Metastrongyloidea

overall

characteristics

small thin appearance

reduced bursa

adults in lungs

small buccal cavities

most pass as L1 in feces

Metastrongyloidea

Metastrongylus

D.H. - swine

adults found in lungs

impt - pasture pigs

earthworm I.H.

Metastrongylus

Paralaphostrongylus

D.H. - White Tailed Deer

adults found in meninges

impt - aberrant hosts with neurologic disease/death

elk and moose are possible aberrant hosts

no harm in WTD

Metastrongyloidea

Angiostrongylids & Crenosomatids

D.H. - Cats, Dogs, & Rodents

Adults found in lungs & vasculature

Impt - interference with breathing

L1 found in feces

Snail I.H.

Predators of snails serve as paratenic hosts

Metastongyloidea

Angiostrongylids & Crenosomatids

Aelurostrongylus abstrusus

Lungworm of cats

Adults found in subpleural nodules in parenchyma

Metastrongyloidea

Angiostrongylids & Crenosomatids

Angiostrongylus vasorum

"French Heartworm" of dogs

Adults in Pulmonary artery

Metastrongyloidea

Filaroides

D.H. - dogs

Adults found in lung

Impt - chronic cough

larvated eggs in feces

Direct life cycle

L1 infective stage

transmitted by ingestion of vommitus, lung tissue, or feces from an infected host

Metastrongyloidea

Protostrongylids

D.H. - sheep and goats

adults found in lungs

impt - wildlife

L1 in feces

Snail I.H.

Overall characteristics of

Rhabditoidea

small nematodes: 1-5 mm long

free-living form (rhabditiform) & parasitic form

ID: long esophagus in parasitic females

small, thin shelled larvated egg or L1 seen in fresh feces

True or False

Strongyloides = Strongyloidea

False

Rhabditoidea

Free-living form characteristics

Bulbed (rhabditiform) esophagus

haploid males

diploid females

saprophytic

Rhabditoidea

Parasitic form characteristics

long, cylindrical (filariform) esophagus

ALL are triploid females (parthenogenetic)

eggs are a mixture of triploid, diploid, and haploid

complex movement in host

vertical transmission

in humans autoinfection and hyperinfection can occur

Rhabditoidea

Parasitic form movement within the host

Infective larvae pentrate the skin

blood carries them to the lungs

break through the alveoli

migrate up the trachea

migrate down the esophagus

mature in the small intestine

Rhabditoidea

Where are these Important species found

Strongyloides stercoralis

S. papillosus

S. westeri

S. ransomi

Strongyloides stercoralis: dogs, cats, & humans

S. papillosus: ruminants

S. westeri: horses

S. ransomi: pigs

Rhabditoidea

Strongyloides stercoralis

Control and treatment

Dogs excrete larvae that develop in the soil and infect humans through skin penetration

Treat all animals on premises; isolate puppies with diarrhea, kennel sanitation; dogs on wire floors

Inform clients of risks and inform then to seek advice from their physician

Spirurida

General characteristics

No bursa, but some have caudal alae

Indirect Lifecycle

D.H.'s are vertebrates

Larval stages develop in arthropods

Spirurida with Dipteran (fly) I.H.

Thelazia

Draschia & Habronema

Dirofilaria immitis

Setaria

Onchocerca

Parafilaria

Spirurida

Thelazia

Characteristics

eyeworms

I.H. - face flies (a Diptera)

D.H.'s: cattle, dogs, and horses

adults found in conjuctival & lacrimal sac

Impt: irritation, minor pathogenesis

Distingushing characteristics: nematodes around eyes

Spirurida

Draschia & Habronema

Characteristics

I.H. - house & stable flies (Diptera)

D.H. - horses

Adults found in the stomach

Impt: stomach irritation, "summer sores"

Distinguishing characteristics: adults have deep, sclerotinized buccal cavities

Spirurida

Dirofilaria immitis

General characteristics

D.H.'s: dogs, cats, & ferrets

I.H. - Mosquitoes

Adults found in the pulmonary artery

Impt: potentially fatal

Distinguishing characteristics: long, slender nematodes without buccal cavities

Spirurida

Dirofilaria

Reproductive cycle from L1 to L3

Adults in pulmonary artery of D.H. give birth to live young (Viviparous)

L1's (microfilariae) released directlyinto blood

Microfilariae enter mosquito with blood meal

Migrate to mappighian tubules and molt to L3

L3's then migrate to mosquito salivary glands

Development in the mosquito takes about 2 weeks

Serve only as a biological vector do NOT replicate in I.H.

Spirurida

Dirofilaria

Reproductive cycle from L3 to adult

L3's in the salivary glands enter the mosquito's next host during feeding

Molt into L4's in the skin of the D.H.

L4's live in subcutaneous tissue for 60-90 days then molt to L5's

L5's then migrate to pulmonary arteries

Spirurida

Dirofilaria

Development of microfilariae

Fertilized females appear after 120 days

Fully deveoped L1's in utero by 180 days

Microfilariae first observed in peripheral blood between 180-210 dpi (days post infection)

Means prepatent period is 6-7 months

Prevalence in well cared for dogs

15 cases per 1000 dogs

Prevalence in Shelter dogs

Approximately 15%

Spirurida

Dirofilaria

Pathogenisis

No clinical disease during prepatent period

Disease occurs after microfilariae are in peripheral blood

Thought to be associated with obstruction of blood vessels by adults and progressive obstructive fibrosis

Wide range of responses from subclinical to fatigue, hepatic failure, pulmonary distress, right heart failure, and death

Severity correlated with adult worm burden

Spirurida

Dirofilaria

Factors affecting severity

Worm burden and location

Duration of infection

Activity level of the dog: working/active dogs may show signs sooner; coughing, exercise intolerance, and possibly syncope (fainting)

Host response to infection: immune inflamatory response in the lungs can lead to thromboembolism and arteritis

Spirurida

Dirofilaria

diagnosis

primary screening

A. microfilaria in peripheral blood

     1. blood smears, modified knott's test

     2. important to distiguish from Dipetalonema

B. occult infections

     serology or radiography

Spirurida

Dirofilaria

diagnosis

dogs undergoing chemoprophylaxis

1. diethylcarbomazine: test for microfilariae

2. Macrolides: antigen test

posatives should be retested

(false posatives infequent but possible)

Spirurida

Dirofilaria

Treatment

Adults: arsenamide

Microfilaria: Macrolide

L3-L4: prophylactic treatments

Spirurida

Dirofilaria

Treatment of adults

Immiticide (Melarsomine dihydrochloride)

organic arsenical chemotherapeutic agent

Low margin of saftey

given at 3 times the recommended dose can cause pulmonary inflamation, edema, and death

1. Diethylcarbamazine daily

2. Macrolide monthly

3. Slow release macrolide semiannually

Some dogs remain posative for microfilariae post-immiticide

even though they are

antigen negative again

and

recieved repeated treatments with ivermectin at          200 ug/kg

Feline Heartworm

basics

Lower tolerance of adults when compared to dogs

Amicrofilaremic

Use antigen &/or Antibody detection

Preventative thearapy available

Heart worm lifespan in cats

Typically live for 2-4 years in cat

when worms die they cause severe inflammatory reaction

(parenchyma, airways, vasculature)

coughing, dyspnea, vomiting, collapse, and sudden death

Erratic migration of adult worms can cause death

Heart worm prevalance in cats compared to dogs

Higher in all but 5 states

National average double the posatives on a percentage basis

Many more dogs are tested than cats

Heartworms in Cats

signs

Primarily associated with lungs

coughing and asthma-like signs

neurologic signs (convulsions, blindness) due to aberrant worm migration

peracute collapse and sudden death

(normal, then dead one hour later)

Spirurids

Setaria

General characteristics

D.H. - cattle and horses

Adults found in serous membranes

Impt. occasional neurologic disease when migrating larvae invade CNS

Distinguishing characteristics: microfilariae in peripheral blood; adults have a 'crown' on anterior end

American Heartworm Society

Recommendation on the use of adulticildal treatment in cats

NOT recommended

death of worms often causes severe clinical disease

Spirurida

Onchocerca

General characteristics

D.H. - bovids, equids, and humans

adults found in connective tissue

I.H./Biological Vectors: black flies or biting midges

Impt. - summer 'mange' in horses (Onchocerca cervicalis); river blindness in human beings (O. volvulus)

Distinguishing charac.: microfilariae in skin, lymph & C.T.

Spirurida

Parafilaria

General characteristics

D.H. - cattle & horses

Adults found in subcutaneous and intermuscular CT

I.H. - Haematobia & Musca spp.

Impt. summer bleeding in horses; trim losses in cattle

Disting. chara. - bleeding from pea-sized nodules in sunshine during summer with microfilariae observed in dried blood from nodules

Spirurida

Thelazia

common name

Spirurida

Draschia & Habronema

common name

Spirurida

Dirofilaria immitis

common names

Spirurida

Setaria

possible sign

Spirurida

Onchocerca

common name

fistulous withers

&

river blindness

Spirurida

Parafilaria

common name

Spirurida

Species with a Copepod (Cyclops spp.) I.H.'s

Dracunculus

&

Gnathostoma

Spirurida

Dracunculus

general characteristics

common name - guinea worm

D.H. - D. insignis=carnivores & D. medinensis=humans

Adults found in the subcutaneous tissue

Impt. -  minor in carnivores; painful irritation in humans

Spirurida

Gnathostoma

General Characteristics

D.H. = carnivores

adults found in stomach

Impt. - larval migrations in D.H.

rupture of adult-containing cystic nodules into peritoneal cavity

Spirurida

Dracunculus

Distinguishing features

long slender sub-Q nematode associated w/ ulcer in the D.H. skin

L1's released though ulcer when wet

Frogs can be paratenic hosts for D. insignis

Spirurida

Gnathostoma

Distinguishing characteristics

adults have spiny doughnut-shaped collar at anterior end

amphibians, reptiles and fish can serve as paratenic hosts

Spirurida

with Coleoptera (beetles) I.H.

Physaloptera

&

Spirocerca

Spirurida

Physaloptera

General Characteristics

D.H. = carnivores

Adults found in the stomach

Impt. = vomiting and possibly confusion with more pathogenic nematodes such as Toxocara

Spirurida

Physaloptera

Distinguishing characteristics

larvated eggs with medium thick shell in feces

white to pink adults seen in vomit and during endoscopy

Spirurida

Spirocerca

General characteristics

common name = esophageal worm

D.H. = dogs

Adults found inside nodules of esophagus, stomach and aorta

Impt. =

excessive vomiting

malignant tumor development

secondary pulmonary osteoarthropathy of long bones

Spirurida

Spirocerca

Distinguishing characteristics

small larvated eggs that resemble paper clips

require high specific gravity to float (1.360)

Numerous paratenic hosts, most notably chickens with regard to infection of dogs

Nematode with a Oligochaete I.H.

&

What is an Oligochaete

Dioctophyme renale

an earthworm

Dioctophyme renale

characteristics

Largest known nematode parasite of domestic animals

females up to 1m x 1cm

males up to 40cm, w/ fleshy bell-shaped bursa

D.H. = dogs, mink, swine, & occasionally humans

I.H. = oligochaete

paratenic hosts = fish and frogs

adults found in right kidney or abdominal cavity

eggs are large, globular, with inconspicuous bipolar plugs and found in urine

Superfamily

Oxyuroidea

general characteristics

common name = pinworms

no bursa

bulb at posterior end of esophagus

small to medium size

females possess long slender tail

direct lifecycle

host specific

large intestine

ova flattened on one side w/ single plug

Oxyuroidea

Oxyuris

General characteristics

D.H. = horses

adults found in the large intestine

Impt. = pruritis ani

Oxyuroidea

Oxyuris

Distinguishing characteristics

spherical at posterior esophagus

larger than other pinworms

egg masses cemented to anal skin

Impt. species in the superfamily

Oxyuroidea

Oxyuris

Skrjabinema

Enterobius

Heterakis

Oxyuroidea

Syphacia

general characteristics

D.H. = Rodents

Adults found in large intestine

Impt. = laboratory animals

Oxyuroidea

Skrjabinema

General characteristics

D.H. sheep & goats

adults found in the large intestine

Impt. = considered harmless

Oxyuroidea

Enterobius

General characteristics

D.H. = humans & great apes

adults found in large intestine

Impt. = pruritis ani and insomnia

school outbreaks

eggs are infective w/in hours

reinfection increases intensity

Oxyuroidea

Enterobius

Distinguishing characteristics

small adults

eggs should be collected from anal region

do NOT infect dogs or cats

Oxyuroidea

Heterakis

general characteristics

common name = cecal worm

D.H. = poultry

adults are found in the cecum

Impt. = minor pathogenesis (nodules)

transmission of Histomonas meleagridis

Oxyuroidea

Heterakis

Distinguishing characters