Lecture Quiz 2 - Exam 1 - Introduction To Helminthology (Part 2)

Front 1

Transmisison routes for A. caninum

Back 1

Infective L3 can be acquired by:
1. Skin penetration
2. Ingestion - food/water, arrasted larvae in paratenic hosts, lactogenic transmission (major source of infection of puppies)

Transplacental route = unimportant

Front 2

Pathogenesis of Hookworms

Back 2

Blood sucking activity

1. Attach to mucosa and pull a plug of intestinal mucosa into the buccal capsule

2. Use teeth to lacerate mucosa

3. Secrete proteolytic enzymes and anticoagulant

4. Change sites frequently so old sites continue to bleed

Anemia develops

1. Initially normocytic, normochromic

2. Becomes microcytic, hypochromic with time

Front 3

Variable Clinical Signs of Canine Hookworm Disease

Back 3

Severity depends upon:
1. Dosage
2. Age resistance, acquired immunity and premunition
3. Iron reserves (low in puppies)
4. Nutritional status
5. Other stress factors, infections

Front 4

Clinical Signs of Canine Hookworm Disease: Anemia

Back 4

1. Pale mucous membranes
2. Decreased stamina, weakness
3. Melena or possible bloody feces
4. Unthrifty appearance (thin, rough hair coat)

Front 5

Clinical Syndromes of Canine Hookworm Disease

Back 5

1. Peracute neonatal ancylostomiasis
2. Acute ancylostomiasis
3. Chronic (compensated) Ancylostomiasis
4. Secondary (decompensated) Ancylostomiasis

Front 6

Description of Peracute Neonatal Canine Ancylostomiasis

Back 6

1. Result of lactogenic transmission from dam

2. Onset of signs
a. Often appear healthy 1st week then crash 2nd week
b. Signs can develop as early as 4 days of age
c. Often fatal by 10-24 days of age even with treatment

3. Pups: extremely pale with blood in feces, +/- diarrhea; weak

4. NO eggs in feces (yet)

5. Necropsy findings = blood and immature worms in intestinal tract

Front 7

Description of Acute Canine Ancylostomiasis

Back 7

1. Results from acquisition of large numbers of L3 over short period of time
a. Usually seen in older pups
b. Pallor due to normocytic, normochromic anemia
c. Melena
d. Weakness
e. Often die unless treated promptly
f. STRONGYLE TYPE EGGS PRESENT IN FECES
g. Adult worms and blood in SI at necropsy

Front 8

Description of Chronic (Compensated) Canine Ancylostomiasis

Back 8

Common in mature dogs with low number of hookworms

Dogs asymptomatic unless stressed

Feces are normal in appearance and have low to moderate numbers of strongyle type eggs

Front 9

Description of Secondary (Decompentsated) Canine Ancylostomiasis

Back 9

Mature, usually malnourised dogs
a. Moderate number of worms + many eggs
b. Microcytic, hypochromic anemia (pale, melena: may develop bloody diarrhea)
c. Thin, rough hair coat, lethargic
d. Can be fatal

Front 10

Treatment of Peracute Neonatal Canine Ancylostomiasis

Back 10

Anthelmintic

Supportive care including blood transfusion, O2

Poor prognosis

Front 11

Treatment of Acute and Chronic Compensated Canine Ancylostomiasis

Back 11

Anthelmintic

Front 12

Treatment of Secondary Canine Ancylostomiasis

Back 12

Anthelmintic plus nutritional support

Front 13

Prevention and Control of Canine Ancylostomiasis for adults

Back 13

1. Decrease number of L3 in environment
2. Identify and treat infected dogs
3. Sanitation: remove feces daily + cleaning
4. Impervious flooring
5. Kill larvae in environment

Front 14

Prevention and Control of Ancylostomiasis for puppies

Back 14

1. Prevent transmammary transmission
2. Treat high risk puppies
3.

Front 15

Anthelmintics for Prevention of Canine Ancylostomiasis

Back 15

1. Heartworm/hookworm
a. Ivermectin/pyrantel - Heartgard Plus for adults
b. Milbemycin - Interceptor for adults + larvae

Front 16

Describe Ancylostoma tubaeforme

Back 16

1. Fairly host specific for cats
2. Structure and life cycle similar to A. caninum = infection by skin penetration or ingestion and paratenic hosts with hypobiotic larvae

Front 17

Clincial Feline Ancylostomiasis

Back 17

1. Uncommon
2. Clinical signs: weight loss, regenerative anemia
3. Heavy infection can be fatal
4. Diganosis
a. Strongylid eggs in feces
b. Cannot distinguis different Ancylostoma spp. eggs

Front 18

Describe Uncinaria stenocephala

Back 18

1. More prevalent in northern US
2. Structure
a. Adults with cutting plates instead of teeth
3. Lactogenic transmission important
4. No prenatal transmission

Front 19

Describe Bunostomum spp

Back 19

1. Ruminant hookworms
a. B. phlebotomum in cattle
b. B. trigonocephalum in sheep and goats

2. More prevalent in warmer climates

3. Survive best in warm and wet areas

4. Percutaneous infection most common

Front 20

Life cycle of Bunostomum

Back 20

Adults in small intestine produce eggs and suck blood

Larvae develop in environment to infective L3 stage

Infection by skin penetration or ingestion
a. Enter blood and undergo "tracheal migration" to reach SI
b. Prepaten period = 4-8 weeks

Front 21

Clinical signs of Bunostomum

Back 21

Similar in all ruminant hosts: pruritus, alopecia of lower legs (L3 skin penetration)

Then progressive iron deficiency anemia --> hypoproteinemia --> dependent edema

Anorexia, weight loss or poor growth, diarrhea: fetid, possibly with blood

Infection can be severe-fatal (50 worms can cause severe anemia in a calf and 200-300 worms will kill a sheep)

Front 22

Treatment of Bunostomum

Back 22

Most broad-spectrum anthelmintics effective

Front 23

Identify

Back 23

Ancylostoma caninum egg

Front 24

Identify.

Back 24

Uncinaria stenocephala egg

Front 25

Describe Order Strongylida - Superfamily Ancylostomatoidea

Back 25

1. The hookworms

2. Hooked anterior end

3. Highly cuticularized buccal capsule

4. Equipped with teeth or cutting plates

5. Attach to host intestinal mucosa and suck blood

6. Bursate males

Front 26

Describe the basic hookworm life cycle

Back 26

Direct:
1. Adults in small intestine of host
2. Egg to L3 in environment
3. Routes of infection = skin penetration and ingestion
4. Migrate through host to reach intestine
5. Larval arrest or HYPOBIOSIS can occur

Front 27

Define Hypobiosis

Back 27

A state of arrested or delayed larval development in the host.

Front 28

Hookworms of dogs and cats.

Back 28

1. Ancylostoma caninum - common dog hookworm but rare in cats (most pathogenic species)

2. A. tubaeforme - common hookworm in cats

3. A. braziliense - both dogs and cats

4. Uncinaria stenocephala - mainly dogs

Front 29

Describe Ancylostoma caninum

Back 29

1. Robust worms = 1/2 inch long; fresh worms are red or gray

2. Anterior end bent dorsally ("hooked")
Large buccal capsule with mouth, 3 pairs teeth
Usually firmly attached to mucosa of SI

3. Males - large copulatory bursa with long, thin, flexible spicules

4. Very common in dogs of all ages in MW

5. L3 survive best in moist, sandy-loam soils at moderate temperatures
Do NOT survive freezing or temps greater than 37 degrees C

Front 30

Life cycle of A. caninum and Fate of L3

Back 30

1. Adults in small intestine: females are oviparous

2. In environment:
a. Within egg: morula --> L1 --> hatches from egg
b. L1 develops and molts --> L2 develops (no molt) --> sheathed, infective L3 in environment

Egg --> L3 takes 2-8 days

3. Pre-patent period ~ 16 days

4. L3 ingested or penetrate skin of new host
a. If acquired by skin penetration undergo blood-lung migration
i. Decision time
1. Undergo Tracheal migration (trachea - SI)
2. Undergo Somatic migration (muscles - hypobiotic)
3. Mucosal migration (gastric glands or SI mucosa)

Front 31

Definition of Premunition.

Back 31

A state of resistance to infection which is established after an acute infection has become chronic and which persists as long as the infecting organisms remain in the body.

Front 32

Hypobiotic larvae of A. caninum in a pregnant bitch

Back 32

1. Larvae are "activated"
a. Occur in milk up to 20 days post-whelping
b. Undergo LACTOGENIC TRANSMISSION to nursing pups
c. Develop directly to adults in puppy SI

Front 33

Identify

Back 33

Order Strongylida - Family Ancylostomatoidea (Hookworm)

Front 34

Identify

Back 34

Strongyle-type eggs

Front 35

Identify.

Back 35

Copulating hookworms: males have a copulatory bursa with bursal rays.

Front 36

Identify.

Back 36

Ancylostoma caninum because buccal cavity has 3 pairs of teeth.

Front 37

Identify.

Back 37

Cutting plates of Uncinaria stenocephala

Front 38

Describe cutaneous larva migrans

Back 38

Hookworm L3 that penetrates human skin. It tries to complete the life cycle but is unable to penetrate deeper skin layers. Larval migration tunnels appear as ridges on skin.

Front 39

Describe cutaneous larva migran lesions

Back 39

1. Intensely pruritic
2. Persistent
3. Self-limiting
4. Second degree bacterial infection common
5. More severe and persistent if person hyper-sensitized by prior exposure