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AIDS
Our body’s defense system, the
immune system, helps us fight
disease. In the 1980s, a new
condition called AIDS (acquired
immunodeficiency syndrome)
started to spread. It is caused by
HIV, a virus that stops the immune
system from working properly
so that the body can no longer
defend itself. It can result in death.ENVIRONMENTAL DISEASE
Living conditions affect people’s health. Nuclear
radiation in the atmosphere can cause cancer;
pollution of the air from chemicals such as lead
can affect health, particularly that of
children; and swimming in
water that is polluted
with sewage can cause
serious infections
such as hepatitis,
typhoid, and cholera.
EPIDEMICS
When a disease affects many people
at the same time, it is called an
epidemic. Epidemics of AIDS and
of malaria, a disease carried by
mosquitoes, affect many parts of
Africa. AIDS epidemics are also
affecting industrialized countries.
In Western countries, so many
people suffer from heart disease
and cancer that these diseases are
occasionally described as epidemic.AIDS virus particles under a microscope.HEREDITARY AND CONGENITAL DISEASES
Parents can pass on certain diseases, called
hereditary diseases, to their children. Sickle
cell anemia is a hereditary blood disease.
Hereditary diseases do not usually affect all
the children in a family, and may appear
late in life. Diseases present from birth,
such as spina bifida, a defect of the
spinal cord and nervous system, are
called congenital diseases.Disease
NUTRITIONAL DISEASES
In parts of the world,
particularly Africa and Asia,
many people do not have
enough to eat. Lack of food
can cause many disorders,
including anemia, rickets,
and scurvy. In places such
as Europe and North
America, many people eat
too much. Overeating can
also cause disorders, including
obesity (fatness), diabetes, and
heart disease.Find out more
Drugs
Genetics
Health and fitness
Medicine
Medicine, history of
Microscopic life
ScienceEVERYONE EXPERIENCES DISEASE at some point in their lifetime.
Diseases happen when part, or parts, of the body stop working normally.
They may be relatively harmless or very serious. There are thousands
of diseases that can strike almost any part of the body. They range from
measles and the common cold to heart disease and emotional
disorders, like depression. Some diseases are chronic (last for a long
time), such as arthritis that makes the joints swell painfully. Other
diseases, which are called acute, occur in short, sharp attacks and
include flu (influenza). There are many different causes of disease.
Harmful micro-organisms (microscopic living things) can invade the
body and cause infectious diseases. Poor
living conditions can also cause disease.
Some diseases are present from birth;
others may be passed from parent to
child. The reasons for some diseases
such as cancers are unclear. Scientists
are constantly working to understand the
causes of diseases and find possible cures.There are several different
types of bacteria (below). Each
consists of a single living cell.
Some bacteria cause disease
in humans and animals, but
most are harmless.Causes
typhoidCauses
sore throatViruses are smaller than a living
cell. Viruses cause disease when
they enter healthy cells in order
to reproduce. The flu virus (above)
is spread from person to person by
coughing and sneezing.BACTERIA AND VIRUSES
Infectious diseases are caused
by micro-organisms,
especially bacteria and
viruses, that invade the body.
They are the only diseases
that can spread from person
to person. Typhoid and
cholera are examples of
diseases caused by bacteria;
chickenpox and measles are
caused by viruses.Hereditary diseases are passed from
parents to children in their genes.Covering a sneeze
can help prevent
the flu virus from
spreading.
Causes
boils
Heart disease is often
caused by blockage of blood
vessels in the heart. It has
been linked to a rich, fatty
diet and smoking.