4.1.1 Communicable diseases, disease prevention and the immune system Flashcards
Communicable diseases, disease prevention, and the immune system - Topic 1.1
Communicable diseases, disease prevention, and the immune system - Topic 1.1
Definition
Disease
Impaired functions within the body
Defintion
Health
Good mental and physical wellbeing, plus an absence of disease
Defintion
Infectious disease
A communicable disease that can be transmitted from one organism to another via a pathogen
What is a communicable disease?
They are diseases that can be passed from one organism to another, of the same or different species.
What is a pathogen?
What are the 4 types?
Pathogen: a microorganism that causes disease
4 types:
- Bacteria
- Fungi
- Viruses
- Protocista
What are the components of a bacterial cell?
Bacteria diagram
Contains: (7)
- plasma membrane
- circular DNA
- peptidoglycan celll wall
- capsule
- ribosomes
- cytoplasm
- flagella
Pathogen 1
What are the shapes and function of bacteria?
Cocci (spherical) 🔘:
- has less surface area per volume than bacilli or spirilli so it can survive in denser environments
Vibrio (curved) 🦠:
- has greater S.A:V ratio and can take up nutrients from dilute solutions more efficiently
Bacilli (rod-shaped) ➖:
- has greater S.A:V ratop and can take up nutrients from dilute solutions more efficiently
Spirilli (spiral) 〰️:
- move with a corcscrew motion and therefore meet less resistance from surrouding water
Pathogen 1
Bacteria are characterised by their cell wall
The cell wall affects how bacteria respond to antibiotics.
- Gram Positive:
purple/blue under light micrsocope; stain with crystal violet; e.g. MRSA
- Gram Negative:
red under light microscope; stai with safranin; e.g. e-coli
Pathogen 1
How do bacteria reproduce?
How do bacteria cause disease?
They reproduce via binary fission. To calculate to 2^n. n= no. of divisions
They produce toxins and cause symptoms by cell damage. They damage cell membranes, enzymes, or genetic material.
Pathogen 2
What is the structure of viruses?
What is a bacteriophage?
Structure:
-some genetic material (DNA or RNA) surrounded by a protein shell
-non-living as they cannot replicate by themselves
Bacteriophage: a virus that infects bacterial cells
Pathogen 2
Explain the stages of viral reproduction.
- The virus attaches to a specific host cell
- The genetic material from the virus is injected into the host cell
- The viral genes causes the host cell to make the new viruses
- The host cell splits open releasing the new virus
- Process repeats to other cells producing lots of virus cell
What are the components of a fungus celll?
Fungi diagram
Contains: (7)
- cell wall
- plasma membrane
- cytoplasm
- ribosomes
- vacuole
- mitochondria
- nucleus
Pathogen 3
Fungi
How do fungi grow?
How do fungi cause disease?
- many fungi are sapotrophic and feed on dead and decaying matter
- parisitic fungi feed on living organisms; tese ones are pathogenic
Growth:
budding in yeast (unicellular)
in multicellular fungi, growth occurs at hyphal tips
- they digest living cells and destroy them
- some produce toxins which affect host cells
Pathogen 4
Protoctists
How are they transmitted?
How do they cause disease?
Eukaryotic cells
Protists which cause disease are parisitic
They need a vector to transfer them to their host. They may enter the body directly through water (amoebic dysentry)
They digest and use contents of host cell, then break them open when the new protists emerge. (They don’t take over genetic material)
How do pathogens cause disease?
- travel from host to host
- get into tissues
- reproduce
- cause damage
How are pathogens transmitted?
- vectors
- physical contact
- droplet infection
- non-direct contact
What is direct transmission?
When a pathogen is transmitted directly from one individual to another.
What is indirect transmission?
When a pathogen travels from one individual to another indirectly.
Why is it important to understand how pathogen are transmitted?
It allows us to work out ways to reduce/prevent diseases occuring.
What is a vector?
A living or non living factor that transmits a pathogen from one organism to another.
3 types
What types of direct transmission are there between animals?
1) Direct contact: Any contact with the body fluids of another person; Direct skin to skin contact; Micoroogranisms from faeces transmitted on hands
2) Inoculation: Through a break in the skin; From an animal bite; Through a puncture wound
3) Ingestion; Taking in contaminated food/drink; Transferring pathogens to the mouth from the hands
What types of indirect transmission are there between animals?
1) Fomites: Inanimate objects e.g. bedding socks can transfer pathogens between organsims
2) Droplet infection: Minute drops of saliva and mucus expelled and others breathe in the droplets
3) Vectors: Transmits communicable pathogens from one host to another- usually animals
4) Water: Can act as a vector of diseases
Animals
What are 3 key factors to reduce the spread of disease in humans?
1) regular hand washing
2) improvements in living & working conditions
3) disposal of both bodily & household waste effectively
Factors affecting tranmission in animals
- overcorwded living and wokring conditions
- poor nutrition
- compromised immune system
- poor disposal of waste
- climate change
- culture + infrastructure
- socioeconomic factors
Examples of transmission between humans and animals.
How can this be minimised?
e.g. bird flu strain; brucellosis
minimised by:
- minimising close contact with animals
- washing hands thoroughly folllwoing any contact
What is direct transmission between plants?
Involves direct contact of a healthy plant with any part of a diseased plant.
What types of indirect transmission are there between plants?
1) Vectors: e.g
-wind: bacteria, viruses,fungal,or oomycete spores may be carried on the wind
-water: spores swim in the surface film of water on leaves
-animals: insects and birds carry pathogen and spores from one plant to another as they feed
-humans: pathogens ans spores are transmitted by hands, clothing, fomites, farming practice etc.
2) Soil contamination: infected plants often leave pathogens or reproductive spores from protoctista or fungi in the soil. This can infect the next crop which will be planted on the same soil.
Wht are the 5 key factors to reduce the spread of disease in plants?
1) leave plenty of room between palnts to minimise the spread of pathogens
2) clear fiels as throughly as possible- remove a traces of plants from the soil at harvesting
3) rotate crops
4) follow strict hygiene practices
5) control insect vectors
Wha are the factors affecting transmission in plants?
- planting varieties of crops that are susceptible to disease
- over-crowding increases the likelihood of contact
- poor mineral nutrtion reduces the resistance of plants
- damp, warm conditions & survival & spread of pathogens
- climate change
What is an epidemic?
When a communicable disease spreads rapidly to a lot of people at a local/national level.
What is a pandemic?
When a communicable disease spreads rapidly to a lot of people across a number of countries.
List some bacterial diseases
1) Tubercolosis
2) Bacterial meningitis
3) Ring rot
Tubercolosis
casual agent: mycobacterium
symptoms: bloody cough, weight loss, ashy skin, chest pain
transmission: air-borne drplets
treatments: antibiotics, vaccines
economic impact: 1% of people every year infected, 10-15% get TB later on
Bacterial Meningitis
casual agent: Streptococcus preumoniae
symtpoms: vlotchy rash that doesnt dissapar, temperature, hearing loss, bulging fontanelle, irritability
transmission: nose, thorat, drect, repsiratory
treatments: vaccines, antibiotics
economic impact: 10% of infected die, 25% of infected and recovered have some permenant damage, mainly affects young children an teenagers 15-19
Ring rot
casual agent: Clavibacter michiganesis
symptoms: damages leaves, poattoes (udnergorund) and tomatoes
transmission: direct contact, direct handling of infected and non-infected plants, infected seed tubers
treatments: nothing- farmer has to leave field unsued for 2.5 years
economic impacts: big impact by farmer losing field and crops- redundant field and can’t earn anything from it
List some viral diseases
1) HIV/AIDS
2) Influenza
3) Tobacco mosaic virus
HIV/AIDS
casual agent: human immunodeficieny virus
symptoms: sore thorat, tiredness
transmission: sharing/exchange of bodily fluids, unprotected sex, shared needles, contaminated blood
treatments: anti-retro viral drugs slow down the progress of the disease
economic impacts: ~39 milllion (around 70% of global total) have HIV. 800k people have died due to HIV
HIV: infected AIDS: when you get another illlness due to HIV (weakend immune system)