Some disabilities are permanent, or last
forever. Others are temporary, or last for
only a short time. A disability can be
something a person was born with. Or it
can be the result of an illness or an accident.
A physical disability is a problem with
the body. Physical disabilities may affect
the eyes, the ears, the muscles, or the
interior organs. Some people with physical
disabilities may use wheelchairs to
move around.
A mental disability is a problem with the
brain, or mind. Mental disabilities
The smallest dinosaurs were less than 3 feet (0.9 meter) long.
BRITANNICA STUDENT ENCYCLOPEDIA Disability 53
include developmental disabilities (mental
retardation), mental illness, and
learning disabilities, such as dyslexia. A
person with a mental disability may have
trouble learning or getting along with
other people.
With medical treatment or other help,
people with disabilities can do many of
the things that nondisabled people can
do. A person with a missing leg can
learn to walk with an artificial leg. Many
kinds of mental illness can be treated
with medication or other therapies.
Organizations in a community can help
people with developmental disabilities
go to school, work, or live on their own.
#More to explore
Special Olympics
Discrimination
Discrimination is unfair treatment of one
particular person or group of people.
Usually the different treatment is because
of the person’s sex, religion, race, age,
nationality, or other personal traits.
Discrimination prevents people from
doing things that other people can do
freely. It can happen in many ways and
in many areas of life. It can happen at
work, in public, and at school. For
example, if a student is not allowed to
go to a school because of his or her race,
the school is discriminating against that
student.
Sometimes even governments have discriminated
against whole groups of citizens.
A government may pass laws that
make it harder for certain groups of
people to vote, to go to school, to travel
freely, or to do other things. For
example, South Africa had a system of
discrimination against the non-white
people of the country for many years.
The system was called apartheid.
Discrimination happens throughout the
world. It is worse in some countries than
in others. In the United States many
In South Africa, during the period called
apartheid, blacks were not allowed to use
the same beaches as whites. Such a rule is a
form of discrimination.
Some children with a physical disability
may use a wheelchair to get around.
54 Discrimination BRITANNICA STUDENT ENCYCLOPEDIA
people have worked to end discrimination.
One of the most important laws
passed to end discrimination was the
Civil Rights Act of 1964. This law protects
people from discrimination based
on race and skin color, the country a
person comes from, sex, and religion.
The U.S. government has also tried to
stop other forms of discrimination.
These include treating people differently
because of their age or because they have
a disability.
#More to explore
Apartheid • Civil Rights Movement
Disease, Animal
Animals other than humans can suffer
from diseases, or illnesses, just as
humans do. People worry mainly about
the diseases that affect animals used for
food, the diseases that affect pets, and
the diseases that can be spread from
animals to people.
Like human diseases, animal diseases
may be divided into two groups: infectious
diseases and noninfectious diseases.
Animal doctors, called veterinarians, can
treat many of these diseases.
Infectious Diseases
Infectious diseases can spread from one
animal to another. These diseases are
caused by germs called viruses and tiny
living things—bacteria, protozoans,
fungi, and worms.
One of the most feared animal diseases
is rabies. Rabies attacks the brain. A
virus found in the saliva of animals with
rabies causes the disease. Rabies most
often spreads through bites. People can
catch rabies, too. However, a vaccine can
protect people as well as animals from
rabies.
Another virus causes Newcastle disease,
which affects chickens, turkeys, and pet
birds. The symptoms are like those of
influenza, or flu. People can catch this
disease from sick birds.
Tuberculosis, a disease caused by bacteria,
affects cattle. The disease harms the
lungs. Tuberculosis can be spread to
people through cow’s milk. Because of
this, milk is often heated in a process
called pasteurization. This kills the bacteria
before they can infect a person.
Mad cow disease is caused by a particle,
or tiny piece, of protein called a prion.
Mad cow disease affects the brains of
cattle. Farmers kill cattle that are sick
with mad cow disease to keep the disease
from spreading. People can catch mad
cow disease by eating meat from sick
cattle.
A veterinarian looks at a bulldog. Veterinarians
can treat many animal diseases.
BRITANNICA STUDENT ENCYCLOPEDIA Disease, Animal 55
Heartworm is a serious disease of cats
and dogs. A worm that infects the heart
causes the disease. Medicines can prevent
and treat heartworm.
Noninfectious Diseases
Noninfectious diseases cannot be spread
from one animal to another. Many of
