PATH FINAL EXAM (everything)

*PHYLUM ACANTHOCEPHALA

Macracanthorhynchus hirudinaceus

Polymorphus spp.

Piscine Acanthocephalans

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MORPHOLOGY:

• elongate, no digestive tract

• praesoma - proboscis and lemnisci

• metastoma (trunk) - sexual organs

• armed proboscis with nerves that reach down main body

• lemnisci - sensory nerve bundles from proboscis

• giant nuclei with cuticle

• MALE

  • central testes and cement gland

  • copulatory bursa

• FEMALE

  • ventral ligament sac - eggs

  • uterine bell - sorts eggs in ventral ligament sac and ejects them into uterus

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LIFE CYCLE:

• eggs with partially developed acanthors in feces > IH > hatch and penetrate gut wall, lodges > develops proboscis and loses hooks > acanthella

• mature nonfunctional gonads > cystacanth > DH > sexual maturity

*Macracanthorhynchus hirudinaceus

PHYLUM ACANTHOCEPHALA

HOST: Swine, humans rarely (DH); beetle grub larvae (IH)

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• large, pink

• acquired through ingestion of IH

• typical lifecycle

*Polymorphus spp

PHYLUM ACANTHOCEPHALA

• may be found in high numbers in duck, can be very pathogenic

• proboscis causes local damage to mucosa > penetration and hooks

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LIFE CYCLE:

• typical life cycle

• acanthella and cyctacanth develop in freshwater copepods

• modify behaviour

*Piscine Acanthocephalans

PHYLUM ACANTHOCEPHALA

• numerous species affecting fish

• more than one IH

• relatively common in freshwater and marine environments

*PHYLUM PLATYHELMINTHES (flatworms)

Class Monogena (ectoparasitic flatworms)

Class Trematoda (trematodes)- Aspidogastrea, Digenea

Class Cestoda (tapeworms)

*CLASS MONOGENA (ectoparasitic flatworms)

PHYLUM PLATYHELMINTHES

• pest in caged fish farming and aquaria

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MORPHOLOGY:

• hermaphrodites, male organs mature before female

• distinct anchor with sucker and complex hook arrangement

• divided into 2 types

  • Mono-opistocotylea

  • Poly-opisthocotylea

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LIFE CYCLE (direct, cyclodevelopmental):

• ectoparasites of fish (gills)

• no asexual reproduction, no IH

• some lay eggs > oncomiracidium (larval stage)

  • search out fish host by swimming with cilia

*CLASS TREMATODA (trematodes)

ORDER DIGENEA

• intestinal: Alaria spp., Nanophyetus salmincola

• blood: Schistosoma spp.

• lung: Paragonimus spp.

• liver: fasciola hepatica, fascioloides magna, opisthorchis sinensis

• others: lancet liver fluke, green-banded broodsac, swimmer’s itch

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ORDER ASPIDOGASTRIA

*ORDER DIGENEA

CLASS TREMATODA
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MORPHOLOGY:

• dorso-ventrally flattened, spiny cuiticle, esophagus and blind ceca

• ventral and oral suckers, shared genital pore

• hermaphroditic (most)

• female: ovary, uterus, vitellaria

• male: paired testes

• eggs: oval, operculate, brown-yellow, contents fill eggs completely

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LIFE CYCLE (indirect):

• miracidium > sporocyst > redia > cercaria > (sometimes meta/mesocercaria)

  • most immature stages in IH, some in environment

• HOST: specific snail (IH), varied vertebrate (DH)

• geographic distribution of parasite follows snail host

• miracidium > operculum > penetrate IH > asexual replication (sporocyst and redia) > cercaiae

• cercariae

  • penetrate DH > mature

  • encyst on vegetation or in another IH > metacercaria

  • penetrate IH > mesocercaria

*Alaria spp. (intestinal fluke)

CLASS TREMATODA, CLASS DIGENEA

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HOST: cats/dogs (DH), snails/tadpoles (IH), various (PH) - CAN INFECT HUMANS

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MORPHOLOGY:

• small, anterior flattened, cylindrical posterior

• anterior region has oral and ventral suckers

• eggs: yellow-brown, operculate, segmented embryo when egg in feces

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LIFE CYCLE (indirect):

• immature eggs in feces > miracidium hatch in water > IH > cercariae

• IH/DH/PH > mesocercariae > lungs > metacercariae > respiratory tract and swallowed > mature in SI

• Zoonotic threat: cercariae > tadpoles > mesocercariae

  • eating uncooked PH

• only replicate in IH

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PATHOGENESIS + DIAGNOSIS

• tightly packed in clusters in SI

• not normally pathogenic except in heavy infection

• egg on fecal float

*Nanophyetus salmincola (Salmon Poisoning Fluke) (intestinal fluke)

CLASS TREMATODA, ORDER DIGENEA

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HOST: dogs/cat/mink (DH), snail, fish (IH)

• restricted to Pacific Northwest and Siberia

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MORPHOLOGY:

• small, creamy white

• eggs: small, INDISTINCT operculum, yellow-brown

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LIFE CYCLE (typical):

• eggs in feces > miracidia in water > snail IH > cercariae > fish IH > metacercariae > DH > fluke > SI

PATHOGENESIS + TREATMENT

• vector of Neorickettsia helminthoeca

• not really pathogenic

• treated with tetracyclines

*Paragonimus spp. (lung fluke)

CLASS TREMATODA, ORDER DIGENEA

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MORPHOLOGY:

• ovoid, large, in cysts in pairs, reddish-brown, spiny cuticle

• egg: small, distinct operculum, yellow-brown

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LIFE CYCLE (typical):

• eggs in cyst > shed into bronchioles > swallowed > eggs in feces > miracidia > snail IH > cercariae > crayfish IH > metacercariae

• DH > release fluke into SI > lungs and associate in pairs in lung parenchyma near bronchioles > fibrotic cyst

*Fasciola hepatica (liver fluke)

CLASS TREMATODA, ORDER DIGENEA

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HOST: humans can be infected

• usually imported animals, restricted geographically in Canada

MORPHOLOGY:

• large, leaf-like, cephalic cone

• eggs: indistinct operculum

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LIFE CYCLE (typical):

• eggs in feces > miracidium > IH > cercaria > vegetation > metacercaria

• DH ruminant > fluke released > SI > liver capsule > migrates through parenchyma > bile duct > mature

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PATHOGENESIS:

• pipe-stem fibrosis of liver

• within bile ducts, extensive fibrosis of duct wall

*Fascioloides magna (liver fluke)

CLASS TREMATODA, ORDER DIGENEA

-

HOST: wild cervids (DH, Canada)

• widely distributed geographically

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MORPHOLOGY:

• large, leaf-like, no cephalic cone

• egg: typical fluke

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LIFE CYCLE (typical):

• eggs pass through bile duct > eggs in feces > miracidium > IH > cercariae > vegetation > metacercaria

• cervid DH > fluke released > SI > liver capsule > liver parenchyma > cyst in bule duct

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PATHOGENESIS AND DIAGNOSIS:

• diagnosed post-mortem in domestic animals, no patency

• no clinical signs in wild and domestic cervids

• fluke eggs seen on fecal float

• CATTLE:

  • no clinical signs, no patency, accumulate

• SHEEP:

  • no encysting, migrate constantly, mortality before patency

*Opisthorchis sinensis (liver fluke)

CLASS TREMATODA, ORDER DIGENEA

• can infect humans

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LIFE CYCLE:

• eggs in feces > snail IH > cercariae > metacercariae in skin/flesh of fish

• human DH > excyst in duodenum > mature in billiary duct

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PATHOGENESIS + DIAGNOSIS:

• inflammation, obstruction of biliary duct, acute pain, chronic infection

• small, operculate egg in stool or duodenal aspirate

• treatable

*Schistosoma spp. (blood fluke)

CLASS TREMATODA, ORDER DIGENEA

• mansoni, japonicum, haematobium

• can infect humans

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LIFE CYCLE:

• eggs in feces/urine > miracidia > snail IH > sporocysts > cercariae released

• penetrate DH skin > cercariae lose tails > schistosomulae > portal blood in liver > mature > pair

• can cause immune interactions during egg migration

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PATHOGENESIS AND DIAGNOSIS:

• acute (eosinophilia)

• chronic: bloody diarrhea, portal hypertension, pulmonary hypertension

• diagnose by egg morphology, intestinal species in feces/urine

• treatable

*ORDER ASPIDOGASTREA

CLASS TREMATODA

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MORPHOLOGY:

• large ventral sucker, anterior mouth

• posterior sucker modified into large adhesive disk/plate

• eggs shed into enviro > hatch to larvae or ingested and hatch

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LIFE CYCLE:

• generally not host specific

• Obligate: mollusk > fish (DH)

  • eggs > mollusk > form that is not sexually mature > larval form > fish host > SI > matures

• facultative:

  • eggs/larvae > mollusk > mature adult

  • mollusk > fish/turtle host > establish in digestive tract > produce egg

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PATHOGENESIS:

• not associated with diseases

*Class Cestoda (tapeworms)

Cyclophyllidean: (long strobila, proglottids)

• Taenia Pisiformis, Taenia Taeniaeformis, Taenia Crassiceps, Taenia Saginata, Taenia Solium

• Echinococcus Granulosus, Echinococcus multilocularis

• Arthopodan: Dipylidium Caninum, Anocephala perfoliata, Monezia spp.

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Pseudophyllidean:

• Crustacean: Diphyllobothrium latum

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DH: host specific, do not replicate, not very pathogenic

IH: usually host specific, a prey species, may be pathogenic

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MORPHOLOGY:

• most are large (some small)

• 3 body regions

  • scolex, neck, strobila

• no mouth/digestive tract, hermaphroditic

• eggs: hexacanth embryo within embryophore, shed in segments/feces

• larva: various stages

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LIFE CYCLE (indirect):

• eggs in feces/segments > hexacanth embryo > IH > migrates to final site of development > infective

• IH eaten > scolex attaches to DH gut > matures

• most species only have 1 IH, some aquatic use 2

*LARVAL FORMS CLASS CESTODA

Cyclophyllidea:

• Taenia spp: cysticercus, strobilocercus, coenurus

• Echinococcus spp: hydatid cyst, alveolar hydatid cyst

• Dipylidium, Noezia, Anoplocephala: cysticercoid

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Pseudophyllidea:

• Diphyllobothrium: procercoid, plerocercoid

*Taenia pisiformis (rabbit tapeworm)

Class Cestoda, Cyclophyllidea

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HOST: dogs (DH), rabbits (IH)

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MORPHOLOGY:

• shiny white strobila, rectangular segment

• scolex 4 suckers, 2 rows of hooks on rostellum, single genital pore

• Larva: cysticercus, fluid filled bladder

• egg: typical taeniid, thick radially striated shell, found singly

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LIFE CYCLE:

• eggs from segments > IH > hexacanth larva hatches > peritoneal cavity/liver > cysticercus

• DH > scolex in cysticercus evaginates > attaches to gut > strobila

-

PATHOGENESIS:

• non-pathogenic, motile gravid segments

*Taenia taeniaeformis (rat tapeworm)

Class Cestoda, Cyclophyllidea

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HOST: cats (DH), rodents (IH)

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MORPHOLOGY:

• scolex 4 suckers, 2 rows of hooks on rostellum

• larva: strobilocercus

• egg: typical taeniid

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LIFE CYCLE:

• similar to Taenia pisiformis

  • IH in liver, DH in small intestine

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PATHOGENESIS:

• not pathogenic, gravid segments in feces

*Taenia crassiceps

Class Cestoda, Cyclophyllidea

• can infect humans if dog infected

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HOST: foxes (DH), groundhogs (IH)

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MORPHOLOGY:

• larvae: budding cysticercus

*Taenia saginata (beef tapeworm)

Class Cestoda, Cyclophyllidea

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HOST: humans (DH), cattle (IH)

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MORPHOLOGY:

• unarmed rostellum, 4 suckers, segments with 1 genital pore irregularly alternating

• larva: cysticercus

• egg: typical taeniid

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LIFE CYCLE:

• segments in feces > eggs emerge > IH > hexacanth larvae > SI > muscles

• hexacanth larvae > cysticercus (viable for long periods of time)

• DH > uncooked meat > SI > matures

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DIAGNOSIS + TREATMENT:

• relatively benign, little damage

• cysticercosis not possible in humans

• improve sanitation

*Taenia solium (pork tapeworm)

Class Cestoda, Cyclophyllidea

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HOST: humans (DH);swine, humans (IH)

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MORPHOLOGY:

• armed rostellum, 2 rows of hooks, irregular alternating genital pore

• larvae: cysticercus

• egg: typical taeniid

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LIFE CYCLE: same as T. saginata

• segments in feces > eggs emerge > IH > hexacanth larvae > SI > muscles

• hexacanth larvae > cysticercus (viable for long periods of time)

• DH > uncooked meat > SI > matures

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PATHOGENESIS + DIAGNOSIS

• cysticercosis possible in humans (self-infection > humans IH)

  • eggs shed fully mature and immediately infective

• sanitation, determine source, avoid eggs

*Echinococcus granulosus

Class Cestoda, Cyclophyllidea

• zoonotic threat

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HOST: wolf (DH), moose (IH)

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MORPHOLOGY:

• smallest tapeworm of dogs, scolex 4 suckers, 2 rows of hooks, 3-4 segment strobila

• larvae: hydatid cyst (asexual reproduction)

• egg: typical taeniid

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LIFE CYCLE:

• eggs in segments > IH > hexacanth larvae > intestine > lungs > hydatid cyst grows

• DH > scolex attach to SI mucosa

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DIAGNOSIS + TREATMENT:

• non pathogenic (DH), unaffected usually (IH)

• space occupying lesions in humans

• eggs in feces (cannot distinguish from Taenia), surgery

*Echinococcus multilocularis

Class Cestoda, Cyclophyllidea

• zoonotic threat

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HOST: fox (DH), rodents (IH) - Canada

• cosmopolitan distribution

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MORPHOLOGY:

• smallest tapeworm of dogs, scolex 4 suckers 2 rows of hooks, strobila 3-4 segments long

• larva: alveolar hydatid cyst (asexual replication, budding mass)

• egg: typical taeniid

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DIAGNOSIS + TREATMENT:

• massive replication, budding and metastasis in IH (liver, other organs)

• eggs in feces (cannot distinguish from Taenia), drugs, surgery

*Dipylidium caninum (Flea tapeworm)

Class Cestoda, Cyclophyllidea

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HOST: dogs, cats, humans - rare (DH); fleas (IH)

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MORPHOLOGY:

• scolex with 4 suckers, rostellum with several rows of hooks, long strobila, barrel segments, pores each side

• larvae: cysticercoid

• eggs: in packets, thick unstriated embryophore

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LIFE CYCLE:

• eggs in segments (motile) > IH > hexacanth larvae > body cavity > cysticercoid

• DH > scolex attaches to SI mucosa

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DIAGNOSIS + TREATMENT:

• non-pathogenic (vertebrates)

• differentiate between taeniid

• migrating segments in feces, rarely eggs in fecal floats, cestodicide

*Anocephala perfoliata

Class Cestoda, Cyclophyllidea

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HOST: horse/ponies (DH), orbatid mites (IH)

• role in stomach upsets

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MORPHOLOGY:

• lappets on scolex, in ileocecal junction

• irregular eggs with pyriform apparatus

• treatable

*Monezia spp.

Class Cestoda, Cyclophyllidea

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HOST: cattle/sheep/goats (DH), orbatid mites (IH)

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MORPHOLOGY:

• in small intestine

• irregular eggs on fecal with pyriform apparatus

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DIAGNOSIS:

• clincal signs only in heavily infested and young

• treatable

*Diphyllobothrium latum

Class Cestoda, Pseudophyllidean

• humans can get infected

HOST: fish-eating mammals (DH); 2 IH - copepod (procercoid) > fish (pleurocercoid)

MORPHOLOGY:

• pair of bothria (grooves) on scolex, large strobila

• eggs: operculate, light brown, ciliated hexacanth larva > coracidium

PATHOGENESIS + TREATMENT:

• usually non-pathogenic, B12 deficiency

• potentially treatable

*PHYLUM NEMATODA

Order Rhabditida (rhabditids, threadworms)

Order Strongylida (strongylids, hookworms, lungworms)

Order Oxyurida (pinworms, oxyurids)

Order Ascaridida (ascarids)

Order Spirurida (spirurids, filarids, Dracunculus)

Order Enoplida (trichurids/whipworms, Dioctophyme, capillarids, Trichin

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MORPHOLOGY:

• elongate tubular bodies,

• thick, resistant cuticle, muscles under

• hydrostatic pressure to maintain shape and rigidity

• simple alimentary tract, separate sexes

• male: tube with testes, vas deferens, ejaculatory duct, copulatory bursa, cuticular spicules (sometimes)

• female: pair of blind-ended ovaries to uteri, vagina, vulva, can store sperm

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LIFE CYCLE:

• egg > L1 > L2 > L3 (infective) > L4 > L5 > adult

• life cycle can be divided among different hosts

*Infection and Migration in Nematodes

Infection:

• oral ingestion (fecal-oral)

• penetrate skin

• transplacental, transmammary

• predator-prey with IH or PH

• vector borne

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Migration:

• tracheal: enter bloodstrem by penetrating gastrointestinal wall, end up in airway and swallowed

• somatic: trachea migration but stay in bloodstream, distributed around body

• mucosal: unrelated to tracheal and somatic, penetrate gastric pits/mucosa before returning to lumen

*Order Ascaridida (ascarids)

Phylum NEMATODA

• Toxocara canis, Toxocara cati

• Toxascaris leonina, Parascaris equorum

• Ascaris lumbricoides, Ascaris suum

• Ascaridia galli, Heterakis gallinarum, Baylisascaris procyonis

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GENERAL:

• generally robust, heavy bodied

• infect SI (DH) - except Heterakis gallinarum

• highly host specific, various life strategies

• eggs often resistant to enviro (infectious for long times)

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LIFE CYCLE (direct, may have PH):

• prolific, many alternate migration routes

• eggs mature with L3 in enviro (usually oral infection)

• L3 penetrate SI > migration > SI > mature

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PATHOGENESIS:

• poor growth, potbelly, obstruction, minor lesions from migration

• possible zoonoses (ocular/visceral larval migrations)

*Toxocara canis (canine roundworms)

ORDER ASCARIDIDA

• can infect humans

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HOST: dogs (specific)

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MORPHOLOGY:

• large, heavy bodied

• egg: thick shelled, pitted, single cell in feces

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LIFE CYCLE: PPP 4-5w, 3w

• eggs in feces > L3 > oral transmission > gastrointestinal

• migration route dependent on age

  • tracheal (<3mo), somatic (6+mo), mixed (3-6mo)

• pups often born with parasite (transplacental, hypobiotic larvae)

  • partial tracheal migration

• potential PH with larvae ingestion

  • short patency, no migration

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PATHOGENESIS + TREATMENT:

• mainly light infections, usually non-pathogenic

• heavy infection: unthriftiness, stunted growth, dry skin, dull coat

• potentially painful abdomen, death may occur before patency, eosinophilic gastroenteritis, lung issues, focal lesions

• vomition = heavy infection

• many treatments

  • some antihelmintics could potentially cause obstruction

*Toxocara cati (feline roundworms)

ORDER ASCARIDIDA

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HOST: cats (specific)

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MORPHOLOGY:

• arrowhead cervical alae (cuticular extension), large

• egg: thick shelled, pitted, single cell in feces

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LIFE CYCLE: PPP 4w

• eggs in feces > L3 > oral transmission > gastrointestinal

• L3 penetrates stomach wall > tracheal (young) OR somatic (older)

• transmammary infection possible

• PH ingestion can cause infection (cats that can hunt)

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PATHOGENESIS + TREATMENT:

• not as pathogenic as T. canis

• vomiting even in moderate, unthriftiness and diarrhea (unusual)

• fewer treatment compounds

*Toxascaris leonina

ORDER ASCARIDIDA

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HOST: dogs, cats (generalist)

• not as common as Toxocara spp.

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MORPHOLOGY:

• same size as T. cati, no cervical alae

• eggs: smooth shells, undulating membrane, single cell that does not fit shell

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LIFE CYCLE: PPP 2mo

• eggs feces > L3 > oral transmission > gastrointestinal

• no tracheal migration > L3 intestinal wall > mucosal migration > lumen > mature

• possible infection by PH ingestion

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PATHOGENESIS + TREATMENT

• not as pathogenic as Toxocara spp.

• usually not heavy burdens

• similar treatments as Toxocara spp.

*Parascaris equorum (equine roundworm)

ORDER ASCARIDIDA

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HOST: horses, ponies donkeys

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MORPHOLOGY:

• heavy bodied, white

• eggs: sub-spherical, thick protein coat

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LIFE CYCLE: PPP 10-12w

• tracheal migration > liver and lung

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PATHOGENESIS + TREATMENT

• clinical signs in foals and weanlings

• heavy burdens can impact colic

• unthrifty, loss of appetite, hypoalbuminenia

• typical eggs can be found in feces

• can be treated

  • some compounds can cause obstruction

*Ascaris lumbricoides (human roundworm)

ORDER ASCARADIDA

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HOST: humans, swine

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MORPHOLOGY:

• heavy bodied, white, smaller males

• eggs: sub-spherical, thick protein coat

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LIFE CYCLE: PPP 6-8w

• tracheal migration > liver and lung

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PATHOGENESIS + TREATMENT:

• milk spots on liver

• pulmonary hemorrhage/edema, mild enteritis

  • erratic migrations problematic

• typical eggs can be found in feces

*Ascaris suum

ORDER ASCARIDIDA

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HOST: swine

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MORPHOLOGY:

• heavy bodied, white, males smaller

• eggs: sub-spherical, thick protein coat

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LIFE CYCLE: PPP 6-8w

• tracheal migration through liver and lung

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PATHOGENESIS + TREATMENT:

• milk spots on liver

• pulmonary hemorrhage/edema, mild enteritis - affects growth

• typical eggs can be found in feces

• sanitation, feed antihelmintics, deworming

*Ascaridia galli

ORDER ASCARIDIDA

-

HOST: birds

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MORPHOLOGY:

• heavy bodied, white

• eggs: smooth shelled

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LIFE CYCLE: PPP 30-50d

• L3 larvated eggs > hatch > L3 into mucosal > L4 > re-enters lumen of SI > matures

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PATHOGENESIS + TREATMENT:

• hemorrhage/diarrhea during larval mucosal migration

• decreased production, low mortality

• eggs can be found in feces of birds

*Heterakis gallinarum (cecal worm)

ORDER ASCARIDIDA

-

HOST: chickens, turkeys, etc.; earthworms (PH)

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MORPHOLOGY:

• slender, in ceca

• eggs: thick, smooth shell

-

LIFE CYCLE: PPP 24-30d

• eggs in feces > L3 > oral ingestion > gastrointestinal tract

• migrate in mucosa of cecum > re-enters lumen > molts 3x > mature

-

SIGNIFICANCE:

• true IH of Histomonas meleagridis

*Baylisascaris procyonis

ORDER ASCARIDIDA

• zoonotic threat

-

HOST: raccoons, dogs (DH); various (PH)

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MORPHOLOGY:

• large worms

• eggs: thick, smooth shell

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SIGNIFICANCE:

• visceral larval migrans

• long period for eggs to become infective

• sanitation, raccoon latrines

*Order Rhabditida

PHYLUM NEMATODA

• strongyloides spp (threadworm)

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GENERAL:

• usually free living, infect vertebrates during part of life cycle or accidentally

• mainly small

*Strongyloides spp. (threadworms)

ORDER RHABDITIDA

HOST: various species with assorted hosts

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MORPHOLOGY:

• thread-like, no parasitic males

• eggs: oval, thin shelled, L1 inside

  • S. stercoralis = L1 free in feces

• NOT freeze tolerant

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LIFE CYCLE:

• parasitic with/without free living stage

• free-living: complete, M+F produce eggs

• Routes of infection

  • mucosal: ingestion of L3

  • tracheal/somatic: skin penetration

  • transmammary

• S. stercoralis can cause autoinfection in humans

• generally cleared from young animals at 6mo

• L1 in feces > L3 > mature > oral/skin > tracheal/somatic/mucosal> embed in mucosa SI villi > lumen

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PATHOGENESIS + DIAGNOSIS:

• non-bloody enteritis, worms deeply embedded

• Baermann for larva in feces

*ORDER ENOPLIDA

PHYLUM NEMATODA

• Trichurus spp. (whipworm)

• Capillaria spp.

• Diocytophyme renale (giant kidney worm)

• Trichinella spiralis

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GENERAL:

• elongate esophagus surrounded by stichocytes

• host specific, many hosts, location varies by genus

• deeply embedded in epithelium

-

MORPHOLOGY:

• slender, white

• eggs: oval, distinct bipolar plugs

• larvae: only in Trichinella spp. in intestinal tract/muscles

-

LIFE CYCLE:

• direct and indirect, oral transmission

  • larvae mature in egg > DH or IH

• trichinella larvae > intestine > tissue > hypobiotic

*Trichuris spp. (whipworm)

ORDER ENOPLIDA

• humans can become infected

-

HOST: highly specific

• each host has its own species that will not infect other hosts

-

MORPHOLOGY:

• whip shapped, anterior 2/3 narrow

• egg: smooth, oval shell, prominent plug, fills shell, yellow-brown

• eggs are frost and enviro resistant

-

LIFE CYCLE (direct): - PPP long

• larvae in egg (infective) > oral transmission > mucosal migration in SI > L1 in cecum > mature

-

PATHOGENESIS + DIAGNOSIS:

• thin anterior portion deeply embedded

• malabsorption, diarrhea, protein loss, blood feeders

*Capillaria spp.

ORDER ENOPLIDA

-

HOST: highly specific (host and location), some have IH

• can be infected by multiple species at different sites

-

MORPHOLOGY:

• slender, uniform, fine, hair-like, prominent stichocytes

• egg: smooth (less than Trichuris), oval shell, prominent plug, fills shell

-

LIFE CYCLE:

• if IH, many use earthworms

• eggs in feces/urine depending on location of adults

• C. hepatica - lays eggs throughout liver and released when host dies

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IN BIRDS:

• C. contorta

  • wall of crop thickened, weakness, unthriftiness

• C. caudinflata + obsignata

  • edematous intestinal wall with reddish fluid

  • necrosis of mucosa - heavy

  • reddish diarrhea, emanciation

  • decreased production

*Giant Kidney Worm (Diocytophyme renale)

ORDER ENOPLIDA

• can infect humans

-

HOST: mink (primarily), dogs, humans (DH); invertebrate (IH)

• found locally in Thames river valley

-

MORPHOLOGY:

• bright red, usually seen coild in (right) kidney

• females up to 100cm long and 1cm diameter

• males have bell shaped copulatory bursa

• eggs: bipolar plugs, pitted outer shell

-

LIFE CYCLE: PPP 3-5mo

• eggs in urine > IH > larva (infective)

• may go up food chain > DH oral transmission > intestine > kidney > mature

-

PATHOGENESIS + TREATMENT

• affected kidney destroyed - surgery

*Trichinella spiralis

ORDER ENOPLIDA

• can infect humans

-

HOST: swine, meat eating animals

-

MORPHOLOGY:

• females: 3-4mm, slender, uterus with larvae

• males: 1.5mm, 2 small cloacal flaps on tail

-

LIFE CYCLE:

• each host is both DH and IH

• larvae > oral transmission eating meat > mature > lay ~1500 larvae > distribute around body

-

PATHOGENESIS + DIAGNOSIS:

• fatal dose of larvae in humans, cannot tolerate

• gastroenteritis, diarrhea, muslce pain, inflammation, eosinophilia

• muscle biopsy to identify heavy burden

• preventative, no viable treatment

• trichinoscope

*ORDER OXYURIDA

PHYLUM NEMATODA

• enterobius vermicularis (human pinworm)

• oxyuris equi (horse pinworm)

-

GENERAL:

• highly host specific, large intestine

• usually not overtly pathogenic, irritating

-

MORPHOLOGY:

• most are small (except O. equi)

• long tapering tail in both sexes

• eggs: oval, some operculate, asymmetrical (flat + round sides)

-

LIFE CYCLE:

• direct, simple

• eggs in feces > deliver to perianal region > larva

• fecal-oral transmission > eggs hatch in intestine > large intestine > mature

*Enterobius vermicularis (human pinworm)

ORDER OXYURIDA

-

HOST: humans (large intestine)

-

MORPHOLOGY:

• long tapering tail in both sexes

• eggs: oval, some operculate, asymmetrical (flat + round sides)

-

LIFE CYCLE:

• direct, simple

• eggs in feces > deliver to perianal region > larva

• fecal-oral transmission > eggs hatch in intestine > large intestine > mature

-

PATHOGENESIS:

• egg laying gives highly puritic perianal region = scratching

• abdominal upset

• IH of Dientamoeba fragilis

*Oxyuris equi (horse pinworm)

ORDER OXYURIDA

-

HOST: horses, ponies, donkeys

-

MORPHOLOGY:

• larger, long tapering tail in both sexes

• eggs: oval, some operculate, asymmetrical (flat + round sides)

-

LIFE CYCLE:

• direct, simple

• eggs in feces > deliver to perianal region > larva

• fecal-oral transmission > eggs hatch in intestine > large intestine > mature

-

PATHOGENESIS:

• egg mass deposition gives puritis = local abrasions, rat tails

• inflammation and ulceration (heavy)

• wide ragne of treatments

*ORDER STRYONGYLIDA

Trichostrongyles

Strongyles

Hookworms

Lungworms

-

GENERAL:

• most have single host (except lungworms)

• wide range of hosts, varies

-

MORPHOLOGY:

• smaller

• slender (trichostrongyles and lungworms) vs stout bodied (hookworms and strongyles)

• Eggs: thin-shelled morulated; GIN eggs

-

LIFE CYCLE:

• direct (except lungworms)

• eggs/larvae in feces > oral transmission (sometimes ksin) > extra-intestinal migrations

*HOOKWORMS

ORDER STRONGYLIDA

• Ancylostoma duodenale and Necator americanum (human)

• Ancylostoma caninum

• Uncinaria stenocephala

*Ancylostoma duodenale and Necator americanus (human hookworm)

ORDER STRONGYLIDA, HOOKWORM

-

HOST: humans; warm moist climate

• easy to acquire, modify host behaviour

-

MORPHOLOGY:

• large buccal cavity, teeth (A), plates (N), moderate size

• males: colulatory bursa

• eggs: morulated, L1 in egg

• rhabditiform L2 and L3

• filariform L3 infective

-

LIFE CYCLE:

• eggs feces > rhabiditiform larvae > L3

• penetrate skin > tracheal migration > intestine > mature

• A.duodenale may undergo somatic and potentially transmammary

-

PATHOGENESIS + DIAGNOSIS:

• blood loss at attachment sites, anemia

• bulbous abdomen

• ground itch (L3 penetration), respiratory symptoms (pulmonary migration)

*Ancylostoma caninum (canine hookworm)

ORDER STRONGYLIDA, HOOKWORM

-

HOST: dogs

-

MORPHOLOGY:

• stout, bend in body at buccal cavity - 3 pairs of teeth, red if filled with blood

• egg: morulated, LESS THAN 70umI

• environment will affect L3

-

LIFE CYCLE:

• eggs feces > L1 > L3 > penetrate skin

• tracheal migration (young), somatic (older)

• possible patent if ingest L3 > mucosal migration

• transmmary infection possible (hypobiotic larvae)

-

PATHOGENESIS + DIAGNOSIS:

• blood loss, anemia, protein loss, enteritis, melena, emaciation

• can die before patency (heavy infection) due to blood loss

*Uncinaria stenocephala

ORDER STRONGYLIDA, HOOKWORMS

-

HOST: dogs, cats; northern

-

MORPHOLOGY:

• similar to Ancylostoma but has pair of cutting plates in buccal cavity (vs 3 pairs of teeth)

• eggs: morulated, oval, MORE THAN 70um

• L3 are freeze tolerant and hardy

-

LIFE CYCLE:

• eggs in feces > L1 > L3

• L3 ingested (skin uncommon)

• no extra-intestinal migration

-

PATHOGENESIS + TREATMENT:

• much less pathogenic than Ancylostoma spp.

• anemia, protein loss, mild enteritis

• antihelmintics used for ascarids

*LUNGWORMS

ORDER STRONGYLIDA

• Muelerius capillaris

• Filaroides and Oslerus spp.

• Aelurostrongylus spp.

• Crenosoma spp.

*Muellerius capillaris

ORDER STRONGYLIDA, LUNGWORMS

-

HOST: sheep/goats (DH), snails/slugs (IH)

-

LIFE CYCLE (indirect):

• eggs in feces > L1 > penetrate IH > L3

• oral transmission into DH > gastrointestinal tract > lungs via bloodstream > alveoli and terminal bronchioles > mature

-

PATHOGENESIS + DIAGNOSIS:

• alveolar rupture, focal interstital pneumonia, granuloma

• L1 in feces = diagnostic stage

• raised regions on lungs, calcification

• no registered compounds to treat

*Filaroides and Oslerus spp.

ORDER STRONGYLIDA, LUNGWORMS

-

HOST: dogs, foxes, wolves

-

MORPHOLOGY:

• small, slender

• eggs: thin walled, fully larvated eggs laid by female, hatch quickly

• larvae: small, passed in feces

-

LIFE CYCLE: PPP 10w (O), 5w (F)

• L1 in feces > tracheal migration

• O. osleri = trachea/bronci

• F. hirthi = bronchioles/alveoli

-

PATHOGENESIS + TREATMENT:

• usually asymptomatic (F), nodules and wheezing cough + trachitis/bronchitis (O)

  • visualize nodules via bronchoscopy

• dyspnea (heavy)

• diagnosis of larva by sputum/Baermann

• treatments available, nodules surgically

*Aelurostrongylus spp.

ORDER STRONGYLIDA, LUNGWORM

HOST: cats (DH); snal/slug (IH)

MORPHOLOGY:

• small, slender

• larvae: bent tail, dorsal spine

LIFE CYCLE:

• larvae in feces > IH > stomach > lungs > terminal respiratory/lung parenchyma > mature

• PH common source of infection

  • frog, rodent, lizard, bird

PATHOGENESIS + TREATMENT:

• focal pneumonia with granuloma

• chronic cough and dyspnea (heavy)

• larva diagnosed in sputum/Baermann

• treatments available

*Crenosoma spp.

ORDER STRONGYLIDA, LUNGWORM

HOST: dogs/wolves/foxes/racoons (DH); mollusk (IH)

MORPHOLOGY:

• small, slender, anterior cuticle has crenations (folds)

• egg: thin-shelled, morulated,

• eggs with L1 or first stage larvae released

LIFE CYCLE:

• larvae/egg in feces > IH > DH ingests L3 larvae

• migrate stomach > lungs > bronchi > bronciole > mature

PATHOGENESIS + TREATMENT:

• focal lesions

• rhinotracheitis, bronchitis (heavy)

• larva diagnosed in sputum/Baermann

• treatment available

*TRICHOSTRONGYLES

ORDER STRONGYLIDA

• Ostertasia/Teladorsagia spp. (medium-sized/brown stomach worm)

• Haemonchus spp.

• Nematodirus spp.

• Others: cooperia and Trichostrongylus spp., (ruminant) Hyostrongylus rubidus (swine)

-

GIN EGGS

*Ostertagia/Teladorsagia spp. (medium-sized or brown stomach worms)

ORDER STRONGYLIDA, TRICHOSTRONGYLES

-

HOST: cattle (O. ostertagi), sheep/goats (T. circumcincta)

-

MORPHOLOGY:

• slender, brown

• egg: thin shelled, morulated, GIN egg

• larvae and egg can overwinter and survive on pasture

LIFE CYCLE:

• larvae in eggs > pasture hatch > L3

• ingested > gastric pits > lumen > mucosal migration

• hypobiosis possible

  • depends on environment

-

PATHOGENESIS:

• largely associated with developing L3 in gastric pits and sudden emergence from hypobiosis

• PH rises to neutral, gut leakage, emaciation

• altered mucosa with nodules

• type 1: summer, no hypobiosis

• type 2: winter, hypobiosis

• pre type 2: fall into winter

*Haemonchus spp

ORDER STRONGYLIDA, TRICHOSTRONGYLES

-

HOST: cattle, sheep (H. contortus), goats

-

MORPHOLOGY:

• slender, spiral - R&W with blood

• egg: thin-shelled, morulated, GIN egg

• larvae and eggs no overwintering on pasture

-

LIFE CYCLE:

• larvae in eggs > pasture hatch > L3

• ingested > brief mucosal migration

• hypobiosis is major factor

  • depends on environment

-

PATHOGENESIS:

• largely associated with developing L4 and adults blood feeding on mucosa of abomasum

• anemia, hypoproteinemia, focal areas of hemorrhage

• pale carcass, watery blood, edema (acute)

• continuing blood loss, bottle jaw, muscle weaness, dark and hard feces (chronic)

*Nematodirus spp.

ORDER STRONGYLIDA, TRICHOSTRONGYLES

-

HOST: cattle, sheep, goats

-

MORPHOLOGY:

• very slender, multiple worms found coiled together

• egg: thin-shelled, morulated, GIN egg, visible in adult female, hatch after freezing stimulus (some)

• can overwinter on pasture

-

LIFE CYCLE (direct):

• larvae in eggs > L3 > hatch on pasture

• larvae > develop deep between villi of SI > adults > lumen

• no hypobiosis

-

PATHOGENESIS

• villus atrophy, diarrhea, anorexia

*STRONGYLES

ORDER STRONGYLIDA

• Strongylus vulgaris

• Strongylus equinis and edentatus

• Cyathostomes

• Oesophagostomum spp.

• Syngamus trachea (gapeworm)

-

GENERAL:

• migratory (strongylus spp.) vs non-migratory (cyathostome)

• all parasites of equids with adults in cecum and colon

-

MORPHOLOGY:

• Strongylus spp buccal cavity = deeper than whide

• Cyathostome buccal cavity = wider than deep

-

LIFE CYCLE:

• larvae in eggs > pasture hatch > L3

• ingested > dramatic extra-intestinal migration (S) OR mucosal migration (C) > mature and feed in cecul and colon

• some hypobiosis, some can overwinter on pasture

*Strongylus vulgaris

ORDER STRONGYLIDA, STRONGYLES

-

HOST: equids

-

MORPHOLOGY:

• dark red, large stoma, lobed teeth in deep buccal capsule base (mickey mouse teeth), medium

• egg: thin-shelled, morulated, GIN eggs

-

LIFE CYCLE (migratory):

• larvae in eggs > pasture hatch > L3

• ingested > extra-intestinal migration > adults in cecum and colon

-

PATHOGENESIS:

• largely associaed with L4 as they move extraintestinally in crainal mesenteric artery (long development 2mo there)

• larvae induce arteritis and thrombosis

• insufficient number usually to cause lesions

• acute disease from arteritis (heavy)

• intermittent colic- obstruct bloodflow (chronic)

*Strongylus equinis and edentatus

ORDER STRONGYLIDA, STRONGYLES

-

HOST: equids

-

LIFE CYCLE (migratory):

• larvae in eggs > pasture hatch > L3

• ingested > extra-intestinal migration > adults in cecum and colon

-

GENERAL:

• bowl-shaped buccal cavity, no teeth, large

• undergo long life cycle in equid host

• not highly pathogenic during larval migration

• hemorrhage, colon inflammation (heavy)

  • adults feed on blood

  • larvae re-enter intestinal tract

*Cyathostomes

ORDER STRONGYLIDA, STRONGYLES

-

HOST: equids

• many species, can often co-occur in same host

-

MORPHOLOGY:

• cylindrical buccal cavity (flat bottomed), small sized, large stoma, may/may not have teeth

• egg: thin shelled, morulated, GIN egg, smooth shell

LIFE CYCLE (non-migratory):

• larvae in eggs > pasture hatch > L3

• ingested > mucosal migration > adults in cecum and colon

• hypobiosis possible

PATHOGENESIS:

• primarily associated with larval mucosal migration

• nodules around encysted larvae = impede mobility, poor weight gain, inflammation, edema, ulcer when emerging

• anorexia, weight loss, diarrhea, colic, acute larval cyathostomiosis (when hypobiosis ends)

• non-specific clinical signs

  • unthriftiness, upset digestion (large adult numbers) = intermittent and recurring

*Oesophagostomum spp.

ORDER STRONGYLIDA, STRONGYLES

-

HOST: ruminants, swine

-

GENERAL:

• typical life cycle, prominent nodule formed during larval migration

• no overwintering, hypobiosis in nodules

*Syngamus trachea (gapeworm)

ORDER STRONGYLIDA, StRONGYLES

-

HOST: gallinaceous birds

-

MORPHOLOGY:

• males (2-6mm), females (5-40mm) - permanent copulation

• Y-shaped structure attached to trachea

• egg: elongate, ellipsoidal, smooth, operculum at each end, morulated

-

LIFE CYCLE:

• larvae in eggs (some hatch) or soil, or some PH are infective

• penetrate intestines > lungs > alveoli > trachea > attach to mucosa

• suck on blood and mate in pairs

-

PATHOGENESIS:

• worms in trachea > gape and gasp

• increase in mucous, mild anemia

• reduced production

• mortality from asphyxiation (heavy)

• raised, ulcerated lesions at attachment site

*ORDER SPIRURIDA

PHYLUM NEMATODA

• Spirurids

  • Habronema spp and Draschia megastoma

• Filarids:

  • Dracunculus medicinus (guinea worm)

  • Wucheria bancrofti and Brugia malayi (lymphatic filariases)

  • onchocera volvulus (river blindness)

  • dirofilaria immitis (canine heartworm)

-

GENERAL:

• mainly stomach worms, some in eyes/connective tissue

• indirect life cycles, simple life cycle in DH (no complex migrations)

• use arthopodan intermediate host

• PH commonly used for food chain

• lengthy PPP

• FILARIDS:

  • highly host-specific, require blood-sucking insect IH OR arthropod

  • infect conenctive tissue/body cavity

  • long-slender adults

  • microfilaria

*Habronema Spp. and Draschia megastoma (stomach worms of horses)

ORDER SPIRURIDA, SPIRURIDS

-

HOST: equids (DH); house/stable fly (IH)

-

LIFE CYCLE (indirect);

• eggs in feces > L1 > IH > L3 in fly larvae

• L3 exit from proboscis or whole fly eaten

• L3 move directly to gastric pits > mature

-

PATHOGENESIS + TREATMENT:

• Habronema

  • chronic gastritis with mucous

  • adults and larvae treatable

• Draschia

  • tumour-like nodules, lesions largely asymptomatic

  • only larvae treatable

• summer sores > lesions and inflammation (attracts more flies)

*Dracunculus medicinus (Guinea worm)

ORDER SPIRURIDA, FILARID

-

HOST: humans (DH), freshwater copepod (IH)

-

MORPHOLOGY:

• slender, females ~1m long

• within subcutaneous tissue

-

LIFE CYCLE:

• unfiltered water > larvae penetrate stomach and intestinal wall

• fertilized female > skin surface > emerge

• larvae released in water as female emerging > IH > L3

-

PATHOGENESIS + TREATMENT:

• non-pathogenic and asymptomatic during subcutaneous migration

• painful burning blister and ulcer

• no antihelmintic, simple sieve prevention

*Wucheria bancrofti and Brugia malayi (lymphatic filariases)

ORDER SPIRURIDA, FILARIDS

-

HOST: humans (DH), mosquitoes - culicine (IH)

-

MORPHOLOGY:

• slender, live 10-15y

• restricted to tropics (temperature)

• microfilariae are sheathed, live 3-5y

-

LIFE CYCLE:

• mosquito > L3 enter skin > mature in lymphatics > sheathed microfilariae > lymph and blood channels

• mosquito > microfilariae penetrate gut > larvae > L3 > migrate to proboscis

-

PATHOGENESIS + DIAGNOSIS

• lymphodema, lymph accumulation at body sites

• diagnosed by finding microfilariae in blood

*Onchocera volvulus (river blindness)

ORDER SPIRURIDA, FILARIDS

-

HOST: humans (DH), blackflies (IH)

-

MORPHOLOGY:

• slender, within subcutaneous nodules

• microfilariae unsheathed, in subcutaneous connective tissue

-

LIFE CYCLE:

• blackfly > L3 into bite wound > mature in subcutaneous nodules > unsheathed microfilariae

• blackfly > microfilariae penetrate gut > larva > L3 > migrate to proboscis

-

PATHOGENESIS + DIAGNOSIS:

• subcutaneous nodules form around adults

• retinal lesions = blindness

  • from migrating microfilariae

• diagnosed through skin snips to isolate microfilarea from subcutaneous location

*Dirofilaria immitis (canine heartworm)

ORDER SPIRURIDA, FILARIDS

-

HOST: dogs (primarily) (DH); culicine mosquitoes (IH)

-

MORPHOLOGY:

• slender, ~35cm long, right caudal lobar artery

• microfilaria tapered anterior end

• infections can also be in pulmonary arteries and right ventricle

• temperature dependent development (>14C)

  • Canada = June-October

-

LIFE CYCLE (indirect)

• mosquito > microfilaria in blood > circulate

• mosquito > L3 > migrate to proboscis

• DH > larvae > pulmonary circulation > arteries > mature

-

PATHOGENESIS + TREATMENT:

• inflamation and arteritis, thromboemboli (lung capillaries)

• increased vascular resistance = hypertension

  • heart dilation, hyperthropy, congestive heart failure

• damage may take time to develop

• antigen testing and knotts test available

ARTHOPODA LIFE CYCLES

Simple

Complex

CLASS INSECTA (general)

Jointed appendages - paired bilaterally, symmetrical

Chitinous exoskeleton (most important identifier)

Body segmented: exoskeleton does not flex

• 3 body divisions: head, thorax, abdomen

• 3 pairs of legs

• Sometimes wings – usually 2 pairs

Separate sexes

ORDER DIPTERA life cycle

complex metamorphosis

• egg > larva (1) > larva (n) > pupa > adult

Culcids, simulids, ceratopogonids Psychodids, tabanids - require aquatic/semi-aquatic habitats for egg laying and development of immatures

Muscids - breed in immature animal manure/decaying organic matter

Hippoboscids - most of life on host

Sarcophagid, Calliphorid - egg laid on host/decomposing carcass, larvae develop in decomposing flesh in living/dead animal, pupae in soil

Bot flies - egs laid on hair of host/near burrows, larvae develop in host, pupate in soil

SUBORDER NEMATOCERA (general)

Family Culicidae: Culcinae, Anophelinae (mosquitoes)

Family Simulidae: Stimulium (blackfly/buffalo gnat)

Family Ceratopogonidae: Culcoides (midges/no-see-ums)

Family Psychodidae: Lutzomiya (sandflies)

• characteristics

  • Long, segmented antennae

  • Piercing-sucking mouthparts

  • Females only blood feed to generate eggs

  • Males nectar feeders

  • Worldwide distribution

• Significance

  • Annoying, causes worry

    • Stress generated by attacking insects leads to a physiological response > will change behaviour to avoid getting attacked

  • May cause anemia

  • Some transmit pathogens

    • Are neat blood feeders (siphoned), transmitted usually through saliva during next blood meal

CULCINAE

Diptera > Nematocera > Family Culcidae

• “Northern” mosquitoes

• Transmit viruses – West Nile, Yellow Fever, non-human malarias

• Biological vectors of filarial worms

• Common “pest” mosquitoes

• Frequently numerous even in northern temperate areas

• Strong fliers, can frequently bite in both day and night

  • Sight feed and track by carbon monoxide

LIFE CYCLE:

• Females feed with abdomen held horizontally

• Eggs laid in groups forming rafts

  • Females lay eggs while on surface tension of water

• Larvae hang vertically in water

ANOPHELINAE

Diptera > Nematocera > Family Culcidae

• Anophelinae (‘anophelines’): warm temperate and tropical areas

• Transmit viruses – human malaria vectors (some)

• Biological vector of some arboviruses (ex: malaria)

• Relatively weaker fliers, frequently bite in evening/night

  • Crepuscular – twilight feeders

  • Feed when air is still and more humid – follow carbon monoxide

LIFE CYCLE:

• Females feed with abdomen in raised position

• Eggs laid singly

• Larvae hang horizontally in water with a siphon for breathing

STIMULIUM (blackfly/buffalo gnat)

Diptera > Nematocera > Family Simulidae

• Gets name from thorax hump that resembles buffalo

• Usually associated with running water

  • Larvae found attached to rocks

• Biological vectors of river blindness (Onchocera volvulus – nematode-caused)

  • Parasite causes damage to retina

• Biological vector of Leucocytozoon simondi

• Painful and annoying biters

CULCOIDES (midges/no-see-ums)

Diptera > Nematocera > Family Ceratopogonidae

• Larva sually associated with still water

  • Feeds when air is still and humid

• Dappled wings

• Quite small, painful bites

• Some transmit arboviruses and other agents of disease (ex: malaria-like parasites – birds)

• Biological vector of Haemoproteus

LUTZOMIYA (sandflies)

Diptera > Nematocera > Family Psychodidae

• Dainty, hairy flies

• Biological vectors of parasitic disease Leishmania (caused by flagellates)

SUBORDER BRACHYCERA (general)

• Characteristics

  • Stylate antennae

  • Slicing mouthparts, feed by telmophagy

  • Both sexes blood feed

• Significance

  • Painful bites – can get repetitive bites from the same fly

  • Loud fliers, persistent, can cause worry

  • Are good at mechanically transmitting parasites

SUBORDER CYCLORRHAPHA (general)

Family Muscidae: Musca domestica (house fly), Stomoxys calcitrans (stable fly)

Family Hippoboscidae: Melophagus Ovinus (sheep ked)

Family Sarcophagidae (flesh fly)

Family Calliphoridae (screworm/blow fly/bottle fly)

Family Hypodermatidae: Hypoderma (cattle grub/warble fly)

Family Cuterebridae: Cuterebra (rodent/rabbit bot)

Family Gasterophilidae: Gasterophilus (stomach bot)

• Characteristics

  • Aristate (feathered) antennae

  • Various mouthparts depending on what they feed on

• Include various robust flies

  • House, stable, face, flesh, warble, bot flies

MUSCA DOMESTICA (house fly)

Diptera > Cyclorrhapha > Family Muscidae

• Characteristics

  • Robust, hairy body

  • Aristate (feathered) antennae

  • Sponging-lapping mouthparts - non-biting

  • Strong flier: usually uses sight to navigate, can feed during day

• Life cycle (complex, extremely prolific)

  • Eggs are laid in undisturbed cattle feces or other rotting organic matter

  • Maggots eat organic debris

  • Pupation occurs in soil

• Significance

  • Annoying, nuisance

  • Efficient mechanical vector for pathogens – macroscopic structures get stuck on hairs around mouthparts while feeding

  • Feeding habits promote transmission: regurgitation from past feeding items

  • Biological vector – Habronema and Draschia of horses

STOMOXYS CALCITRANS (stable fly)

Diptera > Cyclorrhapha > Family Muscidae

• Characteristics

  • Body similar to that of Musca spp.

    • Slightly smaller and have a proboscis for blood feeding

  • Aristate (feathered) antennae

  • Bayonet-shaped mouthparts – less mechanical transmission than sponging-lapping, biting

• Life cycle (complex)

  • Eggs laid in decaying vegetation

  • Maggots develop in damp straw, etc.

  • Pupation in soil, overwinter as pupae

  • Adults attack mammals during midday – strong fliers, rely on sight for feeding

    • Adults pierce the skin for blood, are persistent and annoying

• Significance

  • Painful bite, persistent feeders that are easily disturbed

  • Can cause annoyance and worry

    • Could lead to reduced milk production and weight gains in production animals

  • Intermediate host for Habronema sp. (nematode of horses)

FAMILY MUSCIDAE CONTROL

• Sanitation Measures

  • Timely removal of manure to reduce number of breeding sites

  • General cleanliness to remove sites with rotting vegetation

  • Ensure proper drainage to remove areas of standing water/muck

• Insecticides

  • Ear tags with topical organophosphates or botanicals against face and horn flies

  • Spray/pour-on formulations

  • Back rubbers

  • Chitin inhibitors in feed of cattle to make manure unsuitable for larval development

    • Efficient for fly control but pasture productivity may be affected negatively

    • Are rarely used for flies anymore

MELOPHAGUS OVINUS (sheep ked)

Diptera > Cyclorrhapha > Family Hippoboscidae

• Characteristic

  • Wingless fly

  • Flattened dorso-ventrally

  • Leathery, hairy

  • Permanent ectoparasite of sheep in their wool

• Life cycle (complex)

  • Mature larvae laid by females spin cocoons immediately

    • No free-living larvae except for when it is laid before immediately going into pupa form

    • This method was adapted for survival in wool surroundings

• Significance

  • Irritation, blood loss

  • Wool damage through rubbing and staining

• Control

  • Topical insecticides

  • Usually a winter issue

    • higher proximity of animals and weakened immune systems/stress

    • humidity and cold temperatures can increase parasite survivability

Myiasis

invasion of healthy or damaged flesh by the larvae of dipteran flies

• invasion is usually accidental, role is to get rid of rotting composition

facultative: usually accidental, not necessary to continue life cycle

• generally start with a wound of some kind that attracts flies

• accidental egg disposition on living animal, mistakenly recognizes would as a dead animal

• Family calliphoridae, Family Sarcophagidae

obligate: do not need a wound, invasion of tissue needed to survive, on live animals only

• Bot flies > Hypoderma, Cuterera, Gasterophilus

FAMILY SARCOPHAGIDAE & FAMILY CALLIPHORIDAE

Diptera > Cyclorrhapha > Facultative Myiasis (2)

• larger than a housefly

• sponging lapping mouthparts

• C: metallic colouring (adult), screw worm (larvae) - large and robust

• S: checkboard patterning (adult), maggots (larvae) - large and robust

• larva have pointed anterior end with mouth hooks, posterior end broad and flat with spiracular plates

• life cycle

  • eggs usually laid in or around wounds, soiled skin/wool, decaying carcasses

  • species-specific level of decomposition preferred

  • larvae develop at or near site of oviposition

  • mature larvae leave host to pupate

• predisposing causes for fly attack

  • open wounds from any cause, especially putrefying flesh

  • decomposing wool on soiled/wet sheep (wool strike)

    • may result from heavy rain, urine, uterine discharge, diarrhea, sweat, etc.

    • wool is a type of protein, wool can start rotting in certain conditions

    • locally, intestinal parasitosis resulting in diarrhea are a significant cause of wool decay and subsequent fly attack

BOT FLIES (general)

Hypoderma, Cuterebra, Gasterophilus, Dermatobia hominis

• characteristics (obligate myiasis)

  • all energy required for life cycle are obtained in larval form

    • large larvae must store energy for metamorphosis and egg-laying

  • large, bee-like adults (protective mimicry) – do NOT feed

    • do not sting, have no working mouthparts

  • usually well-prescribed sites of development, adapted specific hosts and locations

HYPODERMA (cattle grub/warble fly)

Diptera > Cyclorrhapha > Family Hypodermatidae

• Hypoderma bovis: Northern Cattle grub

  • Larvae overwinter in spinal canal or epidural fat

• Hypoderma lineatum: Southern/common cattle grub

  • Larvae overwinter in esophageal connective tissue

• Life cycle (complex, once cycle per year in ON)

  • Eggs laid on legs of cattle by non-feeding adult flies

  • Larvae penetrate skin > migrate to overwintering sites by winter

    • Have thin exoskeletons, no need for large air source

  • In late Feb to Apr > migrate to back and produce warble (subcutaneous cyst)

  • Larvae mature, drop out of cyst and pupate

• Pathogenesis

  • Gadding – disperse flies, results from oviposition, reduced production (takes energy)

  • holes in hides reduce value, lesions may require trimming

  • in horses, loss of use if warble is in saddle area

CUTEREBRA (rodent/rabbit bot)

Diptera > Cyclorrhapha > Family Cuterebridae

• characteristics

  • adults – robust and bee-like flies with vestigial mouthparts

  • larvae – large with prominent spines, found within subcutaneous cysts of host

  • are strong fliers, tend to affect ground rodents and squirrels

• life cycle (complex)

  • eggs found near burrow openings

  • larvae enter host via nose/mouth (most likely through animal grooming habits)

    • when they detect CO2 = means that animals are near

  • migrates to skin and cuts breathing hole

    • needs air once it reaches a particular size

    • breathing hole is location of emergence = area depends on size of animal

  • pupation on ground (over-wintering)

  • adults mate and lay eggs the following year

• pathogenesis

  • subcutaneous fibrotic cyst – never gets septic (larvae produce antibiotic substances) - usually around neck in cats and dogs

  • wet coat in neck region, small hole

  • larvae can, but rarely, enter CNS

DERMATOBIA HOMINIS (human bot fly)

Diptera > Cyclorrhapha > Family Cuterebridae

• Life cycle

  • female bot flies capture blood sucking arthopods and lay eggs on their bodies

    • use glue-like substance for adherence

  • bot fly larvae develop within eggs but remain on paratenic host until it takes a blood meal

    • larvae hatch in response to heat of vertebrate’s skin and penetrate host tissue

  • feed for a few weeks and cut breathing hole in skin

  • mature larvae drop into ground and pupate

GASTEROPHILUS (stomach bot)

Diptera > Cyclorrhapha > Family Gasterophilidae

• Gasterophilus intestinalis: most common in horses

• Gasterophilus nasalis: in horses, more uncommon locally

• Life cycle (complex)

  • Most eggs laid on forelegs

    • Intestinalis: feed on food inside stomach but do not invade stomach lining

  • Oral migration > 2nd stage larvae is swallowed

    • nasalis: hatch from eggs near mouth and crawl into mouth

    • intestinalis: hatch from eggs only when horse links/muzzles area containing eggs > larvae enter mouth

  • Larvae overwinter in stomach and pass out with feces

• Pathogenesis

  • Usually asymptomatic, gastric lesions can be significant

  • Rarely see perforations (can occur giving abscesses and peritonitis)

• Control: Many registered compounds are available (ex: insecticides, endectocides)

ORDER MALLOPHAGA (biting/chewing lice)

• Characteristics

  • Highly host-specific

  • Feed on skin, hair, secretions, feathers

    • rersults in rubbing and scratching > hair loss and hide damage

  • Wingless, flattened dorsoventrally

  • Head is as broad or broader than the thorax (looks like letter M)

    • Large head holds muscles to help with biting and chewing

• Life cycle (simple)

  • Eggs (nits) cemented to hairs/feathers

  • Life cycle around 2-4w

  • Entire life cycle on host, generally short survival of of the host

  • Are usually active or highly active

    • Fast moving, can move around if disturbed > difficult to see on living animal