hookworms

Question 1

hookworm morphology

Answer 1

small, stout worms (10-16mm)
dioecious, sexually dimorphic, females larger
-males w copulatory bursa
anterior end curved dorsoventrally
buccal cavity w 3 pairs teeth
esophagus club-shaped (very muscular and powerful pump)
-voracious blood suckers!
develop into infective stage in environment
occupy small intestine of host

Question 2

ancylostoma caninum

Answer 2

canine hookworm

Question 3

ancylostoma caninum life cycle

Answer 3

direct
-eggs passed
-larvae develop in environment 7-14 days

Question 4

ancylostoma caninum host infection

Answer 4

skin penetration
oral ingestion
tracheal migration through somatic tissues
adults in small intestine, 17-21 days following infection
-lifespan 12-18 months in absence of reinfection

Question 5

ancylostoma caninum arrested larvae via lactogenic route

Answer 5

most important!
larvae do not appear to migrate
mature in small intestine following attachment
clinical signs of anemia 8 days post infection
peak blood loss between 15-18th day
nursing puppies may pass eggs as early as 10-12 days after birth

Question 6

sources of infective larvae L3 for oral infection

Answer 6

environmental (pet park)
paratenic host

Question 7

hookworm pathogenesis

Answer 7

cause disease bc voracious blood suckers!
severity depends on:
-intensity of infection
-age of host
-nutritional status
-degree of iron reserves
-presence of acquired immunity

Question 8

peracute infection

Answer 8

signifigant blood loss
-rapid progression to hypochromic anemia within hours of days as worms feed @ 8 days post infection
-pale mucous membranes
-diarrhea w black tarry stools
large # worms in short time
naiive immune status
deficient nutrition-insufficient iron reserves

Question 9

acute infection

Answer 9

exposure of older puppies and adults
acuired from environment over short period of time
cumulative process w prolonged exposure and progressive acquisition of additional worms

Question 10

chronic compensated infection

Answer 10

presence of infection w/o overt clinical signs
measurable reductions in PCV, erythocyte count

Question 11

secondary decompensated infection

Answer 11

older dogs w other primary health issues
malnourished animals

Question 12

diagnosis peracute disease

Answer 12

neonatal puppies showing profound anemia
pale mucous membranes
hematocrit or PCV <20%
weakness, listless, anorexia
bloody diarrhea
FECAL MAY BE NEG

Question 13

diagnosis acute disease

Answer 13

older animals (>3-4 months-adult)
PCV<25%
listless w pale mucous membranes
diarrhea w black-tarry stools
low BCS
poor hair coat
dermatitis on feet
thin shelled eggs on fecal

Question 14

diagnosis chronic compensated disease

Answer 14

older animals
PCV on low end
low weight for age/ low BCS
poor hair coat
dermatitis on feet
thin shelled eggs on fecal

Question 15

diagnosis secondary decompensated disease

Answer 15

older animals
PCV below normal
emaciated w low BCS
poor hair coat
dermatitis on feet
eggs on fecal
parasitic disease secondary to underlying!

Question 16

treatment peracute

Answer 16

immediate anthelmintic treatment
assessment based on age, clinical presentation, hematocrit
supportive care (fluids, electrolytes) important to keep alive for treatment to be effective
pyrantel is drug of choice, fast acting and peak serum levels quickly
-safe to use in young animals bc pass quickly through gi

Question 17

treatment of animal w/o signs

Answer 17

target is removal of egg laying adult worms from S.I
-pyrantel pamoate
-fenbendazole & albendazole
-heartworm prophylaxis regimens (adequate for control, not prevention)

Question 18

prevent perinatal infections

Answer 18

daily administration fenbendazole
-40th day gestation through 14th day lactation
-attacks reactivated larvae in moms tissue and prevents infection of pups
ivermectin
-4-9 days prior to whelping and 10 days post
treat puppies at 2 week intervals for 4 treatments (pyrantel)

Question 19

arrested development

Answer 19

vacant gut is repopulated by worms in arrested development
-frustrating to vets and clients, explain lifecycle
rationale for post-treatment confirmation of treatment efficiency
-evaluate 7-10 days following treatment

Question 20

ancylostoma tubaforme

Answer 20

feline hookworm
morphologically similar to A. caninum, eggs on fecal smaller

Question 21

ancylostoma tubaforme life cycle

Answer 21

eggs passed
larvae develop in environment
L3 or paratenic host ingested
tracheal migration
adults in S.I
-rodent paratenic host play sig role bc predator-prey interaction

Question 22

Ancylostoma braziliense

Answer 22

endemic in southern US
more prevalent in cats than dogs
identification of infection status and clinical correlation not possible

Question 23

Ancylostoma braziliense morphology

Answer 23

adult worms smaller than A. caninum, female still larger
buccal capsule w 2 teeth
eggs on fecal slightly smaller

Question 24

Ancylostoma braziliense lifecycle

Answer 24

eggs passed in feces
larval development prefers warmer conditions
no vertical transmission!

Question 25

uncinaria stenocephala

Answer 25

dog, cat, fox
-cats appear to be largely refractory to infection
endemic to temperate climates

Question 26

uncinaria stenocephala morphology

Answer 26

size comparable to other hookworms
cutting plates rather than teeth in buccal capsule
eggs on fecal exam large

Question 27

uncinaria stenocephala lifecycle

Answer 27

eggs passed in feces
larvae develop in cooler climates
no vertical transmission in dogs/cats

Question 28

uncinaria stenocephala treatment

Answer 28

ivermectin- only 1/2 effective against

Question 29

cutaneous larval migrans

Answer 29

skin penetration by infective L3
-inflammation under skin of host
common in SE U.S
all hookworms may be implicated in CLM
-histologic differentiation difficult

Question 30

visceral larval migrans

Answer 30

larval stage hookworms penetrate deep and reach pulmonary circulation
non-specific respiratory illness, dry cough, dyspnea
diffuse pulmonary infiltrates on radiograph

Question 31

hookworm associated gastroenteritis

Answer 31

successful colonization of human S.I
-adult of advanced L4 stage
transmission by cutaneous or oral route
prevent by feces removal in backyard