Details of…Endoparasites

Laboratory Procedures

Remember Endoparasites?

Major Classes of Endoparasites

Helminths Nematodes Tapeworms Flukes

Arthropods Insects Arachnids

Protozoa

Nematodes

In general are round in cross section, longer than they are wide and are unsegmented.

Can be in a variety of lengths. (Males smaller than Females)

Significant cause of disease in dogs and cats

Have varied life cycles

Roundworms

Medical Name: Toxocara canis, Toxocara cati, Toxascaris leonina

All three of these are common among dogs and cats.

Live in the small intestine Vary in length from 3 – 18 cm (average ~

7” in length)

Roundworms – cont’d

Methods of transmission:Direct (fecal/oral)TransplacentalTransmammaryPredation of foreign hosts

Roundworms – cont’d The eggs of T. canis can survive on the soil for

several years. (Fresh feces are NOT infective) Eggs are ingested and hatch in stomach,

penetrate bowel wall, enter portal bloodstream, wander through the liver and end up in the lungs.

They are coughed up and swallowed, molt in stomach and mature in small intestine.

Entire life cycle can take as little as 4-5 weeks.

Toxocara canis ova

Adult Roundworms

Toxocara sp. Clinical Signs

Heavy infections can produce abdominal cramps and distention, and obstruction of the intestinal tract.

Pulmonary edema, coughing, nasal discharge, and increased respiratory rates may also be seen.

Vomiting, diarrhea, emaciation, dull hair coat and restlessness are also often seen.

Toxocara Transmission to Humans

Toxocara larvae can cause:Visceral larval migransOcular larval migransNeural larval migrans

Hookworms

Medical name: Ancylostoma caninum, Ancylostoma tubaeforme, Ancylostoma braziliense, and Uncinaria stenocephalaOf these, the most commonly seen is

Ancylostoma caninum

A. caninum

Seen in over 20% of adult dogs Live in the small intestine Methods of transmission:

Skin penetrationDirect (Fecal/Oral)Transmammary/intrauterine

A. caninum

Growth and maturation process after ingestion is between 18-21 days.

Female can lay up to 30,000 eggs per day In environment, there are 3 stages: egg,

hatchling and larvae. (Takes 5 days) Larval stage is infective stage.

A. Caninum - Migration

Once in new host, some will burrow back into intestine to complete maturity

Others may burrow from intestines to lungs and mature there. Ascend up trachea, cause coughing and is

swallowed. Worm goes back to intestine to mature.

Ancylostoma ova

Adult Ancylostoma caninum

Ancylostoma Clinical Signs

Major CS are associated with blood loss and GI irritation.

Weakness, anemia, diarrhea, bloody or tarry stools, anorexia, depression, and death may also occur.

Larvae may wander into other organs causing secondary signs of hepatitis and pneumonia

Ancylostoma Transmission to Humans

Infective larvae can penetrate the skin causing cutaneous larval migrans

Whipworms

Medical name:Trichuris vulpisTrichuris serrataTrichuris campanula

Of these, most common is Trichuris vulpis

T. vulpis

Common in young and adult dogs (not often seen in very young b/c of prepatent period of 70-190 days)

Rare in cats Not often seen in very young animals Live in jejunum Method of transmission:

Primarily fecal/oral (direct)

T. vulpis

Eggs are passed in the stool Eggs are ingested by host and hatch in

small intestine. Larvae migrate caudally, where they

mature.

T. vulpis – Clinical Signs

Depend on the number of parasites present, but can include: Intermittent diarrhea, weight loss, emaciation,

anemia, abdominal pain, flatulence, and “flank suckling”.

Trichuris vulpis ova

Trichuris vulpis

Eggs are double operculated(Have 2 opercules, have an opercule on each end)Makes it easier for larva to hatch from egg

Eggs can live under proper conditions in the soil for up to five years.

Adult Whipworm

Heartworms

Medical name: Dirofilaria immitis Vector is mosquito Common in dogs, cats, ferrets and some

humans Pseudoheartworm exists that is not

pathogenic (Dipetalonema reconditum)

Microfilaria v- Dipetalonema

Remember that Microfilaria are one of the juvenile forms of Heartworm

Dipetalonema are usually non-pathogenic There are 3 main physical differences

between the two:HeadTail shapeType of movement

Microfilaria v- Dipetalonema

Microfilaria:Straight tailTapered headUndulating movement (no forward mvmt.)

Dipetalonema:Button-hooked tailBlunt headDefinite forward movement

Dirofilaria immitis Named “Heartworm” because it lodges in the

venous return of the heart; primarily the right atria, & right ventricle. Inhibits the flow of blood to and from the heart.

Vector is mosquito Prepatent period = 6 months Adults can live up to ~3-5 years Microfilaria can live up to 3 years

D. Immitis – Clinical Signs

Usually progressive as disease progresses.Gradual weight lossLoss of enduranceCoughingAccumulation of abdominal fluidLabored breathing Increased temperatureCyanotic MM

D. Immitis - Diagnosis

“SNAP” testDetects the hormone from the adult female

worm Blood smear

Looks for microfilaria in the blood Once diagnosed, disease state is

classified (graded) from 1-4

Classes of Heartworm Disease

Class 1 (Mild)    Occasional cough, fatigue with exercise, or mild loss of

condition          

Class 2 (Moderate)  Occasional cough, fatigue with exercise, or mild to moderate

loss of condition 

Class 3 (Severe)  General loss of condition: fatigue with mild activity;

occasional or persistent cough 

Class 4 (Very Severe) Caval Syndrome http://www.youtube.com/watch?v=VOLzFsNOJ-

4&feature=player_embedded             

“Reverse D” of Caval Syndrome

Cestodes

Dipylidium caninum (flea tapeworm) Taenia (tapeworm)

Dipylidium caninum (Flea tapeworm)

Most common tapeworm found in dogs and cats Animal becomes infected by ingesting the

intermediate host, the flea. Can infect humans Indicates presence of fleas May see on perianal area or can see egg baskets

on fecal flotation. The asexual process of forming segments is termed strobilation

Taenia (Tapeworm) Found as taenia pisiformis, taenia hydatigena, and

taenia ovis. Acquired by eating cysticerci (larval form) in rabbits.

(Predation of the host)

Trematodes (Flukes)

Platynosomum fastosum (lizard poisoning fluke of cats)

Nanopyetus salmincola (salmon poisoning fluke of dogs)

Alaria (intestinal flukes of dogs and cats) Fasciola Hepatica (common liver fluke)

Platynosomum fastosum (Lizard poisoning fluke of cats) Adult flukes of cats inhabit the liver, gall

bladder, bile ducts, and small intestine.

Nanophyetus salmincola (Salmon poisoning fluke) Vector for Neorickettsia hemintheca, Salmon

poisoning disease in dogs. Called “Elokomin fluke fever” Causes hemorrhagic enteritis with generalized

lymphadenopathy, vomiting, diarrhea, lethargy, inappetence, fever, and death.

Found in Pacific Northwest region of North America

Alaria (intestinal flukes)

Found throughout the northern half of North America

Mostly non-pathogenic. Lung migration may cause some damage Minor zoonotic potential from larval stages

from intermediate hosts.

Fasciola Hepatica (Liver Fluke) Requires an ________________ as an intermediate host. Has been identified World-wide and is responsible for substantial

losses of cattle and sheep. _____________ stage that migrates to the _________ after

ingestion is the infective stage. Feeds on liver tissue for _________ before migrating to the bile

duct where it begins to produce eggs. (Can reproduce ___________)

Mild infection = about ________ eggs produced per day per fluke with one animal depositing about ______________ eggs daily in a pasture.

Is capable of causing disease in humans who _______________________________ growing near snails habitat.

Clinical signs in animals include ________________, and __________________. (_____________is only occasionally seen)

Fasciola Hepatica Ova

Coccidians and Protozoans

Are single-celled organisims Are generally very host specific Primarily live in small intestine of dogs and

cats. Rarely a problem in the mature animal.

Coccidians (Are a type of protozoa)

Isospora spp. Toxoplasma gondii Cryptosporidium Sarcocystis

Coccidians – cont’d

Produce a condition called “coccidiosis” in the young animal.

Most common Clinical Sign is diarrhea which can lead to death, possibly due to dehydration and other loss of nourishment.

Diagnosed by seeing oocyst in fecal floatation of fresh feces.

Eimeria oocyst vs- Nematode ova

Toxoplasma

Is zoonotic Definitive host is any member of feline

family Can cause placental barrier in humans

and cause spontaneous abortion.

Sporozoites: “Super egg” that can remain dormant for a considerable amount of time in the environment until ingested by a host.

Tachyzoites: “fast dividers” Are the eggs that are rapidly dividing and causing infection in the host.

Bradyzoites: “slow dividers” Are the eggs that are semi-dormant in a host that is not the definitive host. Can begin life-cycle again if this host is consumed by definitive host. May also cause chronic infection.

Toxoplasma gondii (Toxo)

May cause transient diarrhea in cats

Highly pathogenic to humans, especially fetus in utero

Protozoans (Are not necessarily coccidians)

Anaplasma (and other blood parasites) Giardia

Are a flagellate protozoan NOT a coccidianCause diarrheaOccur as cysts or trophozoites in fecal

floatationTransmitted primarily by drinking stagnant

water

Giardia trophozoite