Parasites Flashcards
Size of small strongyles vs Large strongyles
Small: 1.5 cm x 1 mm
Large: 1.5 - 4.5 cm x 2 mm
Morphologic difference between small and large strongyles
Large have a substantial buccal capsule that allow them to strongly attache to the mucosa. Smalls don’t have a strong buccal capsule
Mention the most important Strongyle subspecies (3)
- Vulgaris
- Edentatus
- Equinus
Where do this parasites migrate?
1. Vulgaris
2. Edentatus
3. Equinus
- Vulgaris: Blood vessels (cranial mesenteric artery)
- Edentatus: Liver and retroperitoneum
- Equinus: Liver and pancreas
Prepatent period of large strongyles
6-7 months
Prepatent period of small strongyles
6- 10 weeks
Prepatent period of:
1. S. edentatus
2. S. equinus
- 10-12 months
- 9 months
Describe life cycle of Strongylus vulgaris
Ingestion of L3
Absorbed small intestine
Travel blood vessels
Develop to L4
L4 gets to cecum and ventral colon
Adults - produce eggs
Eggs will feed from manure and convert to L1-L2-L3
Infecting again
Describe migration and stages of S. edentatus
S. edentatus: L3 is the one migrating, arrived to liver and develop to L4, when L4 will produce nodules that will break into large colon
Describe migration and stages of S. equinus
L4 is the one that will migrate and stay in pancreas, after mature will travel to large colon and become adult
Lessions that Strongylus vulgaris will cause in the GI
Verminous aneurysm or thromboembolism of the cranial mesenteric artery will result in ischemia of the GI
If you do a fecal float and see strongyles, how do you differentiate between small and large and which percentage will be each?
You cannot differentiate of the eggs are from small or large. But previous evidence will claim that about 95% will be small
Other than a fecal egg account, what other diagnosis you have to differentiate small vs large strongyles ?
Fecal culture - give conditions for the eggs to growth
PCR - will differentiate types of subfamilies of strongyles
Pathologic findings in Strongylus vulgaris
Hemomelasma ilei (1 cm haemorrhage in serosa of ileum)
Arterial thrombi
Arterial walls thickened or fibrosis
4 clases of dewormers used in horses
- Benzimidazoles : Fenbendazole
- Heterocyclic compounds: Piperazine
- Macrocyclic lactones: Iver/Moxide
- Tetrahydro-pyramidines : Pyrantel
Pre-patent period of small strongyles
6-10 weeks
Describe cycle of small strongyles
L3 ingestion - invade mucosa and submucosa of the cecum and ventral colon - EL3-LL3-EL4-LL4- adults - eggs - growth in manure - L1-L2-L3
For how long Strongyles eggs can live in the pasture?
> 2.5 years
When does small strongyles could cause a clinical problem?
When all the encysted died or emerge at the same time
When is the ideal season of the year for encysted strongyles to emerge?
Late winter, later summer and autumn
Pathological findings of small strongyles
Tubular glands in the large intestine leading to goblet cell hyperplasia
Hyperplasia and hypertrophy and destructions of the glands
How can you see if there is resistance to dewormers?
Fecal egg count reduction
How to perform fecal egg count reduction?
Before and after 2 weeks of the treatment:
EPG (preTX) - EPG (postTX) / EPG (preTx)/100=
> 90% pyrantel
>95% the rest
Do not do it if less 200 eggs initially
How does large strongyles travel thru the arteries?
They travel to the endothelium of the blood vessels
What’s the infective larve form of Parascaris?
L2
Clinical signs of Strongyloides in foals
- Diarrhea
- Frenzied syndrome (itchy because larvae are in skin)
Forma of transmission of Strongyloides westeri
- Skin
- Oral - mucous membranes
- Udder (skin or milk)
Prepatent period of Strongyloides westeri
14-16 days
How does a foal get Strongyloides westeri
Thru the milk that contains the larvae or sucking around and licking at the skin (larvae on the skin)
Reproductive characteristics of Strongyloides westeri cycle
It doesn’t need a male to fecund the egg
It can complete the cycle outside of the host
How does Strongyloides westeri travels from the sling to small intestine?
Skin, Blood vessels, heart, and small intestine
Describe cycle of Parascaris equorum
L2 infective form, swallow, small intestine, enteric circulation, liver l4, lungs, breaks in the capillaries of the alveoli, travel thru the trachea, cough, swallow and small intestine (adults)
Prepatent period of Parascaris
2 months
Deworming option for Parascaris
Fenbendazole
Deworming option for Strongyloides westeri
Moxidectin
Prevalence of Strongyloides westeri
1.5%
Mention the three species of anophocephala
- Perfoliata
- Magna
- Manillana
Prepatent period of A. Perfoliata
6-16 weeks
What kind of cycle does A. Perfoliata has? Direct or Indirect?
Indirect because it has an intermediate host
Which is the intermediate host of A. Perfoliata?
Oribatid mites
Mention where do these parasites settle in the GI tract:
1. A. Perfoliata
2. A. Magna
3. A. Mamillana
- Perfoliata: ileocecal valve
- Magna and
- Mamillana: small intestine
Why is hard to see proglotids in manure?
Because they are ingested in the large colon
Describe the life cycle of A. Perfoliata
Ingestion of the infective cysticercoid within the mite, attached to the GI mucosa in large intestine, proglotid development, production of eggs, eggs in feces will chemoatract mites, mites will eat it and oncosphere will develops until their infective cysticercoid form
Prevalence of A. Perfoliata
Will vary depending on the state from 20-40-50%
But for sure yearling more prevalent
How can you diagnose A. Perfoliata?
ELISA or special fecal float with sugar saturated solution or zinc sulfate
Main clinical signs related to A. Perfoliata ?
Ileocecal intusuception
Some cases related with cecal impactions
Top choice dewormer for A Perfoliata
Ivermectin +/- Praziquantel
Which part of GI tract does Oxyurus stays?
Small colon and dorsal colon
Describe life cycle of Oxyurus
Ingestion if L3, hatched out in the mucosa of the large colon, L4, attached to proximal large intestine, molt to adult, move to distal colon, female will come out overnight to put eggs around the anus
Main clinical signs of Oxyurus
Itchy ass, alopecia in the case of the tail
How can you Dx Oxyurus ?
Scotch tape
Tongue depressor with mineral oil
Look under microscope
Two main clinical signs that horses can get with Anophlocephala Perfoliata
Cecal intusuception
Ileocecal intusuception
Best dewormer for tape worms
Praziquantel
Gasterophilus species that affect the horse
G. intestinal
G. nasals
G. pecorum
G. haemorrhoidalis
Life cycle of Gasterophilus
Botflies are in legs, many and flanks - horse eats it - attached in gastric mucosa - detach spring and early summer - passed in feces - under the soil - pulpate - adult flies - place eggs again in their bodies
Is the only Gasterophilus specie that place eggs in the grass not in horses body
G. pecorum
Which Gasterophilus specie lay eggs in the nose?
G. haemorrhoidalis
Which Gasterophilus specie can cause gingival necrosis
G. nasalis
Treatment/Management recommendations for Gasterophilus control
Ivermectin
Control flies
Clipping hair
Removing eggs
Synonyms of Habronemiasis
Summer sores
Bursatti
Swamp cancer
Main species of Habronema that affects horses
- Habronema muscle
- Habronema mujus (microstoma)
- Draschia megastoma
Which Habronema species can be found free in the mucousa of the stomach (glandular)
H. muscae and H. mujus
Which Habronema specie is the inly one that can cause granulomatose masses in the glandular mucosa of the stomach?
Draschia megastoma
Characteristic if granulomas creates from Draschia megastoma?
Granulomas have an opening from where the larvae will come out to the stomach
How does Strongyloides Western pass to the foal?
The foal will eat it from the skin and also eggs can be found in the milk
Describe life cycle of Habronemiasis
Larvae will be in the mouth, eyes, wound, penis or prepares (moist areas), horse will ingested, passed to feces as L1, flies will eat eat, mature to L3 and sit in the mouthparts, eggs will be laid in the same moist sites
What is the pathogenesis for the lesions found in habronemiasis?
Hypersensitivity IgE mediated to the larvae
Main clinical signs of Habronemiasis
Granulomatous ulcerative lesions
+/- prurito
Rare: pulmonary habronemiasis
Differentials for Habronemiasis
- Phycomycosis
- Zygomycosis
- Fungal granulomas
- Exuberant granulation tissue
How do you diagnose habronemiasis?
Gross appearance of the lesions
Smears and biopsy: may see the larvae
eosinophils / mast cell infiltration
Treatment for habronemiasis
Ivermectin
Treatment of the lesion: Organophosphates, corticosteroids and DMSO
Name of parasite - Lungworm infection
Dictyocaulus arnfieldi
Reservoir of Dictyocaulus arnfieldi
Doneys and mules
Prevalence of Dyctyocaulus arnfieldi (horses, donkeys and mules)
Horses 2-11%
Mules 29%
Donkeys 68-80%
Clinical signs of lungworm
Donkeys and mules - no clinical signs
Horses - cough, expiratory effort, mimic asthma clinical signs (crackles and wheezes)
Describe life cycle of Dyctocaulus arnfieldi
Horse will ingest L2- get to the gut-travel through lymphatics, arrive lungs - L4-maturation in peripheral bronchioles and been in adult stage-eggs-mucocilliary and pharynx traveling-swallow-GI- excreted in poop
Diagnosis of Dyctocaulus arnfieldi
Clinical sings + donkeys interaction
Endoscopy:may see parasites
BAL: worms + eosinophils
Treatment for Dyctocaulus arnfieldi
Ivermectin
Moxidectin
Species of Onchocerca that affect horses
O. gutturosa
O. reticulate
O. cervicalis
Location site of the adults of:
1. O. gutturosa
2. O. reticulate
3. O. cervicalis
- Gutturosa: nucal ligament
- Reticulate: tendons and suspensory ligament
- Cervicalis: nucal ligament, ventral midline, pectoral area, whothers inguinal and eyelids
Which is the most common onchocerca specie in horses
O. cervicalis
Intermittent host of Onchocerca
Culicoides (for all)
Mosquitos (cervicalis)
Simulium (gutturosa)
Pathogenesis of onchocerciasis
Cutaneous lesions - type I and III hypersensitivity to microfilariae
Clinical signs of Onchocerca
Cutaneous lesions
Secondary immune mediates uveitis
Thinning of the hair and crusting
Pruritus
Vitiligo
Other eye problems
Diagnosis for Onchocerca
Skin scrapings and direct smears blood from lesions: sometimes presence of parasite
Minced skin biopsy
Biopsy incubation - look foe microfilaria
Treatment for Onchocerciasis
Ivermectin
usually improves in 2-3 week period
Differential diagnosis for Onchocerca
Culicoides hypersensitivity
Dermatophytosis
Fly-bite dermatosis
Mites
Food hypersensitivity