How pathogens spread

Question 1

What is a vector?

Answer 1

Any living organism that can carry a disease-producing pathogen (like a mosquito)

Question 2

Describe the cycle of how malaria is spread

Answer 2

an infected mosquito bites a human
the protist that causes malaria is injected
the liver cells become infected
the red blood cells become infected
any mosquito that bites that human becomes infected with the parasite
the mosquito bites someone else, spreading malaria

Question 3

Describe HIV and how it is spread

Answer 3

• HIV (human immunodeficiency virus) enters the blood
• reproduces inside white blood cells
• white blood cell destruction
• too many white blood cells are destroyed
• the immune system stops working (AIDS)
• the person catches diseases that would not be a problem with a healthy immune system

-it is spread through bodily fluids

Question 4

Describe Ebola and how it is spread

Answer 4

-it infects humans from other infected creatures/objects that have been in contact with the virus
-the virus infects:
liver cells
cells that line blood vessels
white blood cells

• the virus multiplies inside cells, destroying them, causing symptoms
• it is spread through bodily fluids

Question 5

How can you reduce or prevent the spread of cholera?

Answer 5

• boil water to kill bacteria before drinking

- wash hands thoroughly after using the toilet to prevent spread by touch

Question 6

How can you reduce or prevent the spread of tuberculosis?

Answer 6

• ventilate buildings to reduce chance of breathing in droplets containing bacteria/mucus
• diagnose people quickly and give them antibiotics to kill the TB bacteria
• isolate infected people to prevent them passing on the infection

Question 7

How can you reduce or prevent the spread of malaria?

Answer 7

• prevent mosquito vectors biting people
• killing mosquitoes
• keeping them off skin (mosquito net)

Question 8

How can you reduce or prevent the spread of stomach ulcers?

Answer 8

• cook food thoroughly to kill bacteria
• wash hands thoroughly before preparing food
• wash food

Question 9

Describe the ways (not pathogens) in which these diseases are spread:

(a) cholera
(b) malaria
(c) HIV
(d) tuberculosis
(e) Ebola
(f) stomach ulcers
(g) Chalara ash die-back

Answer 9

(a) through contaminated food and water
(b) through a mosquito carrying infected blood (vector)
(c) through unprotected sex, sharing needles or from a pregnant mother to child (bodily fluids)
(d) through droplets containing the TB bacteria in the air (air)
(e) from touching the bodily fluids of a dead or infected person or from raw bush meat (bodily fluids)
(f) from kissing or food (mouth)
(g) on the wind (air)

Question 10

Using malaria as an example, explain the difference between a pathogen and a vector.

Answer 10

The mosquito is a vector because it infects the human with the parasite/pathogen

Plasmodium/the protist is the pathogen because this infects the cells and causes the disease/symptoms

Question 11

How can you reduce or prevent the spread of Haemorrhagic fever (Ebola virus)?

Answer 11

• isolate infected people to stop the virus from spreading

- wear protective gear when working with infected people or dead bodies

Question 12

What precautions can be used to prevent the spread of disease?

Answer 12

• ensuring the water is clean
• cleaning surfaces
• washing hands with soap
• treating/cleaning/covering wounds
• keep food cold
• wash hands before preparing food
• cook food to kill pathogens
• use condoms/protection

Question 13

How do pathogens cause infections?

Answer 13

(Pathogens cause disease by either:

1 Producing toxins
2 Damaging host tissue)

Pathogens cause infection by:

• pathogens enter the body and begin to multiply
• the immune system attacks the pathogen