Parasitology Flashcards
Define parasitism
An interaction where only one organisms benefits to the detriment of the other
Define mutualism
An interaction where both organisms of different species benefit
Define commensalism
An interaction where only one organism benefits but not to the detriment of the other
Define facultative parasite
A parasite that may survive in the absence of a host
Define obligate parasite
During one stage of their life cycle they cannot survive without a host
Define endoparasite
A parasite that lives internally in a host
Define ectoparasite
A parasite that lives on the surface of a host
Define definitive host
The host which the parasite sexually reproduces in
Define intermediate host
The host which the parasite uses but doesn’t sexually reproduce in
Define permissive host
A host not usually used by the parasite but still favours the life cycle completion
Define non-permissive host
A host that the parasite cannot use to complete its life cycle
Define reservoir host
A temporary host used in the absence of a natural host
Define paratenic host
A host used for transport
Define biological vector
An organism that carries a parasite
Define mechanical vector
A vector which mechanically spreads the parasite but is not used in its life cycle
Define direct life cycle
Parasitic stages only occur in one host
Define indirect life cycle
An intermediate host in needed for development
State four parasitic phyla
- Microspora
- Apicomplexa
- Ciliophora
- Myxozoa
State 6 portals of entry that a parasite could take into the body
- Mouth
- Eyes
- Skin
- Sexual
- Congenital
- Inhalation
How can microscopy of blood identify some blood parasites?
Can be changes in shapes, sizes and colours of red blood cells if parasite is inside them. Or specific parasitic worms can be seen moving through the blood plasma
What technique can be used to count parasitic eggs in fecal samples?
McMaster
What is the taxonomy name for the canine heartworm?
Dirofilaria immitus
What is the life cycle of the canine heart worm? (5)
- Microscopic larvae in an infected hosts blood produced by adult parasites
- A mosquito bites the victim
- Larvae develop in the mosquito mouth parts
- Mosquito bites an animal and the parasite enters the bite wound
- Parasite migrates through tissues to vessels and mature
Where does the L3 stage of canine heartworm disease occur?
In the mosquito mouth parts
What are some of the clinical symptoms of canine heartworm disease? (4)
- Dyspnoea
- Intolerance to exercise
- Cough
- Pleural effusion due to right sided heart failure
What is caval syndrome?
A life threatening presentation of heartworm disease
What occurs during caval syndrome? (4)
- Heart worms accumulate in the right ventricle
- Worms move towards the right atrium and entangle in the tricuspid valve
- Severe regurgitation occurs and as a result right heart failure
- haemolysis can occur due to the shear stress
How can canine heartworm be treated? (3)
- Surgical removal of adults
- immiticide kills adults
- ivermectin kills microfilaria
How can heartworm disease be diagnosed by laboratory techniques? and what are the limitations of each technique? (3)
- Knotts test to analyse blood smears, may not be seen if few present
- ELISA to detect antigens, antigens only present in females, so if only males or small N.o females then false negative
- ultrasound, appear as parallel lines, need experience
How can lungworm disease be diagnosed? (6)
- baermenns fecal technique
- Larvae in faeces
- Ausculation of lungs - crackles
- parasitic pneumonia signs
- Radiographs
- Bronchoscopy
What is the difference between lungworms, and nematodes that also cause respiratory signs, and why might the two be confused?
Lungworms use the lungs as the residing tissue, nematodes just have a lung phase so they cause similar symptoms, but their residing tissue is elsewhere
Name the most common cattle lungworm
Dictyocaulus vivipirus
What is the life cycle of the cattle lungworm? (5)
- L1 eggs hatch in bronchi and are coughed up and swallowed by the host
- Eggs are excreted in faeces and develop into L2+L3 in pasture
- Cattle ingest infective larvae
- infective Larvae penetrate intestine walls and migrate to the lungs
- Adult worms mature
Name the most common canine lungworm
Angiostrongylus
What is the life cycle of the canine lungworm? (5)
- L1 eggs are coughed up and swallowed and excreted
- Snails and slugs ingest the eggs and they develop into L1+L2
- A dog eats the snail and the eggs reach the intestines
- The adults migrate via the lymphatics to the veins and right heart
- The adults in the pulmonary artery release eggs into the pulmonary capillaries which move into the alveolar walls
Name the most common horse and donkey lungworm
Dictyocaulus arnfieldi
What other animal lungworms life cycles the horse lungworms life cycle the same as?
Cattle
Name the most common sheep and goat lungworm
dictyocaulus filaria
What is the life cycle of the sheep and goat lungworm? (5)
- L1 eggs hatch in bronchi and are coughed up and swallowed by the host
- Eggs are excreted in faeces and develop into L2+L3 in pasture
- sheep ingest infective larvae
- infective Larvae penetrate intestine walls and migrate to the lungs
- Adult worms mature
How is the life cycle of dictylocaulus arnfieldi different to that of dictyocaulus vivipirus?
Eggs hatch in faeces for D.arnfieldi but in bronchi for D.vivipirus
What are the 3 possible ways a dog can become infected with Toxocara Canis?
- Obtain L3 from mothers milk
- Obtain L2 as a foetus via the placenta
- Ingest infected eggs
what is the life cycle of toxocara Canis? (5)
- L3 adults are found in the small intestines, they can be passed to puppies via milk and reside straight into ilium
- eggs are excreted in faeces or passed to foetuses
- Once eggs are excreted they reach L2 in environment
- L2 eggs are ingested and migrate to the lungs via blood
- Eggs travel up the trachea and L3 are swallowed where they mature to L5 in the ilium
Name the most common cat lungworm
Aelurostrongylus Abstrusus
What is the life cycle of the cat lungworm? (7)
- L1 eggs are past in the cat faeces
- L1 eggs are eaten by an intermediate host (snail)
- L3 develop in the intermediate host
- Intermediate host eaten by paratenic host
- Paratenic host eaten by cat
- L3 migrate to the lungs via the lymphatics
- L1 coughed up and swallowed
Name the most common pig roundworm?
Ascaris suum
What is the life cycle of the pig roundworm? (5)
- Pig ingest egg
- Egg hatches as L2 in intestine
- L3 migrate to the heart and lungs via hepatic vein
- Adults coughed up and swallowed
- Eggs released in faeces
Which canine lungworm has a direct life cycle?
Oslerus osleri
What is the life cycle of Oslerus osleri?
- Adults live in bronchi and trachea
- eggs coughed up and swallowed
- L1 excreted in faeces
- L1 ingested by another dog
- L1 migrate to the lungs and mature into adults
What epidemiological factors can influence the prevalence of lungworm disease? (4)
- Presence of intermediate hosts
- Presence of immunological naive populations
- humidity
- wet weather
What blood indictors can change during parasitic infection? (3)
- eosinophilia
- thrombocytopenia
- neutrophilia
State two drugs that can be used in horses to destroy parasites
- Ivermectin
- fenbendazole
State two parasites that live in the nasal tract and trachea of animals
- pneumonyssus canium
- enoculus boehmi
How might nasal and tracheal parasites be diagnosed?
- Nasal swab
- Nasal wash
- faecal sample
What is the life cycle of oestrus ovis? (4)
- Female fly squirts larvae into sheep nostrils
- Larvae crawl caudally and feed on mucosa
- once transformed to L3 they move to the frontal sinus
- larvae are sneezed out and become flies outside the sheep
Name a parasite of the bird trachea
Syngamus trachea
Describe the life cycle of the parasite of the bird trachea
- Eggs are shed in faeces
- Earthworms ingest eggs
- Bird ingests larvae containing worm
- Eggs hatch and migrate to lungs where the adults attach to trachea
By what means can parasites be transmitted? (6)
- Contaminated food/faeces
- insect bite
- contaminated water
- invasive surgery
- sexual
- blood transfusion
Name a taxonomic features that parasites can be identified with and describe what it is
Cheliceria- teeth like structures
Name a common parasite of the exotics
Pentasomes
Describe the general life cycle of pentosomes
eggs are excreted in faeces, eaten by intermediate hosts like rodents, host eaten by reptiles, eggs migrate to lungs where they form adults which mate and release eggs that are coughed up and swallowed
What species do leucocytozoans usually infect and where about do they reside?
Birds blood
