Parasitology exam 1 Simplified

Symbiosis

Symbiosis

Parasitism is a type of ________

Phoresis

To carry

No physiologic dependency

Mutualism

two organisms living together in a situation that benefits both

Obligatory mutualism

Both organisms are metabolically dependent on each other
Ex. Rumen Microbes

Commensalism

Relationship in which the commensal benefits from an association with a host where the host is passive to there relationship

metabolic needs
Habitat

Parasites depend on the host for

Parasitism

one organism lives in or on another organism at the expense of the host

Organism = yes, (+) positive effect
Host = no, (-/0)

Parasitism
Physiologic dependence (organism to host) = ?
Effects on participants?

Helminths

Multi-cellular
Roundworms, flatworms, thorny headed worms

Protozoa

Single celled
Amoebae, flagellates, ciliates, apicoplexans

Arthropods

Multicellular
Fleas, ticks, mites, flies, mosquitoes, ets

Endoparasite

any parasite that lives in the internal organs of animals

Ectoparasite

Any parasite that lives on the exterior of animals

Infection

The entry and development or multiplication of an infectious agent within the body of an animal

Infestation

The lodgement, development, or reproduction of parasites on the surface of the body or superficial tissue

obligate parasite

must live a parasitic lifestyle or die

Facultative parasite

opportunistic parasite that can survive without the host

Definitive host

Host in which a parasite reaches maturity and if applicable reproduces sexually

intermediate host

a host in which a parasite goes through its larval or developmental stages

Paratenic host

a host in which the parasite remains viable but does not undergo any further growth or development

Direct life cycle

Requires a definitive host but not an intermediate

Parasite infects new definitive host Via the environment

Direct

Describe the lifestyle in the image

Indirect life cycle

Requires >1 intermediate host(s) in addition to a definitive host to complete its cycle

Indirect

Indirect or Direct?
Fasciola spp.

Direct
Note= can involve a proteinic host too

Indirect or Direct?
Toxocara spp.

accidental parasite

a parasite that invades an organism other than its natural host

aberrent parasite

Parasite wanders to wrong site within host and cannot complete life cycle

pseudoparasite

any object or organism that resembles or is mistaken for a parasite

spurious parasites

Parasites that pass through the GI tract of a non-host species and are mistaken as parasites of the non-host

aberrant

Heartworm in the eye of a dog
Aberrant or accidental parasite?

spurious

SPURIOUS PARASITE OR PSEUDOPARASITE?

Eimeria from an herbivore; found in dog feces

Incubation period

time interval between entry of an infectious organism into a host and the first appearance of clinical signs of disease in the host.

Pre-patent period

time interval between entry of an infectious organism into a host and the first time we can detect the organism in the host.

Oviparous

Female lays eggs with an undeveloped embryo

Ovoviviparous

female lays an egg that contains first stage larvae

Viviparous

Female gives birth to larvae instead of laying eggs

Lifecycle of Nematodes

1. Pre-parasitic stages occur outside host
2. Stage exiting the host is usually an egg or L1
3. Stage infecting host is most ofter an L3
4. Parasitic stages occur inside host

Blood worms, red worms

Common names for true strongyles include:

Ingestion of L3 larvae

How does Strongylus vulgaris enter the body?

Equids

Species affected by strongylus vulgaris/ large strongyles?

Yes, Penetrate intestinal wall and migrate to the cranial mesenteric artery

Do strongylus vulgaris migrate within the body of the horse?

Cecum and colon

Where do adult strongylus vulgaris live?

Larval migration

The pathology of the strongylus species is ____

Strongylus vulgaris

Thromboembolic colic / Verminous
arteritis ==> infarction

Verminous arteritis

Acute disease of strongylus vulgaris

Colic
Anemia
Arteritis
Thrombosis
infarction of gut wall
altered intestina motility

Symptoms associated with strongylus vulgaris?

Strongylus Vulgaris

The only nematode with larval development in the arterial system of horses?

Ingestion of L3 Larvae

How do strongylus edentatus enter the body?

Yes, L3 penetrate the intestinal wall and migrate to the liver via the bloodstream. from the liver they migrate to the peritoneal cavity

Is there migration within the host of strongylus edentatus?

Cecum

Where do adult strongylus edentatus live?

Fecal float/FEC
ID adults at necropsy, look for lesions

Test to ID Strongylus species

Liver
Peritoneum - peritonitis
gut wall - adhesions

What kind of damage do strongylus edentatus cause?

Strongylus vulgaris
Strongylus edentatus
Strongylus Equinas

What strongyles belong to "Large Strongyles"

False, all strongyle type eggs look the same

T/F You are able to tell "Strongyle-type" eggs apart in the feces

Equids

Definitive host of cyathostomes

(60-120) x (35-60)

small Strongyle type eggs can be ___ x ____ in size

True

T/F Small strongyle eggs cannot be differentiated from large strongyles

cecum/ colon lumen

Adults of cyathostomes can be found in

Larval = Synchronous emergence of arrested larvae

-Non responsive diarrhea, hypoproteinemia, edema, weight loss, seasonal

Chronic = normal maturation/life cycle

-Poor hair coat, weight loss, loose stool, pot belly

Describe the difference between Larval cyathostominosis and chronic cyathostominosis

Arrested development of L3
Larval cyathostominosis
Direct life cycle

Describe the development of small strongyles

Cyathostomes

Small strongyles are also considered

Quantitative float

What is the method to test for small strongyles/ cyathostomes

Selective therapy

Describe the best method of treatment for small strongyles?

Parasites are unevenly distributed (overdispursed)

Strongyle egg shedding is consistent over time (in adult horses)

Selective therapy relies on what two observations:

Control populations in order to avoid clinical signs
Control/slow the development of resistance
Reduce eggs on pasture

Goals of selective therapy

Binomial negative distribution
80% of the worms
carried by 20% of the population

Describe the 80/20 rule

Refugia

Untreated/ non dewormed animals are ________

Fecal egg count reduction tests annually

No anthelmintic will eliminate all parasitic stages from a horse

Continue using fecal egg counts once or twice a year

Deworm all horses at a baseline rate (once or twice a year) and target selected horses more often based on FEC

Important AAEP guidelines

Oesophagostomum spp.

What parasite would you expect to see a cervical vesicle and shallow buccal cavity

reinfection that produce lesions of localised immune-mediated reaction around larvae in mucosa

The pathology of Oesophagostomum spp. is unique in that they can cause ________

Oesophagostomum spp

Nodular worm

Ruminants and swine

Oesophagostomum spp are known to affect what species of animals

Primary infection can be harmless but enteritis can emerge if a large number of larvae emerge from mucosal cysts

Pathology of oesophagostumum spp

Many drugs can kill adult worms, none target encysted larvae, this results in reinfection

What is unique about the treatment of Oesophagostum spp

Stephanurus Dentatus

Swine kidney worm

stongyle type eggs in Fresh urine

How can one detect the eggs of stephanurus dentatus?

yes, but the eggs cannot survive the cold and dry

Can pigs raised outside get Stephanurus dentatus

True

T/F Pigs can get stephanurus dentatus from Parentenic host: earthworms that penetrate the skin, ingestion of larvae, or ingestion of infected earthworms

Haemonchus
Ostertagia
Trichostrongylus
Cooperia

HOTC

Haemonchus cortortus

Barber pole worm

Haemonchosis

Haemonchus contortus can cause the clinical condition _________ in Sheep, goats, camelids

Haemonchus cortortus

The most important parasite of sheep, goats, and camelids

Haemonchus Placei

Cattle Wireworm

Haemonchus Placei

This abomasum cattle worm can be found worldwide and also infect sheep primarily in warmer locations

Haemonchus spp

Both sexes are blood suckers
Strongyle type eggs

Haemonchus spp.

The pathogenesis of this worm can cause Voracious/ Excess blood loss resulting in decreased RBC's and proteins

Hypopreteinemia

decreased oncotic pressure

Haemonchus spp

Unless mixed with other strongyles, diarrhea is generally not a feature of infection unless mixed with other strongyles

Anemia and dependent anemia

FAMACHA
Younger animals
Quantitative fecal can be helpful

The best test and indication of Haemonchus spp

Ostertagia ostertagi

This is historically the most important economically helminth parasite in cattle in the US although its distribution is worldwide

Ostertagia ostertagi

Brown stomach worm

Hypobiosis of L4 is seasonal and emerge in the next season

Ostertagia ostertagi is unique lifecycle in that

Morocco leather of cobblestone appearance of the abomasal mucosa

Changes to mucosa

Change in abomasal pH

The pathogeneis of Ostertagia ostertagi shows

Type 1 ostertagiasis: No developmental arrest - no hypobiosis

Type 2 ostertagiasis: Developmental arrest - hypobiosis

The difference between type 1 and type 2 ostertagiasis

True strongyles

Hookworms

Trichostongyles (mostly)

Direct lifecycles, eggs/freeliving L3

meningeal worm

Indirect lifecycles with snail/slug intermediate host

Lungworms

Some direct life cycle, eggs with larva; some indirect lifecycle with snail/slug intermediate host

Trichostrongylus axie

stomach hair worm

Erosion of the abomasal epithelium +/- haemorrhage
Horse: hyperemic gastritis

Pathogenesis of trichostrongylus axei

Diarrhea, weight loss, anorexia

Clinical signs of trichonstrongylus axei

Cooperia spp

What small intestine trichostrongylus is extremely hard to kill with macrocyclic lactones?