Transcript Toxocara canis

Order: Ascaridida
› Family: Toxocarida
› Genus: Toxocara
› Species: T. canis
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Geography: Worldwide
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Both males and females have three prominent lips
Each lip has a dentigerous (teeth bearing) ridge
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Eggs are 75-90 micrometers
embryonated when laid
Have pits
Very resistant to various weather and chemical conditions
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Males:
› 4-6 cm long
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Females:
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6.5 cm long
can be as long as 15 cm
The vulva is about one-third the body length
The uteri can contain up to 27 million eggs at a time.
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Toxocara egg
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Larvated eggs
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Larvae
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Adults
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Humans become infected by ingesting infective
eggs, often due to close contact with puppies or
from egg infected with soil
Transuterine transmission
› puppy can get from mother during
pregnancy or from mother’s milk.
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Definitive host: Dog or other canid
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Paratenic hosts: mice, rabbits, and
monkeys
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Accidental host: Humans
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Toxocara cati
› Very similar to Toxocara canis
› One of the most common feline helminths
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Toxocara canis causes toxocariasis: a
zoonotic infection caused by the
parasitic roundworms found in the
intestine of dogs.
1) Ocular larva migrans (OLM):
 Toxocara infections can cause an eye disease which can cause blindness.
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OLM occurs when a microscopic worm enters the eye
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Each year more than 700 people infected with Toxocara experience
permanent partial loss of vision.
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OLM occurs when larvae enter the eye. This results in a loss of vision or severe
ocular inflammation
http://www.youtube.com/watch?v=-8K9R2M-LfE
2) Visceral larva migrans (VLM):
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Repeated Toxocara infections can cause a disease that causes
swelling of the body’s organs or central nervous system.
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When the larval parasite migrates through the human body it is
known as larval migrans.
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In the UK alone there are over 300 cases of toxocariasis diagnosed
each year.
 Symptoms
:
› VLM: include abdominal pain, fever, coughing,
wheezing and asthma
› OLM: include ophthalmologic lesions
› Often found in children aged between 2 & 7
› Can also be asymptomatic
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Is usually made by serology or the finding
of larvae in biopsy or autopsy specimens.
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ELISA –
› positive in 78% of those with visceral larva
migrans
› positive in 45% of those with ocular toxocariasi
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Cross-section of Toxocara Larvae in liver
tissue
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Prednisone
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Albendazole or Mebendazole
Don’t allow dogs to lick your face
 Wash hands after playing with pets
 Avoid infected areas
 De-worm dogs
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Small children are susceptible
 Prelevant because every puppy is
assumed to have this helminth
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http://course1.winona.edu/kbates/ascarids.htm
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http://www.soton.ac.uk/~ceb/Students/Toxocara.htm
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http://www.dpd.cdc.gov/dpdx/html/Toxocariasis.htm
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http://animaldiversity.ummz.umich.edu/site/accounts/i
nformation/Toxocara_canis.html
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http://www.merckvetmanual.com/mvm/index.jsp?cfil
e=htm/bc/23505.htm
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http://www.scielo.cl/scielo.php?pid=S071777122008000100012&script=sci_arttext