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Visceral larva migrans

Finded

Morphology

Clinical features

Life cycle

Toxocara canis

Toxocara cati

Habitat

The mouth has a buccal capsule with 4 hook-like teeth ventrally and a median cleft dorsally

Male: 8-11 mm in length. Its copulatory bursa is supported by flashy rays.

Copulatory spicules: two projected from the bursa.

Female: 10-13 mm in length.

Eggs:

• 60-80 µm: oval, colorless. They have a thin transparent shell. In feces contains segmented ovum. There is a clear space between the ovum and the shell.

Confined to the outer layer of the human skin.

Itching papules, these develop into serpiginous tracks into the epidermis.

Scratching: secondary bacterial infection.

Treatment

Albendazole, thiabendazole

Eggs are passed in the stool , and under favorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days and become free-living in contaminated soil. These released rhabditiform larvae grow in the feces and/or the soil , and after 5 to 10 days (and two molts) they become filariform (third-stage) larvae that are infective . These infective larvae can survive 3 to 4 weeks in favorable environmental conditions. On contact with the human host, typically bare feet, the larvae penetrate the skin and are carried through the blood vessels to the heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed . The larvae reach the jejunum of the small intestine, where they reside and mature into adults. Adult worms live in the lumen of the small intestine, typically the distal jejunum, where they attach to the intestinal wall with resultant blood loss by the host . Most adult worms are eliminated in 1 to 2 years, but the longevity may reach several years.