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.