Adaptations of pathogens

Question 1

What must a pathogen do to enter and cause disease in the host?

Answer 1

1. Enter the host
2. Multiply in host tissues
3. Resist or stimulate host defence mechanisms
4. Damage the host

Question 2

Describe vectors as an adaption for host invasion

Answer 2

Animal pathogens need to overcome the skin barrier, e.g. biting insects can overcome skin barrier without it being broken

Malaria transmitted by female anopheles mosquitoes that can penetrate into host’s skin

Question 3

Describe helicobacter’s adaptation to invade host

Answer 3

• Causes stomach infections

To combat the acidic environment of gut:
* Has flagella to swim through mucous
* Produces mucous to neutralise stomach acids

Question 4

Describe antigenic variation as an adaptation for pathogens to invade the host

Answer 4

• Some pathogens change their antigens so the host cannot recognise the pathogen on secondary exposure
• Gives the pathogen more time to colonise host

e.g. influenza virus is constantly changing to produce new antigens

Question 5

How does a host’s symptoms aid in the spread of a disease?

Answer 5

• In animals, symptoms help remove pathogens and flush disease, e.g. diarrhoea, coughing, sneezing
• Contaminate water, food, surfaces

Question 6

Identify two transmission adaptations of pathogens

Answer 6

• Fungi –> use adhesion molecules to adhere to host cells
• Prion –> secretes TNF that enables prions to invade dendritic cells in lymphoid tissues