Respiritory Parasites Flashcards
Describe the life cycle of some of the species of parasites which live in the nasal tract and trachea
Describe the life cycle of Oestrus ovis and discuss its importance in UK agriculture
Describe the life cycle of Syngamus trachea and discuss its importance in UK agriculture
Give examples of the different ways in which nasal and tracheal parasites may be diagnosed
List the nasotracheal arthropods
Tongue Worms
Linguatula serrata
The Bot Fly
Oestrus ovis
The Nasal Mite
Pneumonyssus caninum
List the nasotracheal nomatodes
Eucoleus (Capillaria) boehmi Dogs & foxes
Oslerus osleri (Filaroides osleri) Dogs
Eucoleus aerophilus (syn. Capillaria aerophila) Dogs
Filaroides spp (F. hirthi and F. milksi) Dogs
Crenosoma vulpis Dogs & foxes
Syngamus trachea (Gapeworm) Non-aquatic birds
Explain the lifecycle of Linguatula serrata (tongue worm)
The adults live in the upper respiratory system and nasal airways and frontal sinuses of the carnivores, especially dogs as final hosts.
Eggs which discharge with nasopharyngeal secretions of the definitive host can be swallowed by herbivores (as intermediate hosts) such as cattle, buffalo, sheep, goat, etc.
Then, the larvae hatch from the eggs and migrate mainly to mesenteric lymph nodes (MLNs) and other visceral organs (such as liver, lung, spleen, heart, etc.).
The parasite can be transferred to the final host through consumption of meat or viscera of infected intermediate host
Outline the structural features of Linguatula serrata
Pentastomid (not an arthropod)
- Anterior end of the body, mouth hook and 4 clawed legs
- Chitinous cuticle
- Nervous system similar to arthropods
- Lacks many organs e.g., respiratory, excretory
Males ~ 20 mm & females 30-130 mm
List the clinical signs for Linguatula serrata
Mucopurulent nasal discharge (contains mucus & pus)
Epistaxis (bleeding from the nose)
Sneezing
Outline the diagnosis of Linguatula serrata
Fecal Examination: Fecal examination can reveal L. serrata organisms in some cases.10,11
Nasal Cytology: Occasionally, L. serrata can be diagnosed by examination of nasal swabs/washings or seen grossly in nasal discharge (Figures 1, 2).11
Rhinoscopy: L. serrata can be visualized on rhinoscopy. Inflammation of the nasal cavity may also be present
Provide an overview of the treatments available for Linguatula serrata
Nasal flushing using warm salt water can help to detach the adult parasite
Treatment with Milbemycin oxime Dogs are able to expel the adult stage through nasal discharge
Explain the lifecycle for Oestrus Ovis (Bot Fly)
The female is viviparous and infects the host by squirting larvae into the nostrils of sheep in a jet of liquid.
The larvae crawl caudally into the nasal cavity and feed on the nasal mucosa and mature, before returning to the nostrils.
The larvae move to the frontal sinuses, where they transform from L2 to L3.
They only move to the frontal sinuses under warm conditions. If these conditions are not achieved, the larvae will stay in the nostrils for an extended period of time, until the warm conditions come about.
The larvae are then sneezed out into the ground, and pupate on the ground. The adults develop, and are active throughout the year. Adult flies only live for 2-3 weeks
Outline the epidemiology of Oestrus Ovis
Endemic areas in UK south of latitude 520
Abattoir surveys in 1999 showed 13% of sheep in endemic areas were infected
Prevalence within flock may be as high as 80% (Bates et al., 1999. Med. Vet. Entomology)
Studies have reported between 50-100% flock infestation in France, Turkey, Spain, Russia, USA, Australia, Africa, South America and Central Asia
Economic importance in many countries not considered high
List the clinical signs of Oestrus Ovis
Avoidance behaviour
Excess (sometimes bloody) nasal discharge
Laboured breathing
Loss of appetite
May induce non-localised symptoms due to secondary bacterial infection (e.g., lung abscess/interstitial pneumonia)
Outline the diagnosis of Oestrus Ovis
Serological testing using ELISA may be used in some countries
Outline the treatments used for Oestrus Ovis
Nitroxinyl, moxidectin, ivermectin, closantel
Explain the pathology for Nasopharyngeal myiasis (The Nasal Mite)
Fly deposits larvae in or around nostrils of the host
Pathology associated with feeding on mucous membranes in nasal cavity and sinuses
Other examples of myiasis occurs with blow flies e.g. ‘fly strike’ in sheep and rabbits
Explain the pathology of Pneumonyssus caninum (Nasal mite in dogs)
Lives in the nasal and paranasal sinuses of dogs. It also may be found around the nares and on the muzzle.
Nasal mites can cause an inflammatory reaction in the nasal cavity and sinuses.
List the clinical signs of Pneumonyssus caninum
The extent of clinical signs varies, and some affected patients are asymptomatic
Sneezing/snuffling to nasal discharge/bleeding (epistaxis)
The olfactory mucosa and tonsils may also become inflamed.
Describe the etiology of Pneumonyssus caninum
Mobile, oval in shape, pale yellow, and 1-1.5 mm in length. All legs are found on the anterior half of the body
Outline the diagnosis of Pneumonyssus caninum
From nasal swabs (adult mites)
Physical examination
Complete blood counts
Outline the treatment available for Pneumonyssus caninum
Sub-cutaneous selamectin, moxidectin, milbemycin oxime. No drug licensed as yet
Explain the life cycle pf Eucoleus (capillaria) boehmi (nasal worm of dogs and foxes)
Unknown
Likely via ingesting of eggs discharged from the nasal tract of infected dogs, or earthworm involved as a paratenic host (This is the case with E. aerophilia)
Outline the epidemiology of Eucoleus (capillaria) boehmi
Infects mucosa of nasal cavity/passage and the frontal and paranasal sinuses.
Known as ‘nasal capillariasis’
Most reports from the USA
Rhinoscopically (1.5 cm-4 cm) on the epithelial lining of the nasal turbinates
List the clinical signs of Eucoleus (capillaria) boehmi
Sneezing
Rhinitis
Serous to mucopurulent nasal discharge
(Sometimes) severe epistaxis (requires blood transfusion).
Reverse sneezing (air quickly inhaled through nostrils-response to nasopharyngeal irritation-dog makes honking/gagging sounds)
Outline the diagnosis for Eucoleus (capillaria) boehmi
Eggs (diagnostic stage) can be found in dog faeces by faecal flotation , and from nasal swabs/flushes.
Although nasal washings to remove adults have been most successful
Eggs are confused with whipworm (Trichuris vulpis) and another lungworm (E. aerophilus). Eggs of the 3 species have an average size of 60-30 μm and two polar plugs at both ends
Explain how to differentiate between the eggs of whipworm (Trichuris vulpis), E. Aerophilus (lungworm) & Eucoleus (capillaria) boehmi
E. boehmi egg has a rough ‘pitted’ surface;
E. aerophilus egg has a shell with striation;
Trichuris vulpis egg has a smooth shell
Outline the treatments available for Eucoleus (capillaria) boehmi
Rx: Fenbendazole at 50 mg/kg PO q 24 hr for 2 wk.
Ivermectin has been also used.
Dog are treated with antibiotics, antihistamines, and steroids prior to diagnosis of nasal worm infection
Explain the lifecycle for Oslerus Osleri (Filaroides osleri)
Females are ovoviviparous; the eggs hatch inside the female.
Both larvated eggs and larvae are passed by the female nematode.
The first-stage larvae – which are the infective stage - are released into the tracheal lumen and move up to the pharynx, are swallowed and then pass out in the faeces.
Infection of the definitive hosts is by ingestion of first-stage larvae.
First stage larvae cross the intestinal wall and travel via lymphatics or blood to the lungs.
Auto-infection may occur with O. osleri, in which the infective first-stage larvae penetrate into the intestinal wall without leaving the host, migrate to the trachea, and develop into adult parasites.
Explain the pathology of Oslerus Osleri (Filaroides osleri)
Metastrongyloid nematode with direct life cycle
Infection occurs via ingesting L1-infected faeces or by direct transfer of L1 in sputum (hence NO GASTROPODS ARE INVOLVED)
Adults live (within nodules on the mucosa) in the distal trachea and tracheal bifurcation
World-wide distribution, but unknown prevalence in UK
List the clinical signs of Oslerus Osleri (Filaroides osleri)
Chronic cough
Wheezing, and may develop to exercise intolerance
Dyspnoea
(Sometimes) death
Immune response to adults in trachea and bronchi causes the worm to encapsulate
Outline the diagnosis for Oslerus Osleri (Filaroides osleri)
Bronchoscope: Characteristic nodules can be seen particularly at the tracheal bifurcation
L1 in faeces or in BAL fluid (+ many eosinophils)
Resolution of tracheal/bronchiole nodes may take several weeks post-treatment
Explain the lifecycle in Eucoleus aerophilus (syn. Capillaria aerophila)
In the direct life cycle, a definitive host ingests the infective larvated egg from the environment, the larva hatches and travels through the small intestine wall, enters the lymphatics or bloodstream to the lungs, breaks out into the airways and completes its development to adult.
In the indirect life cycle the eggs are ingested by an earthworm intermediate host in which the eggs hatch to release the infective first stage larva. A definitive host then ingests the earthworm and the larva follows the same path as in the direct life cycle. The prepatent period is 6 weeks.
Outline the pathology of Eucoleus aerophilus (syn. Capillaria aerophila)
Inhabits trachea, bronchi & bronchioles of dogs, cats, foxes, wolves, racoon dogs, hedgehogs, lynxes, and mustelids
Animal ingests an infective egg or an earthworm (paratenic host) containing an infective larva in its tissues. Then, larva will find its way to the lung
List the clinical signs associated with Eucoleus aerophilus (syn. Capillaria aerophila)
Apart from a slight cough, infection is usually asymptomatic in dogs and cats
Outline the diagnosis for Eucoleus aerophilus (syn. Capillaria aerophila)
Using faecal floatation or tracheal wash of eggs with characteristic bipolar plugs and a rough ‘netted’ surface.
Outline the pathology of Filaroides spp (F. hirthi and F. milksi)
Live in the terminal airways, bronchioles and alveoli in dogs
Explain the lifecycle of Filaroides spp (F. hirthi and F. milksi)
Direct, and infection occurs via ingestion of L1s
First stage larvae passed in the faeces or in saliva and is immediately infective to another dog
Outline the diagnosis of Filaroides spp (F. hirthi and F. milksi)
Detection of L1s or embryonated eggs in faeces or in airway cytology specimens
Radiographic examination may show a diffuse interstitial or focal nodular pattern
Explain the life cycle of Crenosoma vulpis (Fox Lungworm)
Indirect and transmission requires ingestion of molluscs as intermediate hosts (e.g., common garden snail Helix aspersa)
List the hosts of Crenosoma vulpis (Fox Lungworm)
Foxes,
wolves,
coyotes,
raccoon dogs and
badgers
in Europe and N. America
domestic dog in the UK (1992_MF & MC)
What are the target sites of Crenosoma vulpis (Fox Lungworm)?
Trachea, bronchi and bronchioles
Explain the life cycle of Syngamus trachea (Gapeworm)
L1-L3 develops in the egg. Infection may be via ingestion of L3 in the egg, or a hatched L3, or ingestion of a paratenic host, most commonly the earthworm and the slug.
The L3 penetrate the intestine and then enter the lungs. The L3 then undergo two further moults, and copulation occurs in the trachea a few days later.
The prepatent period of S. trachea is between 16 and 20 days.
List the clinical signs of Syngamus trachea (Gapeworm)
Infection may be sub-clinical
Bird size and level of infection is important (younger birds with smaller trachea most affected)
‘Gaping’- Bird opens mouth wide and extends neck
Weight loss
Outline the Diagnosis for Syngamus trachea (Gapeworm)
Eggs (containing larvae) in faeces/ adults in trachea following post mortem
Outline the available treatments for Syngamus trachea (Gapeworm)
Flubendazole, mebendazole and fenbendazole
