Toxocara species Flashcards
_____disease from stray dogs and cats
zoonotic
Larvae causes the disease:
• Toxocara____: dog roundworm
• Toxocara____: cat roundworm
canis
cati
Life cycle is completed in_____
dogs or cats
Female dogs
•_____ eggs may be reactivated and infects their puppies ->__________ transmission
Encysted
transplacental or transmammary
Epidemiology
• Common among_____ than adults
• Tendency to play in soil
• Exhibit geophagia or soil eating
• Common in places where dogs and cats are not dewormed
children
Biology
• Accidental Host:
Humans
Paratenic Host:
• Rabbits and small mammals
Definitive Hosts:
Dogs or cats
Infective Stage:
• Humans
• Embryonated ova
• Encysted larvae in small mammals like rabbit
Diagnostic Stage:
• Larvae encysted in tissues
• Shed unembryonated ova
Dogs and Cats
External environment
• Undergo_____ -> infective (ova containing L3)
embryonation
Embryonated Ova
- Ingested by the_____
- Ingested by____
definitve hosts (dogs/cats)
paratenic host
Host?
• Infective ova hatch to larva -> penetrate the gut wall
Definitive Host
Young dogs:
larvae undergo lung migration
Older:
larval encystment in tissues is more common
Female Old Dogs:
encysted larvae reactivated during pregnancy
Transplacental and transmammary
(T canis)
Transmammary > Transplacental
(T cati)
Habitat:
small intestine (usual young dogs)
• Major source of environmental egg contamination
Young dogs
2._______ Hosts - like rabbits
• Ingest embryonated ova (generally Toxocara canis)
• hatch to larvae and encyst in various tissues
Paratenic
What host?
• Ingestion of embryonated ova, or infected paratenic host (Food-borne) -> L3 penetrate intestinal wall
• -> liver, heart, lungs, brain, muscle, eyes
Humans as accidental host
Pathogenesis and Clinical Manifestations
• Migration of the larvae and death in different organs -> intense inflammatory response as eosinophilic granuloma
Visceral Larva Migrans (VLM)
Pathogenesis
• Solitary mass -> seizures, encephalitis, optic neuritis, eosinophilic meningitis
CNS: Neurological Toxocariasis
: pneumonia, respiratory failure
: hepatomegaly, necrosis
: Loeffler endomyocarditis
Lungs
Liver
Heart
Pathogenesis and Clinical Manifestations
• Common among children 5-10 years old: unilateral visual impairment and strabismus
• Retinal Invasion: most serious consequence
Ocular Larva Migrans (OLM)
Pathogenesis and Clinical Manifestations
• Less specific syndrome or may be asymptomatic
Covert Toxocariasis (CoTOX)
Diagnosis
• Definitive:________
• Other Tests(2)
Tissue Biopsy demonstrating larva
• ELISA test for IgG
• PCR
has no role in the diagnosis of human toxocariasis
Stool exam to demonstrate eggs
Treatment
• Most patients recover without therapy
• If therapy is warranted:
•____ or _____PLUS ____
• For those with CNS, cardiac, or lung complications
Albendazole or Mebendazole PLUS anti-inflammatory drug (Steroids)
Treatment is more difficult for_______ -> prevent progressive damage to the eye
Ocular Toxocariasis
Prevention and Control
• Control and capture of stray dogs and cats
• Cleaning up feces from soil and pavements
• Closing of potentially contaminated areas to animals and children
• Gardens should be fenced to prevent fecal contamination by dogs and cats
• Vegetables gathered from possible contaminated gardens should be washed thoroughly.
• Avoidance of consumption of raw or undercooked meat of potentially infected animal.
• Hand washing at all times.
Prevention and Control
• Strategic antihelminthic treatment of dogs and cats
• Puppies: start____ weeks of age, repeated every 2 weeks until 12 weeks age
• Adult: treated every__ months
• Female: after each____ cycle
2-3
6
estrus
Ingested by paratenic host
L3 larvae in tissue
Adults in (habitat) of definitive host
small intestine
Unembryonated egg is embryonated in the _____
External environment
Paratenic host ingests _____
Third stage larvae
Humans ingests _____ from environment/ paratenic host
Third stage larvae
