Nematode I Flashcards
Ascarids
– Superfamily Ascaridoidea
Brief Description
Ascarids, very common intestinal large roundworms.
*often just called roundworms.
*some of the largest known.
*several inches up to 2 feet! Zoonotic
Ascarids
– Superfamily Ascaridoidea
Common in?
Dogs, cats, pigs, cattle, horses, chickens, and other animals.
*most frequently found in young animals.
Ascarids
– Superfamily Ascaridoidea
Direct or indirect life cycle?
Direct.
-transmitted by ingestion of egg by a new host.
Ascarids
– Superfamily Ascaridoidea
Where are they in the host?
Juvenile stages are not confined to the intestinal lumen (invade other tissues).
*often feature migration within the host.
Ascarids
– Superfamily Ascaridoidea
What do males have?
Curved tails.
Ascarids
– Superfamily Ascaridoidea
General Life Cycle
- Eggs are very resistant.
- Eggs contain J1 when excreted in feces.
- Juveniles develop into J2 in egg.
- New host ingests infective eggs.
- Eggs hatch in host intestines.
- Juveniles burrow through intestinal wall and enter bloodstream.
- Travel to other parts of the body to further develop.
- Eventually make their way back to intestines where adults form and produce eggs.
- Eggs excreted in feces.
Ascarids
– Superfamily Ascaridoidea
Eggs are….?
- Found in fecal polluted soil.
- Can survive and remain infective in soil for many years.
- Eggs are infective.
Ascarids
– Superfamily Ascaridoidea
What is usually the infective stage?
The J2 in egg.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum is the?
Intestinal roundworm of pigs, and the most common parasite found in pigs.
*more common in pigs less than 1 year.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
Parascaris equorum
Toxocara canis
Toxocara cati
Life Cycle
- Eggs containing J1 excreted in feces.
- Eggs containing J3 ingested by new host.
- Eggs hatch in intestine and travel to liver.
- J3’s go from the liver to the lungs.
- Travel up the bronchial tree to pharynx and are swallowed.
- Mature to adults in the small intestine (produce eggs).
- Eggs excreted in feces. Process takes 6-8 weeks (prepatent period)
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
What type of migration do they have?
Hepato-trachael larval migration.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
Parascaris equorum
Symptoms
- Poor growth.
- Coughing (hemorrhagic lesions in lungs).
- Milk spots on the liver.
- Intestinal or bile duct blockage (due to adults)
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
What happens to the milk spots on the liver, why are they important?
They will eventually go away. They are important because they are a reason for meat condemnation.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
What causes the most damage to the host?
Larval migrations.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
Parascaris equorum
Diagnosis
Eggs in feces, will NOT see them during the prepatent period.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
Parascaris equorum
What do the eggs look like?
- Oval and thick shelled.
- Rough, sticky, external surface.
*very highly resistant to standard disinfectants.
Ascarids
– Superfamily Ascaridoidea
Ascaris suum
Parascaris equorum
Prevention
Regular deworming does help, but it does not totally prevent.
Ascarids
– Superfamily Ascaridoidea
Parascaris equorum
Brief Description
Large conspicuous roundworm of horses.
*females may be up to 50 cm (20”).
Ascarids
– Superfamily Ascaridoidea
Parascaris equorum
What is the predilection site?
Small intestine of equines.
Ascarids
– Superfamily Ascaridoidea
Parascaris equorum
Symptoms (especially in foals)
Similar to Ascaris suum, add:
-Death due to heavy infestation.
*from intestinal impaction or rupture.
*not that common.
- Reduced weight and appetite.
- Intermittent diarrhea, constipation, colic.
*after the parasite reaches adult.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Brief Description
Common roundworm of dogs (especially puppies). Found rarely in cats.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Paratenic Hosts
Many mammals can serve as paratenic hosts. Especially mice and other rodents.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Prepatent Period
19-34 days!
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
How are animals infected?
By ingestion of an egg, mostly by ingestion of a paratenic host. Often a mouse.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Predilection Site
Small intestine of dogs.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Symptoms in Adults
- Asymptomatic in adults with light infections.
- May be thin with a light coat.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Symptoms in Puppies
Puppies with heavy infections:
- Unthrifty
- Often pot-bellied
- Abdominal pain
- Diarrhea
- Vomiting
- Worms may be found in vomitus
- May cause death
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Diagnosis
Eggs in the feces. Eggs are thick shelled and mammillated.
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
How is it transmitted from mother to pup?
In two ways:
- Transplacental (major)
- Transmammary (minor)
Ascarids
– Superfamily Ascaridoidea
Toxocara canis
Prevention
Regular deworming works well. Dogs shouldn’t get it.
Ascarids
– Superfamily Ascaridoidea
Toxocara cati
Brief Description
Common roundworm of cats.
Ascarids
– Superfamily Ascaridoidea
Toxocara cati
Differences from Toxocara canis.
- Paratenic hosts more important cause of infection (cats hunt more).
- No transplacental infection.
- Transmammary infection is major route in kittens.
- A wide range of common paratenic hosts.
*chickens, earthworms, cockroaches
- Adult cats are more likely to get severe disease.
- Often seen in vomitus.
Ascarids
– Superfamily Ascaridoidea
Toxocara cati
Toxocara canis
Zoonosis, Two Diseases
Causes:
- Visceral Larval Migrans (VLM)
- Ocular Larval Migrans (OLM)
Ascarids
– Superfamily Ascaridoidea
Toxocara canti
Toxocara canis
Visceral Larval Migrans
Larvae migrate through the human host’s liver, lungs, heart, and brain. They cannot mature to adults in humans.
Ascarids
– Superfamily Ascaridoidea
Toxocara canti
Toxocara canis
Visceral Larval Migrans, Symptoms
Depends on the number of larvae and the organs affected.
- Fever
- Myocarditis
- Eosinophilia
- Coughing
- Splenomegaly
- Abdominal Pain
- Itchy or pruritic rash
Ascarids
– Superfamily Ascaridoidea
Toxocara canti
Toxocara canis
Visceral Larval Migrans, Treatment
Antihemitic drugs and anti-inflammatories. Will usually go away by itself since the worm cannot complete its life cycle in the human.
Ascarids
– Superfamily Ascaridoidea
Toxocara canti
Toxocara canis
Ocular Larval Migrans
Toxocara invade the eye.
- Usually occurs in school aged children.
- Presents as eye pain and loss of vision.
- Results in retinal granulomas that are sometimes misdiagnosed as retinoblastoma resulting in unnecessary removal of the eye.
Ascarids
– Superfamily Ascaridoidea
Toxocara canti
Toxocara canis
Zoonosis, How is it acquired?
Eggs are usually ingested from soil in an area where infected dogs or cats have defecated. Also the hair of an infected animal may contain infective eggs.
-Eggs become infective two weeks after excretion.
Pinworms
– Superfamily Oxyuroidea
General Characteristics
- Direct Life Cycles
- Females have long, pointed tails.
*the reason they are called pinworms.
- Have a realively low ability to migrate in host.
- Common in many mammals, birds, reptiles, amphibians, insects.
*not found in dogs and cats