Hookworms Flashcards
Hookworm classification
Phylum: Nematoda
Order: Strongylida
Superfamily: Ancylostomatoidae
- large animals: Bunostomum phlebotomum, trigonocephalum
- small animals: Ancylostoma caninum, braziliense, tubaeforme, Uncinaria stenocephala
Which large animal hookworm belongs to cattle only?
Bunostomum phlebotomum
Which small animal hookworm belongs to dogs only?
Ancylostoma caninum
Which small animal hookworm belongs to cats only?
Ancylostoma tubaeforme
Bunostomum phlebotomum pathology
Highly pathogenic, blood feeders!!
- heavy infections with adults = diarrhea, anemia, hypoproteinemia
- calves: marked weakness, emaciation, submandibular edema
B. phlebotomum - entry site skin
- irritation and pruritus
- swelling, scabs
- penetration of larvae may cause cattle to stamp their feet; lick their legs
B. phlebotomum - entry site intestines
- vili loss
- inflammation
- hemorrhagic lesions (ulcers)
Bunostomum phlebotomum - hosts
DH: wild and domestic ruminants (cattle, zebu)
- site of adults: small intestines (duodenum)
- distribution: worldwide in temperate regions, US (south and midwest)
B. phlebotomum - life cycle
Adults in SI –> eggs in feces –> L1 –> L2 –> L3 ensheathed (infective) –> L3 penetrates skin (most common) –> L3 enters circulatory system –> L3 migrates to heart, lungs, alveoli –> L4 coughed up , swallowed –> L4 in SI
Alternate route: L3 ingested (less common) –> L4 in SI
Bunostomum phlebotomum - clinical signs
- anemia
- diarrhea
- submandibular edema
- emaciation
- weakness
- death is possible
Bunostomum phlebotomum - diagnosis
Eggs - fecal float - thick shell, dirty looking Adults - robust worms, chitinous cutting plates - large buccal cavity
Bunostomum phlebotomum - treatment and control
- approved medication
- avoid moist pastures
- promote dryness
- hygiene (remove manure)
Bunostomum trigonocephalum - hosts
DH: sheep, goats, alpacas, llamas
- site of adults: small intestine (jejunum, ileum)
Bunostomum trigonocephalum - clinical signs
- irritation at entry site
- progressive anemia
- diarrhea (dark)
- edema (bottle jaw)
- death possible (200-300 worms)
Bunostomum trigonocephalum - life cycle
Adults in SI –> eggs in feces –> L1 –> L2 –> L3 ensheathed (infective) –> L3 penetrates skin (common) –> L3 enters circulatory system –> L3 migrates to heart, lungs, alveoli –> L4 coughed up, swallowed –> L4
- alternate route: L3 ingested –> L4
Bunostomum trigonocephalum - diagnosis and treatment
- fecal float
- levamisole labeled for sheep
Which small animal hookworms affect both dogs and cats?
- Ancylostoma braziliense
- Uncinaria stenocephala (more common in colder climates in US)
Small animal hookworm morphology
Curved on anterior end (hooked), males have copulatory bursa
- Ancylostoma caninum, A. tubaeforme: 3 pairs of teeth
- Ancylostoma braziliense: 1 pair of teeth
- Uncinaria stenocephala: cutting plates
Ancylostoma caninum - hosts
DH: canids PH: vertebrates (rodents), cockroaches - site of adults: small intestine - distribution: tropical/subtropical, does not tolerate freezing, larvae like well drained soil, shade, warmth, humidity - more prevalent in southeast than north
What are 4 potential routes of infection for A. caninum?
- L3 penetrate skin: goes to circulatory system, lungs –> cough and swallow
- DH ingests L3, enter SI crypts
- PH ingests L3: L3 arrest, reactivated, enter SI crypts, DH ingests PH
- pregnant bitch ingests L3: L3 –> lungs –> somatic tissue, arrests, reactivated –> mammary glands –> nursing pup ingests L3 –> L3 enter SI crypts in pup
Ancylostoma caninum - peracute disease
Occurs in puppies
- pale membranes, dark feces
- possible rapid decline in health at 2 weeks (before eggs produced)
- 0 eggs per gram
- coma, death
Ancylostoma caninum - acute disease
Older pup, mature
- severe anemia
- may still have 0 EPG
Ancylostoma caninum - chronic disease
Asymptomatic or slightly anemic
- eggs in feces
- immunocompetent host
Ancylostoma caninum - secondary disease
Older animals
- profound anemia
- immunocompromised
- secondary to other disease
Ancylostoma braziliense - hosts
DH: canids, felids
- site of adults: small intestine
- distribution: tropical/subtropical, larvae prefer moist, sandy soil, warmth
Ancylostoma tubaeforme - hosts
DH: felids
- site of adults: small intestine
- distribution: worldwide, increased prevalence in warmer climates
Which Ancylostoma spp has transmammary transmission?
A. caninum
Ancylostoma spp - pathology
- larvae: dermatitis, pneumonia
- adults: anemia, enteritis, edema
Which Ancylostoma spp is most pathogenic?
A. caninum!!
Ancylostoma spp - clinical signs
Primarily in warmer seasons!
- severity of disease dependent on: ability to compensate, # of parasites, ancylostoma spp involved
- adult dogs have anemia, anorexia, emaciation, weakness –> dark, tarry diarrhea, more likely in stressed and malnourished dogs
Number of hookworms able to mature in SI will be influenced by ______
- age
- acquired immunity
- premunition: residual population of hookworms confers resistance to new infection
How does immunity to infection develop?
- mature dogs may harbor small numbers of worms
- contaminate environment
- if well nourished and immunocompetent show few, if any, signs of disease
All hookworms suck ______
Blood!!
A. caninum disease summary
Voracious bloodsucker
- more pathogenic than A. braziliense
- most severe in pups by transmammary transmission
- pale mucous membranes
- anemia, ill thrift, failure to gain weight, poor hair coat
- dark tarry diarrhea
- death
- survivors are poor doers with chronic anemia
Respiratory disease and pneumonia
In puppies when large numbers of larvae migrate through lungs
- respiratory signs with hookworm-induced anemia
Penetration by larval hookworms
- dermatitis with errythema, puritus, and papules
- lesions most commonly on feet, interdigital spaces
- A. caninum and A. braziliense most often
Ancylostoma infection diagnosis
Fecal float
- thin shelled eggs
- oval
- if fecal is less than 24 hrs old, may see free L1
Ancylostoma adult characteristics
3 pair of teeth in adults
- A. caninum and A. tubaeforme
1 pair of teeth
- A. braziliense
Uncinaria stenocephala - hosts
DH: canids, felids
PH: rodents
- site of adults: small intestine
- distribution: cooler climates, larvae resistant to freezing!!
- less common than A. caninum in the southeast
What are 3 potential routes of infection for Uncinaria stenocephala?
- L3 penetrates skin (uncommon) –> circulatory system –> heart/lungs, cough and swallow
- DH ingests L3 –> enter SI crypts
- PH ingests L3 –> somatic migration –> L3 arrest, reactivate –> enter SI crypts –> DH ingests PH
Is there transmammary transmission with U. stenocephala?
No!
Uncinaria stenocephala - pathology and signs
May be asymptomatic, least pathogenic hookworm in dogs (rare in cats)
- minimal lesions from larvae
- adult blood feeding: heavy infection, catarrhal infection
- ingest 1-2% of blood volume than A. caninum ingets
Uncinaria stenocephala diagnosis
Eggs - floatation - similar to ancylostoma Adults - chitinous plates (no teeth)
Dog hookworm treatment suggestions
- A. caninum: fenbendazole, milbemycin oxime, moxidectin, pyrantel pamoate
- U. stenocephala: pyrantel pamoate, fenbendazole, moxidectin
- A. braziliense: pyrantel pamoate
Cat hookworm treatment suggestions
- A. tubaeforme: emodepside, ivermectin, milbemycin oxime, moxidectin, pyrantel, selamectin
Cutaneous larval migrans
Creeping eruption
- L3 penetrate surface layers of human skin and migrate
- walking barefoot or sitting on contaminated soil or sand
- no maturation (wrong host)
Which hookworm species is most important for CLM?
Ancylostoma braziliense
- gulf coast
- southeastern states
- highest prevalence
CLM pathogenesis
- papules
- inflamed tracks
- thickened skin
- pruritus
- systemic eosinophilia (uncommon, occurs in Australia)
- A. caninum: adults found in human intestines, single worms, no eggs, percutaneous transmission not oral!
