Parasites Flashcards
What is a parasite?
Organisms which inhabits another organism (host) and benefits by deriving nutrients at the others expense
What is symbiosis?
Organisms lives in close association
What is mutualism?
both species benefit from the interaction
What is Parasitism?
parasite derives benefit and the host gets nothing in return but always suffers some injury
What is commensalism
parasite only is deriving benefit without causing injury to the host
What is definitive host?
Host harbours adult/or sexual reproduction occurs (humans usually definitive)
What is the Intermediate host
Host harbours lavae/asexual stages of parasite
What is the paratenic
Parasite is viable with no further development
How are parasites classified?
Protozoa - micro parasites Helminths - macro parasites (worms)
How are helminths subdivided?
Platyhelminths - flat worms Nematodes - round worms
What is involved in a direct life cycle?
Only one host - definitive host
What is meant by a simple indirect life cycle?
2 hosts - definitive (adult and sexual stage) and intermediate stage (asexual/lavae stage)
What is meant by a complex life cycle?
More than 2 intermediate hosts and definitive host; there can be paratenic host too
Describe the ascariasis lifescycle..
Direct lifecycle - human = definitive host
Describe the 2 phasis of ascariasis..
Lung migration phase - loefflers syndrome - dry cough, dyspnea, wheese
Intestinl phase - worm burden - malnutrition
How is ascariasis diagnosed?
Eggs/worms in faeces
How is ascariasis treated?
Albendazole
What is the life cycle of schistomiasis?
Male/female reporduce in human (definitative host) -> eggs releases in faeces -> infect snails (intermediate host) ->asexual reproduction in snail forming motile larvae -> penetrate human skin and blood vessels
What are the clinical manifestations of schistomiasis?
- Swimmers itch
- Katayama fever
- Chronic schistomiasis
- Urinary schistomiasis - haematuria, bladder fibrosis, squamous cell carcinoma in bladder
- hepatoschitomiasis - portal hypertension, liver cirrhosis, abdo pain, hepatosplenomegaly
How is schistomiasis treated?
Praziquatel
What type of host are humans in hydatid diease?
Intermediate Host - accidental host (usually dogs/sheep)
What is the life cycle of a hydatid disease?
Humans are the intermediate host - catch it from faeces of dogs (as dogs dont eat humans, usually stops at humans) - naturally, passes to sheep and dogs eat sheep
What are the clinical manifesatations of hydatid disease?
Cysts - 70% liver, 20% lungs
What type of parasite is malaria?
Protozoa (micro) - plasmodium
WHat is the host of malaria?
Female anopheles mosquito
What plasmodium type is most clinically relevant?
P Falciparum
What are the clinical features of malaria?
Rupture RBCs, block capillaries and cause inflammatory reactions (associated symptoms)
What is the lifecycle of cryptosporis?
DIrect life cycle - humn are the only host (feacal oral contamination)
CLinical features of cryptosporis
Incubation period (2-10 days)
Watery, mucous diarrhoea (no blood)
Self limiting - up to 2 weeks
Bloating, nausea, cramping, vomiting
How does cryptosporis spread?
Human -> human - swimming pools, child care workers, resisdents/carer, healthcare workers, traveller
Animal -> human - backpackers, farm workers, visits to farms/petting zoos
