12.3 Flashcards
(22 cards)
What are the two main types of transmission in animals?
- Direct transmission
- Indirect transmission
What is direct transmission?
Direct transmission – where the pathogen passes directly from one individual to another.
What is indirect transmission?
Indirect transmission – where the pathogen is passed through an intermediate like a vector, fomite, or the environment.
What are the three main ways direct transmission can occur in animals?
- Direct contact
- Inoculation
- Ingestion
How does direct contact allow the direct transmission can occurs in animals?
Direct contact – through kissing, sexual contact, skin-to-skin contact, or contact with faeces (e.g., bacterial meningitis, STIs, athlete’s foot).
How does inoculation allow the direct transmission can occurs in animals?
Inoculation – through a break in the skin, animal bites, puncture wounds, or sharing needles (e.g., HIV/AIDS, rabies, septicaemia).
How does ingestion allow the direct transmission can occurs in animals?
Ingestion – consuming contaminated food or water or transferring pathogens from hands to mouth (e.g., amoebic dysentery, diarrhoeal diseases).
What is indirect transmission?
Indirect transmission is when the pathogen is transferred from one host to another via an intermediate.
Give three examples of methods of indirect transmission.
- Fomites: e.g. bedding or towels transmitting Staphylococcus.
- Droplet infection: e.g. coughing or sneezing spreading influenza or tuberculosis.
- Vectors: e.g. mosquitoes spreading malaria, or fleas spreading plague, water too.
How can humans contract zoonotic diseases? Give examples.
Humans can contract zoonotic diseases by:
* Close contact with infected animals: (e.g. bird flu H1N1 from poultry, brucellosis from sheep).
* Consuming contaminated animal products.
* Through bites or contact with infected fluids: People can also act as vectors for diseases like foot-and-mouth, transferring pathogens between animals.
What are the 7 main factors that affect the transmission of communicable diseases in animals?
- Overcrowding in living or working conditions.
- Poor nutrition.
- Weakened immune system (e.g. HIV, immunosuppressants).
- Poor sanitation (e.g. breeding grounds for vectors).
- Climate change (e.g. spread of mosquitoes into new regions).
- Cultural practices (e.g. reuse of tools in traditional medicine).
- Poor healthcare infrastructure, such as a lack of vaccination programs or public education.
How are communicable diseases transmitted directly in plants? Give 4 examples.
Direct transmission in plants occurs when a healthy plant comes into physical contact with an infected plant.
Examples include:
* Ring rot
* Tobacco Mosaic Virus (TMV)
* Tomato and potato blight
* Black Sigatoka
What are the five main ways that indirect transmission occurs in plants?
- Soil contamination
- Wind
- Water
- Animal vectors
- Human activity
How does soil contamination allow indirect transmission in plants?
Infected plants often leave pathogens (bacteria or viruses) or reproductive spores from Protoctista or fungi in the soil. These can infect the next crop (e.g., TMV, ring rot, P. infestans).
How does wind allow indirect transmission in plants?
Wind – spores of fungi or bacteria can be carried over long distances (e.g., Black Sigatoka across Caribbean islands).
How does water allow indirect transmission in plants?
Water – water splashes can carry spores to other plants.
How does animal vectors allow indirect transmission in plants?
Animal vectors – insects like aphids transmit pathogens when feeding.
How does human activity allow indirect transmission in plants?
Human activity – hands, tools, clothes, and global trade (e.g. farm equipment spreading ring rot, TMV in tobacco products).
What environmental and human factors increase the transmission of plant diseases?
- Planting susceptible crop varieties.
- Overcrowding, which increases physical contact.
- Poor mineral nutrition, reducing resistance.
- Warm, damp conditions, ideal for spore survival and spread.
- Climate change
Give examples of impacts of climate change that may increase the transmission of plant diseases?
- Increases rainfall and wind.
- Promotes the spread of animal vectors.
- Expands pathogen range.
Describe five ways to prevent the spread of communicable plant diseases.
- Plant crops with sufficient spacing to reduce direct contact.
- Clear crop debris after harvest to remove infected plant materials.
- Rotate crops so pathogens die off without access to hosts.
- Practice good hygiene, such as cleaning boots, tools, and machinery.
Control insect vectors with biological or chemical means.
Why is climate change increasing the spread of some communicable diseases?
Climate change can increase the spread of some communicable diseases:
* Expand the range of vectors like mosquitoes.
* Increase temperatures, which support the lifecycle of pathogens.
* Raise humidity and rainfall, promoting the spread and survival of spores and pathogens in both plants and animals.
