Nematode Parasites of the Respiratory System - Lecture 15

The following general morphology and biology represents nematode parasites of which system:

• small worms with superfifical resembalnce to hookworms

• dioecious and sexually dimorphic

• males with rudimentary copulatory bursa

• generally feed on host cellular tissue

• companion and production animals

• most develop to infective stage in obligate intermediate host (there are some exceptions)

• occupy lungs, pulmonary vasculature

respiratory system

Metastrongyloidea has what common name?

dog lungworms

Which species of dog lungworms is described by the following:

• adult worms are parasitic in lung parenchyma

• prepatent period approximately 35 days (5 weeks)

Filaroides hirthi

Which species of dog lungworms is described by the following:

• adult worms are parasitic in nodules in the trachea and bronchi

• nodules detected by bronchioscope at 2 months

• prepatent period approximately 6-7 months

Filaroides osleri

This image matches which species?

Filaroides hirthi

This image matches which species?

Filaroides osleri

The following life cycle matches which species:

• direct life cycle

• 1st stage larvae passed in feces of infected mother (ovoviviparous: eggs hatch within uterus of adult female worms)

• puppies infected by ingestion of first stage larvae through coprophagy, ingestion of larvae in regurgitated stomach contents, tracheal migration by hepatic circulation

Filaroides spp

What is the prepatient period for F. hirthi?

aprrox 32 days post infection

What is the prepatent period for F. osleri?

approximately 6-7 months post infection

What is the only nematode where the 1st larval stage is infective to the final host?

Filaroides spp

How do we diagnose Filaroides spp (dog lungworm) or Aleurostrongylus abstrusus (cat lungworm)?

fecal examination via Baermann exam or zinc sulfate flotation

The image matches which species?

Filaroides spp

The larvae description matches which species:

• larvae approximately 350 micrometers

• kinked tail with dorsal spine

Filaroides spp (dog lungworm) or Aleurostrongylus abstrusus (cat lungworm)

Which exam techinque is described:

• developed in 1917 by Dutch physician working in Java for recovery of hookworm larvae in soil samples

• preferential for recovery of live larvae in fecal samples and cultures

• active migration of larvae out of fecal sample suspended in water

• larvae concentrate in stem by gravity

• microscopic wet mount by pipetting larvae from bottom of stem

Baermann exam techinque

Which exam technique is shown in this image?

Baermann exam technique

Which first stage larvae is shown in the image? How do you know?

Filaroides spp (dog lungworm) or Aleurostrongylus abstrusus (cat lungworm), kinked tail

What are the clinical signs of Filaroides spp?

• generally asymptomatic

• hard, dry coughing stimulated by cold air or exercise

The pathology of Filaroides spp is seens as focal areas of inflammation and necrosis where?

in the parenchyma of the lung lobes

Severe disease of Filaroides spp can be seen in which animals?

those that are hyper-infected and immunocompromised

What can occur with nodular fomation in hyper-infections of Filaroides spp?

obstruction of trachea

What is the treatment and prevention protocol for Filaroides spp?

• prevention by avoiding contact with infective larvae (easier said than done)

• treatment with FBZ at 50mg/kg SID x7 days resolved symptoms

• IVM at 1000 micrograms/kg for one dose 44% effective, for two dises 74% effective

• criteria for efficacious chemotherapy includes clinical imrpvoement, cessation of symptoms, resultion of nodular lesions, and cessation of larval shedding

What is the common name for Angiostrongylus vasorum?

French heartworm

Is Angiostrongylus vasorum zoonotic?

No

The following description matches which species:

• small worms living in the right heart or pulmonary artery

• widepsread in Europe

• associated with pulmonary thrombosis, clotting disorders, hemorhhage from deposited eggs and larvae

Angiostrongylus vasorum

How do we treat Angiostrongylus vasorum?

0.5mg/kg Milbemcyin weekly x4 weeks

Which Angiostrongylids have zoonotic significance?

• Angiostrongylus costaricensis

• Angiostrongylus cantonensis

Which Angiostrongylid is described:

• associated with abdominal pain, fever, vomiting from worms living in emsenteric artiers

• endemic to central and south america and caribbean

• spread in FL associated with deaths in primate colonies

• sperad to africa with cuban mercenaries in angola in 1980s

Angiostrongylus costaricensis

Which Angiostrongylid is described:

• associated with neurologic disease from larvae in the meninges and inflammatory response

• naturally occurring in rats in southeast asia

• spread to north america 1986-87 in wharf rats from asia

Angiostrongylus cantonensis

What is the common name for Aleurostrongylus abstrusus?

cat lungworm

The lifecycle described matches which species:

• indirect

• 1st stage larva passed in feces ingested by snail/slug intermediate host

• 3rd stage larvae are infective stage

• mice/birds are opportunistic paratenic hosts

• prepatent period 5-6 weeks

Aleurostrongylus abstrusus

Tiny adult worms of Aleurostrongylus abstrusus are parasitic where?

in the terminal bronchioles and alveolar ducts

Where are eggs of Aleurostrongylus abstrusus laid in the host?

lung parenchyma

How do “nests” of Aleuostrongylus abstruse appear?

small nodules with associated inflammatory response and focal necrosis

What is the most common lungworm parasite in companion animals?

Aleurostrongylus abstrusus

What clinical signs are associated with Aleurostrongylus abstrusus?

• often clinically inapparent and unremarkable

• coughing and dysorexia may be associated with moderate infection

• cough, dyspnea and polypnea in severe cases

What is the treatment and prevention protocol for Aleurostrongylus abstrusus?

• prevention by reducing predation of paratenic hosts and infective larvae (easier said than done)

• FBZ at 50mg/kg SID x3-15 days has been standard treatment with moderate success

• criteria for efficacious chemotherapy includes clinical improvement, cessation of symptoms, and cessation of larval shedding

The image depicts what species?

Troglostrongylus sp

What is the lifecycle of Troglostrongylus sp?

indirect lifecycle with infective 3rd stage larvae in snail intermediate host

Which parasite has been increasingly recognized as an agent of feline respiratory disease in Europe and Mediterranean?

Troglostrongylus sp

The image depicts what species?

Capillaria spp

Which parasite species are small worms with whip like anterior ends and are parasites of all class of vertebrates?

Capillaria spp

What is the lifecycle of Capillaria spp?

highly variable: some are simple direct, some facultative indirect with paratenic host, and others obligate indirect with intermediate hosts

What is the common name for Capillaria sp?

cat AND dog lungworms

Which Capillaria spp has adults that are parasitic in bronchi?

Capillaria (Eucoleus) aerophila

Which Capillaria spp has adults that are parasitic in nasal sinuses?

Capilaria (Eucoleus) bohemi

What are the clinical signs of Capillaria spp in dogs and cats?

• silent cough, sneezing

• bronchopneumonia, rattling wheezy respiration, coughing, not doing right

How do you diagnose infection with Capillaria spp?

fecal flotation

How do we control infection of Capillaria spp?

environmental hygiene

How do we treat Capillaria spp?

macrocyclic lactone drugs

Capillaria aerophila and Capillaria bohemi can have direct or facultative indirect lifecycles. What is the paratenic host for facultative indirect?

earthworms

What are the lungworm parasites of domestic livestock (cattle, sheep, goats)?

• Muellerius capillaris

• Dictyocaulus spp.

The following life cycle matches which species:

• obligate indirect

• tiny parasites embed into respiratory tissue of goats and sheep

• larvae are then coughed up, swallowed, and passed in feces (1st stage larvae are diagnostic via recovery by Baermann method)

• 1st stage larve ingested by snail/slugs with development to infective stage

• ingested 3rd stage larvae migrate to lungs, adults reproduce, and begin apssing larvae approximately 4 weeks post infection

Muellerius capillaris

How do we treat Muelerius capillaris?

macrocyclic lactone drugs at 200 to 500 micrograms/kg

What are the clinical signs of Muellerius capillaris?

• most infections are asymptomatic in healthy adult animals

• clinical signs resulting from heavy infections in immunocompromised animals may include coughing and rapid breathing, weight loss, etc

What class do Muellerius capillaris belong to?

Metastrongyloides

What classification do Dictyocaulus spp belong to?

Trichostrongyloidea

The following lifecycle mataches which species:

• direct

• larvated eggs hatch before passage in feces

• 1st stage larvae are diagnostic stage via recovery by Baermann technique

• development to infective stage in 5 days

• ingested larvae migrate to lungs via mesenteric lymph nodes and thoracic dict, arrive in lungs approximately 5 days post infection

• adults reproduce and begin passing eggs approximately 4 weeks post infection

Dictocaulus spp

Which Dictyocaulus spp is found in the respiratory passages of horses and donkeys?

D. arnfeldi

Which Dictyocaulus spp is found in the respiratory passages of cattle?

D. viviparus

Which Dictyocaulus spp is found in the respiratory passages of sheep and goats?

D. filaria

Light infections of Dictyocaulus spp have what symptoms?

often asymptomatic

Heavy infections of Dictyocaulus spp have what symptoms?

• occlude airway and obstruct airflow

• clinical signs include increased respiration, harsh breathing, occasional crepitation

• decreased eating/weight gain resulting from increased stress to breathe

How do we treat infections of Dictyocaulus spp?

macrocyclic lactones

Host resistance is a function of what for Dictyocaulus spp?

age, vigor, genetics, established infection, and acquired immunity

The image depicts what species?

Dictyocaulus

The image depicts what species?

Mullerius

What is the common name for Metastrongylus sp?

Swine lungworm

The image depicts what species?

Metastrongylus elongatus

The following life cycle matches which species:

• direct/facultative indirect

• hatch, larvae ingested by earthworm, and develop to infective stage

• migrate to lung, reproduce

• prepatent period with eggs in feces approx 25 days post infection

Metastrongylus sp

The following description matches which species:

• adult worms live in respiratory tract, most often in bronchioles and trachea

• thread-like, superficial resemblance to hookworms

• 3 species

Metastrongylus sp

How do we diagnose infection of Metastrongylus elongatus?

fecal flotation

The following egg description matches what species:

• superficial resemblance to Ascaris suum

• 40×50 micrometers

• thinner shell

• embryonateed with larvae in feces or sputum

Metastrongylus elongatus

What is the clinical significance/clinical signs of Metastrongylus elongatus?

• presence in lungs results in alveolitis/bronchitis

• chronic and paroxysmal coughing

• unthriftiness/fail to meet ADG production goals

• secondary pneumonia with dyspnea and abdominal respiration

What is the control and prevention protocol for Metastrongylus elongatus?

• prevention by treatment to remove patent infections (FBZ effective for removal of adults and immature stages, Ivermectin and Doramectin for 21-24 days)

• clean farrowing environemnt for sows

• raise in confinement when possible

Parasitic infections of Filaroides olseri and Filaroides hirthi are associated with respiratory complaints in which species?

Dogs

Parasitic infections of Aleurostrongylus abstrusus are associated with respiratory complaints in which species?

cats

Parasitic infections of capillaria aerophila and Capillaria bohemi are associated with respiratory complaints in which species?

dogs and cats

Which species is an important emerging zoonosis and One Health issue in the FL gulf coast region of the U.S?

Angiostrongylus cantonensis

What species can act as an asymptomatic reservoir for Dictyocaulus infection in horse sharing pastures?

donkey

Larvae that look like this were found on a Baermann exam of a fecal sample from a yorkie presenting with a chronic cough aggravated by cold air. What are they?

first stage larva from Filaroides sp

A 2 year old poodle mix presented with a chronic dry cough. The owner believes it is worse on mornings when the air is cooler. Bronchoscopy reveals nodules in the trachea and bronchi that look like this. What parasite is implicated?

Filaroides osleri

The eggs in the accompanying image were seen on the fecal flotation of a beagle with occasional sneezing. The eggs measure approximately 65 micrometers. What is the diagnosis?

Capillaria Eucoleus) bohemi