Exam # 1 Flashcards
1
Q
What is a parasite?
A
organism that lives on or in a host organism and gets its food from or at the expense of its host
2
Q
What is parasitism?
A
- is a form of symbiosis, in which the parasite, usually the smaller
- symbiont, is metabolically dependent on the host.
3
Q
What is the relationship between host and parasite?
A
One symbiont (host) is harmed, while the other symbiont (parasite) benefits.
4
Q
What are the characteristics of a parasite?
A
- Depends on the host for survival
• Has adverse effects on the host
• Has greater fecundity than host
• Is usually smaller than its host
• Doesn’t want to kill its host
host dies-parasite dies
• In the case of Macroparasites
(Helminths) – Are over-dispersed among the host population
5
Q
How can a parasite harm a host?
A
- Cause clinical/sub-clinical diseases
- Trauma
- Nutrient Robbing
- Toxin production
- Inflammatory responses/ Interaction with host immune
6
Q
Why do we study parasites in veterinary medicine?
A
- Impact animal health/welfare, Economic loss
- Negatively impact the human-animal bond
- Pose a challenge in wildlife conservation
- Pose a risk to human health. Parasitic zoonoses
7
Q
What is a direct life cycle?
A
Free living —> Host, no intermediate hosts
8
Q
What is an indirect lifecycle?
A
Egg/Larvae in another host(s)–> host. Intermediate hosts present.
9
Q
What is the lifecycle shown in this picture?
A
Direct lifecycle
10
Q
What kind of lifecycle is shown in this picture?
A
Indirect
11
Q
What is a microparasite?
A
E.g. Protozoa, Viruses (Malaria, Giardia, Toxoplasma)
- Tiny, Unicellular, microscopic
- Multiply within hosts
- Short life cycles
12
Q
What are macroparasites?
A
E.g. Roundworms, Tapeworms, Ticks, Fleas
Large, Multicellular, adult macroscopic
Reproduce in definative hosts
Generally longer life cycles
13
Q
What are endoparasites?
A
- Adults inside body of host
eg: Nematodes, tapeworms, giardia
14
Q
What are ectoparasites?
A
Parasites that live on the body of the host.
E.g. Ticks, mites, bugs, flies, mosquitos
16
Q
What is an Obligatory parasite?
A
Only parasitic stage- no free living environmental stage
eg: trichinells spp. Plasmodium spp.
22
Q
What are facultative parasites?
A
- Both parasitic and non parasitic lifestyles
- opportunistic parasite, can complete lifecycle without hosts.
eg: strongyloides spp
24
Q
What are Spurious parasites?
A
Incidental finding. Parasite is found in unusual host. Usually resulted from predation or accidental ingestion/ contamination.
Eggs/ larvae do not develop in unusual host
25
Q
What is a pseudoparsite?
A
- object or organism that resembles or is mistaken for a parasite.
26
Q
What are the three major groups of parasites?
A
- Protozoa
- Helminths
- Arthropods
27
Q
How do protazoa reproduce and are they single celled or multicellular?
A
Single celled - microscopic • Reproduce mostly asexually -
Multiply and increase in number • Some sexually – fusion of
gametes
e.g. Giardia, Cryptosporidium Toxoplasma, E. coli
28
Q
What is some important information on Helminths?
A
Multicellular – Adults easily visible • Produce offspring • Well developed organs, systems • Prepatent period and patency is
long
e.g: Hookworm, Tapeworms, Flukes
29
Q
What is some important information about arthropods?
A
- Multicellular – Visible
- Segmented bodies, jointed limbs
• Parasites themselves or vectors
of other microbes
• Insects – 6 legs
• Arachnids 8 legs (adult)
e.g. Flies, ticks, mites
30
Q
What is definitive host?
A
Main host. Supports sexual reproduction of the parasite. Parasite reaches
sexual maturity. E.g. Dogs for Toxocara canis
31
Q
What is an intermediate host?
A
Supports the parasite’s development and asexual reproduction
(multiplication)—E.g. Slugs and snails for some lungworms.
32
What is a paratenic host?
Development, multiplication does not occur in this host. Help in
maintaining the lifecycle but not necessary. E.g., Rodents for some nematodes
33
What is a transport host?
Carrier of the parasite from one host to another. No development or
multiplication. E.g., Houseflies for some parasites. Aka mechanical hosts.
34
What is an aberrant/ unusual host?
Non-natural host. The parasite may cause pathology in aberrant hosts.
E.g., Dogs are aberrant intermediate hosts for Racoon roundworms.
35
What is a vector?
- Carrier of an infectious agent between organisms of a different species. Can be
intermediate hosts or transport hosts. Usually used in case of human infections. E.g., mosquitoes
for heartworm, malaria.
36
What is a reservoir host?
Maintains the infection without being harmed—e.g., White-tailed deer for
brainworm.
37
What are the routes of transmission?
* Fecal-oral- most intestinal parasites (Giardia, hookworms)
* Skin penetration ( per-cutaneous)- bot fly
* Vector transmission/ innoculation- heartworm via mosquitos
* Direct contact : ectoparasites
* Sexual transmission- Tritichomonas foetus
* Vertical transmission: mother to offspring
* Placental/ Prenatal (toxocara canis)
* Through milk- Transmammary/ Lactogenic transmission (eg: ancyclostoma spp.)
* Iatrogenic Transmission: Blood transfusion through contaminated surgical instruments, needles. (e.g. Blood protozoa, bacteria, virus)
38
How do you diagnose parasites?
* Fecal test
* Float, Sedimentation, Qualatative, Quantitative
* Urinalysis- ex dioctophyme
* Examination of blood
* Blood protazoans, arthropods, and some helminths
* Direct smear, stained smear, knotts test (HW disease)
* Exam of tissue
* Ex: Trichinella
* Tissue digestion/ tissue squash
* Exam of hair/ skin
* Primarily ectoparasites. Ex: fleas mites, lice
* Skinscrape, KOH digestion of scrape, direct observation.
* Necropsy
* Fatal cases
* Adult parasites/ stages, characteristic lesions formed by parasites.
* Histopathology
* PCR/Genetic Markers
* Species level ID
* Primers/ probes used to amplify species specific genetic markers
* can be done from extracted egg/larvae/ adult.
* Immunological Tests: Elisa, IFA, CFT, ect.
* Serological tests- tests for antibodies against parasites
* In house testing
* Commercial tests.
39
What are the important methods of parasite management or control?
- Kill/Neutralize the parasites in the definitive hosts – Antiparasitic drugs
- Prevent or reduce the production of offspring in the host
- Immunization - Vaccines
- Optimize host health to resist transmission
- Kill/clear free-living stages in the environment
- Prevent contact with/consumption of intermediate/paratenic hosts
- Kill/neutralize intermediate/paratenic hosts
BREAK THE LIFECYCLE
40
What is a serious emerging issue in parasitology?
Drug resistance
- Judicial use of paraciticides is critical
41
TRUE or FALSE: Arthropods are the smallest phylum in the animal kingdom?
False - they are the largest
42
What groups are encompassed within Arthropods?
Crustaceans (crabs, lobsters, shrimp), Arachnids (spiders, ticks, mites, scorpions), and Insects
| (bugs, ants, bees, moths, flies, fleas, mosquitoes)
43
What are some problems caused by arthropods?
- Annoyance
- toxins/ Venom
- Allergic Reactions
- Invasion of host tissues/ trauma
- Disease/ pathogen transmission
44
What are the important arthropod groups?
- Arachnids and Insects
45
What are 2 groups within Arachnids?
Mites and Ticks
46
What is some important general information about arachnids?
2 distinct body parts – cephalothorax and
abdomen
• 8 legs attached to cephalothorax, no
wings or antennae
• Actively feed on host tissues and fluids at
some stage of their lifecycle
47
What are the 4 groups within Insects?
- Hemiptera (Bugs)
- Phthiraptera (Lice)
- Siphonaptera (Fleas)
- Diptera (Flies)
48
What is some important general information about insects
3 distinct body parts – head, thorax, abdomen
• 6 legs, 2 antennae, 2 pairs of wings attached
to thorax
• Actively feed on host tissues and fluids at some
stage of their lifecycle
49
What are some important characteristics of mites?
- Dorsally flattened
- small \< 1mm
- 6 legs as larvae to nymph
- 8 legs as an adult
50
What are the features of mites that are diagnostically important?
l length of pedicel ( stalk connecting leg to caruncle) and caruncle (cup like sucker)
- Chilicerca (feeding mouthparts)
- Location of anus and anal plate
51
What are the two types of mites? What are some differences between them?
- Burrowing mites- Short stumpy legs, circular shape, smaller than surface mites. They tunnel into skin.
ex: Demodex
- Surface mites- Long distinct legs, generally round to oval shape, larger than burrowing mites, remain on the surface
ex: Otodectes
52
What is the lifecycle of mites?
Egg -\> Larvae-\> Nymph -\> Adult
53
How are mites transmitted?
By contact (direct and indirect)
54
What symptoms/ issues can mites cause?
- No effect to sever dermatitis (mange)
- Hypersensitivities ( allergic reactions)
- Excoriation and secondary bacterial infection.
56
What are some key features of ticks?
- Dorso-ventrally flattened
- Larvae 6 legs, nymph and adults 8 legs
- Not very host specific
- Sexual dimorphism obvious
57
What are Ticks?
Well-known vectors of human and veterinary pathogens (e.g Lyme, Ehrlichia etc.)
- Most important in veterinary field \*\*
58
What are some important features of Hard ticks?
Mouthparts visible when seen from above
• “Plate” on the back – Scutum
• Found in habitats rich with vertebrate hosts,
moist woodlands, forest edges, hiking trials
• More important (parasitize more people/animals
and more diseases in the US)
59
What are some important features of Soft ticks?
* Mouthparts invisible when seen from above
* Lack scutum – wrinkled body
• Found in animal burrows, dens. Can survive
hot and dry conditions
• Less common. Species of veterinary
importance are Ornithodorous spp., and
Otobius spp.
61
What is the lifecycle of 3 host tick?
1. ) Adults will feed/ mate on third host
2. ) Female will drop off host and oviposit
3. ) Eggs will hatch and 6 legged larva will feed on first host.
4. ) Larva will leave after feeding and then molt to nymph
5. ) 8 legged nymph will feed on second host, then leaves and molts to adult
6. ) Cycle repeats
62
What is the life cycle of the one host tick?
1. ) Eggs hatch and 6 legged larva find host.
2. ) Larva has 2 molts on host.
- First molt to 8 legged nymph.
- 2nd molt to adult on host
3. ) Adults mate
4. ) Female drops off host and oviposits
5. ) cycle repeats
63
What is the action the tick is doing in this photo?
Questing- Host seeking behavior
64
What are the two types of ticks?
Hard ticks (Ixodidae) and Soft ticks (Argasidae)
67
What ticks are the most important in veterinary medicine?
Hard ticks and 3 host ticks
71
What are some issues ticks can cause?
All ticks can cause:
- Anemia
- Dermatitis, alopecia
- Local bacterial infection of bites
Some ticks:
- Paralysis: Salivary toxin of female tick
- Pathogen transmission
- Alpha-gal syndrome (red meat allergy)
72
What are some general characteristics of lice?
- Dorso-ventrally flattened
- 6 legs
- High host specificity, also site specific
- Divided into two main groups
73
What are the two types of lice?
Chewing/ biting lice (Mallophaga)
Sucking louse (Anoplura)
74
What are the key characteristics of Chewing/ biting lice? Sucking louse?
Chewing/ Biting Lice:
- Wider head (wider than thorax)
- Occurs mainly on birds, occasionally on mammals
- Stout mandibles
Sucking Louse:
- Head narrower than thorax
- Nearly every mammal can be infested by sucking louse
- Piercing mouthparts
75
What is the duration of the lifecycle of lice?
Entire lifecycle (20 – 40 days) on the host
76
How long can lice live off of the host?
Can live 2-3 weeks off the host but usually less than a week
77
How are lice transmitted?
Direct or indirect contact – Grooming instruments
78
When is infection more likely to occur with lice and what are the effects lice can have on the patients?
- Infestation more common in the winter in northern climates – long
hair
79
What are some key features of fleas?
- Laterally flattened §
- 6 legs
- Not host specific
- Lack wings but strong claws (attachment) and hind legs adapted for jumping
- Chewing mouthpart
80
What is the diagnostic feature for fleas?
Shape of head and combs
81
What is the flea lifecycle? What conditions are optimal for growth/ survival of fleas?
Egg -\> Larvae (1-3) -\> Pupae -\> Adult
Conditions: Warm and humid ( 75-90 degrees, 60-85 % humidity)
More Descriptive Life cycle:
1. ) Eggs laid on hosts and are dislodged from the coat while shaking, scratching
2. ) Development to larvae, pupae (inside cocoon) in the animal resting site.
3. ) Larvae feed on flea poop “flea dirt”
4. ) Adult hatch from cocoon when the host is nearby
82
What do flea larvae feed on?
Adult flea poop or "flea dirt"
83
What are some examples of Biting Flies?
- Horsefly
- deer fly
- Horn fly
- Stable fly
- Black fly
- Biting midge
- Sand fly
- mosquitoes
84
What are some examples of non biting flies (nuisance flies)?
- Face fly
- Head fly
- House fly
85
What are some examples of myiasis causing flies?
- Blowfly
* Horse bot fly
* Human bot fly
* Nasal bot fly
* Screwworm fly
* Warble fly
86
What is the lifecycle of biting flies?
1. ) Adult flies feed on horse
2. ) After each meal, female lays eggs on ground with suitable substrate
3. ) Eggs hatch in 12-24 hours to first instar larvae
4. ) Larvae mature through three instars to pupae within puparia, then to adults within puparia.
5. ) Adults emerge from puparia and can fly within an hour.
Life cycle completes within 12-20 days depending on environmental conditions.
87
What is the lifecycle of horse bot flies?
1. ) Fly lays eggs no hairs, around legs, shoulders, neck and mouth.
2. ) Horse injests eggs
3. ) Eggs will attach to stomach / intestinal wall and grow into larvae (here they will live for 8-10 months)
4. ) Larvae pass out in feces
5. ) Larvae mature through three instars. Pupae withing puparia, and then to adults within puparia. This occurs in about 3-10 weeks.
88
When do adult fleas hatch from the cocoon?
When host is nearby.
89
What signs/ symptoms can effect patients with fleas?
- Dermatitis
- Flea bite hypersensitivity (Flea allergy dermatitis, FAD in dogs)
- Anemia (rare, young animals)
90
What are some pathogens that can be transmitted by fleas?
- Pathogen transmission:
- Plague
- Flea-borne typhus
- Feline parvovirus
- Tapeworms (D. caninum)
- Nematode (A. reconditum)
91
What arthropod are these?
Flies
92
What is this arthropod?
Bug (Specifically bed bug)
93
What is this arthropod?
Fleas
94
What is this arthropod? Bonus: What is its scientific name?
Chewing/ Biting Lice
Bonus: Mallophaga
95
What is this arthropod? Bonus: What is its scientific name?
Sucking Louse
Bonus: Anoplura
96
What is this arthropod? What subtype is it?
Bonus: What family is it from?
Tick
Subtype: Hard Tick
Family: Ixodidae
97
What is this arthropod? What subtype is it?
Bonus: What family is it from?
Ticks
Subtype: Soft Ticks
Family: Argasidae
98
What is this arthropod? What is its subtype? Bonus : Example of one of them.
Mites
Subtype: Burrowing Mite
Example: Demodex
99
What is this arthropod? What is its subtype? Bonus : Example of one of them.
Mites
Subtype: Surface Mites
Example: Otodectes (Ear mites)
100
What is some general information about bugs?
- Dorsoventrally flattened. Some bugs look like lice
- Variable host specificity
– e.g Bed bug can bite both people and pets
- Blood feeders
- Bugs don't live on people/pets, they bite host only when they need blood meal
- Mostly feed at night, during day hide in crevices
101
What is the lifecycle of bugs?
Eggs -\>Nymph (5 instars (stages) ) -\> Adult
- Bloodmeal is needed before each molt.
- Adults can live for up to 1 year and can survive long period without feeding
102
What are some key characteristics of flies?
§ Important group of animal ectoparasites
§ Most have one pair of wings (adults)
§ Greatly vary in size, colour, food preference and
developmental stage that parasitize animals.
§ Adults feed on blood, saliva, tears, mucous of
hosts
§ Vectors and Intermediate hosts for many
pathogens microparasites
§ Larval stages may cause myiasis (s/c tissue,
respiratory track or GI track
103
What are the 3 types of flies and what is some general information about each?
1. ) Biting fly - Damaging stage is adult fly, blood sucking.
- Scissor like mouthparts
2. ) Non- biting (nuisance flies)- can cause nuisance and stress.
- Mouthpart has soft, spongy structure called labella and proboscis.
3. ) Myiasis causing flies- Damage caused by maggots (larvae) that feed on host tissues. Adults are non biting.
ALL CAN TRANSMIT DISEASES
109
What is the pathogenesis of flies?
- Harassment (common)
- Anemia (rare)
- Dermatitis/local infection
- Hypersensitivity
- Organ-specific damage
- General tissue necrosis
- Pathogen transmission
110
List the arthropods in order of decreasing host specificity.
Lice
Mites
Fleas
Ticks
Flies
111
How do you diagnose arthropod parasites?
- Morphology of adult/ larval/ egg stages
- Skin inspection
- Ticks/ flies - easily visible (remove intact organism and look at with disecting microscope)
- Examine third instar larvae of flies- spiracular plate
- Mites- skin scraping- superficial/ deep
- Tissue digestion using 5% KOH (for mites during deep scraping)
121
Why are arthropods an important group of ectoparasites?
- Intermediate hosts for other parasites and vectors for micro-parasites
- Very successful and adaptable – high reproductive potential
122
What are some arthropods that cause allergic reactions?
Bites or stings by lice, bugs, fleas etc
123
What are some arthropods that cause disease/ pathogen transmission?
Kissing bugs – Chagas disease
Mosquitoes - dog heartworm
Ticks - Lyme, Anaplasmosis, ect
124
What is the consequences of arthropods that invade host tissue?
- Cause trauma
- Invade the body tissue of the host
- Fly larvae invasion – Myiasis
- Dermatitis, pruritus (itching
125
How long does it take a mite to go through an entire life cycle? Where does it take place?
- Entire lifecycle completes on the host.
- Length of life cycle varies, few day (Sarcoptes) to weeks
126
How long can mites last in the environment?
Environmental survival limited (Only some species can survive few weeks outside the host)
127
What is a consequence of infection of lice?
- Pediculosis – Pruritus, alopecia, excoriation, hair loss, anaemia
128
Fleas can be intermediate hosts to what ?
Some nematodes
129
How are bugs transmitted?
Through contact. They live mostly in the environment, in crevices
130
What are helminths?
Worms! Invertebrates, Macroparasites
131
What Phylum do roundworms belong to?
Nematodes
132
What Phylum do Flatworms belong to?
Platyhelminthes
133
What phylum do thorny- headed worms come from?
Acanthocephala
134
Platyhelminthes can be divided into 2 classes. What are they and what is the common name of those within them?
Cestodes (tapeworms) and Trematodes (flukes)
135
Where can you find Nematodes?
Present in every imaginable habitat. Arctic, Soil, Deep Sea, ect
136
TRUE or FALSE: Nematodes are Coelomates?
No they are pseudoceolomates
137
What is the target of antihelmintic drugs?
Nerve function. It is necessary to survival for nematodes
138
What are key features of nematodes?
- chitinous cuticle, presence of complete digestive system. - Sexual dimorphism, Reproduce sexually
139
Which nematode does not reproduce sexually?
Strongyloides
140
Male nematodes have what reproductive structure and what is it for?
BONUS: What is the structure made out of?
Males have copulatory bursa for grasping females, and copulatory spicules for guiding sperm.
Bonus: It is made out of a cuticle modification.
141
What are the 3 cuticular modifications in nematodes?
- Various size/ shape of buccal cavity
- leaf crown/ alae
- Copulatory bursa
142
Which nematodes have a large Copulatory bursa?
Strongyles
143
What is the infective state of nematodes?
L3 and sometimes L1
144
What is the adult stage of nematodes referred to?
L5
145
Where are eggs shed from the nematode in regard to the host?
L1 in feces (sometimes in urine), some dont shed at all
146
What is the most common migration of nematodes?
Hepatic-Tracheal migration
| (ascarids)
147
What are critical external components for larval/ egg development?
Temperature and Humidity
148
What is hypobiosis?
-Inhibited larval development to avoid adverse conditions for development and
maturation – adaptation to host and environmental conditions
- Development starts once condition become favorable
149
How do you diagnose infections of nematodes?
- Morphological identification
- Identifying eggs/ larvae
- Molecular/ serological testing.
150
What are the 6 major nematode orders?
1. ) Strongylida
2. ) Rhabditida
3. ) Ascaridida
4. ) Oxyurida
5. ) Spirurida
6. ) Adenophorea
151
What is the segments of the cestodes body called?
Proglottids
152
What are some unique features of cestode anatomy?
* Flatworms - dorsoventrally flattened body.
* Tiny (2 mm) to enormous (12 m)
* Segmented body (Proglottids) 3 to 100s
* Head with suckers (slit/cup like) - attachment or Bothria
* Hemaphrodite
* Acoelomate
* Alimentary canal absent - feed by absorption
* Body covered by tegument
* Indirect life cycle
153
What kind of lifecycle do cestodes have?
Indirect. Most vertebrate intermediate hosts/ some arthropods.
154
What are two important orders of cestodes?
Cyclophylidea
Pseudophylidea
155
Within Cyclophylidea, what are the categories of tapeworms of veterinary importance?
Taeniid tapeworms:
- Taenia spp.
- Echinococcus spp.
Non taeniid tapeworms:
- Dipylidium
- Mesocestoides
- Moniezia
- Anoplocephala
156
What are the two important genus's of pseudophylidea?
- Diphyllobothrium (fish tapeworm)
- Spirometra (tapeworm of dog, cats and wild
carnivores)
157
What are two important characteristics of cyclophylidea?
- Organ of attachment: Suckers
- Eggs are non operculated
158
What are two important characteristics of pseudophylidea?
- Organ of attachment: Bothria
- Eggs operculated
159
How many intermediate hosts do pseudophyllidean cestodes usually have?
2 intermediate
160
What kind of larvae do cestodes have?
hexacanth larvae
161
What are cestodes infective larvae called?
Metacestode in final intermediate hosts.
162
What kind of cestode eggs are these?
All Taenia species have same egg morphology.
The eggs have an embryo with 6 hooks (hexacanth larvae) and thick straited egg shell
163
What kind of cestode eggs are these?
Operculated eggs
Diphyllobothrium and Echinococcus spp. ) have same egg Spirometra morphology – commonly called taeniid eggs. Moneizia
(note, most trematodes have operculated eggs too)
166
What are tapeworms named according to?
Morphology of the cyst
167
What are the names of tapeworms cysts?
1. Cysticercus
2. Cysticercoid
3. Hydatid
4. Coenurus
5. Strobilocercus
Cysticercus – A single protoscolex in a fluid filled cyst
Hydatid cyst
6. Plerocercoid
7. Tetrathiridum
168
What is the adult morphology of trematodes ?
Flat, leaf like body
Easily visible
hermaphrodite
Two suckers (Oral and ventral)
169
What kind of lifecycle do trematodes have?
Lifecycle is always indirect. Most have 2 hosts, some have 3 hosts (2 IHs)
170
What intermediate host must always be present in trematode lifecycles?
a snail ( terrestrial or aquatic)
171
What environmental factor is extremely important in the life cycle of most trematodes?
WATER
172
What is the name for the infective stage for most trematodes?
Metacercaria
173
Where do trematodes typically infect in the host?
Definitive host: may infect GI tract, Liver, Lungs, circulatory system
174
What kind of eggs do trematodes have?
Eggs are operculated except heterobilharzia)
175
What is a unique feature of fluke eggs is important to know?
It doesnt float. Sedimentation method is important
176
What is key morphology of acanthocephalans?
- No digestive tract, separate sexes, retractable spiny attachment (Proboscis)
177
What kind of lifecycle do acanthocephalans have?
indirect
178
what is the intermediate host for acanthocephalans
Arthropods (beetles)
179
TRUE OR FALSE:Ancanthocephalans are a very common group of parasites
False
180
In Acanthocephalans, how are nutrients absorbed?
No digestive tract. Nutrients absorbed through tegument.
181
What parasite is this?
Tapeworm
182
What is the image pointing at? Hint: This is a nematode
Spicule
183
What parasite is this cross section from?
Nematode or roundworms
184
What is this image of overall? What parasite is it from? and What are the red lines pointed at?
1. ) Buccal Cavity
2. ) Nematode
3. ) Teeth
185
What are the projections (indicated with the black arrow) in this photo?
Cervical Ale
186
What kind of parasite is this?
Trematodes
187
What kind of parasite is this?
Thorny headed worm or Acanthocephalans
188
Recap
189
Where are Acanthocephalans found?
Vertebrate digestive tracts
190
What is an important note for Acanthocephalan eggs?
- eggs are very heavy and contain larvae
199
Nematode development can be completed where?
Entirely at the predilection site.
Larvae/pre-adults can also migrate during development
200
Nematodes that generally develop ONLY in the gut are ?
Generally asymptomatic with low pathogenicity.
201
Where do larvae migrate to in the case of tracheal ascarid?
Larvae will migrate to the liver, lungs, and heart.
Can cause hepatic damage, respiratory signs, lung lesions, etc.
202
Name the two morphological factors that help differentiate between Nematode eggs:
Egg shape
Egg shell thickness
203
Give an example of nematodes with thick egg shells?
Astarids
Tape worms
204
Give an example of parasites with thin egg shells?
Hookworm, Strongyloides
205
What is spring rise?
Spring rise is the build of larvae of the egg during the spring
206
What is periparturient?
When the immune system is compromised during parturition → increased number of eggs/larvae
207
Where can adult Nematodes be found?
In vomit and feces.
208
How can you ID Nematode eggs/larvae in feces ?
Eggs = fecal smear, flotation, sedimentation
Larvae = Baermann method (larval sedimentation)
209
The entire head of a Cestode is called a?
Scolex
210
The parasite that causes these lesions can travel a considerable distance before settling in their predilection site, what are they?
Larva Migrans
211
In case of Pig ascarid, larval migration from the intestine on to the liver and the lungs can cause what kind of damage to the pig?
hepatic damagerespiratory signs, lung lesions
212
What does the scolex give rise to?
The proglottids
213
How is being a hermaphrodite beneficial for Cestodes?
Cestodes can self fertilize and cross fertilize.
214
What does Acoelomate mean?
Lacking a coelum/body cavity.
215
What is the opening indicated by the arrow called? What is it for? What phylum and order are they found in?
Bothria
Function: Organ of attachment
Phylum: Cestode
Order: Pseudophylidea
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What is the main function of the Cestodes Tegument?
The tegument's main function is nutrient absorption.
217
What is the main difference between Taeniid tapeworms and Non-taeniid tapeworms?
Egg morphology differs.
218
Define Hexacanth.
Hexacanth
Canth = small hooks
Hexa = 6
Usually can count 6 hooks in the egg.
219
Describe in detail the life cycle of the Cestode.
1. Larva develop into adults in the intestine of the definitive host
2. Egg with hexacanth larvae form in the definitive host
3. Contaminate feces (environment)
4. Egg with hexacanth larvae OR gravid proglottids (environment)
5. Ingested by intermediate host; eggs change into oncosphere; penetrate gut wall and reach various tissues.
6. Larvae (metacestodes) form cysts in various tissues (intermediate host)
7. Ingestion of intermediate host tissue with cysts containing infective larvae enter new definitive host
8. Cycle starts again
220
Cysticercus is a ?
Single protoscolex in a fluid filled cyst.
221
Metacestodes are named according to?
Morphology of cysts.
222
What kind of lifecycle do nematodes have?
Direct lifecycle, indirect lifecycle, oviparous, viviparous, ovoviviparous, obligatory,
facultative
225
What are oncospheres?
A hatched hexacanth
226
What stage of development is L5 in nematodes?
Adult
227
What is contained within each proglottid?
A male and female reproductive system
229
230
Is Protozoa multicellular or unicellular? What else is important about them?
Unicellular
- single celled, distinct nucleus, microscopic, with greater complexity than other unicellular forms ( bacteria)
- Each protozoa possess specialized organelles
and function as independent organism
231
Are most Protozoa pathogenic?
Most are free living and are not pathogenic but some co-
exist with animal hosts (parasitic protozoa)
232
What is the life cycle of Protozoa?
Life cycle – direct (e.g Eimeria) or indirect (e.g Sarcocystics, Trypanosoma)
233
What kind of reproduction is seen in Protozoa?
Asexual (e.g Giardia) or alteration of sexual and asexual lifecycle (e.g Toxoplasm
234
Do Protozoa gravitate to a specific host?
Varied host specificity – High (e.g Sacocystics, Eimeria) or low (e.g Cryptosporidium)
235
What is the pathogenicity caused by protozoa?
Pathogenicity is caused either by destruction of host cells, toxins or by changes in host immune
system
236
What is an important consideration for protozoa?
Important to consider zoonotic potential
237
What is important to remember when trying to control, diagnose, and treat protozoal infections?
- Control requires knowledge of complete lifecycle
- Diagnosis – Morphology, Serological and molecular
- Treatment may not kill all stages
238
What are the four groups of Protozoa of veterinary importance? What are they grouped by?
Flagellates
Amoebas
Ciliates
Apicomplexans
They are grouped based on their locomotion
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What is some important characteristics of Flagellates?
- Locomotion by flagella
- Mucosoflagellates (Direct life cycle, ex: giardia)
- Haemoflagellates (Arthropod transmitted, ex: trypansoma)
240
What is some important characteristics of Ameobas?
Locomotion by pseudopodia
- Direct life cycles
- Ex: Naegleria fowleri, E. Histolytica
241
What is some important characteristics of Cillates?
Locomotion by cillia
- Direct life cycles
- Eg. balantidium coli
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What is some important characteristics of Apicomplexans?
Locomotion by gliding
Coccidia:
* Direct life cycle (Ex: elmeria, crypto)
* Indirect life cycle (Ex: Toxoplasma)
Haemosporida
* Arthropod transmitted (Ex: Babesia)
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What is the morphological characteristics of muscoflagellates?
- Pear shaped
- Most have direct life cycle
- e.g Giardia, Tritrichomonas spp. – direct lifecycle
- Histomonas – Indirect lifecycle ( transmitted by another
parasite)
Two stage: Cyst and Trophozite ( only stage in Trypansoma)
248
In Muscoflagellates, what are the key differences between Trophozoites and cysts?
Trophozoite
• Active motile form
• Vegetative form – divides by binary
fission
• Doesnot survive well in the
environment
• Only stage in Trypanosoma
Cyst
• Non-motile
• Environmentally resistant stage
• Can survive for months in wet and
cool conditions
249
In muscoflagellates, what is a more simple breakdown of trophozoite vs. cyst stages?
Trophozoite stage is the feeding stage of the protozoan. Cyst stage is the dormant, resistant infectious stage of the protozoan
250
How are hemoflagellates transmitted?
Arthropod transmitted
251
Where are hemoflagellates found?
Lie in blood/ tissues of animals/ humans
252
What are the 3 different forms of hemoflagellates and what makes them differ from one another?
- Amastigote – Mammalian intracellular form
No flagella or undulating membrane
- Promastigote – Arthropod gut form
Long flagella, spindle shaped body
- Trypomastigote- Mammalian blood form
Long flagella, spindle shaped body
253
What are apicomplexans? What are some key characteristics?
- Obligate intracellular pathogens
- Designed to get inside cells – Apical complex (organelle for invasion)
- Complex lifecycle – Direct (D) or indirect (I)
- Life cycle alternates between sexual and asexual reproduction
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What are 3 types of apicomplexans?
1. ) Intestinal (coccidia)
2. )Systemic
3. ) Blood
255
What kind of life cycle do intestinal apicomplexans have and what are some examples?
Direct Lifecycle (Examples: Cryptosporidium, Eimeria, Cystoisospora)
256
What kind of life cycle do Systemic apicomplexans have and what are some examples?
Indirect lifecycles ( Toxoplasma, Neospora, Sarcocystis)
257
What kind of life cycle do blood apicomplexans have and what are some examples?
Indirect- Arthropod transmitted
| (Ex: Babesia, Cytauxzoon)
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What are the steps to the lifecycle of intestinal coccidia?
1.) Dog is infected (sporulated oocysts of isospora enter the gut)
2.) The shell of the oocyst Sexual reproduction breaks down and (GAMETOGONY) – releases parasitic production of male and sporozoites, which female gametes and penetrate intestinal fusion, resulting in epithelial cells
fertilized zygote
3. ) Asexual Reproduction (Merogony)
4. ) Sexual reproduction breaks down and (GAMETOGONY) – releases parasitic production of male and sporozoites, which female gametes and penetrate intestinal fusion.
5. ) Zygote is created
6. )Zytoge developes into an oocyst that exits the canine host in feces\\
(6) the oocysts sporulate (SPOROGONY) in the environment in a few days and becomes infectious to new dogs.
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What is the lifecycle of systemic coccidia (toxoplasma)?
Asexual (merogony) and sexual
(gametogony) phase in definitive hosts
- Only asexual (division, multiplication) in
Intermediate hosts
- Only for toxoplasma, transmission can
occur between intermediate hosts!
- For other systemic coccidia (Sarcocystis,
neospora)
- transmission to definitive hosts occurs
by ingesting the cysts in the tissue of
the IH, and - transmission to IH occurs via ingestion
of sporulated oocyst!
260
What is the lifecycle of blood apicomplexa?
Ex: Babesia Canis
1. ) Tick has blood meal from infected animal, and sporozoites remain in the salivary glands of ticks.
2. ) Sexual reproduction of protazoa occurs within the tick, and tick takes bloodmeal from new host.
3. ) New host is innoculated via bite.
4. ) Asexual reproduction occurs within the hosts erythrocytes.
Cycle repeats.
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What is a rare way blood ampicomplexans can be transmitted, other than through an arthropod vector?
Iatrogenic transmission is also possible
through blood transfusion or blood- contaminated fomites.
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How can you diagnosis a protozoal infection? What does each test detect?
1. ) Fecal testing- microscopy (fecal float/ smear for intestinal protozoa)
- can detect f cysts, torphozoites, oocysts in feces (quick diagnosis in clinical cases)
2. ) Blood testing- Direct smear, stained smear (Blood protozoa are specific on the types of blood cells they infect!)
3. ) Serological/ Molecular methods
- Examination of blood/ serum for Antibody against parasites (serology)
- Examination of feces for parasite/ antigen ( active infection)
- Extracting DNA of the parasite and sequencing- High accuracy.
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Why test for parasites?
- Tailor therapy/ prophylaxis for individuals.
- Detect developing resistance
- Reduce unnecessary use of medications in low risk population's.
- Detect emergence of new parasites especially with warming climate.
264
Who needs parasitology testing?
- Clinically ill ( Diarrhea, vomiting, bloody stool, anemia, eosinophilic enteritis, coughing, once bacteria/ virus r/o)
- High risk animals ( young, high exposure, susceptible such as immunocompromised, pregnant, old, young, nursing)
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What is the definition of the word Prevalence?
Proportion of animals (%) infected with a parasite
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What is the definition of Intensity of infection?
Number of parasite/parasitic stage in an individual animal
• Usually expressed in eggs/oocyst/larva per gram of feces • When expressed as mean/median of a herd/population only positive
animals are considered
267
What is the definition of sensitivity?
The ability of the test to correctly detect individuals infected with a parasite
| (true positives)
268
What is the definition of specificity?
The ability of the test to correctly detect individuals without a parasite (true
negatives?
269
What is the definition of a pseudoparasite?
an object or organism that resembles or is mistaken for a parasite
270
What kind of tests can be run on fecal samples?
* Fecal smear
* Fecal flotation
* Fecal sedimentation
* Baermann method
* McMaster method/ FLOTAC
* Coproculture (Fecal culture)
271
What are the most important things to remember when doing a fecal examination?
• Important to have fresh samples, preferably directly collected from the animal
• At least 10 g of feces should be collected
• Feces collected from yard, pen or litter box may be old and egg may embryonate, oocyst
may sporulate
• Refrigerate (4 degree C) to prevent development
• Freezing is inefficient – freeze thaw destroys eggs/larvae
272
What is a direct fecal smear and what are the pros and cons?
- Qualitative fecal exam
- Simple quick and easy
- Good for moving protozoal trophozoites (giardia), mobile amoeba
- Can be fixed with a special stain (e.g for Cryptosporidium)
- Negative result inconclusive, positive result equally valid!
273
What is a fecal flotation and what is the most important thing to remember when preforming the test?
- Based on differential specific gravity of parasite eggs/cysts, fecal debris and flotation solution.
- Flotation solution must have higher specific gravity than parasite eggs or oocysts.
- Specific gravity of most parasite eggs are 1.1 – 1.2 g/ml
- Flotation solutions should be \> 1.2
274
What parasite would a fecal float be best used for?
- Best for most nematodes and cestode eggs, some protozoal (oo)cysts
275
What happens if you use a solution for fecal float that is too low in specific gravity? To high?
- Some fluke eggs won’t float especially if solutions of lower specific gravity are
used
- Higher specific gravity solution – distorts protozoal trophozoite, cysts and
some helminths eggs, larvae – Proper choice of flotation solution
276
What is the ideal specific gravity of a fecal float solution?
\> 1.2
277
What are the steps to complete a passive/ standing fecal float?
1. ) Feces + flotation solution in beaker / cup.
2. ) Strain and transfer into test tube/ fecalizer
3. ) Add coverslip and let it stand for some time
4. ) Examine coverslip under microscope
278
What are the steps to complete a centrifugal fecal flotation?
1. ) Feces + flotation solution in a beaker/ cup
2. ) Strain and transfer to test tube
3. ) Add coverslip and centrifuge ~ 1500 rpm for 5 minutes
4. ) Examine coverslip under microscope
281
What are the pros and cons of using a passive/ standing fecal flotation?
Pro:
- Simple and Fast
- Commercial kits available
Cons:
- Lower sensitivity
- Qualitative or semiqualitative.
282
What are the pros and cons of using centrifugal fecal flotation?
Pro:
- Recovers more eggs/ ova
- Higher sensitivity
- Can be quantitative
Con:
- More labor intensive
- More expensive
283
What is most important to remember when deciding between a passive/ standing fecal floatation or a centrifugal fecal flotation?
Centrifugation increases the sensitivity of your tests. Centrifugation recovers 3-5 times as many eggs over other passive floatation techniques
284
What is the McMaster Method?
- Commonly used quantitate technique for helminth eggs in
livestock
- It uses a counting chamber that enables a known volume of fecal
suspension to be examined microscopically
- Based on the principle of passive flotation (no centrifugation
required)
- Quantitative
285
What is the steps to preforming the McMaster method?
1. ) The fecal slurry is made with a known amount of feces and a known amount of flotation solution
2. ) The slurry is sieved through a strainer
3. ) Filtrate is used to fill the counting slide chamber
4. ) Calculation (according to the protocol)
286
What is the Wisconsin double centrifugation?
Sensitive test that has 2 centrifugation steps, it is quantitative.
```
Most sensitive flotation technique in low
infection intensities (1 epg or less)
```
287
What are the two centrifugation steps in the wisconsin double centrifugation?
Two centrifugation steps
- 1st – Fecal slurry made up of feces and water
- 2nd – Sediment of 1st step homogenized with flotation solution
288
Why is the wisconsin double centrifugation test challenging in clinics?
- Requires larger space (centrifuges)
- More time
- Expensive
289
What is fecal sedimentation and when would it be used?
- For eggs with higher specific gravity (e.g trematodes and acanthocephalan eggs) that do not float easily or eggs that are easily distorted by flotation solution
- More sensitive than direct smear
290
What are the steps to the traditional sedimentation method?
Mix 10 g of feces with 100 ml of water
1. ) Mix and strain, collect filtrate in a beaker
2. ) Allow to sediment for 5 minutes
3. ) Allow to sediment for 5 minutes
4. ) Siphon off supernatant
5. ) Examine the sediment
291
What is the Baermann method? What would be a parasite this would be an ideal test for?
- For parasites that shed larvae in the feces (e.g. Dictyocaulus, lungworms)
- Feces suspended in water overnight -\> Migration of live larvae out of the fecesinto water
- Should only be used in fresh feces (live larvae)
292
What is a coproculture (fecal culture)? What is it used for?
- Eggs of strongyles/trichostrongyles are virtually impossible to
diagnose morphologically so eggs are grown in a culture
medium (vermiculite) at room temperature for several days to
the third stage larvae (L3)
- L3s are morphologically distinguishable
- Usually done in pooled samples
293
What are the steps to a coproculture?
1. ) 20-30 grams of feces + tap water vermiculate
2. ) Incubate at room temperature, maintain moisture
3. ) After 7-14 days Larvae recovered (Baermann technique)
4. ) Microscopy
294
What are the limitations of fecal based diagnosis?
1. ) Chances of false negatives
2. ) Chances of false positives
295
Why may there be false negatives on fecal tests?
- Sporadic shedding
- Prepatent period – Parasites not yet mature to shed eggs/larvae
- Single-sex nematode infections
- Senescent infections
- Old feces (hatched eggs)
296
What is a false negative test?
Negative test result but the host has parasites
297
What is a false positive test?
Positive test result but no parasitism
298
Why may there be a false positive on fecal tests?
- Coprophagia/Predation – Spurious
parasites
- Pseudoparasites
- Many parasite species shed identical eggs – Diagnostic challenge
299
What is a direct blood smear? What kind are there?
S implest blood parasite detection procedure is by direct microscopic examination of whole blood.
- Thick smear
- Thin smear
300
What is a thick bloodsmear and what is a parasite it is good to use for?
o Examining a drop of blood on a slide
o Mainly for motile microfilariae of D. immitis
o Quick and easy method but less reliabl
301
What is the Modified Knotts test used for?
Rapid detection and identification of microfilariae (larvae) of filarial nematodes in
blood
- Concentrates microfilaria from 1 ml of blood à more sensitive
302
What is a thin bloodsmear and what is a parasite it is good to use for?
o A drop of blood spread on the slide
o Not suitable for microfilaria larvae
o Suitable for Trypanosomes, Babesia, Thelaria, Anaplasma
303
What is superficial skin scraping? What wouls you use it for? Where should you scrape?
- On animal with pruritic or scaly skin ( Scabis, Cheyletiella, Otodectes etc.)
- The best areas to scrape are typically crusty ear margins and crusty areas on the elbows or hocks.
304
What is deep skin scrapping? What is a parasite this is used for, and what is the process to take a deep skin scrape?
For mites that reside deep in the hair follicle (E.g. Demodex )
- Squeeze the skin
- Scrape unitl there is light capillary bleeding – multiple sites
305
What is the steps for thin blood smears?
1. ) Make slide ( Make blood smear, you know how to do this)
2. ) Fix in methanol for 2 minutes
3. ) Stains ( Giemsa, fields stain)
307
What is tissue digestion used for? What are the general instrictions? What is an example of a parasite you can use this for?
- For parasites that have their larval or adult stages in host tissues and organs
- Tissue is digested in digest solution (mostly acid pepsin) at a certain temp for certain time -\> centrifugation -\> digest examined
(e. g – Trichinella spp., some arthropods)
308
What is the peri-anal tape method? What are its pros and its cons?
- Preferred method to detect eggs of pinworms in large animals
- Eggs often attach to perianal region and may not been present in the feces
- In dogs/cats- used to detect segments and eggs of cyclophyllid cestodes (e.g Taenia spp.)
- Risky technique in regions where Echinococcus spp. is endemic.
309
What can be used to diagnose ectoparasites?
- Skin scrapping KOH digestion
• Collection and examination
312
What are coproantigen tests? What is an example?
Coproantigen tests: Parasite antigens in feces Increasingly common for in-house detections (e.g cyst wall antigen for Giardia in dog/cat feces)
Example: Blood antigen test – E.g. 4dx snap test (IDEXX)
Coproantigen ELISA exists for Ascaris, hookworms, giardia.
313
What immunological tests are available for protozoal infections?
Antibody tests – Protozoal infections
- Complement fixation test
- Immunodiffusion
- Haemagglutination test
- Florescent antibody test
314
What is KOH digestion? What/ when is it used for?
If the scrapping contains much debris § If lice/mites are suspected and not found by inspection
315
What are the steps to KOH digestion?
1. ) 1 volume of skin scrappings + 10 volumes of KOH in large beaker
2. ) Heat until hair disolves
3. ) Centrifuge and transfer the sediment to a petridish and observe under microscope at 10x ( you can see mite eggs, mites, and lice with this)
318
What are immunologic tests against parasites? What is an example of one?
```
Detecting antibodies (against the parasites) and antigens (of the parasites)
• ELISA – testing serum antibodies against parasites, parasite antigens
```
319
What are the strengths of Immunologic testing for parasites?
* Can identify presence of parasites when eggs are not recovered by flotation (e.g prepatent infection, intermittent egg shedding)
* Relatively simple, fast (commercial kits)
320
What are the limitations of immunological testing of parasites?
* Measures immune response to exposure – not necessarily active infection
* Cross-reactivity
* Not universally available
323
What are PCR tests for parasites?
- Extraction of parasitic DNA from eggs/larvae in feces (Copro PCR); blood or tissue stages, or adult stage
- Amplification of a specific genetic marker/gene or genes
- Analyzing the DNA sequence to ID the species
324
What is the Advantages of PCR parasite testing?
- Higher Sensitivity ( copro pcr than egg based method)
- Accurate
- Sequences for species level ID, genotyping, phylogenetics
325
What are limitations of using PCR testing for parasite identification?
- Not possible in clinics
- Expensive, Highly technical
