Parasites Focus Flashcards
What is the best knowledge to have about parasites, to aid in their control?
The lifecycle
What is the definition of a parasite?
One organism living at the expense of another
Can parasite life cycles involve many hosts or vectors?
Yes
The host where sexual reproduction occurs is the ________ host
Definitive
The host where immature forms develop to sexual maturity is the ________ host
Intermediate
Vectors enable dispersal of parasite in dispersed host populations. What is usually the vector?
Flying insects
Is a parasite eukaryotic or prokaryotic?
Eukaryotic
What are the characteristics of a eukaryotic cell?
Has a nucleus, mitochondria etc
What are the 2 types of eukaryotic parasites?
Protozoa (unicellular, like yeast) and Helminths (worms)
What are 4 types of helminths?
- Nematoda (round worms)
- Flatworms (flukes, tapeworms)
- Horse hair worms (marine parasites)
- True segmented worms (leeches, earth worms)
What is the protozoa that causes malaria?
Plasmodium spp
What is the vector related to malaria, related to reproduction and then transmission?
Anopheles mosquito
What does malaria do?
- Red blood cell destruction
- Lack of blood to brain tissue
- Death
How is malaria diagnosed?
Blood test - find parasite in blood
Who is the definitive host of malaria?
The mosquito (because sexual reproduction occurs in the mozzie)
How do we prevent malaria?
Remove the vector
What am I?
* Caused by eukaryotic parasite (protozoa) subphylum Mastigophora (flagellates)
* I cause diarrhoea
* Simple life cycle - cyst ingested in contaminated water/food > cyst ‘excyst’ & colonize small intestine > cysts passed in faeces > enters water/food
* 2 lifestyle stages
- motile, invasive, actively causes disease
- dormant cyst
Giardia lamblia (intestinalis)
What am I?
* Protozoa parasite of cats and related animals
* oocysts transmitted to humans via cat faeces (unwormed cat) or from intermediate hosts that humans eat (undercooked meat etc)
* transplacental migration
* drastic affects on foetus (retardation, blindness, deafness)
Toxoplasma gondii
Can helminths spread from human to human?
Yes - round worms can (nematoda)
Describe the shape of round worms
Elongated and unsegmented
Why is pinworm endemic in Australia, very common in children?
It has a simple life cycle, and eggs are immediately infective
What type of helminth is the pinworm?
Round worm / Nematode
Ascaris lumbricoides passes from human to environment to human, in conditions where sanitation is not available. Prevalent in PNG, sometimes patients pass adult worms. What are 3 symptoms?
Ascaris lumbricoides causes:
* GIT symptoms
* Bowel/biliary obstruction
* Pneumonia (eosinophilic - Eosinophilia happens when your body produces too many eosinophils. Eosinophils are one of several white blood cells that support your immune system)
What is an example of a helminth that requires an animal reservoir to then transmit to a human?
Tapeworms
What is the disease caused by the pig tapeworm Taenia solium, that is spread via ingesting undercooked infected pork?
Cysticercosis - lesions that may be cysts or calcified
Neurocysticercosis
* Mass effects/seizures
* Hydrocephalus
* Chronic meningitis
* Spinal cord compression
Other sites
* Cardiac
* Skeletal muscle
What are control strategies for parasitic infection?
- If a vector is involved, eliminate the vector
- Stop faecal/oral transmission
- Prevent faecal contamination (waste hygiene, animals {cats!}, humans)
- Inspect meat and cook meat well!
