12.3 - Transmission Of Communicable Diseases

Question 1

What are the two main types of transmission of communicable diseases between animals ?

Answer 1

Direct and indirect

Question 2

What are the 3 main types of direct transmission in animals ?

Answer 2

1. Inoculation
2. Direct contact
3. Ingestion

Question 3

What happens in ingestion in the direct transmission of animal pathogens ?

Answer 3

• taking in contaminated food or drink
• transferring pathogens to the mouth from the hands
• eg. Diarrhoeas diseases & Amoebic dysentery

Question 4

What are the 3 ways pathogens can be spread via inoculation ?

Answer 4

• through a break in the skin for eg. During sex ( HIV/AIDS)
• from an animal bite for eg. Rabies
• through a puncture wound or through Sharing needles eg. Septicaemia

Question 5

What are the 3 ways pathogens can be spread via direct contact ?

Answer 5

• kissing or any contact with the body fluids of another person for eg. Bacterial meningitis, STD
• direct skin to skin contact for eg.ring worm, athletes foot
• microorganisms fro, faeces transmitted on the hands for eg. Diarroheoel diseases

Question 6

What is indirect transmission ?

Answer 6

Where the pathogen travels from one individual to another indirectly

Question 7

What are the 3 main types of indirect transmission of pathogens between animals ?

Answer 7

1. Formites
2. Vectors
3. Droplet infection

Question 8

What is formite ?

Answer 8

• where an inanimate object such as socks,bedding or cosmetics can transfer pathogens
• eg. Athletes foot & gas gangrene

Question 9

What occurs during a droplet infection ?

Answer 9

• minute droplets of saliva or mucus are expelled from the mouth during talking , coughing or sneezing
• if the droplets contain pathogens when healthy individuals breathe the drops in they may become infected
• eg, influenza & tuberculosis

Question 10

What are the most common types of vector to spread diseases between animals ?

Answer 10

• Mosquito- malaria
• dogs,foxes and bats carrying rabies
• fleas carrying plague

Question 11

What is a non animal example of a vector ?

Answer 11

Water which can transit diarrhoeal diseases

Question 12

What disease can be transmitted between sheep and humans ?

Answer 12

Brucellosis

Question 13

What are some factors which can increase the risk of transmission of diseases between animals ?

Answer 13

• overcrowded living and working conditions
• poor nutrition
• a compromised immune system eg. HIV/AIDS
• poor disposal of waste , providing breading sites for vectors
• climate change = can introduce new vectors and new diseases for eg. Increased temp promote the spread of malaria as or mosquito species is able to survive over a wider area
• culture and infrastructure - in many countries traditional medical practises can increase transmission
• socioeconomic factors - eg. Lack of trained health workers and insufficient public warning when there is an outbreak of disease can also affect transmission rates

Question 14

Can plant pathogens be transmitted directly ?

Answer 14

Yes if a part of a healthy plant comes into direct contact with a part of an infected plant

Question 15

What are some plant pathogens which can be transmitted directly ?

Answer 15

Ring rot , TMV , black Sigatoka, potato blight

Question 16

What are the two main types of indirect transmission of pathogens in plants ?

Answer 16

Soil contamination
Vectors

Question 17

What is soil contamination ?

Answer 17

• infected plants often leave pathogens or reproductive spores from protoctista or fungi in the soil
• this can infect the next crop
• some pathogens or their spores can also survive the composting process so the contaminated compost can infect plants it is spread on
• eg. TMV, ring rot bacteria

Question 18

What are the 4 main types of vectors which can spread plant pathogens ?

Answer 18

1. Wind
2. Water
3. Animals
4. Humans

Question 19

How is wind a vector ?

Answer 19

bacteria, viruses and fungal or oomycete spores may be carried on the wind

Question 20

Explain how water is a vector ?

Answer 20

• spores swim in the surface film of waters on leaves
• raindrop splashes carry pathogens and spores etc.
• eg. Potato blight which swim over films of water on the leaves

Question 21

Explain how animals are vectors ?

Answer 21

• insects and birds carry pathogens and spores from one plant to another as they feed
• insects such as aphids inoculate pathogens directly into plant tissues

Question 22

Explain how humans are vectors ?

Answer 22

pathogens and spores are transmitted by hands, clothing, fomites, farming practices and by transporting plants and crops around the world

Question 23

What are some factors affecting the spread of communicable diseases between plants ?

Answer 23

• plant varieties of crops that are susceptible to disease
• over crowding increases the likelihood of contact
• poor mineral nutrition reduces resistance of plants
• damp,warm conditions increase the survival and spread of pathogens and spores
• climate change - increased rainfall & wind promote the spread of diseases
• changing conditions allow animal vectors to spread to new areas , drier conditions may reduce the spread of disease