BCSE > Parasitology > Flashcards

Parasitology Flashcards

Identify and manage internal and external parasites using diagnostic, preventive, and therapeutic approaches. (52 cards)

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1
Q

What is the primary tick vector responsible for transmission of Anaplasma phagocytophilum infection in the midwestern and northeastern U.S.?

A

Ixodes scapularis

(the black-legged deer tick)

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2
Q

Which flea species is most commonly associated with dogs and cats?

A

Ctenocephalides felis felis

(the cat flea)

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3
Q

What is distinctive about the macroscopic appearance of female Haemonchus worms?

A

A “barber pole” appearance

(intertwined uterus and intestine)

A common pathogenic abomasal parasite of ruminants that causes anemia, poor condition, weakness, and potentially bottle jaw or sternal edema in severely affected animals.

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4
Q

What are the two known definitive hosts for Neospora caninum?

A
  • Coyote
  • Dog

Neosporosis is a major cause of abortion in cattle worldwide. Clinical signs in adult canids are uncommon; see neuromuscular signs in puppies.

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5
Q

The ELISA heartworm test detects antigen from which of the following?

  • A. Microfilaria
  • B. Adult female worms
  • C. Adult male worms
A

B. Adult female worms

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6
Q

What is the fecal flotation medium of choice for demonstrating Giardia cysts?

A

Zinc sulfate

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7
Q

Cytology of swab samples from the oral cavity and liver of a pigeon carcass reveals flagellate protozoa with an undulating membrane and axostyle.

What is the most likely diagnosis?

A

Trichomoniasis

(Trichomonas columbae)

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8
Q

What is the vector for bluetongue virus?

A

Culicoides spp.

(midges,”no-see-ums”)

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9
Q

Chagas’ disease is caused by which protozoal parasite, carried by which vector?

A
  • Cause: Trypanosoma cruzi
  • Transmitted by triatomine bugs (genera Triatoma, Rhodnius, and Panstrongylus)
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10
Q

Is heartworm disease transmitted by male or female, blackfly or mosquito?

A

Female mosquito

(males do not bite)

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11
Q

Which parasitic infestation in a dog can cause pseudo-hypoadrenocorticism?

A

Whipworm infection

(Trichuris vulpis)

Pseudo-hypoadrenocorticism presents hyponatremia, hyperkalemia, azotemia, metabolic acidosis but normal ACTH stimulation results. Resolves with successful treatment of the whipworm infection.

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12
Q

What are the intermediate hosts of Paragonimus kellicotti?

A
  • Snails
  • Crayfish
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13
Q

Rocky Mountain spotted fever (RMSF) is a tick-borne zoonosis caused by this gram-negative obligate intracellular parasite.

A

Rickettsia rickettsii

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14
Q

What is the intermediate host for the tapeworm Dipylidium caninum?

A

The flea

(Ctenocephalides felis, C. canis, and Trichodectes canis)

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15
Q

Leishmania spp. are intracellular parasites of which cell type, primarily?

A

Macrophages

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16
Q

What is the primary source of coccidiosis infections in nursing puppies?

A

Environmental contamination with oocysts

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17
Q

Which canine parasite is a major cause of abortion among dairy cattle?

A

Neospora caninum

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18
Q

What is the vector for West Nile virus?

A

The mosquito

(primarily Culex spp.)

Birds (mostly passerines) are the reservoir hosts.

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19
Q

Which parasite of white-tailed deer causes neurologic deficits as a result of larval migration in camelids as an aberrant host?

A

Parelaphostrongylus tenuis

(the meningeal worm)

Deer are generally silent carriers.

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20
Q

Which protozoal parasite commonly harbored by cats can be linked to infection in the California sea otter?

A

Toxoplasma gondii

(causes meningoencephalitis)

Often fatal.

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21
Q

Which species is susceptible to infection with Aelurostrongylus worms, and which body system does this parasite affect?

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A
  • Species: Cats (“Aeluro” is the Greek word for cat)
  • Body system: Respiratory system
22
Q

North American tick paralysis (Dermacentor ticks) affects:

  • A. Dogs but not cats
  • B. Cats but not dogs
  • C. Both dogs and cats
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A

A. Dogs but not cats

23
Q

Both Physaloptera spp. and Ollulanus tricuspis are gastrointestinal parasites that can affect cats. Which one also can affect dogs?

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A

Physaloptera spp.

24
Q

What is the infective larval stage of Dirofilaria immitis (heartworm)?

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A

L3

The mosquito deposits L3 into the animal during a bloodmeal and it travels through the host’s tissues for 70-120 days on its way to the venous circulation.

25
**Donkeys** are carriers of which **lungworm**?
*Dictyocaulus arnfieldi* ## Footnote Usually does not cause clinical signs in donkeys, but can see clinical signs in horses.
26
Which **two organisms** are required for completion of the life cycle of ***Parelaphostrongylus tenuis***?
* Deer: definitive host * Snail: intermediate host ## Footnote *P. tenuis* is the meningeal worm, usually causing no clinical signs in its definitive host (deer) but causing neurological signs in accidental hosts (e.g., camelids).
27
Which animal is the **definitive host** for ***Sarcocystis neurona***?
Opossum ## Footnote *S. neurona* causes equine protozoal myeloencephalitis (EPM).
28
What **disease** is caused by the blood-borne parasite ***Theileria equi***?
Equine piroplasmosis ## Footnote Uncommonly reported in the U.S. along the southern border. It is endemic in temperate/tropical regions such as the Caribbean, South/Central America, the Middle East, Africa, and Eastern/Southern Europe.
29
**Milbemycin** is effective against **all but** which of these parasites? * A. *Uncinaria stenocephala* * B. *Ancylostoma caninum* * C. *Otodectes cynotis* * D. *Dirofilaria immitis microfilaria* * E. *Taenia* spp.
E. *Taenia* spp. ## Footnote Milbemycin is ineffective against tapeworms.
30
What **toxin** causes tick **paralysis**?
Salivary neurotoxin | (produced by certain gravid female tick species) ## Footnote It interferes with presynaptic release of acetylcholine at the neuromuscular junction, leading to ascending flaccid paralysis.
31
What is the preferred method for **preventing leishmaniasis** in the U.S.?
Avoid exposure to the vector | (the sandfly) ## Footnote The vaccine is not approved in the U.S., and requires special USDA permitting.
32
How is **cryptosporidiosis** best **diagnosed** in livestock?
Sheather’s sugar flotation with modified Ziehl–Neelsen stain | (most sensitive and cost-effective method) ## Footnote Oocysts appear as small (5–6 µm), red, spherical-to-ovoid structures on stained fecal smears.
33
Why is a **heartworm antigen test** less reliable as a **screening** test in **cats** compared to dogs?
Antigen tests for proteins from female worms ## Footnote Because cats have a lower worm burden, they may have male-only infections or immature worms. Antigen-antibody binding can also lead to false-negative results.
34
In horses, which **parasite** migrates through the **cranial mesenteric artery** and what is the typical **clinical presentation**?
* *Strongylus vulgaris* * Acute severe colic due to intestinal infarction or mild colic/fever/depression due to peritonitis secondary to nonstrangulating intestinal infarction ## Footnote *S. vulgaris* larval migration in the cranial mesenteric artery causes verminous arteritis and thromboembolic colic.
35
In **adult horses**, what **parasite** is the primary target of **deworming programs** and why is it **difficult** to diagnose a clinically relevant worm burden?
* Primary target: Cyathostomes (small strongyles) * Why difficult: Fecal egg counts do not reliably reflect actual worm burden because encysted immature larvae cause most of the clinical disease ## Footnote So, clinical disease is possible even with low or zero egg counts.
36
Which **gastrointestinal parasite** is most common in **pigs** and causes liver “**milk‑spot**” lesions and impaired feed efficiency?
*Ascaris suum* | (large roundworm) ## Footnote Larval migration through liver and lung causes “milk‑spot” lesions, while adults reduce feed efficiency.
37
Which **gastrointestinal parasite** in **pigs** can cause bloody diarrhea, weight loss, and poor growth, especially in young pigs?
*Trichuris suis* | (whipworm) ## Footnote They embed in the cecal and colonic mucosa, causing inflammation, hemorrhage, and reduced growth.
38
A **rabbit** presents with head tilt, tremors, ataxia, polyuria/polydipsia, and phacoclastic uveitis. Which **parasite** is most likely responsible? * A. *Eimeria* spp. * B. *Encephalitozoon cuniculi* * C. *Toxoplasma gondii* * D. *Trichostrongylus* spp.
B. *Encephalitozoon cuniculi* ## Footnote This intracellular microsporidian infects the brain, kidneys, and eyes, causing neurologic, renal, and ocular signs in rabbits.
39
In **weanling foals**, which **parasite** is the primary target of deworming programs, and what is its approximate **pre‑patent period**? * A. *Parascaris equorum*, ~10‑14 weeks * B. *Strongylus vulgaris*, ~6‑12 months * C. *Cyathostomum* spp. (small strongyles), ~5‑6 weeks * D. *Anoplocephala perfoliata* (tapeworm), ~8‑10 weeks
A. *Parascaris equorum*, ~10‑14 weeks ## Footnote Roundworms in foals have a lengthy pre‑patent period of about 10–14 weeks, making early control crucial.
40
An adult horse develops intense pruritus along the mane and ventral midline a few days after routine ivermectin treatment. **Which parasite is most likely responsible?**
*Onchocerca* spp. microfilariae are killed by ivermectin, triggering a local hypersensitivity response evidenced by pruritus and dermatitis
41
In commercial **poultry**, what is the most common **gastrointestinal parasite**, and how can it be **prevented**? * A. *Ascaridia* spp., treat only when diarrhea occurs * B. *Heterakis* spp., provide broad-spectrum antibiotics * C. *Eimeria* spp., use vaccination/trickle exposure, minimize environmental contamination, and/or routine anticoccidials * D. *Capillaria* spp.; isolate sick birds only
C. *Eimeria* spp.; use vaccination/trickle exposure, minimize environmental contamination, and/or routine anticoccidials
42
A **budgerigar** presents with white, porous **crusts** around the cere, beak corners, and occasionally on the legs (“tassel‑foot”). Which **parasite** is most likely responsible?
*Knemidocoptes pilae* | (the scaly face/leg mite) ## Footnote These burrowing mites cause thick, crusty lesions on the face and legs of small psittacine birds that resemble mange.
43
# True or False: **Fecal flotation** is a sensitive method to diagnose **tapeworm** (*Anoplocephala* spp.) infection in **horses**.
FALSE ## Footnote Tapeworm eggs are shed intermittently, making fecal flotation insensitive compared with serum ELISA testing.
44
What causes the clinical signs associated with **pinworm** (*Oxyuris equi*) infection in **horses**?
Egg deposition around the anus by mature female pinworms ## Footnote The sticky eggs deposited on the perianal skin cause intense irritation, leading to tail rubbing and pruritus.
45
What is a **pathognomonic** clinical finding of **cutaneous habronemiasis** (“summer sores”) in **horses**?
Sulfur granules within a non-healing ulcerative skin lesion ## Footnote The yellow, rice-like sulfur granules contain dead *Habronema* larvae + inflammatory debris and are nearly diagnostic of cutaneous habronemiasis.
46
What is the best way to **prevent botfly** (*Gasterophilus* spp.) larvae in **horses**?
Daily grooming to remove bot eggs from the hair | (also preventable with macrocyclic lactones) ## Footnote Botflies are usually non-pathogenic, but larvae can cause oral irritation.
47
**Trichostrongyles** are the most common type of GI parasites in ruminants. Name **two** common **clinical signs**.
* Anemia * Hypoproteinemia * Ill-thrift * Diarrhea * Gastritis * In severe cases, edema (“bottle jaw”) ## Footnote Damage to the abomasal mucosa and blood-feeding by parasites like *Haemonchus* spp. and *Ostertagia* spp. leads to reduced digestion, protein loss, and anemia.
48
What is the recommended **test** for detecting **anemia** caused by ***Haemonchus*** spp. in **small ruminants**?
The FAMACHA system ## Footnote It compares the color of the inferior palpebral conjunctiva to a chart to score anemia from 1 (severe) to 5 (normal), providing a sensitive indicator of *Haemonchus* infection.
49
What is **“refugia”** in the context of gastrointestinal nematode control in **ruminants**, and why is it important?
* Refugia are the populations of parasites not exposed to anthelmintics (in untreated animals or on pasture) * Maintaining them slows the development of drug resistance ## Footnote By leaving susceptible parasites alive, refugia dilute resistance alleles in the population, reducing selection pressure for resistant worms.
50
Which small animal parasite is the most common cause of **cutaneous larval migrans** in people?
Hookworms (*Ancylostoma* spp.) | (especially *A. braziliense*) ## Footnote Larvae in contaminated soil or sand can penetrate human skin, causing itchy, serpiginous tracks, but cannot complete their lifecycle in people.
51
What are the main routes of **transmission for roundworms** (*Toxocara* spp.) in **dogs** and **cats**?
* Ingestion of eggs from the environment * Ingestion of tissue from paratenic hosts * Transplacental (dogs) * Transmammary (cats and dogs) ## Footnote Roundworm larvae can infect young animals via maternal transmission or environmental contamination, and adults develop in the small intestine after lung migration (if ingested as eggs).
52
# True or False: **Ferrets** require **routine deworming** like cats and dogs.
FALSE ## Footnote Ferrets are rarely infected with, or develop disease from, intestinal parasites, so routine deworming is unnecessary.
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