents:Exposure to chronic friction or other mechanical forces may result in
crushing, tearing, sprains, dislocation, fractures or even death.
7- Absence or insufficiency or excess of a factor necessary for health:a- chemical factors:Such as hormones (insulin or oestrogen) , enzymes. b-nutrients-as
mentioned above. c-lack of structure e.g. thymus. d-lack of part of
structure as cardiac defects.