Non Bacterial Pathogens Flashcards
3 modes of transmission for influenza (flu)
Droplets
Direct contact with animal droppings or virus filled mucous from the nose
Surfaces contaminated with the virus
What is a zoonotic infection
Where a mutation occurs causing a virus that will cross the species barrier
What is the mode of infection for the flu
To infect the ciliated epithelial cells of the respiratory system.
The viral RNA reaches the nucleus of the host cell and takes over the biochemistry, producing new virus particles.
The cell eventually lyses releasing more viruses and dying in the process.
A lot of the bodies symptoms are a reaction to the lysis of the cell.
How can influenza result in a secondary bacterial infection
The death of the ciliated epithelial cells leaves the airways open to infection meaning bacterial infections can easily enter (these cause many deaths on top of the original viral infection).
What is the pathogenic effect of the flu
Fever
Shivering
Sweating
Feeling unwell
Loss of appetite
Aching muscles
Painful joints
Headaches
Sore throat
Shortness of breath
What type of virus is the flu
It’s an RNA virus which makes it more prone to mutation
What are fungi
Eukaryotic organisms with cell walls made of chitin and glucans.
What is puccinia graminis - stem rust fungus
A fungus affecting wheat and barley crops reducing yield by 50 - 80%
Mode of transmission for stem rust fungus (puccinia graminis)
It is transmitted when spores from either infected wheat plants or infected berberis are carried to young crop plants by the wind
What is the mode of infection for stem rust fungus (puccinia graminis)
When spores land on the host plant they need water to germinate.
A thread like hyphae then emerges from the spore and penetrates one of the stomata of the leaves or stem which gives the fungus a way into the internal tissues of the plant.
It secretes enzymes which which digests the plant cells and the nutrients are absorbed into the fungus.
The hyphae branch to form mycelium that feeds and grows hidden in the stem or the leaves of the healthy looking plant.
It grows best on hot days, mild nights, and wet leaves as the spores need water to germinate.
What is the pathogenic effect of the stem rust fungus (puccinia graminis)
Symptoms appear after 7-15 days after the plant has become infected
Rusty red pustules appear through the epidermis of the stem or leaf
These contain up to 100,000 rusty red spores which can be blown in the wind to infect other wheat plants
How does stem rust fungus affect crops
Absorbs nutrients from plant reducing yield.
Pustules break epidermis making it hard for plant to control respiration.
Mycelium grows into vascular tissue absorbing water and nutrients interfering with supply to growing wheat plants.
Weakens stems so plants are more likely to fall over in heavy winds and rain so they can’t be harvested effectively.
How to control stem rust fungus in wheat
Bigger spaces between plants to reduce moisture and increase distance for spore to travel.
Reducing the application of fertilisers.
Use of earlier maturing crops which avoid the time of maximum spread.
Remove any wild berberis so part of the life cycle if interrupted.
Fungicides control the growth of stem rust but also stops the plant from reproducing.
How is malaria (plasmodium spp.) transmitted
It is transmitted to a human host by a mosquito vector and the life cycle is split between the two different hosts. Transmission to the human host happens when a mosquito takes a blood meal.
Mode of infection of malaria
When the malaria enters the blood it travels to the liver
It stays in the liver for a time then releases the parasite into a red blood cell in which it reproduces asexually
After 48-72 hours the parasites burst out of red blood cells and infect others
Some parasites are taken into a female mosquito during a blood meal and passed on again
