6.2 non-bacterial pathogens

Question 1

what are pathogens?

Answer 1

-organisms which cause disease, usually microorganisms

Question 2

causative agents

Answer 2

-Infectious diseases are often first classified by the pathogen that causes them
e.g malaria or influenza caused by a virus

Question 3

3 modes of transmission

Answer 3

1.Anthroponoses
2.Zoonoses
3.Sapronoses

Question 4

Anthroponoses

Answer 4

-diseases transmissible from human to human

Question 5

Zoonoses

Answer 5

-diseases transmissible from living animals to humans

Question 6

Sapronoses

Answer 6

-human diseases transmissible from abiotic environment e.g. cholera from water

Question 7

types of transmission- direct

Answer 7

-direct physical contact
-exchange of bodily fluids
-direct contact with animals or animal waste

Question 8

types of transmission- indirect

Answer 8

-transmission through intermediates known as vectors
-airborne; aerosols, droplets
-vehicle borne; surfaces, objects
-food and waterborne

Question 9

mode of infection of flu

Answer 9

-infects cilliated epithilial cells of the respiratory system
-viral RNA reaches nucleus of host cell and produces new virus particles
-cell lyses, releasing more viruses and dying in the process
-reaction of body to the lysis causes symptoms of disease

Question 10

components of influenza virus

Answer 10

-nucleoprotein (RNA)
-lipid envelope
-capsid
-hemagglutinin
-neuraminidase (sialidase)

Question 11

how is influenza spread?

Answer 11

-droplets from coughs and sneezing
-direct contact with infected person
-contact with contaminated surfaces and infected animal waste

Question 12

Virus entry

Answer 12

-some viruses, such as those that infect bacterial cells (bacteriophages) inject only their DNA in host cell
-others such as those that infect animal cells, can be wholly engulfed (endocytosis) or have their lipid envelope fuse with the cell membrane

Question 13

structure of fungi

Answer 13

-normally single celled
-cell walls made of chitin and glycans
-they do not photosynthesise
-many fungi grow as hyphae
-spores used for reproduction

Question 14

pathogenic fungus

Answer 14

some fungi can be;
-poisonous
-cause allergies
-cause parasitic diseases

Question 15

how can fungi impact human existence?

Answer 15

-cause fungal plant disease which has a major impact on food security

Question 16

what does stem rust fungus do

Answer 16

-produces orange spores which infect the wheat plant
-carried by wind to other plants where they land, germinate and cause new infection
-extracts nutrients and causes plant tissue to erupt
-clonal, asexual production

Question 17

the word ‘protist’

Answer 17

-means the very first
-may have been the first eukaryotes to evolve on earth

Question 18

why are protists difficult to characterise?

Answer 18

-massive diversity
-unicellular or multi
-asexual and sexual
-many organelles, chromosonal DNA with proteins
-free living or live symbiotically

Question 19

which mosquitos can spread malaria?

Answer 19

-pregnant females only

Question 20

prevelence of malaria

Answer 20

-one of worlds biggest killers
-kills nearly 800000 people per year
-child dies every 45 seconds
-children most at risk as they have not developed natural immunity

Question 21

why do only females transmit malaria?

Answer 21

-require additional protein from blood to develop their eggs

Question 22

protist life cycle

Answer 22

-some reproduce asexually through binary fission
-some carry out meiosis and reproduce sexually
-some use vectors as a part of their life cycle

Question 23

malaria life cycle (summary)

Answer 23

-involves extracellular and intracellular forms
-includes sexual reproduction in mosquitos
-includes asexual reproduction in liver cells and red blood cells of humans

Question 24

3 key stages of malaria life cycle

Answer 24

1.Exo-erythrocytic cycle (Human liver stages)
2.Erythrocytic cycle (Red blood cell stages)
3.Sporogonic Cycle (Mosquito stages)

Question 25

what actually causes malaria

Answer 25

-pathogen- plasmodium

Question 26

sporogonic stage

Answer 26

-mosquito bites human and secretes saliver into blood stream to prevent coagulation
-disease transferred in form of sporozoites (capable of causing infection)

Question 27

exo erythrocitic stage

Answer 27

-malaria found in the liver and attack liver cells
-reproduce asexually
-cell lysis, burst out in to blood

Question 28

erythrocitic stage

Answer 28

-malaria burts in to blood in form of merozoites
-they invade the red blood cells
-red blood cell lysis releasing malaria and toxins which cause fever attacks

Question 29

what are endemic diseases

Answer 29

-Diseases which are constantly present in a country or area or a certain time of year
-Malaria, chickenpox and the common cold are examples of endemic diseases.

Question 30

living with endemic disease

Answer 30

-requires robust policy response
-response typically not intense for things such as influenza

Question 31

history of malaria treatment

Answer 31

-In 1920, 2 french chemists isolated the chemical quinine
- In late 1800s and early 1900s that protozoa was identified as the pathogen causing malaria and its lifecycle was deduced

Question 32

why is malaria still a global challenge?

Answer 32

-increases resistance to antimalarial drugs and insecticides
-Widespread poverty and inadequate availability of good healthcare systems in malaria endemic countries.
-Increased global air travel and migration, this might have helped the spread.
-New breeding sites for mosquitoes due to environment changes caused by humans

Question 33

why is control more effective than treatment

Answer 33

-complexity of malaria life cycle makes it hard to treat

Question 34

methods of prevention and treatment

Answer 34

-insecticide treated nets
-indoor residual spraying
-breeding site reduction
-biological control
-sudden death

Question 35

intermittent preventative treatment

Answer 35

-IPT is a dose of the drug sulfadoxine pyrimethamine recommended to vulnerable populations (pregnant women and infants) in areas where transmission is high.
-IPT is now integrated into malaria control programmes and is a national policy for pregnant woman across sub-Saharan African countries.

Question 36

antimalarial drugs

Answer 36

-Artemisinin-based combination therapies (ACTs) are the standard treatment.
-act rapidly on parasites in the blood and are able to destroy gametocytes
-different combinations prescribed depending on severity and presence of resistance in the area