Larva migrans is caused by larval migration through tissues. It can be cutaneous (skin), ocular (eyes), or visceral (internal organs). Cutaneous larva migrans is caused by animal hookworms in soil, causing burrowing skin lesions. Visceral larva migrans is caused by dog or cat roundworm eggs in soil ingested by humans, where the larvae migrate through organs causing damage. Ocular larva migrans is caused by the same roundworms migrating to the eyes. Diagnosis is based on symptoms, exposure history, and antibody tests. Prevention involves deworming pets and reducing children's contact with contaminated soil.

1. Larva Migrans

2. Introduction
• It is include larval migration through various tissues and organs of the body.
Sometimes the larvae appear to lose their way and wander around
aimlessly.
• 1- This is generally seen when human infection occurs with non-human
species of nematodes
• 2- when human parasitic nematodes infect immune persons. The immunity
is sufficient to prevent the normal progression of infection.
• 3- Larva migrans can be classified into cutaneous , ocular or visceral types,
depending on whether the larval migration takes place in the skin or in
deeper tissues

3. Cutaneous Larva Migrans
*This condition also known as creeping eruption (also called ground itch) . caused by
burrowing larvae of animal hookworms. The larvae hatch from eggs passed in dog and cat
feces and mature in the soil. Humans become infected after skin contact with contaminated
soil. After larvae penetrate the skin, erythematous lesions form along the tortuous tracks of
their migration.
**The most common cause is non-human species of hookworm (Ancylostoma braziliense
and A. caninum).

4. Pathogenesis
• Parasite eggs are passed in the feces of infected animals into the soil, where the larvae
hatch out.
• Infection is acquired from soil contaminated with excreta of these animals.
• On coming in contact with human skin, the larvae penetrate the skin to cause infection.
• Between a few days and a few months after the initial infection, the larvae migrate
beneath the skin.

5. • In normal animal host, the larvae are able to penetrate the deeper layers of
the skin by reaching there via circulation.
• Once they enter intestine, they mature sexually and lay more eggs that are
then excreted to repeat the cycle.
• However, in a human host, which is an accidental host for the parasite, the
larvae are unable to penetrate the basement membrane to invade the dermis,
so that the disease remains connected to the outer layers of the skin.

6. Clinical Features
• The larvae produce itching papules, which develop into serpiginous tunnels in the
epidermis. With the movements of the larva in the skin, the lesion also shifts, hence the
name ‘creeping eruption’. Scratching may lead to secondary bacterial infection.
• Transient creeping eruptions may be produced sometimes by the human hookworm,
Necator americanus.
• Lowe’s syndrome may occur in one-fourth to one-half of the cases.

7. • A rapidly moving lesion is produced by Strongyloides stercoralis particularly in
immune persons. This is known as larva currents.
• Ectopic infections with Fasciola and Paragonimus may produce creeping
lesions on abdominal wall.

8. Diagnosis
• Eosinophilia is rare and occurs only when Lowe’s syndrome develop.
• 1- Serological tests are not developed.
• 2- On biopsy, larvae are rarely found in the skin lesion.
• 3- Diagnosis is based mainly on clinical features.

9. control
• Puppies and kittens should always be dewormed as a routine.
• There are often many infective eggs around houses from the feces of
household pets and measures should be taken to prevent indiscriminate
defecation and also to prevent young children from playing in and ingesting
contaminated soil.
• In many developed countries children’s play sandpits are now protected with
a fence.

10. Visceral Larva Migrans
*This condition is caused by the migration of larvae of nonhuman
species of nematodes that infect by the oral route.
**The most common cause is the dog ascarid, Toxocara canis and less often
the cat ascarid, Toxocara cati.
***In human, these nematode larvae do not develop into adult worms, but
instead, migrate through host tissues and elicit eosinophilic.

11. Toxocara canis Toxocara cati

12. Pathogenesis
• When the infective eggs present in the soil contaminated by dog and cat feces
are ingested, the larvae hatch in the small intestine, penetrate the gut wall,
and migrate to the liver.
• They may remain there or migrate to other organs such as lungs, brain, or
eyes.
• In humans they do not develop into adults, but induce granulomatous
lesions, which cause local damage.

13. Clinical Features
• Clinical manifestations depend on the sites a acted and the degree and duration of
infection.
• As children are more likely to swallow dirt, this condition is much more frequent in them.
• Fever, hepatomegaly, pneumonitis, hyperglobulinaemia, and pica are the common feature.
• Patients may develop neurological disturbances (neural larva migrans) and
endophthalmitis (ophthalmic larva migrans).
• Marked leukocytosis occurs with persistently high eosinophilia.

14. Diagnosis
• Serological tests, such as passive hemagglutination, microprecipitation, and
more specially, ELISA have been developed for the diagnosis of toxocariasis
(visceral larva migrans).

15. PREVENTION
• Reduce contact with contaminated soil by wearing shoes and protective
clothing and using barriers such as towels when seated on the ground.

16. Difference Between Cutaneous and Visceral Larva Migrans

17. Ocular Larva Migrans
caused by larvae of Toxocara canis (dog roundworm) and less
frequently of Toxocara cati (cat roundworm)

18. Clinical Presentation
• In ocular larva migrans, the larvae produce various ophthalmologic lesions,
which in some cases have been misdiagnosed as retinoblastoma, resulting in
surgical enucleation. ocular larva migrans often occurs in older children or
young adults, with only rare eosinophilia or visceral manifestations.

19. Laboratory Diagnosis
• In this parasitic disease the diagnosis does not rest on
identification of the parasite.
• Since the larvae do not develop into adults in humans.
• a presumptive diagnosis rests on clinical signs, history of
exposure to puppies.
• laboratory findings (including eosinophilia), and the detection
of antibodies to Toxocara.

20. Prevention
• Dogs are the chief culprits in spreading this disease because of their
indiscriminate defecator habits. Some 50% of puppies and 20% of older
dogs are infected with Toxocara. If they cannot be kept away from small
children, they should be dewormed on a regular basis. The more fastidious
feline is usually a problem only if it shares a sandbox with children.