Parasitology 2 Flashcards
Describe Isospora suis
- Coccidian
- Causes coccidiosis
- Very few needed to cause clinical symptoms
- Infection from environment main source
- Oocysts very resistant to external influences
Describe the life cycle of Isospora suis
- Sporogeny
- Ingestion of sporulated oocyst
- Excystation ofoocyst and release of sporozoites
- Schizogeny
- Release of merozoites
- Invade epithelial ells
- Repeat process
- Gametogony
- Oocyst formation
Describe the process of sporogony
- The development of a non-infectious oocyst to an infectious one
- Produce sporocysts
- Asecual preorduction
- Occurs outside host
- Infection only occurs when sporulated oocyst is ingested
Describe the process of schizogony
- Once ingested bile salts and digestive enzymes cause wall to be eroded
- Release and activate sporozoites
- Penetrate intestinal villus epithelium
- Asexual reproduction occuring endogenously
- Trophozoites form, asexual division produces first stage merozoites
- Rupture and enter lumen
What happens to first stage merozoites after they are released
- Invade new cells
- Repeat asexual reproduction to produce second generation merozoites
What happens to the second generation merozoites?
- Can continue invasion and production of merozoites
- Or undergo gametogony
- Sexual division occuring endogenously
- Merozoites differentiate into micro or macrogamont
- Micro into macro leads to fertilisation
Describe oocyst formation
- Macrogametocyte fertilised by micro
- Macro contains wall forming body 1 (WFB1) and wall forming body 2 (WFB2)
- WFB1 forms outer layer of oocyst
- WFB2 forms inner layer
- Oocyst shed in faeces adn begins to sporulate
Describe the clinical symptoms caused by Isospora suis
- Diarrhoea
- High morbidity, low mortality
- Unresponsive to antibiotic treatment
- Pasty watery faeces
- Uneven weight gain, pigs hairy
- Longer time taken to reach final weight
How is the pathology caused?
- Damage to villi due to action of oocysts, reducing absorption and promoting bacterial overgrowth
- Degree of coccidiosis seems not be dependent on number of oocysts ingested
Describe the immunity to Isospora suis
- Strong degree of resistance to reinfection
- Resistance not transferred in colostrum
- Age related resistance
- 3 day old piglets more susceptible than 19 day old piglets
- Age related development (maturation) of innate immune system important
Describe the control and treatment of Isospora suis
- Treat with Baycox
- Good hygiene of pens, avoid mixing age groups
- Resistant to disinfection!
Describe the epidemiology of Ascaris suum
- Global significance
- Often seen in summer
- Greatest effect on pig growth 3-6months of age
- Over 4 months some degree of resistance
- Adults shed low numbers of eggs
- Major economic loss at slaughter
Describe the effects of Ascaris suum
- Milk spots on liver
- Fibrosis caused by migrating larvae
Explain how Ascaris suum can be monitored
- Abattoir monitoring
- Worm egg count in faeces
- In abattoir look for liver damage
Explain why worm egg counts may not be accurate for Ascaris suum
- Egg laying intermittent
- May not be detected in single samplings
What anthelmintics are effective in treating Ascaris suum?
- Avermectins
- Flubendazole
- Fenbendazole
Compare Ascaris suum in housed vs free-range pigs
- More in free range
- Will almost definitely be some infestation
- Inside easier to keep clean, need goo hygiene
- Burn old bedding
- Eggs and larvae survive longer in damp wet conditions
List important parasites of pigs
- Trichuris suis
- Oesophagostomum spp.
- Hyostrongylus rubidus
- Strongyloides ransomi
- Trichinella spiralis
- Ascaris suum
- Isospora suis
Describe Strongyloides ransomi
- Pig threadworm
- PPP 5-7 days
- Warm climate
- Free living forms
- Female can develop into infective L3s or can reproduce with males to produce more L1s
- Only females parasitic
- L3 not ensheathed
- Larvae do not survive well in dry conditions
- Sow infected via skin or mucous membranes of mouth
What causes the pathology in Strongyloides ransomi
- Larvae migration to intestine and burrowing
Describe the pathology caused by Strongyloides ransomi
- In adults similar signs to mange
- In piglet 10-14 days of age joint pain, coughing, bloody diarrhoea, anaemia
- Mortality can be very high
- Failure to thrive most usual sign
Describe the control of Strongyloides ransomi
- Clean and dry farrowing house
- Ivermectin 7-14 days prior to farrowing
Describe the life cycle of Strongyloides ransomi
- Ingest infective L3s
- Develop to L4
- Parasitic females
- Produce females and male L1s
- Males and females can either go straight to L2 and then infective L3 by direct development
- Or males and females can go on to L2, L3, L4 and then free living male
- These then mate to produce more L1s
- L1s then go to L2 and infective L3s
Describe Gasterophilus spp.
- Arthropod
- Stomach bots
- Flies look like small bumblebees
- Larvae overwinter and mature in stomach or small intestine
- Infection very common
Describe the life cycle of Gasterophilus spp.
- Adult flies active in middle of day in warm months
- Lay white/yellow sticky eggs on legs of horses
- Eggs either hatch spontaneously or when stimulated by horse’s saliva whilst grooming
- 1 very small and mobile (develop in mouth, tongue and gums)
- L1-2 occurs in pharynx
- L2 attaches to base of tongue, migrates to stomach
- L3 attaches to squamous gastric mucosa
- Larvae survive here for 10-12 months before being passed out to pupate in faeces
Where do the L3 of Gasterophilus intestinalis attach?
Margo picatus
Where do the L3 of Gasterophilus nasalis attach?
Dorsoproximal part of duodenum
Describe the L3 larvae of Gasterophilus
- Body covered with irritant tools
- 2cm long
- Rows of strong spikes
- 2 strong hooks on mouth pieces
Describe the pupation of L3 larvae
- Expulsion May to September
- Penetrate soil
- Transform into pupae
- Flies hatch 30-40 days later
- Not in bedding, only fields (need soil)
- Killed by frost and moisture/flooding
Describe the diagnosis of Gasterophilus
- Gastroscopy not faecal analysis
- Rarely casue disease
Why is faecal analysis not accurate for the diagnosis of Gasterophilus?
- Survive in intestine for long time before being excreted
- No eggs in faeces
- Larvae obvious if are present though
Describe the control of Gasterophilus
- Cannot control flies, short life span, don’t eat in this time
- Bot knife effective
- Ivermectin kills all stages
- Moxidectin kills L2-L3
- Once in soil cannot do anythign about it
Describe the epidemiology of Habronema species
- Nematode
- Transmitted by flies
- Not common
- Depends on yard cleanliness and fly numbers
- PPP 6-8 weeks
- Reservoir in infected horses adn flies
Describe the life cycle fo Habronema
- Adult worms in stomach
- Eggs or L1 passed in faeces
- Hatch in faeces, L1 ingested by fly maggots
- Develop to L3 in fly maggots
- Infective L3 migrate to mouth parts of fly
- Deposited on lips, nostrils and conjunctiva and skin sores by flies
- Migrate through tissues to stomach
- Adult worms live and reproduce in stomach
Describe the clinical signs of Habronema
- Skin sores
- Conjunctivities
Describe the prevention of Habronema
- Good fly control and muck heap management
- Frequent replacement of bedding
- Collection/removal of droppings in paddocks
- Cover wounds, treat ocular diseases causing ocular discharge
- Killed in horse with worming for other parasites
List horse parasites of the small intestine
- Parascaris equorum
- Strongyloides westeri
- Anoplocephala perfoliata
Describe the epidemiology of Parascaris equorum
- Ascarids
- Life cycle same as all ascarids
- Disease usually in horses under 2 years old
- Common
- Large worms
- 40cm long
- PPP 10-16 weeks
Describe the life cycle of Parascaris equorum
- When temp and humidity increase developed from L1 to L2 in shell
- Eggs containing L2 ingested by horse
- L2 larvae hatch
- pass through intestinal wall, transform to L3
- Migrate to liver via HPV
- Stay in liver for a week, enter vena cava to pulmonary alveoli
- Moult to L4
- Travel up bronchi to trachea
- Coughed up and swallowed
- Return to stomach and SI and mature as adults
Describe the clinical signs of Parascaris equorum
- Coughing and nasal discharge when in lungs
- Poor goat, weight gain, dull, anorexic
- Colicking due to bowel obstruction
- Disorders of bone and tendons
How is Parascaris equorum diagnosed
- Difficult, long PPP
- Repeated faecal analysis
- Endoscopy down to duodenum
- Eosinophils in tracheal washes, BAL
Describe the treatment of Parascaris equorum
- Benzimidazole
- Avermectins
Describe the prevention of Parascaris equorum
- Hard to prevent pasture contamination
- Remove faeces daily
- 3 year rotation of paddocks
- Deworm foals regularly
Describe the epidemiology of Strongyloides westeri
- Foals <1 months
- Transmammary transmission
- Adults from free-living larvae penetrating skin
- Direct or indirect life cycle
Describe the direct life cycle of Strongyloides westeri
- Larvae shed in droppings
- 2 transformations into infective larvae
- Penetrate body through skin or buccal mucosa, stomach or intestine
- Transform twice more to parthogenic females
- Larvae migrate to lungs, to trachea, swallowed, enter intestine as adults
- Enter mammary glands
Describe the indirect life cycle of Strongyloides westeri
- Larvae in droppings
- 4 moults to adults
- Lay eggs, form infective larvae
- Penetrate body through skin, buccal mucosa, stomach or intestine
- Larvae migrate to lungs, to trachea, swallowed enter intestine as adults
- 2 more moults to be adult
What is unusual about the reproduction of Strongyloides westeri?
- Female produces ovum with full set of genes
- Male not needed to fertilise egg
- Threat to biodiversity
- Known as parthogenic females
Describe the diagnosis of Strongyloides westeri
- Faecal analysis in foals
- Look for eggs
- Usually negative in adults so not useful
Describe the clinical signs of Strongyloides westeri
- Profuse non-fetid diarrhoea
- NO temperature
- Sick quite quickly
- Cuase of diarrhoea at foal heat
- Sometimes cough
Describe how Strongyloides westeri can be prevented
- Pick up faeces regularly in paddocks
- Anthelmintics e.g. benzimidazoles (v high doses)
- Avermectins (Ivermectin good for larval and adult stages)
- Worm dam day of parturition and 12 hours later to prevent passage in milk
- Not always practical
Describe the epidemiology of Anoplocephala perfoliata
- Cestode
- Mostly young horses but can be any age
- Ileum, ileocaecocolic valve
- Most common equine tapeworm
- Whole surface can act as digestive tract
Describe the appearance of Anoplocephala perfoliata
- No hooks, large suckers that attach to intestinal mucosa
- Large, fat, short, segmented, wrinkly
- 4-8cm length, 1cm width
Describe the life cycle of Anoplocephala perfoliata
- Reproduce via hermaphroditism (male segment fertilises female segment)
- Reproorgans deteriorate, leaving only uterus full of eggs
- Segment with eggs detaches from rest of worm
- Migrates to LI, ruptures releasing eggs
- Eggs released infective to oribatid mites (intermediate host)
- Eggs ingested by mites, cysticercoid larvae hatches, infective in 2 weeks
- Live in mite for life span
- Horse ingests mites with cysticercoid
- Attach to mucosa, mature into adults in 6-10 weeks
- Adults live for 4-6 months
- Overwintering in horse and mite
Describe the immune response to Anoplocephala perfoliata
- Worms within intestine
- More pronounced reponse in older horses
- More likely to clear infection
Describe the diagnosis of Anoplocephala perfoliata
- ELISA
- Faecal analysis difficult (intermittent egg shedding)
- Flotation methods
- Blood test (most reliable)
Describe the clinical signs of infection with Anoplocephala perfoliata
- Colic (ileal impaction, ileocolic intussecptions, caecal impactions)
- Diarrhoea
- Spasmodic (gas) colic
- Functional and physical blockages
Describe the treatment and prevention of Anoplocephala perfoliata
- 2 drugs
- Pyrantel
- Praziquantel (in autumn, high risk horses also in June)
- Stable horses 48 hours after working to prevent increased pasture contamination as increased expulsion of parasite following deworming
- Cannot kill mites
What are metacestodes?
- immature forms of cestodes
- Cystlike
- Cause the most damage
- Often most significant element of life cycle
- Have different names to adults
Describe the structure of cestodes
- chain of proglottids attaached by head
- Distal segments full of eggs shed in faeces
- Called gravid segments
- Proglottids mature as are shifted down by production of new cells on top of original one
Name the different types of metacestode
- Cysticercus
- Coenurus
- Hydatid
List the nematodes of dogs
- Toxocara canis
- Toxascaris leonina
- Ancylostoma caninum
- Uncinaria steenocephala
- Strongyloides stercoralis
Describe the egg appearance of Taenia spp.
- Simialr to ascarid eggs
- Multi-layer, thick shell
- Lots of striations
- NO protein layers
What is the larval stage of Taenia spp.?
Cysticercus
Describe the structure of the adult Taenia spp.
- Suckers and hookes (2 rows)
- Most have 4 suckers
- Armed rostellum
- Proglottids have one genital pore
What are the main Taenia spp, of dogs?
- Pisiformis
- Hydatigena
- Multiceps
- Ovis
- serialis
Describe the life cycle of Taenia solium
- Pig eats eggs
- Eggs hatch into oncospheres
- Oncospheres migrate to muscle tissues
- Oncospheres form cysticerci in muscle tissues
- Human ingests undercooked meat containing cysts
- Released from muscle in stomach
- Adults mature and live in small intestine
- Gravid proglottids containing eggs released in faeces
What is the main Taenia species of cats?
- Taenia taenieaformis
What is the larval stage of Taenia taeieaformis?
Stroblocercus fasciolaris (in liver)
What is the life cycle of Taenia taenieaformis?
- Indirect
- Rodent intermediate host
- Strobilocercus fasciolaris found in liver
- Cat definitive host
- Adult tapeworm found in SI
Name the intermediate stages of Taenia pisiformis, hydatigena, multiceps, ovis, serialis
- Cysticercus pisiformis
- Cysticercus tenuicollis
- Coenurus cerebralis
- Cysticercus ovis
- Coenurus serialis
Describe cysticerci
- Only on scolex
- Develop into one worm
Describe coenuri
- Multiple scolexes
- Develop into multiple worms
- Leads to more serious infection
Describe the clinical signs of taeniasis
- Infrequent
- Perineal irritation, licking, chewing
- Scooting
- Proglottids found in faeces or on coat (grains of rice)
Describe the general life cycle of Taenia species
- Intermediate host ingests eggs from faeces
- Eggs hatch into oncospheres
- Oncospheres migrate to muscle tissue and develop into metacestode
- Metacestode ingested by definitive host in uncooked meat
- Metacestode develops into adult, proglottids containing eggs shed in faeces
Describe the epidemiology of Dipylidium caninum
- Definitive host SI of dog and cat
- Intermediate host flea/louse
- Adults 30-50cm long
- Eggs laid in pockets
Describe the structure of the adult Dipylidium caninum
- 30-50cm long
- Suckers and protrusible hooks on rostellum
- 4/5 rows of small hooks
- Cucumber shaped mature segments
- 2 genital pores
Describe the life cycle of Dipylidium caninum
- Gravid proglottids released in faeces (or emerge from perianal region)
- Eggs released
- Egg packets ingested by larval stage of flea
- Oncospheres hatch, penetrate intestinal wall
- Cysticercoid larvae develop in body cavity
- Flea develops into adult
- has infective cysticercoid
- Host ingests flea containing cysticercoid
- Animals can transmit to humans, or humans can ingest infected fleas
Describe the epidemiology of Echinococcus epp
- Adults in SI small
- Eggs resistant for 1-2 years in environment
Describe the adults of Echinococcus species
- Terminal proglottid makes up half of length
- 3-4 segments make up inner germinal epithelium
- Buds off brood capsules
- Contain many scolices
- Single genital pore
What is the larval stage of Echinococcus species?
Hydatid cyst
What species of Echinoccus are important in dogs/foxes?
- Echinococcus granulosus (dogs)
- Echinococcus multilocularis (foxes)
Describe the life cycle of Echinoccus granulosus
- Proglottids shed in faeces
- Sheep eats eggs
- Develop to hydatid cysts in liver/lungs
- Dog eats offal containing cysts
- Can be zoonotic
Describe the life cycle of Ancylostomatidea in dogs
- Eggs in faeces
- Within 5 days L1 hatch
- Develop to L3
- L3 ingested or penetrate skin
- If ingested take cariopulmonary route, moult to L4 in trachea
- Coughed up, swallowed, reach intestine to moult to adult
- Somatic L3 larvae can go via milk to pups
Describe the epidemiology of Uncinaria stenocephala
- Dogs
- SI infection
- No pulmonary migration
- Can penetrate skin but will not establish
- Signs rare
What are the clinical signs of Uncinaria stenocephala
- Usually rare
- Diarrhoea
- Dematitis
List the important hookworms of dogs
- Ancylostoma caninum
- Ancylostoma tubaeforme
- Uncinaria stenocephala
- Strongyloides stercoralis
Describe the life cycle of Strongyloides stercoralis
- Direct or indirect
- Direct: eggs hatch to L1, deevlop to L3, L3 penetrate skin, into circulation, lungs, trachea, swallowed, into intestine, parthenogenic female, eggs released
- Indirect: L1 to adult male and female, mate to produce egg, egg to L1-L3, ingested, circulation, lungs, swallowed, intestine, adult, eggs
List some important zoonotic parasites
- Toxocara canis
- Heterphyes heterophyes
- Diphyllobothrium latum
List the important nematodes of birds
- Heterakis gallinarum
- Ascarids
- Trichostrongylus tenuis
- Capillaria spp.
List the important tapeworms of birds
- Amoebotaenia sphenoides
- Choanotaenia infundibulum
- Davainea proglottina
Describe the ascarids of birds
- Ascaridia spp. in SI up to 12cm
- Heterakis spp. in LI up to 1-2cm
- Oval, smooth shelled eggs
- Non-migratory
- Earthworm may be paratenic host
What is the importance of Heterakis gallinarum
Vector for protozoan Histomona meleagridis (blackhead)
Describe Trichostrongylus tenuis
- SI and caeca
- Mostly game birds
- Small (<1cm)
- Direct life cycle
- L3 infective stage
- Can be fatal
Describe the life cycle of Trichostrongylus tenuis
- Parasite eggs shed in bird’s faeces
- Eggs hatch
- L1-L2 development
- L3 crawl to top of vegetation, accumulate in drops of water
- Birds ingest larvae
- Adult feeds on lining of intestine
What are the important Capillaria species in birds?
- Obsiginata
- Caudinflata
- Contorta
Decribe Capillaria obsignata
- Chicken, turkey, pigeon
- SI
- Direct
- L1 in egg infective stage
- No intermediate host
- PPP 3-4 weeks
Describe Capillaria caudinflata
- Chicken, turkey
- SI
- Indirect
- IH: earthworm
- PPP 3-4 weeks
Describe Capillaria contorta
- Chicken, turkey, duck
- Oesophagus, crop
- Indirect
- Earthworm
- PPP 3-4 weeks
Describe Dilepididae of birds
- Amoebotaenia sphenoides
- 4mm long, SI, cysticercoid in earthworm
- Choanotaenia infundibulum
- 20cm long, SI, cysticercoid in house fly/beetles
Describe Davainea prglottina
- 4mm long
- Fowl and pigeons
- Pathogenic
- Rostellum and suckers have hooks
- In duodenum
- Leads to blood loss and enteritis
- larval stage cysticercoid
- Intermediate host slugs and snails
