Parasitism Parasites are organisms that live in or on another organism i.e. the “host”. What do parasites gain?

°Parasites gain: - Nutrition - absorbed from the hosts tissues and fluids, or from the intestine itself °Parasites can be : - ECTOparasites - live on the outside of the body e.g. head louse (suck blood from the scalp of the host) ENDOparasites - live inside the host e.g. blood flukes, roundworms, tapeworms °Hosts can be: - Plants, animals and even bacteria (infected by bacteriophages) The host does not gain and can be harmed

Characteristics of parasites *Can penetrate the host to gain entry *Can attach itself to the host *Have protection against the immune system of the host *Show degeneration of unnecessary organ systems e.g. gut *Produce vast numbers of eggs to increase chance of reaching a new host *Use a vector or intermediate host to reach a new host *Produce resistant stages to survive outside the host

Construct a chart to summarise 9 features: - 1. Name of parasite 2. Entry to host 3. Attachment devices 4. Resistance to host’s immune system 5. Organ degeneration 6. Transfer to immediate host 7. Reproduction 8. Method of feeding 9. Symptoms and treatment

Head louse - Pediculus

1. Name of parasite - Pediculus (head louse) 2. Entry to host - ectoparasite 3. Attachment devices - claws for grasping hair, eggs (nits) glued to base of hairs 4. Resistance to host’s immune system - none 5. Organ degeneration - wingless insect 6. Transfer to immediate host - walk from one hair to another and transfer by close hair to hair contact 7. Reproduction - large numbers of eggs 8. Method of feeding - suck blood form scalp capillaries 9. Symptoms and treatment - itching of scalp/ insecticides in lotions, creams, liquids

Blood fluke - Schistosoma

1. Name of parasite - Schistosoma (blood fluke) 2. Entry to host - snail releases larvae into water bore into skin veins liver/lungs capillaries of bladder/ intestine 3. Attachment devices - suckers in adults 4. Resistance to host’s immune system - thick cuticle 5. Organ degeneration - no sense organs or respiratory system 6. Transfer to intermediate host – eggs into water larvae hatch in water and enter snails released into water from digestive system 7. Reproduction - large number of eggs released in faeces/ urine 8. Method of feeding - red blood cells 9. Symptoms and treatment - schistosomiasis/ bilharzia = enlarged spleen+liver, intestinal damage+bleeding, lethargy / prescribed drugs

Roundworm - Ascaris

1. Name of parasite - Ascaris (roundworm) 2. Entry to host - ingested eggs hatch into larvae blood vessels lungs/ alveoli penetrated coughed up and swallowed gut 3. Attachment devices - 3 lips around mouth 4. Resistance to host’s immune system - thick cuticle 5. Organ degeneration - no respiratory system 6. Transfer to immediate host -eggs ingested from faeces- contaminated food or water, from hands contaminated from soil (usually found in children) 7. Reproduction - large number of eggs (200,000 per day) 8. Method of feeding - absorb from blood and gut 9. Symptoms and treatment - slow growth and slow weight gain, abdominal pain / prescribed drugs result in egestion

Tapeworm - Taenia solium

1. Name of parasite - Taenia solium (pork tapeworm) 2. Entry to host - eating infected uncooked meat (pork) 3. Attachment devices - suckers and hooks into the gut wall 4. Resistance to host’s immune system - thick cuticle and inhibitory secretions to withstand intestinal conditions e.g. acid 5. Organ degeneration - no organs of movement or sense organs, simplified digestive system, no respiratory system 6. Transfer to immediate host - eggs have resistant coats and are ingested from faeces by pigs+ larvae develop in pig muscle and remain dormant until eaten by human 7. Reproduction - large number of eggs 8. Method of feeding - absorb from the gut directly 9. Symptoms and treatment - anaemia, diarrhoea, loss of weight, intestinal pain / prescribed drugs and meat inspection