Download 13.infectiousdiseases

CHAPTER 13
INFECTIOUS
DISEASES
Leonardus, S.Si.
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Content
• Cholera, malaria, tuberculosis (TB) and
HIV/AIDS
• Antibiotics
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Learning Outcomes
Candidates should be able to:
• (a) define the term disease (see page 37) and
explain the difference between an infectious
disease and non-infectious diseases (limited to
sickle cell anemia and lung cancer; see pages
40 and 41);
• (b) describe the causes of the following
diseases: cholera, malaria, TB, HIV/AIDS,
smallpox and measles;
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Learning Outcomes
• (c) explain how cholera, measles, malaria, TB
and HIV/AIDS are transmitted;
• (d) discuss the roles of social, economic and
biological factors in the prevention and control
of cholera, measles, malaria, TB and HIV/AIDS
(a detailed study of the life cycle of the malarial
parasite is not required);
• (e) discuss the global patterns of distribution of
malaria, TB and HIV/AIDS and assess the
importance of these diseases worldwide;
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Learning Outcomes
• (f) outline the role of antibiotics in the treatment
of infectious diseases;
• (g) use the knowledge gained in this section in
new situations or to solve related problems.
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• Infection: the invasion of any living organism by
disease-causing microorganisms (pathogens),
which proceed to establish themselves,
multiply and produce various symptoms in their
host
• Disease: a condition in which the normal
function of some part of the body (cells, tissues
or organs) is disturbed
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• Infectious diseases are transmissible or
communicable diseases. The pathogen can
spread from infected people to uninfected
people
• The pathogen cannot survive outside the
human body, others can survive in water,
human food, feces or animals
• Some people may spread a pathogen even
though they do not have a disease themselves,
such as people are symptom-less carriers
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• The way in which a pathogen passes from one
host to another is called the transmission cycle
• The pathogen also spread up by:
–
–
–
–
–
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Respiratory droplets/vomits
Direct body contact/sexual intercourse
Arthropod vectors
Air borne transmission
Water borne transmission
The fecal-oral route
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CHOLERA
1.It is caused by the bacterium Vibrio
cholerae, water borne transmission
2.It occurs where people do not have access
to proper sanitation
3.If the bacteria do reach the small intestine
they multiply and secrete a toxin,
Choleragen, which disrupts the functions
of epithelium so that salts and water leave
the blood causing severe diarrhea
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CHOLERA
Pathogen
Vibrio cholerae
Methods of transmission
Food-borne, water-borne
Global distribution
Asia, Africa, Latin america
Incubation* period
1 – 5 days
Site of action of pathogen
Wall of small intestine
Clinical features
Severe diarrhoea, loss of water and salts,
dehydration, weakness
Method of diagnosis
Microscopical analysis of feces
Annual incidence worldwide
5,5 million
Annual mortality worldwide
120.000
*Incubation : the phase in the development of an infectious disease between initial infection
and the appearance of the first symptoms.
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MALARIA
1.It is caused by the protist Plasmodium,
2.The vector is Arthropod (insect), female
Anopheles mosquitoes
3.Malaria may also transmitted during blood
transfusion and when unsterile needles are
reuse
4.The sporozoites, merozoites, and
tropozoites attack liver and red blood cells
5.If people are continually reinfected they
become immune to malaria
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MALARIA
Pathogen
Plasmodium falciparum, P. vivax, P. ovale, P.
malariae
Methods of transmission
Insect vector; female Anopheles mosquito
Global distribution
Throughout the tropics and subtropics
Incubation* period
From week and to a year
Site of action of pathogen
Liver, red blood cells, brain
Clinical features
Fever, anemia, nausea*, headaches, muscle pain,
shivering, sweating, enlarge spleen
Method of diagnosis
Microscopical examination of blood
Annual incidence worldwide
300 million (90% in Africa)
Annual mortality worldwide
1,5 – 2,7 million; intropical Africa malaria kills 1
million children under the age of 5
*nausea: A feeling of sickness, with loathing of food and inclination to vomit
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MALARIA
Plasmodium malariae
Quarterner Malaria
Plasmodium vivax
Tertiana Malaria
Plasmodium falciparum
Tropical Malaria
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Acquired Immuno Deficiency Syndrome (AIDS)
1. It is caused by the HIV (Human Immunodeficiency
Syndrome) or Retro Virus
2. The virus infects and destroys cells of the body’s
immune system  T helper Lymphocyte
3. AIDS is not disease, no vector, and cannot survive
outside the living things.
4. Spread up by intimate human contact, sexual
intercourse, blood donation, sharing of intravenous
needles and across the placenta from mother to
fetus.
5. Homosexuals has high risk of AIDS  Why ???
6. HIV is slow virus and after infection there may not
be any symptoms until years later. At this stage a
person is HIV positive but does not have AIDS.
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Acquired Immundeficiency Syndrome (AIDS)
• Structure of HIV and HIV infection
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Acquired Immundeficiency Syndrome (AIDS)
Pathogen
Human Immunodefeciency Virus (HIV)
Methods of transmission
In semen and vaginal fluids during sexual intercourse, infected
blood or blood products, contaminated hypodermic syringes,
mother to fetus across placenta, mother to infant in breast milk
Global distribution
Worldwide, especially in sub-saharan africa and south-east asia
Incubation* period
Initial incubation a few weeks, but up to ten years or more before
symptoms of AIDS may develop
Site of action of pathogen
T helper lymphocytes, macrophages, brain cells
Clinical features
HIV infection – flu-like symptoms and then symptomless
AIDS – opportunistic infections including pneumonia, TB, and
cancer; weight loss, diarrhoea, fever, sweating, dementia
Method of diagnosis
Blood test from antibodies to HIV
Estimated total number of people
infected with HIV world wide in
2002
42 million
Estimated number of few cases of
HIV infection worldwide in 2002
5 million
Estimated number of deaths from
AIDS-related diseases worldwide
in 2002
3,1 million (one third due to TB)
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Acquired Immundeficiency Syndrome (AIDS)
HIV Life Cycle
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Acquired Immundeficiency Syndrome (AIDS)
HIV Infection Graphic
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Acquired Immundeficiency Syndrome (AIDS)
AIDS Victims
There is as yet no cure
for AIDS and no vaccine
for HIV.
How we stop the spread
of HIV ?
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TUBERCULOSIS (TB)
1. It is caused by two bacteria, Mycobacterium
tuberculosis and M. bovis
2. These bacteria particularly attack the lungs, but it
can spread throughout the whole body and even
infect the bone tissue
3. Some people become infected and develop TB
quite quickly, whilst in other the bacteria remain
inactive for many years
4. 30% of the world’s population is infected whit TB
without showing any symptoms of the infection
5. TB is spread when infected people with the
active form of the illness cough or sneeze and
the bacteria are carried in tiny droplets of liquid
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TUBERCULOSIS (TB)
Pathogen
Mycobacterium tuberculosis and M. bovis
Methods of transmission
Airborne droplets; via unpasteurised milk
Global distribution
worldwide
Incubation* period
Few weeks or months
Site of action of pathogen
Primary infection in lungs; secondary infection in
limph nodes, bones and gut
Clinical features
Racking cough, coughing blood, chest pain,
shortness of breath, fever, sweating, weight loss
Method of diagnosis
Microscopical examination of sputum for bacteria,
chest-X ray
Annual incidence worldwide
(1998)
8 million (more than 6000 cases in UK)
Annual mortality worldwide
(1998)
2 million
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TUBERCULOSIS (TB)
Global Distribution of TB
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