Parasitology Flashcards
Describe the four layers on a nematode egg ?
- Uterine layer (not always present)
Common layers
- Vitelline layer
- Chitinous layer
- Lipid layer- resistance to desication and penetration of water soluble compounds.
Describe the morphology of the Order Rhabditida , Family Rhabditidae?
Rhabditida
- clear, transparent
- oesophagus contains a corpus and isthmus + bulb
- normally free living, becomes parasitic when animals are kept on wet dirty bedding
- infects skin, crusty, weeping lesions, loss of hair
- host dog, ox, sheep
- diagnose via scrapping of lesions.
Describe the morphology and characteristics of the Order Rhabditidae family Strongyloides species ?
Threadworm
- worldwide distribution
- free living adults
- adults usually reside in the small intestine duodenum, proximal jejunum, but occassionally in the respiratory tract
- oesophagus long 1/3 of body length
- L3 short lived no sheath, require warm moist environment for survival
- uterus intertwined with intesting
- only12-15 eggs in uteri at any one time
Only females are parasitic
Most distinguishing feature eggs thin shelled and embryonated.
Describe the lifecycle of Order Rhabditida Genus Strongyloides species ?
Complicated life cycle
- note only females are parasitic
- Direct or indirect life cycle
- Homogenic (Autoinfection)
- Heterogenic (indirect life cycle)
- Orally infected or subcutaneous infection
- autoinfection
Oral infection = L3 usually matures in the gut without any migration
Subcutaneous infected = migrate lungs, trachea, pharynx to small intestine to mature
- prepatent time 7-9 days
- may migrate to various tissues and organ especially mammary tissue and muscle. Here may be passed to offspring through milk/ colostrum.
- arrested development may occur
Type of life cycle will depend upon whether the host or environment is more favorable.
What is the prepatent period?
The time that elapses from when a host becomes infected to when the parasites develop into adults.
What is a direct and indirect lifecycle ?
Direct = monoxenous one host
Indirect lifecycle = heterogenous two or more host. Or part of their lifecycle is spent outside the host
What is a paratenic, mechanical and biological host?
Mechanical - no development or multiplication takes place
Biological - development or multiplication takes place
Paratenic - parasite does not undergo development, but remains alive and able to infect another host.
Describe the morphology of a nematode ?
- nema = Greek for thread like
- most cylindrical (round in cross section), elongated and tapered at both ends
- bilaterally symetrical
- pseudocoelom body cavity
- complete digestive system
- doecious, with the female usually being larger than the male
- teeth, cutting plates, leaf crowns or lips
Name four species of Strangloidae, Papillosus, Ransomi, Westeri, Stercoralis and their hosts ?
S. Papillosus = ruminant
S. Ransomi = pigs
S. Westeri = horses
S. Stercoralis = dog, cat and human
Location small intestine
S = Strongyloides or threadworms
Describe the morphological features of Strongylida ?
Strongles
- bursate nematodes
- The bursa is bell shaped with three lobes.
- corona radiata (internal and external leaf crowns)
- 3-6 lips
- eggs thin shelled many cells (morula stage)
- usually have a direct life cycle
Describe the morphological features of Trichostrongylus ?
Strangles
- Tricho = very thin
- mouth small
- bursa well developed
- Locate = small intestine
- excretory pore half way
- most important parasite of ruminants
- generally mucosal browsers, feed on small particulate matter and mucus
Eggs = thin shelled with many cells inside.
Chemo resistance extremely problematic in this group.
Describe the life cycle of the order Strongylida?
- Direct life cycle
- females produce eggs which are passed in the faeces
- generally similar life cycle for all species, except the requirements for optimal temperature and humidity vary.
- development of larvae inside faecal mass
- larvae feed on bacteria and detritus
- location small intestine
L3 retains the cuticle of L2 which is exsheathed anterior to the site of infection.
- L3 more resistant but unable to feed
- Hypobiosis
What is Hypobiosis, and what factors will affect hypobiosis ?
Hypobiosis is when larvae undergo a period of arrested development in the early L3 or L4 stages.
Affected by
- Environmental conditions
- host immune response
- population size of adult worms (what happens with anthelminthic treatment)
- genetic factors
While larvae are in Hypobiosis they are
- nonpathogenic
- not affected by host immunity
- less susceptable to treatments.
Describe the morphology and characteristics of order Trichostrongloidea, genus Trichostrongylus ?
Trichstrongylus = hair worms, black worms and black scour worms
Most predominate parasite in cattle
Defining features
- Location abomasum
- causes villus atrophy
- small slender pale reddish brown worms
- no buccal cavity
- excretory pore in conspicuous ventral notch
- spicules are short brown stout and rigid
Eggs
- thin shell, many cells inside morula stage
- uneven poles
Describe the lifecycle of Trichostrongylus ?
Life cycle = that of Order Trichostrongloidea
but
- female deposits 100-200 eggs a day
- optimal temp 25
- arrested development at L3
- L3 retain cuticle of L2
- PPT 15-21 days
Describe the two species of Trichostrongylus T.Axei and T.Colubriformis ?
- T. Axei
- ruminants, horses and pigs
- Location abomasum stomach
- T. Colubriformis
- sheep and goats
- Location Duodenum
Describe the Morphology of Haemonchus ?
Haemonchus (Barbers pole)
- Order Strongylida
- Heavy infections = sudden death
- L4 feed on blood can cause fatal anemia
- locate abmomasum
- F barbers pole due to coiling of white uterus
- large bursa
- cervical papillae
- small tooth
- vulva flap
- eggs thin shelled lots of cells
Describe the host of the two Haemonchus species Contortus and Placei ?
Haemonchus Contortus = sheep + goats
Haemonchus Placei = cattle
Describe the life cycle of Order Strongylida, Genus Haemonchus ?
Barbers Pole worm
- Order Strongylida
- Very prolific females produce 5000-1000 eggs a day
- larvae low resistance to dehydration during development
- Development 10-15OC with 25-35OC being optimum
Infection occurs through the consumption of L3 from the pasture
Describe the morphology of the Order Strongylida, genus Ostertagia ?
Brown stomach worm
- location abomasum Teladorsagia = sheep
- male spicules relatively short divided distally into two or three processes
- Bursa two large lateral lobes and one small dorsal
- nodules
- has small cervical papillae
- small mouth
Provide the host for two species of Ostertagia Ostertagia and Teladorsagia ?
Ostertagia = cattle
Teladorsagia = sheep and goats
Describe the life cycle of Ostertagia ?
Ostertagia
- Location abomasum
- 100-200 eggs daily
- Larval development between 5 and 35OC, but optimal between 16-25 OC.
Species of Osteragia are well known for their tendancy to arrest as early as L4.
Ingested L3 enter glands in the abomasum where they elicit nodules.
What is type one and two Ostertagiosis ?
Ostertagiosis
Type one = ingestion of large quantities of larvae
Type two = synchronous maturation of large numbers of hypobiotic larvae from the mucosa.
Due to
- low intake of larvae
- mass removal of adult population
Describe the morphology and life cycle
of Order Strongylida Genus Cooperia ?
Cooperia
- Small red worms
- Location within the small intestine
- Small cephalic swelling transversally striated, remainder of body 14-16 longitudinal ridges
- large bursa
Eggs are thin shelled with many cells
Life cycle similar to other species of the Superfamily Trichostrongyloida.
Describe the morphology of Genus Nematodirus ?
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
Describe the lifecycle of nematodirus ?
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
Describe the morphology of Dictocaulus ?
Dictocaulus
- Location = bronchi and trachea
- mouth small four lips
- bursa short
- spiclues brown bent and foot shaped
Eggs
- embryonated eggs
Describe the life cycle of dictocaulus ?
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.
Name the host of species Viviparous and filaria ?
Dictyocaulus viviparous = cattle
Dictocaulus filaria = sheep and goats
Describe the morphology of the Order Strongylida, superfamily Strongloidea ?
Strongyloidea
- usually large buccal capsule
- corona radiata
- bursa well developed
- direct life cycle
- most species occur in the large intestine
- Strongyles
Describe the morphology of Strongylinae S.Vulgaris?
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
Describe the life cycle of Strongylineae Vulgaris ?
S. Vulgaris
- eggs are shed in faeces
- favor 8-39OC
- 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.
Describe the morphology of edentatis ?
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
Describe the life cycle of Strongylus Edentatus ?
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.
Describe the morphology of equinus ?
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
Describe the life cycle of equinus ?
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
Describe the morphology of Triodontophorus ?
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
Describe the life cycle of Triodontophorus spp?
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.
Describe the general morphology of species belonging to the subfamily Cyathostominae ?
Subfamily Cyathostominae (small strongyles)
- <1.5cm
- sometimes red
- usually do not have teeth
- Buccal capsule short cylindrical or ring shaped
Location = colon and caecum
Describe the life cycle of subfamily Cyathostominae ?
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.
Describe the factors which affect whether a larvae of Cyathostominae will become inhibited or not ?
- Environmental conditions become favourable
- Population of Cyathostomes
- immune response
Note this can be affected by anthelmintic treatment, season and immunosuppression
Describe the morphology of Chabertia Ovina?
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
Describe the life cycle of Chabertia Ovina ?
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
Describe the morphology of Oesophagostomum ?
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
Describe the life cycle of Strongyloidea Oesophagostomum spp?
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.
Describe the morphology and life cycle of Oesophagostomum dentatum ?
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.
Describe the morphology of Stephanurus dentatus ?
Stepanurus dentatus
- kidney worm
- pigs and calves
- large and stout
- cuticle transparent
- triangular teeth bottom of buccal capsule
- small bursa
Describe the life cycle of Stepanurus dentatus ?
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
Describe the morphology of Syngamus Trachea?
Syngamous trachea
Location = trachea in fowl
- male and female always coupled Y shape
- red colour
- 8 teeth
- egg ellipsoidal with operculum at each pole
Describe the life cycle of Syngamous Trachea ?
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
Describe the morphology of superfamily Ancylostomatoida, Ancylostoma caninum ?
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
Describe the life cycle of Ancylostoma caninum ?
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
Describe the morphology of Ancylostomatoidea Braziliense ?
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
Describe the lifecyle of the species Braziliense ?
Hookworm Braziliense
- 6-10cm
- Inefction occurs orally, transcutaneously or through consumption of a paratenic host
- eggs passed in faeces
Describe the morphology and life cycle of Ucinaria Stenocephala ?
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
Describe the life cycle of Ancylostoma tubaeforme ?
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
Describe the morphology of Ancylostoma Tubaeforme ?
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
Describe the morphology of Bunstomum Phlebotomum ?
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
Describe the life cycle of Bunostomum phlebotomum ?
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
Describe the general morphology of the order Metastrongyloidea ?
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
Describe the life cycle of Metastrongyloidea ?
Lungworms
- eggs or larva are passed in the faeces
- indirect larva developwithin gastrapods or earth worms
- direct dogs L1 infects host
Describe the morphology of Metastrongulus Apri ?
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
Describe the lifecycle of Metastrongylus Apri
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.
Describe the life cycle, host and location of Protostrongylus Rufescens ?
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
Describe the general characteristic of Angiostrongylus Cantonensis ?
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.
Describe the morphology and life cycle of Oslerus (Filaroides) Osleri ?
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
Describe the morphology of Angiostrongylus vasorum ?
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
Describe the lifecycle of Angiostrongylus Vasorum ?
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
Describe the morphology of Metastrongyloidea, Aelurostrongylus abstrusus?
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
Describe the lifecycle of Aelurostrongylus Abstrusus ?
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
Describe the morphology of Ascaris Suum ?
Ascaris Suum
Locate the small intestine of pigs
- three lips
- stout body
- eggs brown/yellow thick wall one cell inside
- posterior of male bent
Describe the general features of the order Ascardia
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.
Describe the life cycle of Ascaris Suum ?
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
Describe the morphology of Toxocara Vitulorum ?
Toxocara Vitulorum
Small intestine of calves
- three lips
- cervical alae present but reduced
- eggs are thick shelled and finely pitted - one cell inside
Describe the morphology and life cycle of Parascaris Equorum ?
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
Describe the life cycle of Toxocara Vitulorum ?
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
Describe the morphology of Toxocara Canis ?
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
Describe the life cycle of Toxocara canis ?
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
Describe the morphology of Toxocara cati ?
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
Describe the life cycle of Toxocara cati ?
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)
Describe the morphology of Toxascaris Leonina ?
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
Describe the life cycle of Toxascaris Leonina ?
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.
Describe the morphology of Ascarida galli ?
Ascaridia galli
Locate in the small intestine of chickens,geese, ducks and doves
- three lips
- 3-12cm
- circular precloacal sucker
Describe the lifecycle of Ascaridia galli ?
Ascaridia galli
small intestine of chickens, geese and doves
- ingestion of embrionated eggs
- parasites mature large intestine
Describe the morphology of Heterakis gallinarum
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
Describe the life cycle of Heterakis Gallinarum ?
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.
Describe the general characteristics of Order Oxyyurida ?
Pinworms
- small
- oesophagus posterior bulb
- eggs asymetrical
- direct life cycle
- parasites of the large intestine
- male smaller than female
- female long pointed tail
Describe the morphology of Order Oxyurida, Oxyyuris equi ?
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
Describe the lifecycle of Oxyuris equi ?
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
Describe the general characteristics of the order Spiruroidea
Spiroidea pin worms
- no lips
- vestibule
- posterior end of male spirally coiled
- indirect life cycles
- eggs usually ovo-viviparous contain L1 larvae
Describe the morphology of Draschia megastoma ?
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
Describe the life cycle of Draschia Megastroma, and Habronema muscae ?
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
Describe the morphology of Spirocerca Lupi ?
Spirocerca Lupi
Adults oesophagus of dogs
- pink
- coiled in spirals contained within nodules
- trilobed lips
- eggs contain L1
- unequal spicules
Describe the life cycle of Spirocerca Lupi ?
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
Describe the morphology of Ascarops strongylina and Physocephalus sexalatus
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
Describe the life cycle of Ascarops strongylina and Physocephalus sexalatus ?
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
Describe the general morphology of the family Gnathostomatidae ?
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.
Describe the host species and location of the parasites Gnathostomatidae Hispidum or spingerum ?
Spingerum = stomach of dog or cat
Hispidum = stomach of pigs
Describe the morphology of Thelazia rhodes ?
Thelazia rhodes
Host = cattle sheep and goats
Location = conjuntival sac and lacrimal duct
- white
- cuticle prominant transverse striations
- no lips wide vestibule
Describe the general life cycle of Thelazia rhodes ?
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
Describe the host and location of Thelazia callipaeda ?
Thelazia callipaeda
Host = dog, cat, human
location = conjunctival sac under the lid and nictitating membrane.
Intermediate host = fruit flys
Describe the morphology of Oxyspirura mansoni ?
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
Describe the life cycle of Oxyspirura mansoni ?
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
Describe the morphology of Order Spirurida, superfamily Filarioidea ?
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).
Describe the morphology of Dirofilaria immitus ?
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.
Why is Dirofilaria immitus so important ?
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)
Describe the life cycle of Dirofilaria immitus ?
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.
