Module 7 - Infectious Disease Flashcards
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How can pathogens be classified?
- Prions
- Virus
- Bacteria
- Protozoans
- Fungi
- Parasites
Describe prions and the disease it can cause
- defective form of protein molecule
- Non-living and non-cellular
- no DNA or RNA
- 10nm
- Mad cow disease
Describe viruses and the disease it can cause
- Requires living host cell to repllicate
- Non-living and non-cellular
- contains DNA and RNA
- 500nm
- Influenza A
Describe bacteria and the disease it can cause
- Cell wall surrounding cell
- Living
- Prokaryotic, unicellular
- 100um
- Salmonella enterica - Salmonella -> vomiting cramps, dehydration
Describe protozoans and the disease it can cause
- Complex life cycle
- Living
- Eukaryotic, unicellular
- 50-150um
- Malaria - plasmodium sp.
Describe Fungi and the disease it can cause
- Has cell wall and chitin
- Living
- Eukaryotic, unicellular or multicellular
- um-mm
- Athlete’s foot
Describe macro-parasites and the disease it can cause
- arthropods or worms, internal or external
- Living
- Eukaryotic, multicellular
- mm-m
- Tapeworm - malnutrition
Explain the modes of transmission of infectious diseases
Direct contact: person-to-person contact or droplets spread from an infected individual who touches or exchanges body fluids with another individuals through touching, kissing or coughing.
e.g. chickenpox
Indirect contact: Airoborne (suspended in air), contaminated objects, food, or water
E.g. E.coli
Vector transmission: uses living organism as a medium to spread disease through bites
e.g. Malria
Explain the role of Koch’s postulates
Proved that specific microbes caused specfic diseases
- Same microorganism should be found in all organisms suffering from disease
- Microbe is extracted and cultured
- Cultured agent is isolated and healthy host is infected
- Same symptoms should be displayed in host
- Cultured agent from infected host is compared to original microbe and should be identical
Explain the role of Louie Pasteur
Established Germ Theory, disproved spontaneous generation, developed first vaccine, fermentation, pasteurisation
- Two identical flasks of broth are prepared and boiled
- One of the swan necks are removed from the flask while the other remains
- Dust and bacteria in the air enters flask 1, causing microbial growth while flask 2 remains the same
- Disproved the theory of spontaneous generation -> in the air surrounding us
Assess the cause and effects of plant diseases on agricultural production
Fire Blight
Highly infectious worldwide disease caused by bacterium Erwinia amylovora and infecting pome fruits. This results in tissue death and bacterial ooze droplets which can be spread to health plants through rain, wind and insects.
Impact: This cost $AU20 million in revenue when found in Melbourne 1997. However, strict quarantine and biosecurity has removed the disease in Australia.
Assess the cause and effects of animal diseases on agricultural production
Foot and mouth disease
Highly contagious disease infecting cloven-hoofed animals such as cattle, sheep and pigs and caused by FMD virus. This causes fever and blisters in the mouth and hooves, leading to severe production losses as heards become destroyed.
Impact: meat and live animals make up 29% of Austrlia’s agricultural exports. Countries will only import livestock free of FMD, causing severe economic consequences.
Explain the response of a named Australian plant to a named fungal pathogen
Marri Gum is native to Western Australia and is vulnerable to an introduced water mould, P.cinnamomi. The fungal pathogen lives in soil, attacking the roots of plants and leaving them unable to absorb nutrients and water.
Response: Increased lignin production protecting cell wall from pathogens
Analyse responses to the presence of pathogens by assessing the physical and chemical changes in animal cells and tissues
First line of defence - Innate, non-specific
Physical
* Skin: prevents pathogen penetration
* Mucous membrane: traps debris and microbes upon entrance
* Cilia: directs pathogen away from organs
Chemical
* Sweat: breaks down bacterial cell wall
* Amyalse and stomach acid: prevents growth and perforate most microbes,
* Urine: antimicrobal peptides along urinary tract prevent bacteria from growing
Explain the second-line of defence in the immune system response
Inflammatory response: Mast cells in damaged tissues release histamine that triggers the dilation of blood vessels and increases vascular permeability, causing redness, swelling and fever. The increased temperature makes the environment inhabitable for the pathogen.
Phagocytosis: More white blood cells like macrophages and neutrophils move into damaged tissue to engulf the pathogen. This combines with lysosome containing protease which break down the antigen and later undergo apoptosis
Lymph system: picks up the remaining microbes and pus (dead cells) then traps them in lymph nodes to be destroyed by phagocytes
Granuloma: neighbouring cells die, forming a capsule with a wall of necrotic tissue surrouding the infected cells.
Explain the third-line of defence in the immune system response
Specific defence - Adapative immunity
A unique helper T-cell recognises the MHC II antigens presented on infected cells, releasing cytokines to trigger the cloning of specific B-cells and T-cells with unique matching (BCR) or (CD3)
Antibody mediated response
* Plasma B cells: rapidly produce antibodies which bond with antigens, forming an antibody-antigen complex (agglutination and neutralisation)
* Memory B cells: remain stored in body reader for subsequent exposure
Cell mediated response
* Killer T-cells: inject perforins into infected cells causing apoptosis
* Memory T cells: remain in body read for subsequent exposure
* Supressor T cells: stop immune response when antigen is destroyed
How can local, regional and global spread of infectious diseases be limited?
Covid-19
Local: online school, hospitals
Regional: aeroplans,
Global: transport, trading
Analyse procedures that can be employed to prevent the spread of disease
- Hygiene practices: kills pathogens and reduces spread e.g. handwashing, cooking
- Quarantine: strict isolation prevents spread
- Vaccination: passive immunity (injection of antibodies for immediate protection, short-term as no memory) active immunity (inactivated version of pathogen leading to production of antibodies for specific antigen)
- Public health campaigns: health education to minimise spread
- Use of pesticides: chemicals preventing spread of pathogens
- Genetic engineering: modification of organism genome (inserting transgene) to create altered phenotype
Assess the effectiveness of pharmaceuticals
Antivirals: treats viral infections by killing the virus or supressing its ability to replicate.
-> can damage host cell, expensive
Antibiotics: treats bacterial infections (penicilin) interfering with formation of cell membran and DNA replicatin.
-> treats infection, antibiotic resistance
Explain environemental management and quarantine methods
Environemental
* Vacciantion
* Water supply
* Food Source
* Hygiene
Quarantine
* Inspection: entrance
* Regulation: rules
* Restriction of movement: travel ban
* Destruction of diseased organism
