Download Planet Earth and Its Environment A 5000-million

A Search For Better Health
Topic 10: Vaccinations
Biology in Focus, HSC Course
DOT Point(s)
 outline the way in which vaccinations prevent infection
 process, analyse and present information from secondary sources
to evaluate the effectiveness of vaccination programs in
preventing the spread and occurrence of once common diseases,
including smallpox, diphtheria and polio
Introduction
When an antigen is first encountered by the immune system, the
time taken to fight the infection is quite long. This is because, once
the antigen has been identified, the appropriate T cells and B cells
have to be activated and then it takes time to build up clones of
these cells.
www.mayoclinic.com
Introduction
Time is also needed for the
cytotoxic T cells to kill the
infected cells and for the B
cells to produce plasma
cells that then secrete
antibodies and bind with
the antigen to neutralise it.
stemcells.nih.gov
Introduction
If sufficient antibodies are made
to destroy all the infecting
antigens, the person recovers
completely. This is known as the
primary response. At the
same time, memory T cells and
memory B cells specific to the
antigen are produced and remain
in the body.
www.nature.com
Introduction
If the same antigen were to reenter the body in the future, the
response, known as the
secondary response, is much
quicker. After identification of
the antigen, the memory cells
will activate the production of
the cytotoxic T cells and the B
cells.
askabiologist.asu.edu
Introduction
A very large number of B cells
will then form many plasma
cells, which secrete a much
larger amount of antibodies than
in the primary response. The
effect of this is to destroy the
invading antigens before their
numbers are large enough to
cause any symptoms.
www.uic.edu
Introduction
The secondary response:
 is more rapid and requires less
antigen to initiate it
 produces a much greater
quantity of antibodies
 lasts for a longer period of
time
www.care2.com
Introduction
This type of immunity, where
the immune response occurs
and memory cells are produced,
is called active acquired
immunity. It is naturally
induced as the body has to
undergo the immune response
and suffer the symptoms of the
disease in order to develop
immunity to it.
ayurvedic-herbal-cure.blogspot.com
Introduction
Active acquired immunity can also be artificially induced through
the use of vaccines, which cause the production of memory cells
without the body experiencing the symptoms of the disease.
www.ontherecord-unisa.com.au
Vaccinations
Vaccines contain cultures of
microorganisms, which may be either:
 living but attenuated (weakened) and
therefore harmless (rabies,
poliomyelitis, measles), or
 dead (typhoid, whooping cough).
Vaccines may also contain modified
toxins called toxoids (tetanus,
diphtheria). These vaccines may be given
orally, by injection or by scratching the
skin surface.
evidencebasedliving.human.cornell.edu
Vaccinations
 Vaccines are all harmless to
the body and will not cause
the disease that they are
specific for, but still contain
the antigens that cause the
body to undergo an immune
response and produce
memory cells for that
particular antigen.
www.watoday.com.au
Vaccinations
 If the body is exposed to that
antigen in the future, the
secondary response will be
activated and the antigen will
be destroyed before any
symptoms of the disease are
experienced.
The immunity formed in this
way is usually lifelong. Each
vaccine is specific for only one
type of antigen and will therefore
give immunity for only one type
of disease.
discovermagazine.com
Vaccinations
For a vaccine to be effective, a series of vaccinations should be
given over a number of years. Each time the vaccine is introduced
into the body, a small response is produced. Over a series of
vaccinations the lymphocytes will more rapidly recognise the
antigen and the numbers of memory cells produced will be
enough to give immunity for a long time.
www.futurity.org
Vaccinations
In some cases, the numbers of memory cells decrease over time
and booster injections have to be given to increase the number of
circulating memory cells to ensure the immunity is maintained for
that disease. For example, booster injections must be given to
maintain immunity to tetanus as the number of memory cells for
this decreases over time.
www.healthtap.com
Vaccinations
Another type of acquired immunity is passive acquired
immunity, which involves the introduction of antibodies
(immunoglobulins) into the body to prevent a disease from
developing. These antibodies have been produced by another
organism that has suffered the disease.
Vaccinations
For example, if you have been exposed to the disease hepatitis A,
you may be given injections of immunoglobulins (antibodies) to
prevent you from contracting the disease. This immunity will last
for only a couple of months as no memory cells have been
produced.
2012.igem.org
Vaccination Programs
Before much was known about the cause, treatment and
prevention of disease many people, including large numbers of
children, lost their lives to diseases that today have been eradicated
or the incidence of which is very low.
www.davidicke.com
Vaccination Programs
Vaccination has been recognised as one of
the most successful public health
programs used to prevent disease. In
1974, the World Health Organization
(WHO) launched the Expanded Program
on Immunisation (EPI) to increase the
percentage of the world’s infants
immunised against the six target diseases:
diphtheria, tetanus, whooping cough,
polio, measles and tuberculosis. This
increased the percentage of all infants
immunised from 5% in 1974 to 80% in
1997, preventing around three million
deaths each year.
www.nature.com
Vaccination Programs
Mass immunisation programs not only
prevent the occurrence of the disease
in individuals, but also help to
decrease the spread of the disease
throughout the population. If the
majority of the population is
immunised against a disease, the
chance of an infected individual
coming into contact with an
unprotected person is extremely low
and the transmission of the disease is
effectively stopped. This is known as
the principle of ‘herd immunity’.
www.vaccinetimes.com
Vaccination Programs
Despite the success of vaccination programs there has recently
been an increase in the number of cases of diseases such as
pertussis (whooping cough). This is because a number of people
are neglecting to get themselves or their children immunised.
www.abc.net.au
Vaccination Programs
People are becoming complacent and thinking they will not
contract the disease because of the low incidence in the
population. They have also never experienced the seriousness of
these diseases. Individuals may also refuse to have themselves or
their children immunised because they feel the risks of side effects
are too great.
www.c100fm.com
Vaccination Programs
Smallpox, diphtheria and polio are three diseases that were very
common in the world until the implementation of vaccination
programs to try to prevent their spread and occurrence.
newsatjama.jama.com
Smallpox
Smallpox is caused by a virus that may be airborne or spread by
direct contact. It enters the throat and lungs and causes a high
fever and a blistering rash, which first appears on the face, arms
and legs and eventually spreads over the entire body. It is often
fatal.
www.learnnc.org -
Smallpox
There have been numerous
accounts in literature that
smallpox first appeared more
than 10 000 years ago and was
spread around the world by
explorers and traders. It was
introduced into Mexico in 1519
and killed millions of people.
The first recorded incidence of
smallpox in Australia was in
1789 and had a devastating
effect on the Aboriginal
communities.
www.bt.cdc.gov
Smallpox
Smallpox has killed more people than any other infectious disease
and was responsible for one-tenth of all deaths in Europe in the
19th century and more than 300 million deaths in the 20th century.
Each year until 1968, there were 10–15 million cases of smallpox,
resulting in two million deaths.
deakinscicomm.wordpress.com
Smallpox
Edward Jenner developed a
vaccine for smallpox in 1796,
but it did not become effective
because the procedure was not
widely used. The vaccine was
made available for free in
Britain from the 1840s, but was
still not widely used there until
it became compulsory.
freemasonry.bcy.ca
Smallpox
In 1967, there were still 33
countries in which smallpox was
a problem. The overcrowding,
extreme poverty, poor hygiene
and poor nutrition were
conditions present in these
countries that increased the
spread of this devastating
disease.
textbookofbacteriology.net
Smallpox
The WHO committed itself to a
worldwide mass immunisation
program in order to eradicate the
disease. This program involved
routine mass immunisation,
supplementary doses given on
special immunisation days, targeting
people who missed out on the
routine immunisations and sending
out special teams for surveillance on
all possible cases of smallpox
infection.
ecigarettereviewsite.net
Smallpox
This program proved to be very successful, and in 1979 WHO
declared that it had eliminated the virus from the world
population and eradicated the disease smallpox. The only samples
of the virus in the world today are in a couple of research
laboratories where scientists are studying its DNA.
www.humanillnesses.com
Diphtheria
Diphtheria is caused by highly
contagious and fast-acting
bacteria, often killing within a
week of the start of symptoms.
It is transmitted by close
contact with respiratory
droplets.
springwoodhistorians.blogspot.com
Diphtheria
It begins with a sore throat, fever
and rapid pulse and then the
destruction of the lining of the
throat and the formation of a
leathery membrane across the
throat. This can lead to death by
suffocation and, if not, then death
can be caused by toxins, which
cause damage to other organs such
as the heart. Even if the patient
recovers from the infection, they
can be left with permanent nerve
and heart problems.
nationalnursingreview.com
Diphtheria
Prior to development of a
vaccine, mortality rates were
high, with 90% in diphtheria of
the larynx; two-thirds of these
were children under 5 years old.
One hundred years ago
diphtheria was referred to as ‘the
deadly scourge of childhood’. In
1921 there were 206 000 cases
with 15 500 deaths in the United
States of America alone.
commons.wikimedia.org
Diphtheria
A vaccine was released in 1923
but it was not until the 1940s–
1950s that the cyclical epidemics
were reduced to occasional
outbreaks. Immunisation
programs were introduced in
Australia in the 1930s and 1940s
and resulted in a rapid decrease in
the incidence of diphtheria.
Similar programs were also
successful in Europe and other
developed countries.
textbookofbacteriology.net
Diphtheria
In 1974 there were still only 5% of children immunised against
diphtheria worldwide. The introduction of the WHO EPI saw the
percentage of children immunised worldwide increase to 80% by
1990 (only 50% of children in Africa). This corresponded to a
greatly decreased mortality rate reported worldwide.
www.historyofvaccines.org
Diphtheria
There has been only one
reported case of diphtheria in
Australia from 1994–2006. The
current immunisation program
involves the administration of
the triple antigen—diphtheria,
whooping cough and tetanus—
at 2, 4 and 6 months and a
booster injection at school entry
and 15 years. There is the chance
of a resurgence of the disease
due to some people neglecting
or refusing to vaccinate.
www.marketingfutures.com
Polio
Polio, or poliomyelitis, is a viral disease that is transmitted by
inhaling infected droplets and by direct contact. It causes fever and
headache, speech, swallowing and breathing difficulties, and
paralysis. Death occurs in 50% of the cases and nerve damage and
paralysis in 50% of sufferers.
cyrusdurant.wordpress.com
Polio
Polio first occurred thousands of
years ago and, prior to the
development of a vaccine by Jonas
Salk in 1955, thousands of children
died or were paralysed. In the years
following the introduction of the
vaccine, 200 people contracted the
disease from the vaccine and 11 of
them died. A safer vaccine
developed by Albert Sabin was
introduced and, after widespread
immunisation, there was a 60–70%
reduction in the disease.
bowerhillonline.com
Polio
Polio became very rare in industrialised
nations, and the incidence further
decreased after the EPI was introduced in
1974. In 1988, the World Health Assembly
(WHA) voted to launch a global goal to
eradicate polio. This Global Polio
Eradication Initiative involved widespread
vaccination of children under 5 years in
countries where the disease was still
endemic. In 1997, almost 450 million
children under 5 years were immunised
during National Immunisation Days.
thebioside.ning.com
Polio
There were 719 cases of wild
poliovirus in 2000. This
represents a 99% reduction in
cases since the program began in
1988, with 350 000 estimated
cases. Australia has had no
reported cases of polio since
1988 and the current
immunisation program involves
oral Sabin vaccine at 2, 4 and 6
months and a booster at school
entry and 15 years.
www.polioeradication.org
Homework
-Work on your Assessment Task