Transmission of pathogens 4.1.2 Flashcards
State the lifecycle of a pathogen
- Transmission
- Entering the host
- Reproducing
- Leaving the host
What are the two types of disease transmission?
Direct and indirect
What is direct transmission?
From one host to another host
What is indirect transmission?
A second organism (vector) that is unaffected by the pathogen transfers it to a new host
Is direct physical contact direct or indirect transmission?
Direct
How are diseases transmitted through direct physical contact?
- Contact with body fluids e.g. kissing
- Skin to skin (athletes foot)
- Touching a contaminated surface
Is inoculation direct or indirect transmission?
Direct
How are diseases transmitted through inoculation
- Break in the skin
- Animal bite
- Sharing needles
Is ingestion direct or indirect transmission?
Direct
How are diseases transmitted through ingestion?
- Taking in contaminated food or drink
- Transferring pathogens from hand to mouth
Is a droplet infection a direct or indirect transmission of disease?
Direct
How are diseases transmitted through a droplet infection?
- Droplets of saliva and mucus are expelled from your mouth as you talk, cough and sneeze.
- Others breeze in this and if contaminated will pass on a pathogen
Are fomites direct or indirect transmission?
Indirect
How are diseases transmitted through fomites?
Inanimate objects e.g. bedding, socks, cosmetics
Are vectors direct or indirect transmission?
Indirect
How are diseases transmitted through vectors?
- Vectors transmit disease from one host to another
- Mosquitos transmit malaria, and water can transmit diarrhoeal diseases
How is HIV spread?
By intimate human contact, and can only be transmitted by direct exchange of body fluids.
E.g. sexual intercourse, sharing of needles. from mother to child across the placenta
How is tuberculosis spread?
- When infected people with the active form of the disease cough or sneeze, the bacteria enter the air in tiny droplets of liquid
- It is transmitted when uninfected people inhale these droplets
- In some developing countries, meat and milk can be a source of infection
What is a vector by definition?
A vector transmits communicable pathogens from one host to another. A vector is used by a pathogen to enter the host
How is malaria spread?
- Caused by plasmodium
- Transmitted to humans by an insect vector, such as mosquitoes
- These mosquitoes feed on human blood to obtain the protein they need to develop their eggs
- If the human is infected, the mosquito will take up the pathogen and pass it onto the next human
In what other ways can malaria be spread?
During blood transfusion and when unsterile needles are re-used
Name 6 factors that increase the transmission of communicable disease in animals
- Overcrowding
- Low sanitation
- Living conditions
- Access to clean water and food
- Poor ventilation
- Poor disposal of waste
What is an infectious disease?
One that is caused by pathogenic organisms
What is a non infectious disease?
Lifestyle, working conditions, genes
How do pathogens enter the body?
- Ears
- Mouth
- Eyes
- Nose
- Skin
- Vagina/penis
- Anus
- Bladder
How does indirect transmission occur between plants? (Explanation and examples)
Infected plants often leave pathogens in the soil which can affect the next crop. VECTORS
- Wind
- Water
- Animals
- Humans
- Spores
What are 4 factors that increase the transmission of communicable disease in plants?
- Overcrowded
- Poor mineral nutrition
- Damp and warm conditions
- Climate change
