parasit Flashcards
What is the general life cycle/pathogenesis of Eimeria & Cystoisospora?
- Ingestion of sporulated oocyst from environment
- Sporozoites excyst and invade enterocytes in intestine
- Asexual replication (schizogony) –> merozoites
- Sexual replication (gametogony) –> oocyst formation
- Unsporulated oocysts passed in feces –> sporulate in environment
What is the infective stage of Eimeria & Cystoisospora?
Sporulated oocyst
What are key symptoms caused by Eimeria & Cystoisospora?
Diarrhea, intestinal damage, weight loss
What species are commonly affected by Eimeria & Cystoisospora?
Eimeria spp. (poultry, cattle, sheep), Cystoisospora spp. (dogs, cats, pigs)
What is the general life cycle/pathogenesis of Cryptosporidium?
- Ingestion of sporulated oocyst (already infective)
- Sporozoites invade intestinal epithelial surface (epicellular)
- Asexual and sexual reproduction
- Thick-walled oocysts passed in feces
- Thin-walled oocysts cause autoinfection
What is the infective stage of Cryptosporidium?
Sporulated oocyst
What are key symptoms caused by Cryptosporidium?
Watery diarrhea, weight loss, zoonotic risk
What species are commonly affected by Cryptosporidium?
Cryptosporidium spp. (humans, calves, other mammals)
What is the general life cycle/pathogenesis of Toxoplasma & Neospora?
- DH sheds unsporulated oocysts after ingesting tissue cysts (bradyzoites)
- Oocysts sporulate in environment
- IH ingests sporulated oocyst or bradyzoite (in tissue)
- Sporozoites or bradyzoites become tachyzoites –> replicate rapidly –> tissue damage
- Tachyzoites –> bradyzoites form tissue cysts
- Vertical transmission via tachyzoites (esp. Neospora)
What is the infective stage of Toxoplasma & Neospora?
Sporulated oocyst, tissue cyst (bradyzoite), tachyzoite
What are key symptoms caused by Toxoplasma & Neospora?
Abortions, neurologic signs, congenital infection
What species are commonly affected by Toxoplasma & Neospora?
Toxoplasma gondii (cats, many mammals), Neospora caninum (dogs, cattle)
What is the general life cycle/pathogenesis of Eimeria & Cystoisospora?
- Ingestion of sporulated oocyst from environment
- Sporozoites excyst and invade enterocytes in intestine
- Asexual replication (schizogony) –> merozoites
- Sexual replication (gametogony) –> oocyst formation
- Unsporulated oocysts passed in feces –> sporulate in environment
What is the infective stage of Eimeria & Cystoisospora?
Sporulated oocyst
What are key symptoms caused by Eimeria & Cystoisospora?
Diarrhea, intestinal damage, weight loss
What species are commonly affected by Eimeria & Cystoisospora?
Eimeria spp. (poultry, cattle, sheep), Cystoisospora spp. (dogs, cats, pigs)
What is special about Eimeria & Cystoisospora?
- Eimeria: Strictly direct life cycle; no paratenic host
- Cystoisospora: Can also use paratenic hosts (e.g., rodents) where monozoic tissue cysts form
What is the general life cycle/pathogenesis of Cryptosporidium?
- Ingestion of sporulated oocyst (already infective)
- Sporozoites invade intestinal epithelial surface (epicellular)
- Asexual and sexual reproduction
- Thick-walled oocysts passed in feces
- Thin-walled oocysts cause autoinfection
What is the infective stage of Cryptosporidium?
Sporulated oocyst
What are key symptoms caused by Cryptosporidium?
Watery diarrhea, weight loss, zoonotic risk
What species are commonly affected by Cryptosporidium?
Cryptosporidium spp. (humans, calves, other mammals)
What is special about Cryptosporidium?
Unique epicellular location (sits on surface, not inside cells)
- Only parasite in this group capable of autoinfection
What is the general life cycle/pathogenesis of Toxoplasma & Neospora?
- DH sheds unsporulated oocysts after ingesting tissue cysts (bradyzoites)
- Oocysts sporulate in environment
- IH ingests sporulated oocyst or bradyzoite (in tissue)
- Sporozoites or bradyzoites become tachyzoites –> replicate rapidly –> tissue damage
- Tachyzoites –> bradyzoites form tissue cysts
- Vertical transmission via tachyzoites (esp. Neospora)
What is the infective stage of Toxoplasma & Neospora?
Sporulated oocyst, tissue cyst (bradyzoite), tachyzoite
What are key symptoms caused by Toxoplasma & Neospora?
Abortions, neurologic signs, congenital infection
What species are commonly affected by Toxoplasma & Neospora?
Toxoplasma gondii (cats, many mammals), Neospora caninum (dogs, cattle)
What is special about Toxoplasma & Neospora?
- Toxoplasma: Congenital transmission causes abortion in first exposure; lifelong immunity follows
- Neospora: Causes repetitive abortions; can transmit transplacentally across generations
What is the general life cycle/pathogenesis of Monogeneans?
- Eggs hatch into ciliated larvae (oncomiracidium)
- Larvae swim to and attach to fish host
- Develop into adults on gills or skin
- Adults feed on blood, mucus, epithelial cells
What is the infective stage of Monogeneans?
Oncomiracidium
What are key symptoms caused by Monogeneans?
Gill damage, hypoxia, decreased growth
What species are commonly affected by Monogeneans?
Monogeneans (Gyrodactylus, Dactylogyrus in fish)
What is special about Monogeneans?
- Direct life cycle (no intermediate host)
- Egg-layers usually infect slow-swimming fish; live-bearers infect fast swimmers
What is the general life cycle/pathogenesis of Digeneans (e.g., Fasciola, Paragonimus, Alaria)?
- Eggs hatch into miracidia in water
- Miracidia infect snail (1st IH) –> asexual replication (sporocyst –> redia –> cercaria)
- Cercaria exit snail, penetrate 2nd IH or encyst on vegetation
- Form metacercaria (infective stage) in 2nd IH or environment
- Ingestion by DH –> excyst –> migrate to final site and mature
What is the infective stage of Digeneans (e.g., Fasciola, Paragonimus, Alaria)?
Metacercaria
What are key symptoms caused by Digeneans (e.g., Fasciola, Paragonimus, Alaria)?
Liver fibrosis (Fasciola), lung cysts (Paragonimus), enteritis (Alaria)
What species are commonly affected by Digeneans (e.g., Fasciola, Paragonimus, Alaria)?
Fasciola hepatica, Paragonimus spp., Alaria spp.
What is special about Digeneans (e.g., Fasciola, Paragonimus, Alaria)?
All use snails as G8 IH
- Fasciola: metacercaria on vegetation, migrate to bile ducts
- Paragonimus: metacercaria in crayfish, migrate to lungs
- Alaria: includes mesocercaria stage (in tadpoles), migrates through lungs
What is the general life cycle/pathogenesis of Habronema & Draschia?
- L1 in horse feces –> ingested by fly larvae
- Develop into L3 in adult fly
- Fly deposits L3 on horse’s skin or wounds
- If ingested –> gastric infection
- If deposited on skin –> summer sores
What is the infective stage of Habronema & Draschia?
L3 in fly
What are key symptoms caused by Habronema & Draschia?
Gastritis, summer sores (cutaneous habronemiasis)
What species are commonly affected by Habronema & Draschia?
Habronema spp., Draschia megastoma (horses)
What is special about Habronema & Draschia?
Requires fly intermediate host (Musca or Stomoxys)
- Cutaneous form = summer sores (granulomatous lesions)
What is the general life cycle/pathogenesis of Arthropods (Anoplura & Mallophaga lice)?
- Egg (nit) glued to hair/feathers
- Hatch into nymphs (3 molts)
- Nymphs mature into adults on host
- All stages remain on host
What is the infective stage of Arthropods (Anoplura & Mallophaga lice)?
Nymph or adult louse via direct contact
What are key symptoms caused by Arthropods (Anoplura & Mallophaga lice)?
Itching, hair loss, anemia (in heavy infestations)
What species are commonly affected by Arthropods (Anoplura & Mallophaga lice)?
Anoplura (Linognathus, Haematopinus), Mallophaga (Trichodectes, Bovicola)
What is special about Arthropods (Anoplura & Mallophaga lice)?
Anoplura (sucking lice): blood feeders, affect mammals
- Mallophaga (chewing lice): feed on skin debris, affect birds and some mammals
What is the general life cycle/pathogenesis of Mites (burrowing and surface)?
- Eggs hatch on host into larvae (6 legs)
- Larvae –> nymphs (8 legs) –> adults
- Entire life cycle occurs on the host
- Burrowing mites dig into skin (e.g., Sarcoptes, Demodex)
Surface mites live on skin or hair (e.g., Otodectes, Cheyletiella)
What is the infective stage of Mites (burrowing and surface)?
Larvae or nymph (direct contact)
What are key symptoms caused by Mites (burrowing and surface)?
Pruritus, alopecia, crusting, otitis externa
What species are commonly affected by Mites (burrowing and surface)?
Sarcoptes scabiei, Demodex spp., Otodectes cyanotis, Cheyletiella spp.
What is special about Mites (burrowing and surface)?
Sarcoptes: intense pruritus, zoonotic
- Demodex: often commensal, but causes disease in immunosuppressed
- Otodectes: common ear mite in cats/dogs
What is the general life cycle/pathogenesis of Ticks?
- Egg hatches into 6-legged larva (seed tick)
- Larva feeds on host –> molts into 8-legged nymph
- Nymph feeds –> molts into adult
- Adult feeds and mates –> female lays eggs
- Most are 3-host ticks (each stage feeds on a different host)
What is the infective stage of Ticks?
Nymph or adult (via bite)
What are key symptoms caused by Ticks?
Anemia, irritation, tick paralysis, vector-borne diseases
What species are commonly affected by Ticks?
Ixodes spp., Rhipicephalus spp., Dermacentor spp.
What is special about Ticks?
Vectors for Babesia, Borrelia, Anaplasma, etc.
- Ixodes: Lyme disease vector
- Rhipicephalus: Babesia, Ehrlichia
What is the general life cycle/pathogenesis of Fleas?
- Adult fleas live on host, lay eggs into environment
- Eggs hatch into larvae –> feed on organic debris
- Larvae pupate –> emerge as adults when stimulated by heat/vibration
- Adults jump onto host to feed and reproduce
What is the infective stage of Fleas?
Adult flea (jumps onto host)
What are key symptoms caused by Fleas?
Pruritus, flea allergy dermatitis, anemia, tapeworm risk
What species are commonly affected by Fleas?
Ctenocephalides felis, Ctenocephalides canis
What is special about Fleas?
Ctenocephalides felis most common on cats and dogs
- intermediate host for Dipylidium caninum
- Can transmit Bartonella henselae
What is the general life cycle/pathogenesis of Strongylid Nematodes (e.g., Haemonchus, Ostertagia, Strongylus)?
- Eggs passed in feces
- Hatch and develop to L3 in environment
- L3 ingested during grazing
- L3 exsheath and migrate to target tissue
- Mature to adults in GI tract –> feed on blood or tissue
What is the infective stage of Strongylid Nematodes (e.g., Haemonchus, Ostertagia, Strongylus)?
L3 on pasture
What are key symptoms caused by Strongylid Nematodes (e.g., Haemonchus, Ostertagia, Strongylus)?
Anemia, diarrhea, bottle jaw, reduced weight gain
What species are commonly affected by Strongylid Nematodes (e.g., Haemonchus, Ostertagia, Strongylus)?
Haemonchus contortus, Ostertagia ostertagi, Strongylus spp.
What is special about Strongylid Nematodes (e.g., Haemonchus, Ostertagia, Strongylus)?
- Haemonchus: bloodsucker in abomasum (barber pole worm)
- Ostertagia: causes Moroccan leather abomasum in cattle
- Strongylus: large intestinal worms in horses; some migrate through arteries
What is the general life cycle/pathogenesis of Gasterophilus spp. (Bot flies)?
- Adult flies lay eggs on horse’s legs, lips, or flanks
- Eggs hatch into L1 upon licking or exposure to warmth
- L1 migrate to mouth ? L2 migrate to stomach ? L3 mature in GI tract
- L3 passed in feces ? pupate in soil ? adult flies emerge
What is the infective stage of Gasterophilus spp. (Bot flies)?
L1 (after egg hatch on skin)
What are key symptoms caused by Gasterophilus spp. (Bot flies)?
Oral irritation, gastric ulcers, behavioral distress
What species are commonly affected by Gasterophilus spp. (Bot flies)?
Gasterophilus intestinalis, G. nasalis, G. haemorrhoidalis
What is special about Gasterophilus spp. (Bot flies)?
- Not blood-feeding
- Can cause gastritis, gastric ulceration, and rare perforations
- Cause ‘worry behavior’ in horses due to oviposition behavior
What is the general life cycle/pathogenesis of Cuterebra spp. (Rodent bot fly)?
- Adult female lays eggs near rabbit/rodent burrows or animal trails
- Eggs hatch ? L1 larvae attach to host fur ? penetrate skin
- Larvae migrate subcutaneously ? form warble cysts with breathing hole
- Mature larvae emerge, fall to ground, and pupate in soil
What is the infective stage of Cuterebra spp. (Rodent bot fly)?
L1 larva (enters via skin contact)
What are key symptoms caused by Cuterebra spp. (Rodent bot fly)?
Subcutaneous cysts (warbles), swelling, neurologic signs in aberrant hosts
What species are commonly affected by Cuterebra spp. (Rodent bot fly)?
Cuterebra spp.
What is special about Cuterebra spp. (Rodent bot fly)?
NAME?
