larva migrans

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1-Cutaneous Larva Migrans (CLM) 1-Cutaneous Larva Migrans (CLM) 2-Visceral Larva Migrans (VLM) 2-Visceral Larva Migrans (VLM) (Toxocaraiasis) (Toxocaraiasis) Toxocariasis is caused by larvae of Toxocariasis is caused by larvae of Toxocara canis Toxocara canis (dog roundworm) and less frequently (dog roundworm) and less frequently of of T. cati T. cati (cat roundworm), two nematode (cat roundworm), two nematode parasites of animals. parasites of animals. Larva Migrans Larva Migrans

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Larva Migrans. 1-Cutaneous Larva Migrans (CLM) 2-Visceral Larva Migrans (VLM) (Toxocaraiasis) Toxocariasis is caused by larvae of Toxocara canis (dog roundworm) and less frequently of T. cati (cat roundworm), two nematode parasites of animals. . Toxocara canis. Toxocara canis. - PowerPoint PPT Presentation

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1-Cutaneous Larva Migrans (CLM) 1-Cutaneous Larva Migrans (CLM)

2-Visceral Larva Migrans (VLM) 2-Visceral Larva Migrans (VLM) (Toxocaraiasis) (Toxocaraiasis)

Toxocariasis is caused by larvae of Toxocariasis is caused by larvae of Toxocara canisToxocara canis (dog roundworm) and less frequently of (dog roundworm) and less frequently of T. catiT. cati

(cat roundworm), two nematode parasites of animals. (cat roundworm), two nematode parasites of animals.

Larva MigransLarva Migrans

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ToxocaraToxocara caniscanis

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Toxocara cati egg

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Toxocara catiToxocara cati

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Toxocara catiToxocara cati

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Clinical FeaturesClinical FeaturesMany human infections are asymptomatic, with only eosinophilia and Many human infections are asymptomatic, with only eosinophilia and

positive serologypositive serology..  

The two main clinical presentations of toxocariasis are visceral larva The two main clinical presentations of toxocariasis are visceral larva migrans migrans ((VLMVLM) ) and ocular larva migrans and ocular larva migrans ((OLMOLM).).  

In VLM, which occurs mostly in preschool children, the larvae invade In VLM, which occurs mostly in preschool children, the larvae invade multiple tissues multiple tissues ((liver, heart, lungs, brain, muscleliver, heart, lungs, brain, muscle) ) and cause various and cause various symptoms including fever, anorexia, weight loss, cough, wheezing, symptoms including fever, anorexia, weight loss, cough, wheezing, rashes, hepatosplenomegaly, and hypereosinophiliarashes, hepatosplenomegaly, and hypereosinophilia ..  Death can occur   Death can occur rarely, by severe cardiac, pulmonary or neurologic involvementrarely, by severe cardiac, pulmonary or neurologic involvement ..  

In OLM, the larvae produce various ophthalmologic lesions, which in In OLM, the larvae produce various ophthalmologic lesions, which in some cases have been misdiagnosed as retinoblastoma, resulting in some cases have been misdiagnosed as retinoblastoma, resulting in surgical enucleationsurgical enucleation..  

OLM often occurs in older children or young adults, with only rare OLM often occurs in older children or young adults, with only rare eosinophilia or visceral manifestationseosinophilia or visceral manifestations..

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OLMOLM

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Pulmonary granulomaPulmonary granuloma

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Laboratory DiagnosisLaboratory Diagnosis• In this parasitic disease the diagnosis does not rest on In this parasitic disease the diagnosis does not rest on

identification of the parasiteidentification of the parasite..  Since the larvae do not   Since the larvae do not develop into adults in humans, a stool examination develop into adults in humans, a stool examination would not detect anywould not detect any ToxocaraToxocara eggseggs..

  • However, the presence ofHowever, the presence of AscarisAscaris andand TrichurisTrichuris eggs eggs

in feces, indicating fecal exposure, increases the in feces, indicating fecal exposure, increases the probability ofprobability of ToxocaraToxocara in the tissuesin the tissues..

• For both VLM and OLM, a presumptive diagnosis For both VLM and OLM, a presumptive diagnosis rests on clinical signs, history of exposure to puppies, rests on clinical signs, history of exposure to puppies, laboratory findings laboratory findings ((including eosinophiliaincluding eosinophilia)), and the , and the detection of antibodies todetection of antibodies to ToxocaraToxocara..

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Eggs ofEggs of Toxocara canisToxocara canis . .

These eggs are passed in dog feces, especially puppies' feces.

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Antibody DetectionAntibody Detection

• The currently recommended serologic test for The currently recommended serologic test for toxocariasis is enzyme immunoassay toxocariasis is enzyme immunoassay ((EIAEIA) ) with with larval stage antigens extracted from embryonated larval stage antigens extracted from embryonated eggs or released in vitro by cultured infective larvaeeggs or released in vitro by cultured infective larvae..

• The latterThe latter, , ToxocaraToxocara excretoryexcretory--secretory secretory ((TESTES) ) antigens, are preferable to larval extracts because they antigens, are preferable to larval extracts because they are convenient to produce and because an absorptionare convenient to produce and because an absorption--purification step is not required for obtaining purification step is not required for obtaining maximum specificitymaximum specificity.  . 

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TreatmentTreatment

• VLM is treated with antiparasitic drugs, VLM is treated with antiparasitic drugs, usually in combination with antiinflammatory usually in combination with antiinflammatory medicationsmedications..   

• The antiparasitic drug recommended in The The antiparasitic drug recommended in The Medical Letter is albendazoleMedical Letter is albendazole**, with , with mebendazolemebendazole* * as an alternativeas an alternative.  . 

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• Causal AgentsCausal Agents::Trichinellosis Trichinellosis ((trichinosistrichinosis) ) is caused by is caused by nematodes nematodes ((roundwormsroundworms) ) of the genusof the genus TrichinellaTrichinella.  . 

• In addition to the classical agentIn addition to the classical agent TT. . spiralisspiralis ((found worldwide in many carnivorous and found worldwide in many carnivorous and omnivorous animalsomnivorous animals)), several other species of, several other species of TrichinellaTrichinella are now recognized. are now recognized.

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Trichinella sppTrichinella spp..

• 1- T1- T. . pseudospiralispseudospiralis (mammals and birds) (mammals and birds) worldwideworldwide),),

• 2- 2- TT. . nativanativa (Arctic bears)(Arctic bears)• 3- 3- TT. . nelsoninelsoni (African predators and (African predators and

scavengersscavengers))• 4-4- TT. . britovibritovi ))carnivores of Europe and western carnivores of Europe and western

Asia)Asia)..

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TrichinellaTrichinella--adultadult

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TrichinellaTrichinella nativanativa

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Life cycleLife cycle

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Geographic DistributionGeographic Distribution

WorldwideWorldwide..  Most common in parts of   Most common in parts of Europe and the United StatesEurope and the United States..

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Clinical FeaturesClinical Features• Light infections may be asymptomaticLight infections may be asymptomatic..  

• Intestinal invasion can be accompanied by gastrointestinal symptoms Intestinal invasion can be accompanied by gastrointestinal symptoms ((diarrhea, abdominal pain, vomitingdiarrhea, abdominal pain, vomiting).).  

• Larval migration into muscle tissues Larval migration into muscle tissues ((one week after infectionone week after infection) ) can can cause periorbital and facial edema, conjunctivitis, fever, myalgias, cause periorbital and facial edema, conjunctivitis, fever, myalgias, splinter hemorrhages, rashes, and blood eosinophiliasplinter hemorrhages, rashes, and blood eosinophilia..  

• Occasional lifeOccasional life--threatening manifestations include myocarditis, threatening manifestations include myocarditis, central nervous system involvement, and pneumonitiscentral nervous system involvement, and pneumonitis..  

• Larval encystment in the muscles causes myalgia and weakness, Larval encystment in the muscles causes myalgia and weakness, followed by subsidence of symptomsfollowed by subsidence of symptoms..

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Splinter hemorrhagesSplinter hemorrhages 2 2 Swollen eyesSwollen eyes

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AA, , BB:: Encysted larvae ofEncysted larvae of TrichinellaTrichinella in pressed muscle in pressed muscle tissue sampletissue sample..  The coiled larvae can be seen inside the   The coiled larvae can be seen inside the

cystscysts

                                                            

AB

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Trichinella spiralisTrichinella spiralis encysted larvaencysted larva

                                 

 

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CC, , DD:: Larvae ofLarvae of TrichinellaTrichinella, , freed from their cysts, freed from their cysts, typically coiled; lengthtypically coiled; length: : 0.8 to 1 mm0.8 to 1 mm..  

                                           

   

                                              

   

CD

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Laboratory DiagnosisLaboratory Diagnosis

• The suspicion of trichinellosis The suspicion of trichinellosis ((trichinosistrichinosis)), , based on clinical symptoms and eosinophilia, based on clinical symptoms and eosinophilia, can be confirmed by specific diagnostic tests, can be confirmed by specific diagnostic tests, including antibody detection, muscle biopsy, including antibody detection, muscle biopsy, and microscopyand microscopy..

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Antibody DetectionAntibody Detection

Immunodiagnostic tests currently available in Immunodiagnostic tests currently available in the Uthe U..SS. . include enzyme immunoassays include enzyme immunoassays ((EIAEIA).).   

Antigen preparations may be crude antigens Antigen preparations may be crude antigens prepared from homogenates ofprepared from homogenates of Trichinella Trichinella spiralisspiralis muscle larvae or excretorymuscle larvae or excretory--secretory secretory ((ESES) ) products produced by cultured larvaeproducts produced by cultured larvae. .