(5) Examples of
bacterial pathogen communicable diseases
(5a) Cholera is from a bacterium called
Cholera bacteria cause diarrhoea and in severe cases causes
dangerous fluid loss - severe dehydration, which can cause
complications which can be fatal.
What does the cholera pathogen do?
The cholera bacterium produces a toxin
that causes secretion of chloride ions into the small
intestine, reducing the water potential.
Therefore this causes osmotic movement
of water into the gut, causing diarrhoea, dehydration and
loss of salts from blood.
Cholera is a serious medical condition, with
many fatalities to this day in poor countries where people
do not have access to clean potable drinking water fit for
The main symptom of diarrhoea, passing
persists for a few days.
The diarrhoea can be treated using oral rehydration therapy.
A type of fluid replacement used to prevent and treat
dehydration, especially due to diarrhoea.
It involves drinking water with modest amounts of sugar and
salts, specifically those salts of sodium and potassium e.g.
their chlorides and citrates.
The principal source, and cause of spreading, is contaminated water supply containing the
cholera bacterium, which is the means by which the cholera bacteria
Poor hygiene further contributes to the spread
of the infection because
faeces contain the cholera bacteria too.
Cholera is most prevalent in developing
countries where clean water is in limited supply - if at all.
Therefore, prevention is best obtained by using a clean water
supply - there were outbreaks of cholera in Victorian England until
it was realised the source of the infection was dirty water!
(TB) is from a bacterium called
The effects and symptoms of the tuberculosis bacteria
infection include coughing and
lung damage - older people can be severely weakened and further
medical complications may arise - one disease can be compounded with
The bacteria are conveyed through the air when infected people
cough or sneeze out droplets containing the bacterium - note that
coughing and sneezing are the principal symptoms!
Ways to minimise the spread of tuberculosis
Infected people should minimise contact with people
- avoid crowded places, sleep alone.
Although we all should, it is particularly
important that a TB infected person should practice good
hygiene - like coughing or blowing nose into tissues and carefully
disposing them, washing hands regularly, wearing a face mask if
near people, and keeping the
house well ventilated also reduces the chances of transmission.
Stomach ulcers can be caused by the bacterium
The disease, pathogen, symptoms-effects, means of spread and how to
reduce or prevent transmission for a
bacterial communicable disease causing stomach ulcers.
Stomach ulcer symptoms and effects include stomach pain, nausea
The bacteria reduce the stomach's defences against the acid it
produces to digest food and causes inflammation of the stomach
lining and damaging it.
The stomach acid (quite concentrated
hydrochloric acid) penetrates the stomach lining creating a hole
(the ulcer) that exposes the stomach tissue
The bacteria are ingested after eating contaminated food or
drinking contaminated water - referred to as an example of oral
The chances of getting a stomach ulcers by
transmission are greatly reduced by having
access to clean water and watching your personal hygiene e.g.
washing hands when going to the toilet, disinfecting food preparation
spaces and a clean house - especially the bathroom and kitchen.
Treatments for stomach ulcers include the use of antibiotics and
drugs that reduce stomach acid production.
Keywords, phrases and learning objectives for this part on
the bacterial pathogens
Be able to describe the communicable disease
infection of Cholera from the Vibrio cholerae bacteria.
Be able to describe the communicable disease
tuberculosis TB from the Mycobacterium tuberculosis bacterium.
Be able to describe how cholera and TB infections
are transmitted, their characteristic symptoms and treatment of the
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