Multicellular Parasites Flashcards by Sarah Allen

What is parasitism?

Form of symbiosis where one organism ( parasite) benefits at the expense of another organism usually of a different species ( host)

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What is a parasite?

An organism that lives on or in another organism to the detriment of the host

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What do you call parasites that live on surface?

Ectoparasite eg. Lice/ mite

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What do you call a parasite living inside a host?

Endo parasite eg. Tapeworm

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What is the host?

Organism in or on which the parasite lives/ causes harm.

Parasite usually requires more than 1 host for completion of life cycle.

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What is a definitive host?

Organism in which the adult or sexually matured stage of the parasite lives

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What is the intermediate host?

Organism in which the parasite lives during a period of its development only

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What is a vector?

Living carrier- transports a pathogenic organism from an infective to a non infective host

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What is a direct life cycle?

There is a definitive host. Eg. Cow-eggs-worms-cow

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What is the secondary life cycle?

An intermediate host is required eg. Sheep-egg-snail- worms-sheep

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What are the major components of a parasite life cycle?

Growth development, reproduction and transmission

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What are the 2 main groups of parasite?

Parasitic Protozoa (unicellular)
Parasitic helminth (multicellular)

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List the parasitic Protozoa?

Flagellates
Amoebae
Sporozoa
Ciliates

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List the parasitic helminths?

Round worms
Nematodes
Flat worms (Platyhelminthes ) these can be subdivided into tape worms (Cestoda) and flukes (Trematoda)

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List the characteristics of helminth parasites?

Multicellular , eukaryotic, tube like/ flattened bodies exhibiting bilateral symmetry

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How are helminths different from viruses bacteria and fungi?

They don’t proliferate within their host-they grow moult and mature and produce offspring which are voided from the host to infect new hosts

Why are people often a symptomatic with worms?

Slow growing therefore resultant disease is slow in onset and chronic unless you have a large worm burden ( more worms)

List the characteristic of nematodes (round worms)?

Long thin unsegmented tube like bodies- mouth and digestive tract
Fluid filled internal body cavity (hydrostatic skeleton)
Use muscle to thrash for movement
Separate sexes well developed reproductive systems
Eg ascaris lumbricoides, pinworm and hook worm

List facts about roundworms?

WHO 25% world infected
Grow to 13 inches and lay 300000 eggs per day
Cause distension of abdomin in starving children

How are roundworms transmitted?

Contaminated soil and contact with faeces
Travel through organs, coughed up- swallowed and mature in intestine
Migrate to internal tissue

What are the symptoms of round worm?

Distended abdomin
Diarrhoea 
Vomiting
Lethargy
Lack of appetite

What are ascaris lumbricoides ?

Roundworms- large bodies 3 prominent anterior lips
Life cycle : pulmonary migration- larvae released from ingested eggs - invade tissue through lungs- return to gut to mature
Cause gastroenteritis, protein depletion,malnutrition gut obstruction
Transmitted through soil

What are pin worms (threadworms)?

Form of round worm- get from contaminated food
Entire life spent in human host
Adults live in large intestine- females lay eggs at night around the anus
90% children infected through contaminated clothes/ bedding
Direct life cycle

List the characteristics of the hookworm (strongyloids)?

Dorsally curved mouths cut tissue
Larvae develop in external environment before infecting host by penetrating the skin
Undergo pulmonary migration- settle in gut to feed
Cause anaemia

What is the pathology of a hookworm?

Move several time a day to feed on blood- release an anticoagulant so feeding site continues to bleed- chronic haemorrhage Minor symp. Itchy papules at site- cough wheeze with larvae in lungs Major symp. Tired, aches, pallor, SOB, oedema Direct life cycle!

What are the 2 classes of Platyhelminthes ?

Cestodes or tapeworms | Trematoda (flukes)

List some facts about the tapeworm?

Long flat, absorb food from cuticle of host, up to 35 feet long,attach to intestines, adults segmented and have scolex for attachment that contains suckers and hooks. Body made of proglottids that contain male and female reproductive organs. Proglottids farthest from head contain eggs and these break off and carry on the cycle.

Name the 2 types of tapeworm?

Beef- taenia saginata - host cattle- transmitted to humans in contaminated raw/ undercooked meat. Develop in intestines 3-6 months Pork - taenia solium host pigs.

What are the symptoms of tapeworm?

``` Cough, SOB Abdominal pain Nausea and diarrhoea blood in stool Wt loss fatigue Presence of worn in vomit/ stool ```

How do you prevent tapeworms?

Cook beef and pork thouroughly Antihemintic drugs Surgery often not a option as proglottids can be left behind.

List some facts about trematodes?

2 groups monogenea and fastciolosis 24000 species Few cms in length 2 suckers 1 close to mouth 1 on underside of animal

What is the blood fluke ( schistosomiasis )?

Intermediate host- snail Larvae released in h2o and burrow into skin of humans Organs affected liver and lungs Parasite reaches maturity reproduces in human - eggs released in urine

What is human liver fluke disease?

Caused by flatworms- eggs pass out in faeces Endemic in 75 developing countries 600,000,000 infected- treat with anthelmintic drugs. penetrate skin travel to lung then migrate to liver. Can live 4-20 yrs. illness caused by antigens produced by trapped eggs

What is the human bot fly?

Lays eggs in human host - larvae grows and eventually falls out.

What does the filaria worm cause?

Elephantitis- caused by wuchereria bancrofti. Introduced by mosquito bite Migrate to lymph system causing blockage- lymph can't circulate Embryos sense night move to skin surface and wait to be picked up by a mosquito .

What is a castrating barnacle?

Enters the exoskeleton of crab and eventually controls the crab.

What is leucochloridium paradoxum?

Type of fluke Take up residence on snails eyestalks Eaten by birds and cycle starts again

What is cymothoa exigua?

Parasitic crustacean Attaches to fishes tongue feed on blood Tongue atrophies and the parasite takes over as the tongue

What is lamprey?

Type of parasitic fish Attach to fish and feed on blood Very specialised mouth parts.