Antiparasitic Agents p1

Question 1

Endoparasite is…

Answer 1

Parasite that infects internal organs including:
- Stomach, intestines, heart, lungs, kidneys, liver, & muscles

Question 2

Ectoparasite is…

Answer 2

Parasite that infects host in or on the skin

Question 3

Zoonoses is…

Answer 3

An infection that can be transmitted between animals and people

Question 4

Protozoa are…
The parasites include: (3)

Answer 4

Unicellular organisms
1. Giardia
2. Coccidia
3. Toxoplasma

Question 5

Nematodes (roundworms)
Include: (3)

Answer 5

1. Ascarids (Toxocara, Toxascaris, Baylisacaris)
2. Hookworms (Ancyclostoma)
3. Heartworm (Dirofilaria)

Question 6

Trematodes (flukes)
1. Common in who
2. Causes (4)
3. Zoonosis?
4. Prevention (2)

Answer 6

1. Common in ruminants by infecting the bile ducts
2. Cause
   - Weight loss
   - Anemia
   - Liver failure
   - Death
3. Zoonosis can cause liver failure in humans
4. Prevent
   - Control intermediate host snails
   - Tx sheep & cattle to prevent envir contamination

Question 7

Cestodes (tapeworms)
1. Echinococcus zoonosis presents due to __ __.
2. Prevention (3)

Answer 7

1. Hydatid cyst
2. Prevent
   - Tx dogs for Echinococcus to prevent contamination
   - Do not feed raw meat to dogs
   - Good hygiene after working with dogs or soil (Echinococcus is immediately infective!)

Question 8

Define:
1. Adulticide
2. Microfilaricide
3. OTC

Question 9

Define:
1. Anthelmintic
2. Anticestodal
3. Antitrematodal
4. Antiprotozoal

Question 10

Define:
1. Endectocides
2. Coccidiostats
3. Acetylcholine
4. SLUDDE (SLUDGE)

Question 11

Five things the Ideal Parasiticide should have

Answer 11

1. Selective toxicity
   - Kills parasite
   - Doesn’t injure the patient or personnel
2. Doesn’t induce resistance in parasite
3. Economical
4. Effective against all parasite stages with one application
5. Easy to use!

Question 12

Antinematodals (3)

Answer 12

1. Avermectins
2. Benzimidazoles
3. Pyrantel

Question 13

Avermectins (macrocyclic lactones) works by binding to Glutamate ___ ___ in the parasite nerve & ___ cells, causing ___ & death of the parasite.
The representative of this group is ___, used for a wide variety of ___- & ___parasites.
Not effective against ___ or ___!

Answer 13

1. Chloride channels
2. Muscle
3. Paralysis
4. Ivermectin
5. Endo- & Ectoparasites
6. Cestodes or Trematodes

Question 14

Ivermectin Toxicosis
1. What is it?
2. Who’s susceptible?
3. Clinical Signs (4)

Answer 14

1. Inherited abnormality of the blood-brain barrier
2. Collie breeds especially!
3. Signs
   - Sedation
   - Ataxia
   - Dilated pupils
   - Coma possible (esp puppies)

Question 15

Ivermectin Susceptibility Testing
1. Tests what gene?
2. How is it done? (3)

Answer 15

1. MDR1 gene is tested
2. How:
   - Cheek cells
   - Or EDTA blood sample
   - WSU
   ~$60 to test

Question 16

Benzimidazoles
1. How does it work?
2. Effective against what? (2)

Answer 16

1. Work by interfering with cell division at a protein unique to worms
2. Effective against:
   - Ascarids
   - Strongyles

Question 17

Fenbendazole: Spectrum?
Thiabendazole: Use?

Answer 17

1. Wide spectrum of activity; given for 3 consecutive days.
2. Used in topical products

Question 18

Pyrantel
1. How it works
2. Effective against? (2)
3. Use in multiple species?

Answer 18

1. Mimics the action of acetylcholine on nicotinic receptors, causing muscle paralysis or parasite.
2. Effective against
   - Roundworms
   - Hookworms
3. Very safe in many species!

Question 19

What parasite is this?

Answer 19

Heartworm

Question 20

Heartworm lifecycle (5)

Answer 20

1. Host with microfilaria is bitten by mosquito.
2. Microfilariae develop thru L1-L3 stages in mosquito over 2 weeks.
3. Mosquito bites new host & transmits L3.
4. L3 travel to vessels of lung & heart to develop into adults (6 months).
5. Adults breed & shed microfilaria into blood.

Question 21

Heartworm in Dogs
1. Diagnosis (3)
2. Blood tests (4)

Answer 21

1. Dx
   - Clinical signs
   - Rads of heart & lungs
   - Ultrasound of heart
2. Blood tests
   - Direct smear
   - Modified Knott’s test
   - Filter technique
   - ELISA (antibody & antigen)

Question 22

Heartworm Key Points
1. How do dogs & cats present with this parasite?
2. What is recommended for patients in endemic areas?
3. How many mosquitos/bites does it take to get?

Answer 22

1. Present
   - Dogs: Heart disease
   - Cats: Lung disease
2. Monthly preventative is recommended year-round in dogs & cats.
3. Only one mosquito bite to get it!

Question 23

Prevention of Heartworm
1. Done by…
2. Medication methods (3)

Answer 23

Preventing third-stage larvae from reaching maturity (preventative)
Meds:
1. Daily oral: Diethylcarbamazine (DEC)
- Given during mosquito season & two months after.
- Patient must be heartworm neg.
2. Once-monthly Oral
- Ivermectin (Heartguard)
- Milbemycin (Sentinel, Trifexis, Interceptor)
3. Once-monthly Topical
- Selamectin (Revolution)

Question 24

Treatment of Heartworm (2)

Answer 24

1. Adulticide therapy: Melarsomine
   - Given in the epaxial muscles
   - Less toxic than former drug (thiacetarsamide)
   - Side effects include nephrotoxicity & hepatotoxicity.
2. Eradication of circulating microfilariae after infection
   - Ivermectin (given at higher dose as a microfilaricide)
   - Milbemycin