Ascariasis - Larva Migrans

Question 1

What is the host of Toxocara canis?

Answer 1

Dog

Question 2

What is the host of Toxocara catis?

Answer 2

Cat

Question 3

What is the host of Ascaris lumbricoides?

Answer 3

Human

Question 4

What is the host of Ascaris suum?

Answer 4

Pig and human

Question 5

Baylisascaris procyonis, Gnathostoma spinigerum and Strongyloides stercoralis are parasites that cause which infection?

Answer 5

Visceral Larva Migrans (Toxocariasis)

Question 6

Which parasite is found in raccoons?

Answer 6

Baylisascaris procyonis

Question 7

Which parasite is found in dogs and cats?

Answer 7

Gnathostoma spinigerum

Question 8

How is Toxocara transmitted?

Answer 8

Ingestion of embryonated Toxocara eggs in food or soil

Question 9

What happens if the larvae do not develop to adult stage?

Answer 9

They wander through the body, migrate to soft tissues and can cause blindness

Question 10

What is the life cycle of Toxicara in adult dogs and humans?

Answer 10

Embryonated eggs ingested by humans and dogs
Larvae released in intestine and migrate to various organs
Adult worms develop in lumen of intestine, they copulate and produce eggs that are passed in feces

Question 11

What is the life cycle of Toxicara in puppies?

Answer 11

Embryonated eggs ingested and larvae released in intestine
Larvae reaches circulation and adults develop in lumen of intestine
They copulate and eggs are passed in the feces

Question 12

What happens to larvae in heavy infections?

Answer 12

They are passed in feces

Question 13

True or false: In pregnant and lactating dogs, the larvae can be reactivated in the placenta

Answer 13

True

Question 14

Where is Toxicara present in the world?

Answer 14

Worldwide

Question 15

What demographic has the highest incidence?

Answer 15

Children

Question 16

True or false: Risk of exposure is higher in adult dogs than in puppies

Answer 16

False

Question 17

Indicate the type of Toxicariasis based onn the following pathologies
a. Granulomas of the retina
b. Hepatomegaly, pulmonary and neurological symptoms, eosinophilia

Answer 17

a. Ocular
b. Systemic Visceral Larva Migrans

Question 18

What are diagnostic techniques for Toxicariasis?

Answer 18

Fecal egg counts, ELISA using ES antigens, high eosinophilia

Question 19

What is the treatment for Toxicariasis?

Answer 19

Mebendazole

Question 20

What are the preventative measures for Toxicariasis?

Answer 20

Regular de-worming of dogs and cats, dispose of feces, clean up after your dog

Question 21

What are some risk factors of human toxocariasis?

Answer 21

Soil and water, dog and cat ownership, race and ethnicity

Question 22

Where is Ascaris most prevalent?

Answer 22

Tropical countries and socio-economically depressed areas of Europe, Latin America and Asia

Question 23

Which chemicals are Ascaris eggs resistant to?

Answer 23

2% formalin and 50% HCl, nitric/sulfuric acid

Question 24

True or false: Ascaris eggs can live in the soil for up to 15 years

Answer 24

True

Question 25

True or false: Ascaris eggs cannot be transmitted by windborne dust

Answer 25

False, they can

Question 26

How many larval stages do Ascarids go through?

Answer 26

Four

Question 27

What is required to go from one larval stage to the next in Ascarids?

Answer 27

The shedding of the surface cuticle (molting)

Question 28

What is the life cycle of Ascaris?

Answer 28

Human ingests embryonated egg Larvae migrates out of the intestine to the lungs Adult worm develops in intestine Eggs are passed in feces

Question 29

Identify the stage of Ascariasis with its time period a. 2-3 months after infection b. 5-6 days after exposure

Answer 29

a. Intestinal phase b. Lung phase

Question 30

What are the clinical features of the lung phase?

Answer 30

Pneumonitis caused by penetration of juvenile worms into lung capillaries

Question 31

What are the clinical features of the intestinal phase?

Answer 31

Abdominal pain, diarrhea, malabsorption of nutrients, stunted growth

Question 32

What is the cause of pathogenesis of Ascaris?

Answer 32

Wandering worms

Question 33

What are the symptoms of the wandering worms?

Answer 33

Intestinal perforation, blockage of bile ducts, liver abscesses

Question 34

How is ascariasis diagnosed?

Answer 34

Fecal egg counts

Question 35

What is the treatment for Ascaris?

Answer 35

Chemotherapy using benzimidazoles or Ivermectin to increase weight gain and appetite

Question 36

Which cells proliferate in infected Ascaris patients?

Answer 36

Peripheral blood mononuclear cells (PBMC)

Question 37

What cytokines are produced by PBMC?

Answer 37

IL10, IL4, IL5 and IFN-gamma

Question 38

True or false: There is a higher ratio of Th1 PBMCs than Th2 PBMCs in infected patients

Answer 38

False, there is a larger ratio of Th2 PBMCs than Th1 PBMCs