TOXOCARİASİSTOXOCARİASİSToxocariasis is the clinical term applied to Toxocariasis is the clinical term applied to infection in the human host with either infection in the human host with either Toxocara canis Toxocara canis ororToxocara cati. Toxocara cati.

Their definitive hosts are the domestic dogs Their definitive hosts are the domestic dogs and cats.and cats.

They lives hosts lumen of the small They lives hosts lumen of the small intestine.intestine.

►Order : Order : AscarididaAscaridida

►Superfamily:Superfamily:AscaridiodAscaridiodeaea

►Family : Family : ToxocaridaeToxocaridae

Infection can occur :Infection can occur :

1-) By the host ingesting viable , 1-) By the host ingesting viable , embryonated eggs from cantaminated embryonated eggs from cantaminated sources.sources.

2-) They can acquire the infection in utero 2-) They can acquire the infection in utero from the infected mother when she ingest from the infected mother when she ingest more infective eggs. more infective eggs.

The dominant clinical manifestations The dominant clinical manifestations associated classified according to the associated classified according to the organs affected.organs affected.

There are two main syndromes : There are two main syndromes :

1-) Visceral Larva Migrans (VLM): 1-) Visceral Larva Migrans (VLM): Which diseases associated with the major Which diseases associated with the major organs.organs.

2-) Ocular Larva Migrans (OLM): 2-) Ocular Larva Migrans (OLM): Effects Effects on the host are restricted to the eye and on the host are restricted to the eye and the optic nerve.the optic nerve.

►1-) Visceral Larva Migrans (VLM): 1-) Visceral Larva Migrans (VLM): Which diseases associated with the major Which diseases associated with the major organs.organs.

2-) Ocular Larva Migrans (OLM): 2-) Ocular Larva Migrans (OLM): Effects Effects on the host are restricted to the eye and on the host are restricted to the eye and the optic nerve.the optic nerve.

Human infection with Toxocara was first Human infection with Toxocara was first described by Wilder in 1950.described by Wilder in 1950.

Life Cycle of ToxocariasisLife Cycle of Toxocariasis

► Ingestion of embryonated eggs of Ingestion of embryonated eggs of Toxocara Toxocara start the infeection in host.start the infeection in host.

►Children accidentally come into contact Children accidentally come into contact with them when they play sandboxes and with them when they play sandboxes and on playgrounds contaminated with on playgrounds contaminated with Toxocara Toxocara eggs. (This situation exist from eggs. (This situation exist from indiscriminate defecation on these sites indiscriminate defecation on these sites by cats and dogs that include the adult by cats and dogs that include the adult worms.) worms.)

►After ingestion, the eggs hatch to release After ingestion, the eggs hatch to release larvae that penetrate the small intestine larvae that penetrate the small intestine enter the circulation and then are free to enter the circulation and then are free to wander throughout the body.wander throughout the body.

► In the definitive host the juvenile (release In the definitive host the juvenile (release larvae) parasites go on to complete the larvae) parasites go on to complete the life cycle , which , in many ways , life cycle , which , in many ways , resembles that of resembles that of Ascaris Ascaris lumbricoides lumbricoides , the ascarid infecting , the ascarid infecting humans.humans.

►We can see transplacental infection in We can see transplacental infection in dogs and cats.dogs and cats.

► In addition , the definitive host can In addition , the definitive host can become infected by ingesting become infected by ingesting embryonated eggs carried by paratenic embryonated eggs carried by paratenic hosts. Human can develop unusual hosts. Human can develop unusual infections by ingesting these animals.infections by ingesting these animals.

►Worms develop to the adult stage Worms develop to the adult stage

►Worms develop to the adult stage in the Worms develop to the adult stage in the small intestine aboout 60 to 90 days after small intestine aboout 60 to 90 days after the larvae hatch.the larvae hatch.

T. Canis T.cati T. Canis T.cati

Photo of Adult Toxocariasis From Photo of Adult Toxocariasis From Small Intestine Small Intestine

►Embryonation occurs in the soil within a Embryonation occurs in the soil within a week or so after deposition.week or so after deposition.

► Incubation periods of longer duration are Incubation periods of longer duration are due to lower temperatures.due to lower temperatures.

► In northern ; eggs can lie dormant(like In northern ; eggs can lie dormant(like hipobiozy) until the temperature rises in hipobiozy) until the temperature rises in spring.spring.

Clinical AspectsClinical Aspects

►To understand the degree of host To understand the degree of host damage we have two important way :damage we have two important way :

►1-) The number of migrating juveniles.1-) The number of migrating juveniles.

►2-) Age of the host.2-) Age of the host.

They are two additional Factors about the They are two additional Factors about the degree of host damage.degree of host damage.

►The immediate hypersensitivity The immediate hypersensitivity responses to dying and dead larvae in the responses to dying and dead larvae in the viscera , including the lungs , liver , and viscera , including the lungs , liver , and brain , produce symptoms character istic brain , produce symptoms character istic of of VLM.VLM.

► In the eye , migrating third stage larvae In the eye , migrating third stage larvae can damage the retina , inducing can damage the retina , inducing granulomatus reactions leading to granulomatus reactions leading to impaired sight.impaired sight.

DiagnosisDiagnosis►Diagnostic tests for Diagnostic tests for VLM VLM are primarily are primarily

immunological and the secondly immunological and the secondly ELİISA.ELİISA.

►OLM OLM is diagnosed primarily on the basis is diagnosed primarily on the basis of clinical criteria during an ophthal of clinical criteria during an ophthal mologic examinationmologic examination

►The immunodiagnostic tests used for The immunodiagnostic tests used for VLMVLM are not as reliable for are not as reliable for OLM.OLM.

TreatmentTreatment►AlbendazoleAlbendazole is the treatment of choice is the treatment of choice

for for toxocariasis. toxocariasis.

A dose of 400mg of albendazole twice a day for 5 days is the currently recommended therapy.