1 / 22

Toxocara canis

Toxocara canis. Sidney Milliron Aaron Bettenhausen. Taxonomy. Kingdom: Animalia Phylum: Nematoda Class: Secernentea Order: Ascaridida Family: Toxocaridae Genus: Toxocara Species: Toxocara canis. Geographic range. World wide distribution

yoko
Download Presentation

Toxocara canis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Toxocaracanis Sidney Milliron Aaron Bettenhausen

  2. Taxonomy • Kingdom: Animalia • Phylum: Nematoda • Class: Secernentea • Order: Ascaridida • Family: Toxocaridae • Genus: Toxocara • Species: Toxocaracanis

  3. Geographic range • World wide distribution • Found commonly in all domestic dogs and other canids • Possible to have prenatal infections of puppies

  4. Hosts • Primary host is dogs • Adults are infected upon infestation of embryonated eggs, or by eating rodents infected with visceral larva migrans • Worms can penetrate the placenta and infect unborn puppies • Puppies can be born infected • Puppies can also become infected via the transmammary route

  5. Other hosts • If a rodent eats the embryonated eggs the worms will hatch and begin migration before going dormant • If the rodent is then eaten by a dog the dog can become infected • Rodent acts as paratenic host • Rodents develop visceral larva migrans • Humans who ingest the eggs also develop visceral larva migrans

  6. Egg • Eggs • Brownish • Almost spherical • Surficial pits • Unembryonated when laid

  7. Larvated Eggs – Infective Stage

  8. Larvae • Found in Intestines, Circulatory, Lungs and Esophagus of Hosts

  9. Adults • Adults • Large (M=4-6cm; F=6.5-15+cm) • Have 3 lips • Prominent cervical alae in both sexes

  10. 3 Prominent Lips

  11. Life Cycle • Adult worms live in small intestine of their host • Produces prodigious numbers of eggs • Eggs are passed in feces • Develop into L3 in 5-6 days under optimal conditions

  12. Canine Oral ingestion • In Puppies: • Worms hatch and migrate through the portal system and lungs • Get swallowed and find their way back to intestine • Can be fatal to puppies due to malnutrition • In older dogs (secondary immune response) • Juveniles do not complete the lung migration • Wander through the body, eventually entering a developmental arrest for a long periods • Most adult dogs show no symptoms when infected and gain an increased immunity to reinfection as they age

  13. Life Cycle

  14. Infection during canine pregnancy • Dormant juveniles are activated by host hormones late in pregnancy • Reenter the circulatory system • Carried to placentas • Penetrate through to the fetal bloodstream • Complete lung migration en route to the intestine • Juveniles can also be passed by the trasmammary route, in mother’s milk

  15. Other routes • If a rodent or other mammal eats embryonated eggs • Juveniles begin to migrate but then become dormant and continues it’s developmental arrest • If rodent is eaten by a dog • Worms promptly migrate through the lungs to the intestine or into tissues to continue their wait, depending on age.

  16. Visceral Larva Migrans • Occurs when nematode gains entry into paratenic host • They do not complete the normal migration but undergo developmental arrest • Begin an extended, random wandering through various organs and tissues of the body

  17. Pathogenesis • Juveniles provoke a delayed-type hypersensitivity reaction in paratenic hosts • Eventually they will find their way to the brain • In other tissues, juveniles will form a granuloma • Can cause chronic ocular inflammation, as well as retinal granulomas • Rarely can cause eosinophilicmeningoencephalitis

  18. Visceral Larva Migrans • Occurs when a mammal other than the intended host (Dogs) ingest the eggs • Worms hatch and begin migration but eventually undergo developmental arrest • Worms begin a randomly wandering through the body • Can be caused by a number of different species however Toxocaracanisis the most common species that causes this disease in humans • In experimental hosts juvenile worms seem to prefer residing in the brain.

  19. Symptoms in Humans • Fever, pulmonary symptoms, hepatomegaly, and eosinophilia • Worms migrate indiscriminately to and from any organ including but seem to prefer the liver • Can cause blindness if they migrate to the eye • Can cause neurological symptoms • Extent of tissue damage is proportional to the numbers of juvenile worms in the body

  20. Prevalence of infection • In the united states 4.6-7.3% of children ages 1 to 11 years old have Visceral Larva migrans • Up to 30% infection has been found in African American children of low socioeconomic status • Up to 34% infection has been found in Irish school children • In some developing tropical countries the rates of infection among children can be around 50 to 80%

  21. Diagnosis • An ELISA using secretory-excretory antigens • A liver biopsy might reveal a juvenile surrounded by a granuloma • Infected patients may present with high eosinophilia

  22. Treatment and Control • Mebendazole • Periodic deworming of household pets • Proper disposable of animal feces • Don’t let your dog eat rodents • Covering sandpits in public parks when not in use

More Related