Nematodes Flashcards

Question

Order: Strongylida * General Taxonomy

Answer 1

* Trichostrongyloidea ►abomasum/SI * Strongyloidea ► LI * Metastrongyloidea ► lungs * Ancylostomatoidea ►SI

Answer 2

* Direct * in feces : egg → L1-L2 * → **(L3) (infective stage)** → L4 -male/female (both parasitic in host) * L3 exsheathed in rumen and enter duodenal mucosal glands \> L4 \> adult in lumen of abomasum/SI * L3 must be ingested in order to complete LC

Answer 3

* vestigial buccal capsule * copulatory bursa

Answer 4

* black scour worm of sheep * hairlike worm

Answer 5

1. T. colubriformis 1. spicule: barb like tip 2. summer rainfall areas 2. T. vitrinus 1. spicule: tapering end 2. winter rainfall areas 3. T. rugatus 1. spicule: thick and disssimilar 2. drier inland areas 4. T. axei 1. spicule: dissimilar and unequal

Answer 6

PPP= 18-21d female lays: 10-100 eggs/day L3 - overwinter * can become anhydrobic and become active when rehydrated * can survive harsh environment * development occurs in duodenum * \*\*search in 1st 6 meters of SI * moult to L4 (5d) * moult to adult (10d) Intra-epithelial parasite

Answer 7

* villous atrophy * decreased mitosis * inflammation and matted * increased permeability → loss of plasma proteins * protein loss * hypoalbuminemia -20% loss in wool produciton & growth rate * [globulin] increased bc of host immune resp. * \< absorption of Ca & PO4 * decr. absportion in duodenum * incr. Ca as compensation * hypophosphatemia * decreased osteoblastic activity * anorexia * esp. T. vitrinus * diarrhea * secrete parasympathetic analogues (increase parastaltic waves) * release inflam. mediators, ^ capillary/epithelial perm. = exudation * poor absorption, change in osmotic P * predispose to fly strike

Answer 8

* immune respose if \> 5 mo * imunity theshold 3000 worms * against incoming L3 and expel exisiting * ++ baso, eosino, mast cells in lamina propria * histamine, cytokines, serotonin * eosinophils can kill larvae * goblet cell hyperplasia → ^ mucus * entangle worms and paralyses * cellular response : Th2 hypersensitivity 1 * IL5- eosinophil * IL4,9,13- mast cell degran.

Answer 9

* yes * still have increased parastaltic movements and increased mucus from immune response * also won't expell full worm burden

Answer 10

T. vitrinus * autumn moist - larvae develop * larvae migrate up blades of grass in moisture * winter moist- short grass * sheep graze low to ground and ingest

Answer 11

* mid winter (high winter rainfall zone)

Answer 12

* T. colubriformis * development begins w/ incr temp & moisture * spring * overwinter (L3 in environment) * pasture growth can dilute larvae and high temps reduce survival

Answer 13

Mid summer - summer rainfall zone

Answer 14

* \>60,000 load (esp young sheep) * winter rainfall zones can have death mid winter

Answer 15

HOT * **H**aemonchus * **O**stertagia * **T**richostrongylus axei Small Intestine * **N**ematodirus * **T**richostrongylus * **C**opperia

Answer 16

* small intestine * "wire worm" * cattle/sheep

Answer 17

* Size; ~9mm * small cephalic vesicle * **esophageal region - transverse cuticular striations** * body- longitudinal cuticular ridges * spicules- wing like in middle region * **no gubernaculum**

Answer 18

* Genus: Cooperia * Features * **transverse striations on cephalic dilation** * **no gubernaculum** * **wing like spicules**

Answer 19

* Temperate (moderate pathogenicity) * C. oncophora (southern AUS) * C. surnabada * Sub-tropical (very pathogenic- world wide/N. AU) * C. pectinata * C. punctata

Answer 20

* Cooperia * cattle * C. punctata * C. pectinata * C. onchophora

Answer 21

* C. curticei

Answer 22

* Direct * L1 - hatches in environment & feed on bacteria * L3- retains L2 cuticle/withstand harsh conditions * ensheathment in rumen * burrows in mucosal glands * L4 - head in gland & body in lumen * **HYPOBIOSIS - in summer** * Adult - in lumen * PPP= 15d

Answer 23

* temporary cessation in development **inside host** * summer isn't great for free living stages (cooperia/nematodirus/ostertagia) * hypobiosis in summer months * resume development in late autumn * produce eggs when environment is suitable for development of eggs/larval stages * winter hypobiosis (Teladorsagia circumcincta/hemonchus)

Answer 24

* villous atrophy * erosion of epithelium * burden of \> 50,000 cause anorexia/dxa

Answer 25

* winter * (ingest during wet season (summer/winter))

Answer 26

* Thin-necked intestinal worm * sheep/cattle * small intestine

Answer 27

* Genus: Nematodirus * largest of the 3 SI Trichostrongyles (25mm) * coiled * cephalic vessicle * **long thin spicules** * **join at posterior end** * female - spine tail * **VERY LARGE EGGS**

Answer 28

* Nematodirus * L1-L3 occur INSIDE egg * need cold or drying to hatch

Answer 29

* Sheep * N. spathiger * N. fillicolis * N. abnormalis * Cattle * N. helvetianus * Both (in N. America and Europe) * N. battus (most pathogenic)

Answer 30

* Nematodirus * N. filicollis * N. spathiger * N. battus

Answer 31

* L1-L3 inside egg * need drying or cold to hatch * L3 burrows in mucosal glands or coil aroud villi \> moult to L4 * **L4 Hypobiosis common** * adult in lumen * PPP= 18-21d

Answer 32

* Genous: Nematodirus * villous atrophy * erosion of epithelium (from coiling) * L3 burrow into crypts * dxa common

Answer 33

* L3 with egg = resistance * can survive over summer * heavy infections can accumulate in lambing paddocks * greatest larval pick up = WINTER * strong immunity develops

Answer 34

* T. axei * "stomach hair worm" * primarily parasitic in CATTLE * can occur in sheep, horses, pigs, humans

Answer 35

* T. axei * damage to epithelium * protein lost in lumen * mucus produced \> pH rises * 40,000 can kill little lamb * pathogenesis similar to O. ostertagei (T1)

Answer 36

* direct LC * environmental part similar to other trichostongylus spp. * (L1-L2) in feces \> (L3) ingested and exshealthed * host part similar to ostertagia spp. * L4- hypobiosis in abomasal glands * wide host range \> important in mixed grazing * highly pathogenic

Answer 37

* Hemonchus -barbers pole worm * Abomasum * sheep * H. contortus * cattle * H. placei * deer, camel

Answer 38

* **Hemonchus** * 2-3 cm **long** * **red - barber pole in female** * large vuval flap * lancet tooth in buccal capsule * prominent cervical papillae * **asymmetrical dorsal rays** * **spicules with barbs**

Answer 39

* direct LC * INFECTIVE STAGE: L3 * exsheathment * burrows in abomasal glands to moult L4 * L4 re-emerge in lumen * lancet tooth & sucks blood * Adult - feed on blood PPP= 21d

Answer 40

1. microcytic hypochromic anaemia 1. voracious blood suckers 2. white eyes and mucosal membranes 2. hypoproteinemia \> bottle jaw 3. NO DXA 4. reduced exercise tolerance 1. iron deficiency 5. heavy infection \> sudden death

Answer 41

* Pick up low dose daily * trying to compensate blood loss * blood loss\> protein loss * reduced oncotic P * edema \> bottle jaw (localised) or anasarca (generalised)

Answer 42

* Summer rainfall areas most common * maximum : Feb-March * hypobiosis in winter * less common in winter rainfall areas * summer too hot/winter too cold * if mild winter and wet summer \> can be widespread * problems w/ pregnant ewes in autumn * problems w/ lambs in spring

Answer 43

* high biotic potential - 5,000/10,000 egg/day * eggs wont hatch below 10ºC * labile larvae

Answer 44

* Hemonchus * \*\*similar to T1 sensitivity * eosinophil-based damage of worm on second exposure * also vaccine against gut wall proteins (of parasite)

Answer 45

* Abomasum * Brown stomach worm * sheep, deer, cattle

Answer 46

Ostertagia

Answer 47

* **O. circumcincta** \*\*(main) (also Telodorsagia) * O. trifurcata * also Teladorsagia davtiani

Answer 48

* Ostertagia ostertagi

Answer 49

* Direct (free living similar to trichostrongylus) * L1-L3 in feces (2 wks) * L3 ingested \> exsheaths in rumen * winter rainfall area * max: june/july * migrates to lumen of abomasal gland * moult \> L4 \> return to lumen * hypobiosis common (6 mo) * occus in spring * emerge in autumn * cause nodules in abomasum * PPP= 18-21d

Answer 50

* laval migration to gland cells \> hyperplasia & necrosis * reduced parietal and chief cells * red. acid and pepsin \> pH rises (6) * hypoproteinemia * protein digestion stops * leaking plasma proteins into abomasum * ^plasma pepsinogen * ^ secretion & ^ permeability * hypergastrinemia * pouches w/o worms secrete more gastrin * anorexia * dxa (maldigestion) * nematodes promote gastrointestinal motility (parasympathomimetic)

Answer 51

* areas of hyperplasia * raised pin point white foci * towards antrum and folds of fundus

Answer 52

High rainfall southern australia * mainly infects younger animals * immunity seen in older animals & worm burden expelled

Answer 53

* stunted/small and lower fecundity

Answer 54

* Ostertagia ostertagi in cattle * found in TEMPERATE areas * nodules in abomasum * same pathophysiology as in sheep

Answer 55

1. fecal mass as a reservoir for larvae 1. DUNG PAT = HOME 2. inhibited larvae can emerge synchronously 1. L4 resume development from hypobiosis

Answer 56

* cow pat is ideal environ for development * crust on surface prevents desiccation of interior * aeration occurs and larvae dev. to L3 (ensheathed) in moist poo * if dry, crust prevents migration but L3 can still develop over summer * moisture\> emerge onto herbage * picked up by cattle in autumn through spring

Answer 57

* young animals * no immunity * occurs in spring - just a buildup of worms * dx w/ egg counts & plasma pepsinogen

Answer 58

* larvae emerge synchronously (hypobiotic larvae) * can be induced by cooling larvae or removing adults * subtropical: hypobiosis does NOT occur * 2-4 yo animals * precipitated by stress (calving) * erratic occurance * occurs in autumn * dx w/ ^ plasma pepsinogen or ^gastrin

Answer 59

* EU: inhibited in winter * AUS: inhibited in summer

Answer 60

* hemonchus * ostertagia * cooperia * trichostrongylus * nematodirus

Answer 61

* Abomasum * Hemonchus contortus * Teladorsagia circumcincta * Trichostrongylus axei * SI * Trichostongylus spp. * T. colubriformis * T. vitrinus * T. rugatus * Nematodirus spp. * N. spathiger * N. filicollis * N. abnormalis * N. battus

Answer 62

* Abomasum * H. placei * O. ostertagi * T. axei * SI * Cooperia spp. * temperate * C. oncophora * C. surnabada * subtropical * C. pectinata * C. punctata * N. helvetianus

Answer 63

1. fly strike 2. Lice 3. Liver fluke

Answer 64

1. cattle tick 2. buffalo fly 3. internal parasites

Answer 65

1. infections are always mixed 2. all animals infected all the time 3. control rather than eradicate 1. erradication impossible 2. would leave susceptible sheep/cattle 1. no immunity

Answer 66

* strategic drenching * pasture spelling * alternate grazing * rotational grazing * reduced stocking density * nematophagus fungi

Answer 67

* anthelmintics * vaccination * breed for resistance * nutrition

Answer 68

* moisture * temperature * grazing factors * host factors * management factors

Answer 69

* development of L3 in feces * larvae migration to pasture

Answer 70

P/E \> 0.3 (precipitation/evaporation) \* estimates for hemonchus = P/E \> 1.0

Answer 71

* Lateral * heavy rains and floods * fungal spores (L3) * Vertical * films of moisture (up tip of grass blade) * \*\* stay at root when dry or increased temp

Answer 72

* negatively geotropic * photophobic in strong light * sheep graze at dawn/dusk * when water dries out on grass \> anhydrobic state * survival limited by lipid reserves

Answer 73

* slow egg hatching & development

Answer 74

* shorten survival times of L3 on pasture * also have quicker hatching and L3 development

Answer 75

* T. rugatus

Answer 76

bioclimatographs \* based on 10ºC min and rainfall

Answer 77

* sheep do NOT graze uniformly * use indicated by fecal deposits * larval distribution not uniform * sheep graze selectively * avoid certain plants/ contaminated areas * STOCKING DENSITY * ^sheep = ^poop * initially have a high burden but overgrazing will reduce #s bc of UV exposure

Answer 78

* age * genetic susceptibility * can select for resistance * follow negative binomical distribution * only a few sheep will have large burdens * FEC can be skewed * **must sample 10+ sheep** * breed differences * merinos more susceptible than cross breed * Self-cure phenomenon

Answer 79

* "spring rise" in fecal egg count * ^FEC in ewes just prior to **lambing** & first 4-6wks of lactation * Due to: * re-emergence of inhibited larvae * relaxation of immunity * existing worm burden becomes more fecund * increased susceptibility to L3

Answer 80

* time of lambing/calving * grazing management * stocking density * quality and length of pasture * nutritional status * low BCS w/ low burden can be detrimental * strategic use of anthelmintics * FEC pre/post * CHECK EFFICACY * timing

Answer 81

* hypobiosis * arrested development of L4 inside host * more common in AUS * overwintering * L3 in environment resistant to harsh winter * not very common in AUS bc not cold enough

Answer 82

* unfavorable climatic conditions * immune status of animal * density of GINs

Answer 83

* hormonal changes * altered components of immune system * density of the parasite * young animals have more larvae * environmental temperatures

Answer 84

* history "tail to mob" * symptoms/signs * scouring, anemia, poor BCS, dag score * clin path * fecal egg counts * fecal cultures * molecular ID * hematology, biochem and serology * pasture larval counts

Answer 85

* total worm count * gross pathology

Answer 86

* determines # worm eggs per gram of feces (EPG) * **estimate** worm burden * strongyle-type eggs * trichostrongyle & strongyle eggs * req. measured amt. feces and floatation soln. * McMaster slide * **useful in diagnosis of nematode infections \<9mo** * old animals dev. immunity * variability and degree of infection * indicates # **female worms only** * need 10+ samples * \> 500 epg = pathogenic

Answer 87

A. strongyle - type B. nematodirus egg

Answer 88

* starving sheep * increase FEC by 50% * dxa * reduced FEC

Answer 89

* Hemonchus: 5,000- 10,000 eggs/female/day * Trichostrongylus/Ostertagia: 10-200 eggs/female/day * Nematodirus: 50 eggs/female/day

Answer 90

1. host immunity = suppression 1. resist estabilishment of infection 2. deceased fecundity 2. concentration of eggs in feces affected by digesta, dxa, fasting, feed quality, and size of host 3. egg count higher in young sheep (esp. merinos)

Answer 91

A. Ostertagia B. Trichostrongylus C. Haemonchus D. Chabertia E. Oesophagostomum F. Cooperia

Answer 92

A. Teladorsagia circumcincta B. Trichostrongylus spp. C. Hemonchus contortus

Answer 93

* Step 1: pre-amplification * isolation w/floatation (extract eggs) * Step 2: real time PCR * DNA based test for true ID * Data analysis * need to wait at least 1 week for larval culture * PCR takes 24-48hrs and reliable

Answer 94

* direct quantification from pasture * #larvae/kg herbage * **not reliable at low levels of contamination** * collect in M pattern * introduce worm-free "tracer" animals * costly & time consuming * mimic grazing patterns of resident flock

Answer 95

* total worm count * use 1-2 sheep from tail of mob * abomasum & SI assessment * ID genera and species

Answer 96

* hemonchus * fatal : 5,000-10,000 * production loss : \>2500

Answer 97

Ostertagia : produciton loss @ 50,000 Nematodirus : fatal burden 100,000

Answer 98

1. Grazing management 1. Pasture spelling 2. Crops 3. Alt. grazing 2. Anthelmintic drugs 1. more effective in summer in S. Aus 3. Nutrition 1. resiliance \> withstand normal produciton levels w/ good BCS 4. Breeding 1. resistance 5. Use of vaccines 1. barbervax (barbers pole worms) 6. Biological control 1. Duddlingtonia flagrans- nematode trapping fungi 7. Integrated parasite management 1. combination of all of the above

Answer 99

* summer & harrow in summer

Answer 100

* sowing crops reduces pasture contamination * drench onto stubble (Nov/Dec) * L3 will be on ground and eat just above

Answer 101

* age/nutritional status of sheep * older and good BCS hastens immunity * previous exposure to worms * number of worm larvae on pasture * enough worms to activate response * reduced immunity * stress (weaning/transport) * pregnancy/lactation * sex * dry adult ewes \> wethers \> rams

Answer 102

**T. axei** in stomach

Answer 103

* **T. axei** - stomach (**asymmectric spicules**) * **Hyostrongylus rubidus** - stomach * adult pigs \*\*free range not on concrete floors * LC * direct (similar ostertagia L3) * L3 in gastric glands (3rd and 4th moults) * hypobiosis * PPP= 21 * Pathogenesis * dxa, weight loss * Control * **concrete floor** * Tx: fenbendazole, ivermectin, dormectin

Answer 104

* **Ollulanus tricuspis** - stomach * female tail has 3 short cusps * viviparous * L1-L4 inside host * not very pathogenic * transmit in vomit

Answer 105

* **Amidostomum anseris** (gizzard worm) * geese, duck, swan * site: junx of gizzard & proventriculus * highly pathogenic \> massive necrosis * LC- direct; oral infection * **Trichostrongylus tenuis** * site: cecum * wide host range * controls wild grouse pop * pathogenic in domestic birds * nodular lesions & moralities in galliform birds

Answer 106

* Stongyles * Large intestine * well developed buccal capsule w/ leaf crowns * males have bursa

Answer 107

Genus: Strongylus * horses * L1-3 in feces * L3 on herbage * L3 migrates into intestinal gland * L4 emerges to lumen * final moult in lumen * PPP= **long** * +/- **extra intestinal migration**

Answer 108

* strongylinae * large stongyles - MIGRATORY * strongylus\*\*\* * tridontophorus\*\* * oesophagodontus * craterostomum

Answer 109

* small strongyles - NON MIGRATORY * cyathostomum

Answer 110

A. Strongylus equinus * pointed teeth B. S. vulgaris * ear shaped teeth C. S. edentatus * no teeth location: cecum & colon

Answer 111

* Strongylus vulgaris * direct * L1-L2 : dev. in feces feed on bacteria * (L3) : exsheathes SI/LI migrates into mucosa * **development stops below 8C** * L4: ascends to root of cranial mesenteric arteries * remain for several weeks * return to gut \> moult to adult \> enter lumen * feed on gut mucosa/blood * PPP= 6 mo

Answer 112

* migrating larvae * damage arterial wall/inflammation \> fibrous tissue \> thrombus \> emboli/occulde vessels * intermittent colic * ischemia \> infarct, gnagrene * "verminous arteritis" not aneurysm * adults * blood feeders \> anemia, eosinophilia, leukocytosis

Answer 113

* Larvae most abundant in **spring** * desiccated in summer * become egg laying females in autumn * winter reduces larval development * egg output max in spring

Answer 114

* As foals * become infected early in life

Answer 115

Strongylus edentatus * buccal capsule wider than rest of body

Answer 116

* L3 exsheaths in cecum * burrows in gut wall * enter portal veins * migrate to liver (home for 8 wks) * migrate to subperitoneal tissue * L4 moult & return to gut lumen via mesentery * PPP= 10 mo

Answer 117

* liver, kidney, cecum, lung, testes * found post mortem

Answer 118

Strongylus equinus

Answer 119

S. equinus * L3 exsheaths in cecum \> migrates to gut wall * L4 migrate in subserous tissues of intestine * \> peritoneal cavity \> liver (6wks) * migrates via pancreas to gut PPP= 8 mo (pathogenesis similar to other strongylus spp.)

Answer 120

Family: Strongylidae (large strongyles) * Genus: Strongylus (red worms)

Answer 121

3 teeth, numerous external leaf crowns

Answer 122

lancet like esophageal teeth

Answer 123

* strong mouth

Answer 124

* Triodontophorus serratus & T. brevicauda * L3 exsheaths in cecum \> penetrate intestine * L4 moult \> emerge into lumen \> final moult in lumen * adults feed in groups= ulceration PPP= 9 wks

Answer 125

Triodontophorus

Answer 126

small strongyles (cyathostominae) occurs in large numbers (15,000)

Answer 127

Cyathostomum * L3 exsheaths in cecum & enters cecal glands * fibrous capsule (**encysted**) and L4 moult * **hypobiosis of _L3_:** * may be **synchronous** reemergence following removal of adults * seasonal or if adults in lumen * L4 reemerges to lumen and final moult * reemergance may be synchronous after killing off adults with moxidectin (ML) PPP= 5 weeks (min)

Answer 128

* diagnosis * eggs in feces \> 300 epg pathogenic (McMaster chamber) * larval culture (otherwise cant differentiate bw large and small strongyles) * pathogenesis * adults poorly pathogenic * normally 115,000 larvae encysted * visible * large migration of larvae cause dxa & blood loss

Answer 129

S. westeri - immunity develops in first 12 wks of age Strongyles spp- develop immunity after 24 mo * **large** strongyles

Answer 130

they dont develop immunity - horses commonly infected with several species

Answer 131

* L3 encysted - only kills adults and majority are encysted * different to Trichostongylus in ruminants where L4 undergoes hypobiosis but can be killed by anthelmintics

Answer 132

* Chabertia ovina * sheep, cattle, goats * proximal colon \> tissue feeder * globular bell shaped buccal capsule, no teeth, tiny leaf crown

Answer 133

* similar to Tridonophorus (equine lg strongyle) * L1-L2: dev. in fecal pellets * L3: ensheathed\> exsheath in SI * enters ileal mucosa (moults L4) * L4: returns to lumen and migrates to colon * final moult in LI PPP= 8 wks

Answer 134

* **Chabertia ovina** * feed on mucosa \> hemorrhage * excess mucus production * dxa * common temperate worm but in low numbers * pathogenesis = 200 * strong immunity

Answer 135

* Oesophagostomum (nodule worm) * cattle, pigs, sheep * Cecum, colon \> gut content feeders * cylindrical buccal capsule, leaf crowns, cervical collar

Answer 136

* L3 exsheaths in SI \> penetrate mucosa of ileum/colon * moult L4 in nodule * L4 reemerges to lumen and final moult in LI PPP= 5-6 wks

Answer 137

* **Oesophogostomum radiatum** * no external leaf crown/sm. internal leaf crown * **2 parts of cervical collar** * common in Northern AUS * LC typical of genus

Answer 138

* "pimply gut" * Susceptible (young) host * no rxn - normal maturation to adult * Resistant animals (T1 hypersensitivity) * intense inflam. rxn around nodule * filled with eosinophils & giant cells * larva kills \> caseous lesion calcifies * adults irritate gut \> ^ mucus, dxa * loss of plasma protein & Hb into gut * interfere w/ gut motility * anorexia

Answer 139

* Cecum/Colon * **Oesophagostomum radiatum** (stongyles)

Answer 140

Oesophagostomum columbianum Location: colon \*very pathogenic in young worm w/ nodules frequent

Answer 141

* Oesophagostomum venulosum * note single cervical collar * Location: cecum * some scouring and mucus production

Answer 142

Oesophagostomum dentatum * note sing cervical collar

Answer 143

**Stephanurus dentatus** * teeth present in cup shaped buccal capsule * Location: perirenal fat in cysts attached to uteter * pass eggs in urine\*\*\* * Distribution: limited to warm, moist areas in AUS * tropical and subtropical world wide

Answer 144

* Kidney strongyle of pigs * Eggs passed in urine\*\*\* * L3 * percutaneous * travel to liver via lymphatics or lungs/aorta * ingested/Earthworms as transport host * exsheathment \> penetrate gut wall \> mesenteric LN \> moult L4 * L4 passes to liver (portal system) \> migrate in liver for 2-3 mo * Moult to adult \> rupture or penetrate peritoneal cavity and migrate to perirenal fat but can go anywhere in the body * form fibrous capsule and connect with ureter & eggs pass through connection Long PPP= 9 mo

Answer 145

* Stephanurus dentatus * fibrosis in liver * white spots due to extensive migration of L4 * abscesses in carcass/loss of organs * weight loss * elevated liver enzymes (ALT/AST)

Answer 146

* **Syngamus trachea** (gape worm) * Location: trachea * Host: poultry & other birds * Features * up to 10 teeth in cup-shaped buccal capsule * small M joins F \> Y shaped grossly

Answer 147

* eggs coughed up and swallowed * **L1-L3 within egg\*\*\*** * Bird can ingest * earthworm paratenic host * hatched L3 * egg * L3 exsheaths and penetrates gut \> portal circulation to liver\> lungs * L3 moult L4 in lungs \> migrate up airways to trachea PPP= 2 wks

Answer 148

Pathogenesis * causes excess mucus production * block airways w/ lg #s * respiratory distress (gaping) * blood feeders- hemorrhages in trachea Diagnosis * eggs in feces are ellipsoidal w/ thick operculum at both sides

Answer 149

* hookworms * small intestine

Answer 150

* Ancylostomatinae * 2-3 pairs of teeth at mouth opening * Genus: Ancylostoma * Bunostominae * cutting plates * Genera: Globocephalus, Uncinaria, Bunostomum, Gaigeria, Necator

Answer 151

* Adult female lays 15,000 eggs/day * L1-(L3) dev. in feces * oral infection \> moult L4 in mucosal gland\> return to SI lumen \> moult to adult * PPP= 2 wks * Percutaneous infection * circulatory or lymphatics \> lungs \> trachea \> SI (longer PPP) * through tissues \> milk

Answer 152

Ancylostoma caninum - dogs (SI) * oral infection * skin penetration * feet pads & enter venous blood \> heart\> lungs\> swallow\> SI (PPP= 5wks) * can stay in skeletal mm * transmammary/colostral infection important * PPP= 10-15 d * pups 2-3 wks (deworm every fortnight) * male dogs dead end host

Answer 153

* Peracute - neonate pups * pot belly * dont see many eggs bc woms havent fully developed * microcytic hypochromic anemia * death * black tarry faces * Acute- older/mature pups * may see anemia * Chronic- adult dogs * aysmptomatic * can see eggs * immunity develops following exposure * voracious blood sucker\> anemia \*\*\*eosinophilic enteritis in man (through feet)

Answer 154

* northern AUS - warmer climates * shaded/sandy conditions best for larva * \> 5000 eggs significant (relatively small in size) * dissimilar poles

Answer 155

* **Ancylostoma braziliense** * tropical/subtropical * less pathogenic but can cause hypoproteinemia & dxa * creeping eruption in humans * oral and percutaneous infection * erythematous inflammatory tracts w.in dermis

Answer 156

**Uncinaria stenocephala** - dogs SI (Bunostominae) * L3 ingested - no extra-intestinal migration * common in cooler areas * less pathogenic - slight anemia * PPP= 15d * \* eggs larger than Ancylostoma caninum eggs

Answer 157

* Uncinaria lucasi * N. hemi seals * larvae can penetrate skin (flippers) when on sand and transfer to pups **transmammary** * adult seals dont harbor adult nematodes just larvae * U. hamiltoni * anemia of Australian sea lions

Answer 158

A. Ancylostoma tubaeforme B. Ancylostoma braziliense C. Uncinaria stenocephala

Answer 159

* Bunostomum phlebotomum - cattle SI * Bunostomum trigonocepthalum - sheep SI \* mainly found in warms areas \* **percutaneous infection** \> Lung \> L4 \> tracheal migration \* transcolostral PPP= 7wks

Answer 160

* anemia * hypoproteinemia * dxa * **1000 burden fatal** (young animals - transmam)

Answer 161

* Gaigeria pachyscelis * feed on blood- severe anemia & death * low worm burden can be fatal (25 worms)

Answer 162

Globocephalus spp. * tropical areas around the world except AUS * Path * anemia - blood feeder * weight loss * emaciation

Answer 163

* Lung worms \> lung * reduced buccal capsule & copulatory bursa * usually have slugs/snails as intermediate hosts * L1 have characteristic kinks in tail * dx by Baermann technique

Answer 164

**Direct**: (L1 passes in feces) * L1-L3 in feces \> L3 ingested & exsheathment * migrate and moult L4 in mesenteric LN \> lungs (final moult) * Host: **ruminants, horse** * Genus: **Dictyocalus**

Answer 165

**Intermediate Host**- L1 passed in feces * L1-L3 in molluscs /earthworms (snails/slugs) * L3 ingest IH * migrates via lymphatics to lungs (similar to direct) * Host: **ruminants, pigs, cats** * Genera: **Protostrongylus, Muellerius, Metastrongylus, Aelurostongylus**

Answer 166

**Simple Direct** - L1 passed in feces * L1 infects definitive host (L1 passed in vomit) * also transmitted by licking * Host: **dogs** * Genera: **Oslerus, Filaroides**

Answer 167

A. Dictyocaulus filaria - bronchi B. Protostrongylus rufescens - bronchioles C. Muellerius capillaris - alveoli

Answer 168

* Dictyocalus filaria * sm. buccal capsule * **spongy** spicule

Answer 169

* lungworm of sheep * Direct LC - L1 in feces * L3 ingested and exsheaths in abomasum * migrates and moults in mesenteric LN \> Lungs \> final moult to bronchi * PPP= 21d

Answer 170

* damage epithelium * block airways- esp @ tracheal bifurcation * excess mucus * loss of mucocilliary escalator * interstitial pneumonia * detached alveolar macrophages \> consolidation of lung lobules \*\*\* immunity will develop following exposure

Answer 171

**Protostrongylus rufescens** - striated spicule * Indirect - snails * L1 in feces * penetrates foot of snail (L1-L3 in snail) * sheep ingests snail and migrates via lymphatics \> lungs (bronchioles)

Answer 172

**Muellerius capillaris** * L1 passes in feces * Indirect LC w/ snails & slugs as intermediate hosts Diagnosis w/ larval culture - **kinked tail**

Answer 173

**Dictyocaulus viviparous** * Direct LC- similar to D. filaria in sheep (temperate) * larval tail is a short spike * cough, laboured breathing, hypersensitivity rxn * disease mainly seen in calves * develop strong immunity * **Pilobolus spores help L3 move along pasture**

Answer 174

***Dictyocaulus arnfieldi*** * trachea of donkeys, horses, etc - mild path. * Direct LC * DX: **eggs passed in feces not L1** * **larvae have pointy tail**

Answer 175

**Metastrongylus apri, M. salmi & M. pudendotectus** * Location: bronchi * LC: Indirect * **Eggs** coughed up, swallowed & passed in feces * IH: earthworms (L1-L3) \> pig ingests * L3 moults in mesenteric LN \> L4 moults in lungs * Pathogenesis * resp. airway disease/obstruction * nodular formation of lungs & fibrosis

Answer 176

**Parelaphostrongylus tenuis** * adult worms lay eggs in cranial venous sinuses \> eggs carried to lungs & hatch to L1 * L1 enters alveoli and via mucocillary escalator passed in feces * L1-L3 develop in snail - ingest L3 via snail * L3 exsheathment in abomasum migrate through wall * follow nerves\> spinal cord (dorsal horns of grey matter) \> subdural space\> cranial venous sinuses * **Abnormal host** * moose, cattle, sheep * neurologic disease\> fatal

Answer 177

**Elaphostrongylus cervi** * occur in connective tissues & meninges * L1 enters blood & reaches lungs * IH: snail * abnormal host * other ruminants * neurological signs

Answer 178

**Aelurostrongylus abstrusus** * Site: alveoli & blood vessels * LC: Indirect * L1 in feces \> penetrates snail * L3 develops in snail and ingested * other transport hosts * rodents, lizards, birds * L3 penetrates gut wall\> blood\> lungs * PPP= 6 wks Diagnose - larvae in feces - kinked tail

Answer 179

Angiostrongylus vasorum - pulm. artery Oslerus osleri - trachea Filaroides hirthi- alveoli

Answer 180

Pathogenesis * mild cough,interstitial pneumonia * right ventricle/pulm. a. * edema, jugular pulse * congestive heart failure, liver, kidney LC: Indirect PPP= 4-8wks * eggs released in pulm a \> L1 migrates through lungs and passed in feces Diagnose : barbers pole appearance

Answer 181

**Oslerus osleri** * LC: direct (L1 in feces or vomit) * adults migrate from lung to trachea \> larvae penetrate duodenum \> migrate to lung where **all** moults occur * PPP= 9wks * TX: fenbendazole @50 mg/kg/day for 7d

Answer 182

**Filaroides hirthi** * drect LC - L1 passed in feces

Answer 183

**Angiostrongylus cantonensis** * LC- indirect * IH: snails, crabs & prawns and pass in snail slime * L3 penetrate gut\> brain \> L4 \> pulm a final moult * Abnormal host * dog, cat, horse, zoo animals, humans * severe encephalitis (neuro) * eosinophilic meningitis

Answer 184

1. specturm of activity\*\* 2. administration 3. safety margin\*\* 4. selective toxicity 5. withdrawl period 6. economical

Answer 185

1º - broad spectrum but not effective against inhibited larvae or Ostertagia. 3º- highly effective against Ostertagia, will kill hyperbiosed larvae and migrating S. vulgaris * **Tertiary BZ's also have a longer half life** * **modified side chains ^ metab**

Answer 186

* inhibits polymerization of tubulin * microtubules polymerised in nematode gut cells * **OVICIDAL**

Answer 187

Admin: **oral**"white" drenches Metabolism (3º BZs widespread use) * form depot in rumen and absorbed * metabolised to sulphoxide in liver * sulphoxide: anthelmintic properties * sulphoxide to sulphone * sulphone: anthelmintic properties * metabolites diffuse across gut wall from blood to lumen * excreted in urine * ABZ excreted in bile * good for treating liver flukes

Answer 188

* kills all "strongyles", trichostrongyles & lung worms * \*\*fendendazole resistance in trichostrongylus of sheep * kills inhibited larvae & migrating larvae * non toxic (safety index \> 10)

Answer 189

* Drug depot in large intestine * widespread use - kill adult strongyles & migrating S. vulgaris larvae * NOT effective against inhibited cyathostomes (encysted) & widespread resistance (sm. strongyles)

Answer 190

* Mebendazole * no "depot" so must give 3-5 days of doses bc cleared quickly * effective against adult nematodes * not effective against inhibited larvae (Ancylostoma)

Answer 191

* acts on nervous system * cholinergic agonists at synaptic and extrasynaptic nicotinic ACh receptors (motor end plates) \> ^ Na+ into cell * depolarisation causes spastic paralysis

Answer 192

**Imidazothiazoles- Levamisole** Activity * All GINs & lung worms * NOT effective against inhibited larvae & flatworms * immunomodulation at low doses * Safety index: **5** * **NOT ovicidal** Pharmacokinetics * absorbed rapidly and excreted in urine 6 hrs Administration * Oral, SQ, topical, intraruminal inj.

Answer 193

Trichotrongyles

Answer 194

No - causes excitement

Answer 195

hookworms & lungworms

Answer 196

nicotinic agonists- depolarise motor end plates in muscle (same as levamisole) Safety index: 7

Answer 197

Pyrantel tartrate * white powder soluble in water- absorbs well orally in dogs, pigs and rats * in dogs excreted in urine Pyrantel pamoate * yellow power insoluble in water- poorly absorbed in GIT and excreted in feces * safe in young/weak animals Morantel tartrate * water soluble, rapidly absorbed & excreted in urine * used in **ruminants** against GINs not lungwoms

Answer 198

* GINs * NOT lungworms * NOT inhibited larvae

Answer 199

* morantel tartrate * against common GIN * resistance in trichostrongyles * no activity against lungworms

Answer 200

* Pyrantel tartrate against roundworms and nodular worm (Oesophagostomum spp.)

Answer 201

* Pyrantel pamoate - against hookworms (Ancylostoma & U. stenocephla) and roundworms * recommended for all ages (even preg)

Answer 202

* Pyrantel tartrate - lg & sm strongyles * not effective against encysted cyathostomes * & resistance reported * safe all ages * Pyrantel pamoate - lg strongyles and cestodes

Answer 203

They all have similar mechanisms of action

Answer 204

* MLs bind w/ high affinity to a GABA receptor (trigger Cl- influx) * hyperpolarization of neuron and prevents initiation/propagation of normal APs * flacid paralysis * somatic musculature \> parasite unable to stay on host * pharyngeal pump \> affects nutrient ingestion * Death of nematodes and arthropods

Answer 205

MLs- act on all GINs and Arthropods -safe (SI: 20) and effective @ low doses (not ovicidal)

Answer 206

* Admin: oral, injectable or pour-on * absorbed rapidly * short half life after **oral** admin * parenternal half life (ivermectin): 14d * moxidectin (cydectin) half life: 28d * can have long acting (SQ admin): 3 mo \*variability w. pouron bc inter-animal & host licking

Answer 207

* mainly oral - widely used * ivermectin resistance in trichostongyles * cydectin effective

Answer 208

* injectable and pour-on used * kills inhibited Ostertagia * resistance in Cooperia * \*\*lactating dairy cows: use **eprinomectin** * **0 withdraw w/milk & meat** * **pour-on** * Dormectin used

Answer 209

* oral * ivermectin kills 10% of inhibited cyathostomes * moxidectin kills 80% * resistance in cyathostomes

Answer 210

* milbemycin & ivermectin - effective against heartworm larvae present in blood * selamectin - external and internal parasites * moxidectin - SC 55d before pregnancy * prevents nematode transmammary transmission in dogs

Answer 211

* persists in dung - kill arthropods * may have detrimental environ effects

Answer 212

* binds and inactivates AChE irreversibly \> spastic paralysis due to non-inactivation of ACh

Answer 213

Hemonchus (need high doses to kill Trichostrongylus and Ostertagia) * only used in sheep * used in combination where resistance is a problem

Answer 214

* agonist of GABA receptors - flaccid paralysis * hyperpolarisation of nerve endings * disloged from intestinal lumen * expelled from normal peristaltic action

Answer 215

* Narrow spectrum- ascarids & nodular worms * rapidly absorbed and excreted in urine * given orally * low toxicity - safe in all animals

Answer 216

Horses * pinworms and large strongyles (S. vulgaris) Cats/Dogs * just ascarids Pigs * Oesophagostomum spp.

Answer 217

* uncouples oxidative phorphorylation * act in mitochondria

Answer 218

* highly effective against blood feeders * cannot penetrate cuticle * eg. Hemonchus & Ancylostoma * narrow spectrum * Admin: orally - absorbed and binds to plasma proteins\> persists 4-6 wks * Safety Index low : 5

Answer 219

Salicylanilides (Closantel)

Answer 220

* MOA: flaccid paralysis by binding latrophlin receptors in parasitic nematodes * effective against most nematodes - used in **cats**

Answer 221

* binds nematode specific nicotinic ACh receptor - cannot close \> Na+ influx = spastic paralysis * safe bc receptor only in nematodes (SI: 30) - mostly converted to **sulphone** in liver ( long halflife in plasma) and most passes in feces * effective against most GINs in ruminants except lungworms

Answer 222

MOA * nicotinic antagonist \> flaccid paralysis * does NOT kill nematodes Action * effective against Dictyocaulus * successful when combined with Abamectin * "medium spectrum"

Answer 223

1. makes admin easier against mixed infections 2. treated animal will likely be cleared of untreated parasites

Answer 224

* fenbendazole & moxidectin

Answer 225

Pups * tx every 2 weeks pre weaning * tx every 4 weeks post weaning * tx every 3 months after 6 m/o Preg * Fenbendazole 50mg/kg/day from 3 wks prepartum to 2-15 d postpartum * Moxidectin 1mg/kg given SQ on pregnancy day 55 prevents nematode transmammary transmission

Answer 226

-after "lag" period - increase in gene frequency

Answer 227

When one genus of parasite (ostertagia) is resistant to one class of anthelmintic (BZs) while another genus (Hemonchus) is resistant to a different anthelmintic class (levamisole) * use drugs together to eliminate parasites

Answer 228

When a single genus is resistant to 2 drug classes (eg. BZs and levamisole) - though uncommon

Answer 229

when parasites develop resistance to one benzimidazole they are resistant to other benzimidazoles

Answer 230

sheep & goat (BZs and LEV especially) * Trichostrongylus, Ostertagia, & Hemonchus

Answer 231

BZs & avermectins

Answer 232

* polymorphism in nematode population * initial frequency of resistance alleles * number of genes involved * fecunditiy & length of life cycle * shorter LC = higher fecunditiy = higher chance of resistance * resistance gener dominant or recessive * treatment frequency & proportion of nematode population exposed to a drug * deworm only 70-80% of population * pharmacokinetic profile of drug * enough to remove parasite dont want subtheraputic

Answer 233

* Reduced drug uptake * Increased drug efflux * detoxification at its site * Altered target (binding site-receptor)

Answer 234

MLs (most resistance w/BZs and Pyrantel)

Answer 235

Laboratory tests * egg hatching inhibition w/ BZs (ovicidal) * tubulin binding assays w/ BZs * no radioactivity = resistance * L3 paralysis test w/ LEV/ML * migration through mesh * larval development test = Drenchrite test Field * Fecal egg count reduction test * test 2 dif. dewormers in sheep w/existing burdens * FEC \> 250epg * resistance if less than 95% reduction

Answer 236

* isolate eggs from feces * **determine level of resistance for BZ and LEV**

Answer 237

1. check timing & admin of drenches (2 summer) 2. check mgmt practices 1. pre/post trx FEC & pasture mgmt 3. double doses? 1. no use with BZs and temporarily effective w/LEV 4. rotation and mixtures used (eg. BZ,LEV,ABA) 5. Quarantine drenches for all introduced sheep 6. use effective drench (eg. monepantel)