3. Overview on parasites

Question 1

What is a parasite?

Answer 1

A parasite is an organism which is dependent on another organism (the host) at its expense.

Question 2

What are the limitations of the parasitic lifestyle?

Answer 2

1. Specificity to host can pose risk of extinction.
2. Must locate the optimal site on/in the host to ensure food survival.
3. Must adapt to host physiological environments.
4. Must overcome host immune defences.

Question 3

What is the hygiene hypothesis?

Answer 3

The hygiene hypothesis states that if the body is not regularly stimulated by infectious organisms that it will become inappropriately stimulated by other harmless substances resulting in an increase in allergies and autoimmune inflammatory disease.

Question 4

Describe four uses of parasites to treat medical conditions.

Answer 4

1. Helminth therapy: treatment of autoimmune diseases and immune disorder with the deliberate infestation with a helminth.
2. Larval therapy: Inserting live, disinfected maggots into the non-healing skin and soft tissue of a wound to allow the cleaning of the nectrotic tissue.
3. Leech therapy: Leeches are used to remove stagnant blood from a flap or reattached limb.
4. Malariotherapy: treating a disease by raising the body temperature by deliberately infected the patient with malaria. e.g. HIV

Question 5

Mention three other beneficial uses of parasites.

Answer 5

1. Sources for pharmaceutically-active compounds
2. Biological control agents
3. Forensic indicators