4 Main Pathogens
Bacteria
Bacteria are single-celled, microscopic organisms which thrive in many different environments
such as the ocean, soil and the human gut. Bacteria have many organelles such as cytoplasm,
ribosomes and a plasma membrane but something that makes them all similar is the lack of
membrane-bound organelles. Bacteria are also unicellular and extremely small.
Conditions needed for growth:
Warm temperature
Moisture
Environmental pH
Oxygen
Meningitis is a type of bacterial infection which affects the membranes which protect the brain
and spinal cord. Some symptoms of meningitis include high fever, seizures, stiff neck or
drowsiness and this is spread through coughing, sneezing, kissing or sharing utensils such as
toothbrushes with the infected person.
Food poisoning is another bacterial infection which is caused by eating contaminated food
which has been stored or prepared incorrectly, or hasn’t been cooked or reheated thoroughly.
Vomiting, diarrhoea and stomach cramps are signs of food poisoning.
Fungi
Fungi are pathogens which cause disease in humans and other living organisms, they are
eukaryotic and non-vascular which means they reproduce through spores rather than through
the xylem and phloem. Fungi do not contain chlorophyll, therefore cannot photosynthesise and
they have cell walls made of chitin unlike those of plants which have cellulose cell walls.
Conditions needed for growth:
Warm temperature
Nutrients
Varying light conditions
Water activity
Slightly acidic pH
Athlete’s foot is caused by sharing towels, socks and shoes with other people and by wearing
shoes that make your feet hot and sweaty. The symptoms include itchy, white patches between
toes, red, sore flaky patches on feet and skin that may crack and bleed.
Ringworm is a common fungal infection which can affect any part of the body and the main
symptom of ringworm is a red or silver circular shaped rash which can be swollen, scaly and
itchy. Ringworm is spread through direct contact with an infected person, object or soil.
Parasite
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