transmission of pathogens

Question 1

define direct transmission

Answer 1

passing a pathogen from a host to new host , with no intermediary

Question 2

define indirect transmission

Answer 2

passing a pathogen from host to new host via a vector

Question 3

define transmission

Answer 3

passing a pathogen from an infected individual to an uninfected individual

Question 4

define a vector

Answer 4

an organism that carries a pathogen from one host to another

Question 5

what do pathogens have ?

Answer 5

• a life cycle that involves living in OR living on other things

Question 6

what does by-product mean ?

Answer 6

something that’s produced unintentionally when making something else

Question 7

what is the byproduct of this ?

Answer 7

• cause harm to their host

Question 8

what are the stages that the life cycle involves ?

Answer 8

• travel from one host to another (transmission)
• entering the host’s tissues
• reproducing
• leaving the host’s tissues

Question 9

what is the most common form of transmission ?

Answer 9

direct transmission

Question 10

name the ‘1st means of transmission ‘

Answer 10

• direct physical contact –> touching a person who is infected OR touching contaminated surfaces (including soil) that harbor pathogens

Question 11

what are examples of the ‘1st means of transmission’

Answer 11

• HIV , bacterial meningitis , ringworm and athlete’s foot

Question 12

what do factors that affect transmission mean ?

Answer 12

• things that make it easier and harder for something to spread

Question 13

what are the factors that affect transmission and how can one partake in that (‘1st means of transmission ‘)?

Answer 13

• HYGIENE
  –> washing hands regularly - especially after using the toilet
  –> keeping surfaces clean – especially door handles
  –> cleaning and disinfecting cuts and abrasions
  –> sterilising surgical instruments
  –> using condoms during sexual intercourse

Question 14

name the ‘2nd means of transmission ‘

Answer 14

FAECAL
–> oral transmission (usually by eating food OR drinking water - contaminated by the pathogen )

Question 15

what are examples of the ‘2nd means of transmission’

Answer 15

• cholera + food poisoning

Question 16

what are the factors that affect transmission and how can one partake in that (‘2nd means of transmission ‘)?

Answer 16

• human sewage as fertilizer: If not treated properly, it can spread bacteria to crops
• water treatment: proper treatment of wastewater and drinking water reduces the risk of cholera
• washing food: wash fresh food with treated water to avoid contamination
• cooking food thoroughly: proper cooking kills harmful bacteria

Question 17

name the ‘3rd means of transmission ‘

Answer 17

• droplet infection
  –> in which the pathogen is carried in tiny water droplets in the air

Question 18

what are examples of the ‘3rd means of transmission’

Answer 18

• tuberculosis + influenza

Question 19

what are the factors that affect transmission and how can one partake in that (‘3rd means of transmission ‘)?

Answer 19

• catch it - bin it - kill it
• cover your mouth when coughing or sneezing
• use a tissue is disposed of correctly

Question 20

what are the factors that affect transmission and how can one partake in that (‘4th means of transmission ‘)?

Answer 20

• use of mask
• washing skin after contact with soil

Question 21

what are examples of the ‘4th means of transmission’

Answer 21

• anthrax and tetanus

Question 22

name the ‘4th means of transmission ‘

Answer 22

• transmission by spores
  –> which are resistant stages if the pathogen
• can be carried in the air or reside on surfaces or in the soil

Question 23

what are social factors that affect transmission ?

Answer 23

• overcrowding –> many people living and sleeping together in one house
• poor ventilation
• poor health - particularly if a person has HIV/AIDS , as they are more likely to contract other diseases
• poor diet
• homelessness
• living or working with people who have migrated from areas where a disease is more common

Question 24

draw out the cycle of transmission of malaria

Answer 24

a person with malaria
–> gametes of PLASMODIUM in blood
–> female ANOPHELES mosquito sucks blood
–> PLASMODIUM develops and migrates to a mosquito’s salivary glands
–> an uninfected person is bitten
–> plasmodium migrates to the liver
–> plasmodium migrates to blood

Question 25

what is the transmission of malaria an example of ?

Answer 25

indirect transmission

Question 26

how can plant pathogens also be spread ?

Answer 26

through direct and indirect transmission

Question 27

how will pathogens infect plants ?

Answer 27

- as they are present within the soil it allows the plants to enter the roots

Question 28

what is the advantage for the pathogens within the plants ?

Answer 28

- if they have been damaged as a result of replanting , burrowing animals or movement caused by a storm

Question 29

what do many fungi do and how ?

Answer 29

produce spores through asexual and sexual reproduction

Question 30

what could happen to the spores + kind of transmission ?

Answer 30

could be carried in the wind --> airborne transmission (indirect as over a long distance)

Question 31

what could happen to the plant once pathogen has entered ?

Answer 31

the vascular tissue may be infected

Question 32

how are pathogens in the leaves distributed + type of transmission ?

Answer 32

when infected leaves are shed --> carry pathogen back to the soil - infect another plant ( pathogen now in soil so direct)

Question 33

what happens to seeds from infected fruits ?

Answer 33

- will spread the disease with seed dispersal infecting offspring (direct)

Question 34

what is dutch elm disease caused by ?

Answer 34

- caused by fungus and spread by the elm bark beetle (acting as a vector)

Question 35

how does the beetle act as a vector towards the tree ?

Answer 35

- spores attach to a burrowing insect --> which then attacks a plant - when an insect attacks another plant , the pathogen is transmitted to the uninfected plant

Question 36

what type of transmission would it be considered with the beetle and the tree ?

Answer 36

indirect

Question 37

what happens to certain pathogens in certain climates ?

Answer 37

- protoctista , bacteria , fungi can grow and reproduce more rapidly in warm and moist conditions

Question 38

what happens to pathogens in certain type of climates ? (CC)

Answer 38

- in cooler climates pathogens may be damaged or even killed by cold winter weather - such weather will certainly reduce their ability to grow and reproduce

Question 39

where are there greater variety of diseases which leads to ?

Answer 39

- found in warmer climates --> leads to animals or plants living in these regions are more likely to become infected