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Parasitology > Unit 2: Plathyhelminthes: Trematoda, Monogenea, Cestoidea > Flashcards

Unit 2: Plathyhelminthes: Trematoda, Monogenea, Cestoidea Flashcards

1
Q

Flatworm Structure

A

Bilaterally symmetrical and triploblastic (3 cell layers)
No body cavity other than gut (have to be flat, gut is highly branched, respire by diffusion)
No anus
Only one opening to ingest food and expel waste

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2
Q

Class Trematoda (Digenea)

A

Also called flukes
All forms are parasitic
Specialized for parasitism in animal tissues
Parasitic in one, two or more intermediate hosts
Adults parasitize a definitive host

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3
Q

Class Monogenea

A

Usually hermaphrodite
The male reproductive system develops before the female
Direct life-cycles with no asexual repro (unlike Digenea)
Larval stage is generally ciliated (called oncomiracidium) that is responsible for transmission from host to host
Eat blood, mucus, and epithelial cells of host
Ectoparasites on gills

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4
Q

Class Cestoda

A

Tapeworms
Intestinal parasites in vertebrates
Humans are usually definitive hosts (juveniles are worse to have)

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5
Q

Flukes

A

Most common and abundant parasitic worm of all vertebrates
Parasitize nearly every organ
At least two hosts (first is a mollusc)
Many have have second or third intermediate hosts
Infect domestic animals and humans

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6
Q

Stages of development for Digenea larvae (6)

A
  1. Egg - from the host to outside in water
  2. Miricidium - hatches from egg, has cilia that can allow it to swim in water, free living
  3. Sporocyst - develops in the snail - many cells develop
  4. Redia - asexual reproduction in the host
  5. Cercaria - outside of snail (free living) - has a type of tail
  6. Metacercaria - free living - has to be eaten by host
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7
Q

Where do flukes parasitize?

A

Digestive tract, liver, pancrease
Some in lungs, trachea, kidney, bladder, blood vessels
Some in eyes, nose, under the skin, and even brain (rare)

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8
Q

Monostome

A

Only an oral sucker

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9
Q

Amphystome

A

Has oral sucker and acetabulum at the posterior end of the body

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10
Q

Distome

A

Oral sucker on the anterior end and acetabulum is elsewhere on the ventral surface of the body

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11
Q

Fasciola hepatica

A

Sheep liver fluke
Can be found in liver of other animals and humans too
Parasite resides in the bile ducts inside the liver rather than the liver itself

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12
Q

Schistosoma sp.

A

Reside in the veins of the definitive host (can block them and cause problems)
Sexes are separate (dioecious)
No second intermediate hosts (only the snail)
Can be pathogenic to humans
Eggs escape from the body by penetrating the walls of the veins, small intestine, or urinary bladder

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13
Q

Dioecious

A

2 separate sexes

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14
Q

3 Species of Schistosoma

A

S. mansoni
S. haematobium
S. japonicum

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15
Q

How are the 3 species of Schistosoma each passed out of the body?

A

S. mansoni = in feces
S. japonicum = in feces (rarely in urine)
S. haematobium = in urine (rarely in feces)

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16
Q

Gynecophoral canal

A

In schistosomes
The ventral groove on the male where the female worm levels
Adaptation so that they can find a mate really easily

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17
Q

Clonorchis sinensis

A

Chinese or oriental liver fluke

Infects a lot of animals - dogs, cats, pigs, and rodents - can serve as reservoirs

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18
Q

Clonorchis sinensis infection

A

Worm causes irritation of the bile ducts which become dilated and deviated
Liver enlarges, becomes necrotic and tender - function may be impaired
Adults feed on bile, so indigestion of lipids

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19
Q

Modest vs Heavy infections of clonorchis sinensis infections

A

Modest: indigestion, epigastric discomfort, weakness, weight loss
Heavy: anemia, liver enlargement, slight jaundice, edema, diarrhea

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20
Q

Treatment for Clonorchis sinensis

A

Praziquantel or albendazole (treat all flukes)
Cook fish well before consumption
Treat sewage before disposal

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21
Q

Paragonimus westermani

A

Lung fluke in Asia, Africa and South America

Plump reddish brown oval worm

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22
Q

Symptoms of paragonimus westermani

A

Dry cough, followed by the production of blood stained sputum
Pulmonary pain and pleurisy may develop
Worms may migrate to brain where they lay eggs and cause a granulomatous abscess resulting in symptoms similar to epilepsy

23
Q

Treatment of paragonimus westermani

A

Praziquantel taken orally
Adequate cooking of crustaceans
Improved sanitary conditions

24
Q

Fasciolopis buski symptoms

A

Epigastric pain, nausea, and diarrhea - especially in the morning
In heavier infections, can get edema and ascites (accumulation of fluid in the peritoneal cavity)

25
Q

Treatment of fasciolopis buski

A

Praziquantel
Avoid water chestnuts from contaminated areas
Treat sewage before disposal

26
Q

Monogenea body structures

A 
Have haptor (attachment organ - little hooks) on posterior part of body in early life stages
Some adults have prohaptor (for feeding) and opisthaptor (for attachment)
27
Q

Gyrodactylus salaris

A

Ectoparasite mainly lives on skin of freshwater Atlantic salmon
Haptor is situated at the parasite’s posterior end
When feeing, the parasite glues the mouth end to the salmon - everts pharynx through the mouth and releases a digestive solution with proteolytic enzymes to dissolve skin

28
Q

Gyrodactylus salaris treatment

A

Rotenone (indiscriminate so not very good)

Dosing small volumes of aqueous aluminium and sulfuric acid into the river (kills parasite without harming the host)

29
Q

Gyrodactylus elegans

A

viviparous (produces living offspring, not eggs)
4 generations are born out of one ova
Adult gives birth to one young - it contains an embryonic form - which has another - which has another

30
Q

Diplozoon paradoxum

A

Lives on gils of fish

31
Q

Polystoma integerrimum

A

Frog bladde fluke
Its reproductive cycle is in harmony with the frogs
Larval parasites live on the gills of the frogs tadpoles
See slides

32
Q

Gyrocotyle sp.

A

Class cestodia
Related to tapeworms and monogenetic trematodes
Parasites of the intestinal tracts of chimaeroid fish

33
Q

Subclass Eucestoda (tapeworms)

A

Have scolex (holdfast) and proglottids (strobila)
All vertebrates can get infections
Life cycles involve two or more hosts
Adult found in definitive host (small intestine) - much better to be definitive hosts than intermediate
Immature forms (in intermediate host) are called metacestodes

34
Q

Structure of tapeworms

A

Scolex, neck and proglottids
proglottids develop in neck, get pushed back, and grow - separate from each other
Only have repro system - nutrients and oxygen diffuse

35
Q

Monozoic

A

Tapeworms that have only one proglottid

36
Q

Polyzoic

A

Most tapeworms

Bodies consist of a chain of independent proglottids

37
Q

Taenia saginata

A

Beef tapeworm
Long and broad
4 suckers but no hooks or neck (that is visible)
Several hundred segments
Peripheral radial striations and its embryo has 3 hooklets

38
Q

Taenia solium

A

Pork tapeworm
Globular scolex with 4 suckers and a circular row of hooks (solar appearance)
Slightly smaller than T saginata

39
Q

Tapeworm symptoms

A

Light infections remain asymptomatic
Heavier infections may produce: abdominal discomfort, epigastric pain, vomiting, diarrhea
Will see shedding proglottids - crawl out of anus or in feces

40
Q

Cysticercosis

A

T solium eggs can infect humans and cause cysts in lung, liver, eye and brain
Can result in blindness and neurological disorders
Symptoms due to inflammatory/immune responses

41
Q

Tapeworm Treatment

A

Praziquantel!
Have to make sure scolex is out
Inspection of beef and pork
Adequate cooking or freezing of meat

42
Q

Diphyllobothrium latum

A

Fish or broad tapeworm
Worldwide distribution
Get it from eating raw or improperly cooked fresh water fish

43
Q

Diphyllobothrium latum morphology

A

Longest tapeworm in humans (3-10 m) with more than 3000 proglottids
Scolex looks like two almond shaped leaves
Proglottids are broader than they are long
Eggs are 30x50micrometers and embryos has 3 pairs of hooklets

44
Q

Diphyllobothrium latum symptoms

A

May be mild depending on the number of worms (abdominal discomfort, loss of weight, loss of appetitie and malnutrition)
Anemia and neurological problems associated with vitamin B12 deficiency are seen in heavily infected individuals

45
Q

Diphyllobothrium latum treatment

A

Praziquantel is the drug of choice
Freezing for 24 hours, thorough cooking, pickling fish
Fish reservoirs have to be kept free of raw sewage

46
Q

Hymenolepis nana

reservoir, infection mode, light vs heavy infections

A

Dwarf tapeworm
Infects children
Rodents are reservoir
Infection by the oro-fecal mode
Cross infection and auto infection by eggs in feces is normal
Light infects produce vague abdominal disturbanes, heavier infections may cause enteritis

47
Q

Hymenolepis nana Treatment

A

Nicolsamide (NOT praziquantel)

Hygiene is the best control

48
Q

2 Species of Echinococcsis (hydatid)

A

E. granulosus and E. multilocularis

Can cause hydatid cysts - same as cystecerci

49
Q

Echinococcus granulosus

morphology

A

Smallest of all tapeworms (3-9 mm long)
Only 3 proglottids
Forms cysts - has an outer anuclear hyaline cuticula and an inner nucleated germinal layer containing clear yellow fluid

50
Q

Echinococcus granulosus symptoms

A

Comparable to those of a slowly growing tumor depend upon location of the cyst
-Large abdominal cysts produce increasing discomfort
-Liver cysts obstructive jaundice
-Peribronchial cysts produce pulmonary abscesses
-Brain cysts produce intracranial pressure and epilepsy
-Kidney cysts cause renal dysfunction
Contents of a cyst may produce anaphylactic responses

51
Q

Echinococcus granulosus Diagnosis

A

Clinical symptoms of a slow growing tumour accompanied by eosinophilia
Intradermal test with hydatid fluid
Can see calcified cysts with X rays
Detect antibodies with ELISA

52
Q

Echinococcus granulosus Treatment

A

Surgical removal of cyst
Inactivation of hydatid sand by injecting 10% formalin and then removal
High doses of Mebendazole
Avoiding contact with infected dogs and cats and eliminating their infection

53
Q 
Echinococcus multilocularis
(intermediate host, cyst structure, treatment, prevention)
A

Similar to E. granulosus - similar morphology and life cycle except RODENTS are its intermediate host
Cysts are multilocular (many chambers)
Resistant to praziquantel - need high doses of Albendazole
Surgery to remove cyst and rodent control for prevention

Parasitology (18 decks)

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