Parasitology Flashcards

Question

Describe the morphology of Genus Nematodirus ?

Answer 1

Genus Nematodirus * long * filiform with anterior end being thinner * Cephalic vessicle striated * Spiclues long and slender, united * body with longitudinal ridges * long lateral lobes on bursa Eggs * large * Blastomeres gap between them and the shell Location Small intestine

Answer 2

Nematodirus * location : small intestine * Development to the infective L3 stage takes place within the eggs Hatching of larvae requires a prolonged period of chill followed by an increase in temp eg. spring * eggs can survive on pasture for a long time * infection occurs through ingestion of L3 off pasture

Answer 3

Dictocaulus * Location = bronchi and trachea * mouth small four lips * bursa short * spiclues brown bent and foot shaped Eggs * embryonated eggs

Answer 4

Dictocaulus * female produces embryonated eggs * eggs hatch inside the airways or intestine * develop to L3 under optimum condition 25 ^OC in the environment * free-living larvae do not feed * L3 covered in the sheath of L3 and L2, thus L3 geotactic Infection of host occurs through ingestion of L3 from pasture * exsheath abomasum * penetrate intestine * migrate lymph nodes, heart then lungs PPT 3-4 weeks Larval period may be arrested extending PPT to 5 months Larvae inactive dispersed by rain from faeces.

Answer 5

Dictyocaulus viviparous = cattle Dictocaulus filaria = sheep and goats

Answer 6

Strongyloidea * usually large buccal capsule * corona radiata * bursa well developed * direct life cycle * most species occur in the large intestine * Strongyles

Answer 7

Strongylinae 'large strongyles' S. Vulgaris * Location large intestine * blood feeding * larval stages cranial mesenteric artery * upto 5cm long * colour dark red * two leaf crowns internal and external * two ear shaped teeth with dorsal gutter * two thin equal spicules Eggs thin shelled many cells S.Vulgaris host horse

Answer 8

S. Vulgaris * eggs are shed in faeces * favor 8-39^OC * larvae develop with the eggs * L3 emerge from the faeces and migrate to the grass blades, where they are ingested * Larvae are resistant to drying and freezing Migration * exsheath small intestine where they grow and moult to L4 * L4 penetrate submucosal arterioles and migrate against the blood stream to the cranial mesenteric artery * spend 3-4 months at the cranial mesenteric artery * L5 return to the intestine and blood stream Nodules form around the worm in the small intestine which eventually rapture into the lumen of the large intestine releasing parasites.

Answer 9

Strongylus Edentatus * Location large intestine * larvae = liver and subpertoneal tissues * buccal capsule large * dorsal gutter * no teeth * two leaf crowns internal and external * bursa + 2 spicules

Answer 10

Edentatus * Adult large intestine * larvae liver and subperitoneal tissues * Eggs develop outside the host into free living larvae * infection occurs through consumption of L3 with herbage * L3 invade the intestine and by the hepatic portal system reach the liver * L3s develop into L4 within the liver where they form nodules and migrate extensively * L4s travel beneath the liver capsule on the hepatic ligament to the sub-peritoneal tissues on the right flank. From the third month post infestation the worms return by the mesentary wall to the large intestine where they form nodules, which open into the lumen releasing eggs.

Answer 11

Strongylinae Equinus * Location adults large intestine * Location juvenile liver, pancreas * Host horses * Large buccal capsule with three teeth * well developed dorsal gutter * two leaf crwons external and internal

Answer 12

Strongylinae Equinus * direct * L3 invade the cacecum and colon + provide the formation of nodules * Larvae molt to L4 within the nodules and the migrate across the peritoneal cavity to the liver * In the liver they continue to migrate for six weeks or more * no nodules form in the liver * they migrate further to the pancreas before returning to the intestine PPT 8-9 months

Answer 13

Stongylinae Triodontophorus * Location adult caecum or colon * host horse * buccal capsule subglobular, thick walled * three radially arranged teeth * well developed dorsal gutter * corona radiata * oral colar * appears striated

Answer 14

Triodontophorus * L3 ingested migrate to the wall of the caecum and colon, where they moult to L4 * L4 emerges into the lumen * Final moult in luman = adult worms * PPT 9 weeks Note= Triodontophorus feed in groups or nest, which cause ulceration and blood loss.

Answer 15

Subfamily Cyathostominae (small strongyles) * \<1.5cm * sometimes red * usually do not have teeth * Buccal capsule short cylindrical or ring shaped Location = colon and caecum

Answer 16

Order Strongylida Subfamily Cyathostominae 'small strongyles' * Direct * Larvae develop within large eggs shed within the environment * L3 retains L2 cuticle * L3 exsheathed after being ingested After L3 are ingested they enter the glands of Lieberkuhn in the caecum and colon * Either * Moult to L$ - L5 * Inhibited L3 within cyst upto 2.5 years * the emergence of larvae is the pathological stage Note synchronous reactivation depends on environment, population size and immune response.

Answer 17

* Environmental conditions become favourable * Population of Cyathostomes * immune response Note this can be affected by anthelmintic treatment, season and immunosuppression

Answer 18

Strongyloidea Chabertia Ovina Location and host: Large intestine of sheep and goats * large subglobular buccal capsule, which opens anteriorly * two small leaf crowns * transverse ventral cervical groove Male = well developed bursa female = short bent eggs = thin shelled many cells

Answer 19

Chabertia Ovina * stongyles of sheep and goats * eggs passed in faeces, infected L3 larvae * exsheath small intestine, than moult to L4 in the lumen * L4 return to large intestine where they moult into adults PPT 6-7 weeks feed by ingestion of large plugs of mucosa

Answer 20

Oesophagostomum spp * small mouth collar * buccal capsule small ring shaped * cephalic vesicle inflated between mouth collar and ventral groove Eggs thin shelled many cells inside

Answer 21

Oesophagostomum spp * eggs shed in faeces * L3 stage infectious * L3 enters part of the small intestine, where they become inclosed with nodules where they molt to L4 * L4 emerges from intestine and pass to the lumen of large intestine where they moult into adults. Perforations of the intestine.

Answer 22

Oesophagostomum dentatum * Location large intestine of pigs * stout white body * prominent cephalic vessicle * cervical papillae reduced Life cycle * The same as other Oesophagostomum species except L3 mainly enter the mucosa of the large intestine.

Answer 23

Stepanurus dentatus * kidney worm * pigs and calves * large and stout * cuticle transparent * triangular teeth bottom of buccal capsule * small bursa

Answer 24

Kidney worm * eggs passed in urine * infection occurs orally (earth worms) * post infection the larvae molt to L4 and migrate liver - perirenal region - perforate walls of the ureters form cyst and become sexually activ PPT 6-19 months

Answer 25

Syngamous trachea Location = trachea in fowl * male and female always coupled Y shape * red colour * 8 teeth * egg ellipsoidal with operculum at each pole

Answer 26

Syngamous trachea * Eggs coughed up and swallowed in the environment with faeces * L3 travel to liver lungs and trachea Paratenic host = earthworms, slugs and snails

Answer 27

Ancylostoma caninum Hookworm of dogs locate in the small intestine * causes severe anemia * anterior end bent dorsally * buccal capsule with three sets of teeth * posterior female conical, male bursa with two long spicules

Answer 28

Hookworm of dogs * female lay eggs passed in faeces Infection with L3 occurs transcutaneously or orally may have paratenic host mice, rat , bird * Transcutaneous migration heart - lungs - trachea lymph intestine * Adult parasdites mature in the small intestine * some larvae enter somatic tissues and enter arrested development. Reactivated larvae * pregnancy migrate to mammary gland pass to pups * or migrate small intestine to mature * may shed for atleast three lactations

Answer 29

Hookworm Braziliense Location small intestine Host cat and dog * 6-10cm * Large buccal capsule * Two pairs of teeth along the ventral margin * bursa in males, female posteria conical

Answer 30

Hookworm Braziliense * 6-10cm * Inefction occurs orally, transcutaneously or through consumption of a paratenic host * eggs passed in faeces

Answer 31

Uncinaria Stenocephala Host dogs and cats Location small intestine + buccal capsule has cutting plates * eggs released into the environment, where they develop into the L3 * Infection occurs orally, transcutaneously or through consumption of a paratenic host No transmammary transmission occurs

Answer 32

Ancylostoma Tubaeforme The main hookworm of cats Location small intestine * may live up to two years * female parasite deposit eggs which are passed in the faeces * Develop within the environment to L3 Infection occurs orally, transcutaneously and through a paratenic host

Answer 33

Ancylostoma Tubaeforme The main hook worm of cats Location small intestine * Buccal capsule with three pairs of teeth anteriorly * female posterior conical, male bursa Note No transmammary transmission

Answer 34

Bunstomum Phlebotomum The hookworm of cattle located in the small intestine * anterior end bent dorsally * dorsal cone tooth * two pairs of subventral lancets * cutting plates * bursa well developed with long spicules

Answer 35

Bunostomum Phlebotomum Hookworm in cattle locate small intestine * Eggs pssed in faeces of host * blood feeding Infection occurs through skin penetration ( migrate to lungs then intestine) and orally (spend some time in the wall of the small intestine before emerging into the lumen). PPT 2 months

Answer 36

Order Meta strongyloidea lungworms * mouth small even absent * small bursa even absent * direct and indirect life cycles * usually found within the respiratory system/ circulatory system * two trilobed lips

Answer 37

Lungworms * eggs or larva are passed in the faeces * indirect larva developwithin gastrapods or earth worms * direct dogs L1 infects host

Answer 38

Metastrongulus Apri lung worm of pigs = locate lungs, trachea and bronchioles * two trilobed lips * Male bursa with two long striated spicules * female tail is bent * eggs have a corrugated surface and a thicker shell

Answer 39

lung worms Locate lungs trachea and bronchioles of pigs * Females lay eggs within the respiratory tract where they are coughed up and swallowed * eggs pass out into environment through faeces To develop to L3 the eggs must be ingested by earthworms * pigs then consume the earthworms * larvae penetrate the wall of the small intestine migrate via mesenteric lymph to lungs.

Answer 40

Protostrongulus rufescens Location = small bronchioles host = sheep indirect lifecycle through gastropods * Female worms produce eggs that hatch in the lungs * migrate as L1 pharynx - intestine where the larvae are passed in faeces to the environemnt * Develop to L3 within gastropods * gastropods consumed by sheep = larvae migrate to lungs The worms can survive for 4-7 years

Answer 41

Angiostrongylus Cantonensis Definitive host = rats paratenic host = horse, human and dog intermediate host = gastropods * The larvae of infected paratenic host locates within the brain and spinal cord * Infection of L3 can occur through food contaminated with gastropod slime.

Answer 42

Oslerus (Filaroides) Osleri host = wild dogs location = nodules at the junction of trachea and bronchioles Morphology = nodules Life cycle * No development required outside of host * L1 saliva and faeces * L1 do not survive well the environment * Infection ussually occurs between bitch and pups, cleaning food regurgatation

Answer 43

Angiostrongylus Vasorum French heart worm Host = dog Location pulmonary artery, right side of heart * red intestine white ovaries intertwined * small reddish worm * male bursa small, spiclues uneven

Answer 44

Indirect life cycle location = right pulmonary artery host = dog * intermediate host snails slugs * female worms lay eggs in the capillaries of the lung * larvae hatch penetrate alveoli - pharynx - swallowed * passed in faeces as L1 * Develop to L3 in gastropods liver - right ventricle - pulmonary artery

Answer 45

Aelurostrongylus abstrusus lungworm of cats = pulmonary artery * causes development of subpleural nodules firm grey and raised in lungs * tiny slender * black when fresh * male bursa small * female vulva opens near anus

Answer 46

Aelurostongylus Abstrusus Lungworm of cats Location = bronchiole, alveoli and pulmonary artery * Female worms lay embryonated eggs which hatch in alveolar ducts * Migrate respiratory tract - swallow - intestine Intermediate host = gastropods * within gastropod develop L1 to L3 infective stage larva * paratenic host rodents birds and reptiles eat gastropod and are then digested by cat Larvae migrate from stomache to lungs PPT = four weeks

Answer 47

Ascaris Suum Locate the small intestine of pigs * three lips * stout body * eggs brown/yellow thick wall one cell inside * posterior of male bent

Answer 48

Order Ascardia * Adult worms usually locate in the intestine * large, white, opaque stout bodies * three lips * posterior end of male curved * prolific The larve reach infective stage within the eggs - host becomes infected through the digestion of embrionated eggs.

Answer 49

Ascaris Suum Location = small interstine of pigs The host becomes infected through ingestion of eggs in food or water * larvae hatch in intestine and burrow into gut * liver - heart - lungs where they are swallowed and return to intestine to mature * PPT 60 days * adults can survive upto one year

Answer 50

Toxocara Vitulorum Small intestine of calves * three lips * cervical alae present but reduced * eggs are thick shelled and finely pitted - one cell inside

Answer 51

Parascaris Equorum Locate small intestine horses Morphology * three lips * posterior lateral alae * upto 50 cm in length * eggs brown thick shell Life cycle * develop within eggs * liver-heart-lungs-trachea * mature small intestine

Answer 52

Toxocara Vitulorum Small intestine of calves * Cows become infected through ingestion of eggs in the environment (larvae do not mature in the cow) * larvae lungs-trachea-muscles-brain The larva enter hypobiosis The larvae will become reactivated and migrate to the mammary gland around partuition - **_pass in the milk_** * worms mature in the small intestine of the calve * eggs released in calf faeces to environment

Answer 53

Toxocara canis small intestine of dogs * parasites live free in the small intestine * zoonotic CLM in humans * 10-18cm * three well defined lips * cervical alae gradually end at the posterior * male posterior digitiform appendage

Answer 54

Toxocara canis adult locate small intestine of dog Eggs passed into environment - eggs are sticky + worms prolific The dog becomes infected through ingestion of embrionated eggs or paratenic host Larval migration two routes * Tracheal migration = liver - heart - lung - trachea - swallow (Dog \< 3 months) * Somatic migration = lungs - heart - brain (dog \> 3 months) In addition larvae may become hypobiotic * pregnant female * foetal transplacental * transmammary infection

Answer 55

Toxocara cati Locate in the small interstine of cats * zoonotic VLM and OLM * 3-10cm * cervical alae are broad and end abruptly * three lips * thick shell, embrionated eggs

Answer 56

Toxocara cati Locate small intestine Infection = ingestion of embrionated eggs / paratenic host * Tracheal migration liver - lungs - trachea - swallow * Somatic migration some larvae may reach musculature Larvae do not spread to kittens during pregnancy Migration rout of larvae is independant of the cats age Infection through milk is the crucial route (vertical)

Answer 57

Toxascaris Leonina Location = small intestine of dog or cat Infection is by ingestion of embrionated eggs or paratenic host * three lips * cervical alae long and narrow * eggs thick smooth outer layer * The male has no digitiform appendage

Answer 58

Toxocaris Leonina Location small intestine of dog or cat * Infection through ingestion of embrionated eggs or paratenic host * no tracheal migration * no prenatal or milk transmission PPT 2 months Reduced pathogenesis in dogs and cats.

Answer 59

Ascaridia galli Locate in the small intestine of chickens,geese, ducks and doves * three lips * 3-12cm * circular precloacal sucker

Answer 60

Ascaridia galli small intestine of chickens, geese and doves * ingestion of embrionated eggs * parasites mature large intestine

Answer 61

Heterakis gallinarum Host = chicken, turkey, ducks, and pheasants Location = intestine * three lips * two lateral narrow alae * oesophagus ends in well developed bulb * male circular precloacal sucker

Answer 62

Heterakis Gallinarum Location = small intestine Host = chickens, ducks etc * not pathogenic but an important vector of Histomonas meleagridis * The eggs become embrionated in the environment * the host may become infected either by egg consumption or consuming paratenic host earthworms flies etc Larvae hatch in the small intestine but migrate to the caeca to become sexually active.

Answer 63

Pinworms * small * oesophagus posterior bulb * eggs asymetrical * direct life cycle * parasites of the large intestine * male smaller than female * female long pointed tail

Answer 64

Oxyyuris equi pinworm of horses Location large intestine * posterior of female pointed and variable in length * mouth opening hexagonal * posterior of male trunicated * Eggs thick shell embryionated

Answer 65

Pinworm of horses Location large intestine * Female worms excit perinanial area of horses head first while gravid * viscous gleatinous eggs become stuck to perinial area and dry to a yellow crust * this causes the horse to itch spreading embrionated eggs in the environment The host ingest larvae L3 which develop in the small intestine * L4 buccal capsule feed on mucosa * adult locate in lumen of large intestine and feed intestinal contents PPT 5 months test via skin scrappings

Answer 66

Spiroidea pin worms * no lips * vestibule * posterior end of male spirally coiled * indirect life cycles * eggs usually ovo-viviparous contain L1 larvae

Answer 67

Daschia megastoma Adults reproduce in the intestine of horses * two lips seperated from the rest of the body by a groove * no teeth * vestibule * eggs contain L1

Answer 68

Draschia Megastroma Intestine of horses * L! eggs are shed in the environment * eggs are consumed by flys where they develop to L3 * L3 is reached as the juvenile fly excits its papillae * L3 will reach the mouth parts of the adult fly Larvae are stimulated to leave the adult fly as it feeds on moist surfaces * gastric habronemosis horse mouth * pulmonary habronemosis wounds, periocular area, penis prepuse and nostrils

Answer 69

Spirocerca Lupi Adults oesophagus of dogs * pink * coiled in spirals contained within nodules * trilobed lips * eggs contain L1 * unequal spicules

Answer 70

Spirocerca Lupi Oesophagus of dogs Intermediate host = dung beetles * eggs passed in faeces contain L1 * dung beetles consume eggs, and the larvae develop within the intermediate host to L3 * Dog ingest dung beetles or paratenic host Larvae penetrate the stomach - aorta - oesophagus PPT 5-6 months

Answer 71

Ascarops and sexalatus The worm locates within the stomach of pigs * male posterior coiled * egg thin shelled contains L1 larvae * paharnx strengthened by annular and quadriple spirals

Answer 72

Spiruroidea pigs Location in the stomach of pigs * intermediate host coprophagous beetles * female worms lay embryonated eggs which are passed in the pig's feces * The larvae are ingested by coprophagous beetles where they develop * Pig become infected after ingestion of infected beetles

Answer 73

Gnathostomidae Stomach * thick worms * anterior end cuticle swelling * 9-11 sharp hooks * two large tri lobed lips * body covered in spines scale like The eggs are thin shelled with a thickening at one or both poles.

Answer 74

Spingerum = stomach of dog or cat Hispidum = stomach of pigs

Answer 75

Gnathostomidae Intermediate host = copepods and fish Location = stomach * eggs shed in host faeces * larvae in water develop and hatch * infect copepods where they develop further * copepods consumed by fish or frogs where the parasitic larvae develop into L3 infective stage The definitive host then consumes the intermediate host parasites migrate to the liver - stomach where they develop into adults

Answer 76

Thelazia rhodes Host = cattle sheep and goats Location = conjuntival sac and lacrimal duct * white * cuticle prominant transverse striations * no lips wide vestibule

Answer 77

Thelazia rhodes Location lacrimal secretions Host = cattle, sheep and goats Intermediate host = flies * Female worms lay eggs in the lacrimal secretions of the host * larvae ingested by flys which feed off the eyes of the host * Larvae develop to L3 inside fly * Fly feeds off another host eye, transfering larvae to a new host PPT one month

Answer 78

Thelazia callipaeda Host = dog, cat, human location = conjunctival sac under the lid and nictitating membrane. Intermediate host = fruit flys

Answer 79

Oxyspirura mansoni Location inner corner of orbit, nictitating membrane Host = chickens and ducks * cuticle smooth * mouth without lips * posterior is conical and curved in males * spiclues uneven in males

Answer 80

Oxyspirura mansoni host = chickens and ducts location = eyes intermediate host = cockroaches * parasite deposits eggs in the lacyhmal eye secretions - ducts - mouth - swallowed then passed in faeces * eggs ingested by intermediate host cockroaches * the cockroaches are then ingested by the birds * parasite larvae leave the cockroach in the crop and migrate oesophagus - mouth - lachrymal duct - eye PPT 50 days

Answer 81

Superfamily Filariodea (thread worms) * long slender worms * simple anterior and exterior ends * mouth without lips * spicules unequal * vulva located near anterior end Eggs contain microfilariae (no digestive tract) Location = lymph vessels, blood, body cavities and connective tissue Indirect life cycles Intermediate host = haematophagous arthropods (biting flys, midges, mosquitos).

Answer 82

Parafilaria multipapillosa = horses nodules in skin Stephanofilaria spp = cattle skin lesions, buffalo fly Adults locate in the dermis, with microfilaria in the epidermis

Answer 83

Dirofilaria immitus (heart worm) * elongated filiform * mouth circular without lips * female is viviparous (live young) with vulva at anterior end * male posterior is coiled like a pigs tail + spicules uneven and dissimilar.

Answer 84

Dirofilaria immitus (heart worm) main host dog Location = pulmonary artery and right ventricle * tropical subtropical prevalent * severe pulmonary pathology and even death * geographical range increasing over the years * chemoresistance * zoonotic (does not develop in humans)

Answer 85

Dirofilaria immitus (heart worm) Location = pulmonary artery and right ventricle Host = dog and many other species PPT = 6-9 months * Habours intracellular bacteria Wolbachia pipientis which is crucial for the parasites development * Microfilaria live young - non progressive motility. * Intermediate host = mosquitoes become infected with microfilariae when taking a blood meal from an infected host. * concentration of microfilariae in the blood varies with season summer and time (eveneing) high * microfilaria develop and migrate through to mouth parts of mosquito Definitive host becomes infected while the mosquito is taking ablood meal through puncture wound made by the mosquito.

Answer 86

Wolbachia pipientis is a bacteria - endosymbionts Dirofilaria immitis harbours the intracellular bacteria Wolbachia pipientis which essential to the survival and reproduction of Dirofilaria immitis.

Answer 87

Onchocerca cervicalis Host horse Location = funicular portion of the ligamentum nuchae. * filiform worms * female worms lay microvillae that accumulate in skin * intermediate host = midges * Microfilarie develop to L3 within the midgee then migrate to the head and proboscis * transmitted through feeding * alopecia, scaling, crusting

Answer 88

Onchocerca gibsoni host = cattle location = tightly coiled nodules in the brisket, stifle and hip of cattle. * serious economic loss due to carcass trimming * each nodule contains one female and several male (2-5cm) * microfilaria (skin of thorax)

Answer 89

Suborder Trichinellina most widespread zoonotic pathogen in the world, locates = small intestine * anterior end is more slender than posterior end * lack phasmids * males have one spicule or none * no exogenous stages Trichinellina comprises * T.Spiralis = thick collagen capsule mammals * T pseudospiralis = thin collagen capsule, mammals, birds etc

Answer 90

Trichenilla spp * Life cycle depends upon canibilism * infection of the host occurs through ingestion of meat that contains larvae of Trichinella (with cyst) * stomach acid and pepsin releases L1 larvae from cyst * L1 invade mucosa of the small intestine where they molt and become adults * larvae enter the lymphatic vessels, then the blood vessels deliver them to the muscles.

Answer 91

Trichinellina larvae Have three effects upon the host skeletal muscle * acquisation by the cell of a new phenotype nurse cell (larvae take control) * encapsulation of larvae * development of a capillary network around the infected cell The larvae can remain viable for the life of the host. It is generally believed the most active muscles harbour the highest percentage of larvae.

Answer 92

Order Enoplida Trichuris spp Host = mammals, Location = large intestine (anterior end embedded) * anterior end thin, posterior thick * male posterior thick with a single spicule * posterior end of female is curved * egg yellow, with a large plug either end, one cell inside * has a direct life cycle, feeding on blood and cellular components. * Trichuris suis pigs * Trichuris vulpis dogs

Answer 93

Trichuris vulpis Host = dog, location = large intestine * female worm lays eggs which are passed into the environment with faeces * infective larvae develop within the eggs * host becomes infected after the ingestion of embryonated eggs * hatch into the small intestine, develop before invading the large intestine PPT 70-100 days

Answer 94

Phylum Acanthocephala Parasites of the digestive tract in birds, mammals and fish * body covered in a thick cuticle * have a retractable proboscis provided with hooks * flattened * wrinkled * no digestive tract indirect life cycles * seperate sexes

Answer 95

morphology Macracanthorhynchus hirudinaceus Host = pigs, location = small intestine intermediate host = dung beetle * proboscis provided with around 6 transverse hooks * white or pale red * flattened and wrinkled * eggs are thick shelled brown pitted, with three layers * curved * tapered towards posterior end

Answer 96

LC Macracanthorhynchus hirudinaceus * intermediate host = dung beetles * embrionated eggs are shed in faeces * infective stage develops within the eggs within about three months * dung beetle larvae ingest eggs * pigs ingest dung beetles and become infected

Answer 97

Oncicola pomatostomi and Oncicola canis host = cats and dogs, location = small intestine Definitive host becomes infected after ingestion of paratenic host eg birds

Answer 98

Phylum platyhelminthes flatworms * contains trematodes, cestodes and monogeneans * dorsoventrally flattened * bilaterally symetrical * organs embedded in a specialised parenchyma (connective tissue) * syncytial integument * digestive incomplete or absent * muscle layers developed * suckers and hooks * usually hermaphrodites

Answer 99

Subclass trematodes * typically oral and ventral suckers * short and flat * life cycle involevs atleast one intermediate host * ventral sucker **a****cetabulum** * incomplete digestive system no anus * hermaphrodite cross fertilization and self fertilisation

Answer 100

Digenea The life cycle is complex generally involving a molluscan intermediate host * asexual multiplication occurs within the intermediate (usually mollusc host). * produces a large number of free swimming stages * adult digeneans in vertebrates Life cycle stages * Adult lays egg passed in faeces * miracidium often ciliated invade IH * Sporocyst develops within intermediate host * redia (elongated) * Cercaria develop which is shed into the environment (motile and able to swim. * Metacerariae encyst from cercaria, after being ingested develop into adult flukes.

Answer 101

Morphology Fasciola Hepatica Host= sheep, goats, horse, human etc Location = bile ducts (erratic locations such as lung spleen) * leaf shape * broad shoulders * anterior end is cone shaped * oral sucker mouth, ventral sucker around shoulder level * integument is armed with sharp spines * cecae are branched * eggs are yellow operculated

Answer 102

Trematoda * ovary * testes * vitelline gland * cecae * oral and ventral sucker

Answer 103

Life cycle Fasciola hepatica Location = bile ducts, host = sheep,goats, human etc Intermediate host = snails * can survive 7-10 years + lay 20,00 eggs per day * complete development and hatching require the eggs to be seperated from the faeces (temp, humidity) * miracidium (can not survive in the environment long) penetrate the snail - sporocyst * Rediae - develop within sporocyst are motile and may cause damage to the snail * Cercariae develop within the rediae (1 mericedium = 4000 cercaria) * cercaria leave the snail 4-7 weeks post infection * Cercaria settle on various objects such as gras, encyst and turn into metacercaria which can survive upto one year on pasture Infection of the definitive host occurs through the ingestion of metacercaria with grass or water. * metacercaria excyst in the small intestine * young flukes eat liver cells and blood * adult eat blood - spines puncture the blood vessel walls of bile ducts

Answer 104

Morphology paraphistomes (stomach flukes) Host = cattle and sheep, Location = rumen + reticulum * immature stages locate in the duodenum and abomasum (usually pathological stage) * tissue and blood feeders * important species of Australia * anterior sucker mouth, posterior sucker (acetabulum) well developed * caeca are simple * genital pore opens ventrally * testes lobbed and anterior to ovary * eggs operculated, greenish