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IVP: Veterinary Pathogenesis > Parasitology > Flashcards

Parasitology Flashcards

1
Q

Eimeria, “Coccidia”

Host, location, life cycle, lab diagnosis, clinical importance, prevention and control

A
  • Protozoa
  • Cattle
  • Intestinal tract, inside enterocytes
  • Oocytes shed in faeces (extremely resistant, remain viable for years in cool, moist env) –> sporulate –> ingested
  • Detected in faeces with flotation procedure
  • Diarrhoea in young ruminants, if infected at young age - low level infection persists for life
  • Avoid overcrowding and stress, attention to hygiene, keep young away from contaminated soil/pasture
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2
Q

Thichostrongylus or strongylid parasites

Host, location, life cycle, lab diagnosis, clinical importance

A
  • Nematodes
  • Cattle
  • GIT
  • Adult worms in GIT produce eggs that develop in manure –> infective larvae released onto pasture and infect grazing animals
  • Eggs in faeces - quantitative faecal egg count
  • Young animals most susceptible: diarrhoea, anaemia, reduced growth and death in severe cases
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3
Q

Dictyocaulus viviparous, “lungworm”

Host, location, life cycle, lab diagnosis, clinical importance

A
  • Respiratory parasite
  • Nematodes
  • Ruminants
  • Trachea, bronchi, bronchioles
  • First stage larvae coughed from lungs, swallowed and passed in faeces. Infective larvae develops on pasture and ingested by grazing animals - migrate from intestine to lungs where they mature and produce offspring
  • Larvae in fresh faeces, Baernman technique
  • Heavy infections cause respiratory distress
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4
Q

Fasciola hepatica, “liver flukes”

Host, location, life cycle, lab diagnosis, clinical importance

A
  • Trematodes
  • Ruminants
  • Adults in bile ducts
  • Embryos emerge from egg and invade snails –> asexual multiplication produces cercaria which encyst on vegetation –> ingested –> leave GIT and migrate to bile duct in liver
  • Eggs detected using sedimentation test
  • Significant production loss - young animals most susceptible: diarrhoea, anaemia, reduced growth, death
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5
Q

Tritrichomonas foetus

A
  • Reproductive system parasite, protozoa
  • Cattle
  • Uterus & vagina of cows, prepucial cavity of bulls
  • Trophozoites transmitted during breeding
  • Trophozoites detected in vaginal discharges or uterine scrapings –> cultured
  • Chronic abortion and infertility
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6
Q

Babesia gigemina and Babesia bovis

A
  • Blood parasite, protozoa
  • Cattle
  • RBCs
  • Cattle are intermediate host where asexual multiplication occurs. Pathology related to release of merozoites from infected RBCs - transmitted by tick (definitive host)
  • In acute infections, blood smears stained with Giensa can be examined for presence of parasites in RBCs
  • Anaemia, hemoglobulinuria, fever
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7
Q

Cryptosporidium

Host, location, life cycle, lab diagnosis, clinical importance, prevention and control

A
  • Protozoa
  • Cattle
  • Intestinal tract, inside enterocytes
  • Oocytes shed in faeces (extremely resistant, remain viable for years in cool, moist env) –> sporulate –> ingested
  • Detected in faeces with flotation procedure and immunological methods
  • Diarrhoea in young ruminants (5 days- 6 months), if infected at young age - low level infection persists for life
  • Attention to hygiene and management - avoid overcrowding, dairy calves isolated in individual pens, animals kept in similar age groups
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8
Q

Most prevalent parasites for cattle and sheep

A
  • Cattle: ticks

* Sheep: worms, lice, blowfly

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9
Q

Worms in cattle and sheep – order of significance

A
  1. Nematodes (direct)
  2. Trematodes (indirect)
  3. Cestodes (indirect)
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10
Q

Parasites of cattle – what age group?

A

Very young calves (5 days to 3 months) – Cryptosporidium
Older calves (1 month to 6 months) – coccidia
Grown – Babesia, ‘trichostongyloid’ worms, Fasciola hepatica

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11
Q

Symbiosis and categories of symbiotic associations (4)

A

Means “living together”, originally coined to refer to all cases where dissimilar organisms or species live together in an intimate association

Categories of symbiotic associations: phoresis, commensalism, mutualism, parasitism

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12
Q

Phoresis

A
  • One organism is mechanically carried on or in another species (host)
  • No physiological or biochemical dependence on the part of the host of symbiont

e.g. bacteria carried on legs of a housefly to a drinking glass

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13
Q

Commensalism

A
  • One organism (commensal) is feeding on food that was not consumed by the host
  • Commensal receives all the benefit and the other member is neither benefited nor harmed
  • Loose association without either being metabolically dependent on the other

e.g. Remora fish associated with sharks feed on leftover food

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14
Q

Mutualism

A
  • Each member of the association benefits the other
  • Mutuals are metabolically dependent on one another; one cannot survive without the absence of another

E.g. clown fish benefits from housing and protection and sea anemone gets the scapes the fish brings and can sting and digest any large fish the clownfish lures in

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15
Q

Parasitism

A
  • The one form symbiosis in which one species lives at the expense of another
  • Criticism: difficult to pin down “at the expense of the other”
  • Local definition “dependence on another for food and shelter”

E.g. a tick

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16
Q

Kinds of parasites (4)

A
  1. Facultative parasite = organism does not absolutely depend on the parasitic way of life but can adapt to it if placed in such a relationship
  2. Obligatory parasite = organism is completely dependent on the host during a segment or all of its life cycle
  3. Endoparasites = live within the body of their host
  4. Ectoparasites = are attached to outer surface of host
17
Q

Kinds of hosts

A
  1. Definitive host = the host in which the parasite becomes sexually mature
  2. Intermediate host = temporary environment for the parasite (don’t reach sexual maturity but can undergo asexual reproduction)
  3. Paratenic (transfer) = parasite does not undergo development but remains alive and infective to another host
  4. Vectors = any organisms that serve as a definitive/intermediate host as well as carriers for protozoans and other small parasites
  5. Reservoir = harbor an infection that can be transmitted to humans
18
Q

Parasites in domestic vs wild animals

A

Wild – many parasites but seldom massive death - due to normal dispersal and territorialism of host animals

Domestic – can be many parasites, often cause death (epizootic) - Confined to pasture or pens in high numbers → parasite eggs, larvae and cycts become extremely dense in soil, leading to devastating burden of adult parasites within each host

19
Q

Parasite factors that affect the outcome of a parasite attack

A
  • Dose
  • Virulence (microbial)
  • Infectivity (microbial)
20
Q

Host factors that affect the outcome of a parasite attack

A
  • Innate resistance
  • Previous exposure
  • Passive immune status
  • Age
  • Production status (e.g. lactating vs. non-lactating)
  • Reproductive status (e.g. preg vs. non-preg)
21
Q

Environmental factors that affect the outcome of a parasite attack

A
  • Animal stocking density
  • Animal movement between groups
  • Housing (e.g. ventilation, sanitation)
  • Environmental conditions (e.g. temp, humidity)
  • Nutrition
22
Q

Endo-parasites

A

Live within body of the host e.g. gut, lungs, heart, blood, repro tract

PROTOZOA 
o	Diarrhea – coccidia, giardia 
o	Fevers – malaria 
WORMS 
o	Nematodes – rounds 
o	Cestodes – tapes 
o	Trematodes – flukes
23
Q

Ecto-parasites

A
  • Attached to outer surface of host
  • Insects – flies, midges, mosquitoes, fleas, lice
  • Arthropods – ticks, mites
24
Q

Parasites – how are clinical signs caused?

A
  • Removal of something (metabolites, blood)
  • Loss of body fluids (protein losing enteropathy → oedema)
  • Interference with absorption (ingested foods)
  • Blockage of something (heart, gut, bile ducts)
  • Irritation – larvae in airways, diarrhoea
  • Aberrant migration – into CNS
25
Q

Parasites – Production of pathology

A
  • Production of something toxic (tick paralysis) or excreted foreign material (eggs, enzymes)
  • Migration through tissues or residence in tissues
  • Host reaction – allergies and inflammation
26
Q

Parasites – host specificity

A

Host specific: narrow host range, well adapted, niche relation

Non host-specific:

  • Broad host range
  • Possibility of paratenic hosts
  • Possibility of zoonosis (transmission to man)
27
Q

Direct vs indirect lifecycle

A

If an intermediate host is involved –> indirect

IVP: Veterinary Pathogenesis (8 decks)

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