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PARASITOLOGY

INTERNAL PARASITES
STUDY
PLAY
Trematoda Features
- Leaf like, flattened body
- Gut present
- Feed on blood & tissues or intestinal contents
Trematoda Life Cycle
SNAIL HOST -> rainfall/water source, faecal distribution
Factors for transmission: intermediate host, secondary intermediate host, final host feeding behaviours, climate
Fasciola Hepatica
Liver fluke, class trematoda
Found in sheep & cattle, adults in bile ducts & blood
Cause: liver rot, black disease, chronic anaemia, enlargement of liver & bile ducts
Cattle higher risk as sheep prefer dry food
Cestoda
Tapeworms
No gut, Scolex, neck, proglottids
Cyclophyllidea
Scolex armed with 4 suckers, genital pores open laterally, larvae only hatch when eaten, usually 2 host life cycle
Taeniidae
Definitive host: carnivores & people
Intermediate host: mammals (as metacestodes)
Eggs can survive 1 year in environment
Taeniidae Metacestodes
Bladder worms or hydatid
Scolex with cyst forms adult worm, most of bladder digested
Always found in organs of mammallian hosts (adults in SI)
Taenia saginata
Human beef tapeworm
Cow intermediate host
Taenia slolum
Pork tapeworm
Pig or human intermediate host
Uncooked pork -> cysticerci in brain
Echinococcus granulosus
Hydatid cysts
Humans as intermediate host cause severe disease
Adults only a few mm long, 4 segments at one time
Domestic/intermediate cycle (dog/sheep) ingest eggs in faeces
Sentinel host (cattle, pigs) infertile cysts
Family Dilepididae
Cucumber Worm
One of vet = Flea or dog tapeworm
Adults in SI of dog, cat fox
Proglottids bilateral genital pores
Intermediate host flea
Dipylidium caninum
Dog/flea tapeworm
Cucumber worm
Causes scooting
Adults in SI of dog
Intermediate host flea
Family Anoplocephalidae
Definitive host = herbivore
Intermediate host soil/pasture dwelling arthropods like mites
Adult has short wide segments
Phylum platyhelminthes
Flat worms
Moniezia
Sheep family anoplocephalidae
Definitive host: herbivore
Intermediate host: mites
Thysaniezia
Ruminants family anoplocephalidae
Definitive host: herbivore
Intermediate host: mites
Anoplocephala perfoliata
Horses family anoplocephalidae
Definitive host: herbivore
Intermediate host: mites
Causes fatal blockage at ileocaecal junction
Order Pseudophyllidea Features
Scolex with 2 longitudinal bothria (rather than suckers) Genital pores open dorsally or ventrally
Eggs hatch in water
Usually 3 hosts
Order Pseudophyllidea Life cycle
Definitive host = fish & lower vertebrates
2 intermediate hosts required
Spirometra erinacei life cycle
Zipper worm
Adults in cat, dog, fox (mid ventral genital pores look like zipper)
Fluke like eggs passed in faeces
Requires water for hatching coracidium
Eaten by small crustacean develops to procercoid
Infected crustacean eaten by second intermediate host (usually amphibian) develops into plerocercoid
Plerocercoids or spargana in a range of intermediate & paratenic hosts
Spirometra erinacei effects
Zipper worm
Heavy infection can cause ill thrift or enteritis (especially cats)
Spirometra erinacei order
pseudophyllidea
Phylum Nematoda
Roundworms
Phylum Nematoda features
Elongate, cylindrical but tapering at either end
Mouth anteriorly, cloaca & tail posteriorly
Mouth > muscular pharynx or oesophagus > intestine > cloaca
Separate sexes (males smaller)
Order Strongylida (Bursate) Importance?
Most important group in domestic animals
Order Strongylida Sex differences
Sexual dimorphism, males with bursa with rays feamles with muscular ovijector at end of uterus
Order strongylida Superfamily Ancyclostomatoidea
Hookworms
Hookworms Lifecycle
Family Ancyclostomatoidea
Adults in SI of carnivore in ruminants L3 penetrate mucose or skin, blood vessels/lymphatics, heart, lungs, tracheal migration, swallowed into SI transmammary migration
Ancyclostoma and Uncinaria
Hookworms in dogs, cats
Blood suckers of SI
Causes anaemia, ill thrift, diarrhoea, creeping eruption on skin, enteritis
Superfamily Strongyloidea (Strongyles)
Adults in caecum and large intestine of horse ruminants pigs
Some suck blood, others feed on gut mucosa
infection by ingestion of L3
Strongylus vulgaris
Large horse strongyle
Most pathogenic
Larval penetration of gut wall and migration to cranial mesenteric artery
Carried to L1 as cysts, which erode intestinal wall and release worm into lumen
Disruption of blood flow to colon causes colic
SUSCEPTIBLE TO ANTHELMINTICS ( declining significance)
Cyathostomes
Small stronglyes/red blood worms
Horses
L3 invades mucosa of LI lives up to 2 years, L4 emerge from cyst and enter lumen destroys mucosal cells & inflammation
NOT SUSCEPTIBLE TO ANTHELMINTICS (Increasing significance)
Strongyles & Anthelmintics
Strongylus vulgaris susceptible
Cyathostomes not susceptible
Family Trichostrongyloidea Life cycle
Hair worms
Eggs in faeces L1-Ld in faeces or migrate in environment, ingestion, sometimes penetrates mucosa, moulting, adult
Adults in upper GIT (abomasum or SI)
Infection always ingestion of L3
Trichostrongyloidea effects
Hair worms
Abomastitis, anaemia, oedema, necrosis, reduced weight gain, chronic diarrhoea, emaciation, death
Haemonchus contortus
Hair worm/Barbers pole worm
Blood suckers in abomasum
Causes anaemia, bottle jaw
Mixed infection diarrhoea
Heavy infection death during pre-patent period
IMPORTANT FOR SHEEP IN WET AREAS
Important worm for sheep in wet areas
Haemonchus contortus
Ostertagia
(trichostrongyloidea hair worm) Cattle
Abomasum mucous metaplasia & inflammation, nodule formation, loss of plasma proteins, increased pH, decreased food intake, diarrhoea, bottle jaw
IMPORTANT RUMINANTS SUMMER RAINFALL TEMPERATE REGIONS
Important worm for ruminants in Summer wet/temperate areas
Ostertagia & Teiodorsagia
Teiodorsagia
(trichostrongyloidea hair worm) sheep, goats
Abomasum mucous metaplasia & inflammation, nodule formation, loss of plasma proteins, increased pH, decreased food intake, diarrhoea, bottle jaw
IMPORTANT RUMINANTS SUMMER RAINFALL TEMPERATE REGIONS
Dictyocaulus
Lung worm (trichostrongyloidea hair worm)
Lung worm of bronchial tree in ruminants
Coughing respiratory signs ill-thrift
Especially intensively farmed calves
Major disease of calves in temperate regions
Superfamily metastrongyloidea
Lung worms
Adults in lungs/pulmonary vasculature of cattle, cat rat
Require intermediate host, may use paratenic host
L1 passed in faeces (rather than egg) KINKED TAIL
Not important in domestic animals
Angiostrongylus cantonensis
Rat lungworm (metastrongyloidea)
Migrates through CNS after ingestion of intermediate host
Severe neurological disease (dogs, humans)
Aelurostrongylus abstrusus
Cat lungworm (metastrongyloidea)
Lung nematode of cats
L1 in faeces, L3 in mollusc, ingestion of paratenic host, partial tracheal migration, eggs & L1.
Respiratory signs and weight loss
Genus Strongyloides Features
Threadworms
Parsitic adults all female, very small, entwined with SI villi
Genus Strongyloides Lifecycle
Larvated eggs pass in faeces and hatch quickly
Develop into free living adult males or females OR become parasitic and enter host via skin
Ingestion from environment or colostrum
L3 enters blood, tracheal migration, SI parthenogenic females develop in SI
Genus Strongyloides Causes
Threadworms
Significant in very young horses, pigs, ruminants
Diarrhoea, ill thrift, foot rot (lambs) often asymptomatic
Strongyloides ransomi
Pig threadworms
Larvae transfer via colostrum, piglets infected within 24 hours
Severe econimic loss
Transmission uncommon in clean dry piggeries
Other strongyloides
S westeri (horses) S canis (dogs)
Order Ascaridia
Large round worms
Ascarids
Roundworms
Adults in small intestine
Eggs large numbers, sticky, thick walled
L1-L3 in egg must be eaten before hatching
Toxocara canis Lifecycle
Dog roundworms
Somatic migration of L2, larval arrest in tissues (placental/mammary transmission to pups)
TRACHEAL MIGRATION of L2 in pups L3 in pharynx Adults in SI
SOMATIC MIGRATION paratenic host direct development in SI
Toxocara canis Effects
Ill thrift vomiting diarrhoea pot belly pups
Ascaris suum
Pig roundworms
Somatic and tracheal migration via liver and lungs to SI
Pascaris equorum
Horse roundworm
Toxocara cati
Cat roundworm
Order oxyurida
Pinworms
Adults in LI
Direct lifecycle
Egg cememnted on perianal skin or passed in faeces
ighly host specific
Oxyuris equi
Horse Pinworm
Irritation around anus can lead to poor condition
Superfamily habronematoidea
Adults in stomach, thin shell eggs in faeces
L1 ingested by maggot of muscid fly, development to L3 escapes via fly mouthparts during feeding
Habronema spp or Draschia metastoma
Horse
Adults unimportant problem when larvae escapes into inappropriate sites
Superfamily Filarioidea
Adults in circulatory system or connective tissue, no direct route out of host
ingested by arthropods
Dirofilaria immitis
Dog heartworm
Adults in pulmonary aorta and right chaber of heart
Develop into L3 in mosquito, migrate via mouthparts during feeding, L3 and 4 develop in CT, L5 penetrates great veins and carried to distal pulmonary aorta, move proximally as they mature
Cause pneumonitis, congestive heart failure, renal disease
Trichuris species
Whipworm
Adults in L1 of dog, pig, ruminant, human
Long anterior end embeds in mucosa, short broad posterior end
Direct lifecycle, extremely resilient eggs pass in faeces, embryonate to L1 within egg, ingested by definitive host
Most infection light
Coccidiosis
Disease of intensive husbandry: Poultry, young animals, macropods in captivity by ingestion of oocysts
Isopora and Eimera
Coccidia Protists
Highly host specific, nearly all enteric, site in gut differs among secies
Chickens
Cryptosporidium paryum
Mammals, significant zoonosis, diarrhoea in humans, disease of over crowding
Toxoplasma gondii
Coccidia protist. Tissue cyst forming
Wide range of hosts
Benign infection except in immunosupporession or pregnancy (infection in third trimester can kill fetus)
Neospora
Coccidia protist tissue cyst
Direct host: canids, gamogony and oocyst formation, paralysis in pups
Intermediate host: cattle, horse, cysts in CNS, major cause of abortion in cattle
Sarcocystis
Coccidia protist tissue cyst
Muscle cysts in wide range of mammals
Order Haemosporida
Protist parasites of blood cells
Malaria and malaria like parasites in blood cells of vertebrates
Plasmodium
Malaria Protist
Species in Australi affects birds and reptiles
Leucocytozoon
Birds and reptiles, blackflies and midges are vectors. Some species highly pathogenic.
Piroplasmida
Parasites of blood cells. Tick vectors.
Babesia
Tick fever (Piroplasmida protist)
Mucosaflagellates
Alimentary or genital track, close association with mucous membrane
Transmission by faeces of genital secretions as trophozoites or cysts
Giardia
Mucosoflagellates Protist
Pear shaped, binucleate
Trophozoites, adapted for attachment to small intestine where they feed on mucous secretions, excretion of cysts, faecal and water contamination
Causes diarrhoea, malabsorption
Tritrichomonas
Mucosoflagellates Cattle foetus protist
Genital infection (STD)
No cystic stage direct transfer
Infertility in female cows, abortions
Trichomonas gallinae
Mucosoflagellates Birds negrotic ulceration in upper GIT
Haemoflagellates
Life in blood, lymph and/or tissue spaces transmission by blood sucking insects
Trypanosoma brucei
Haemoflagellates
Nagana in animals. Sleeping sickness in humans.
Tsetse fly vector (vector in tropical africa) salivary transmission
Replicates in blood, lymph & CNS causes anaemia, fever, neuro signs
Horses and dogs highly susceptible - rapid course of disease
Ruminants chronic (midly pathogenic)
Leishmania spp
All species infect mammals (especially humans, dogs, rodents)
Amastigotes invade macrophages
Transmission by sandflies
Tropical and subtropical (exotic to Australia)
Cutaneous (curable) and visceral (fatal)
Ciliophora
Possess cilia in at least one stage of life cycle
Most species free living, few are parasitic
Balantidium coli
Pigs and humans. Cysts passed in faeces, contaminate environment, ingestion, release in gut, then LI
Usually subclinical but association with ulcertaion of colon (diarrhoea, dysentery)
Ichtyophthirius multifilis
Whitespot in freshwater fish