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1-Cutaneous Larva Migrans (CLM) 1-Cutaneous Larva Migrans (CLM) 2-Visceral Larva Migrans (VLM) (Toxocaraiasis) Toxocariasis is caused by larvae of Toxocara.

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Presentation on theme: "1-Cutaneous Larva Migrans (CLM) 1-Cutaneous Larva Migrans (CLM) 2-Visceral Larva Migrans (VLM) (Toxocaraiasis) Toxocariasis is caused by larvae of Toxocara."— Presentation transcript:

1 1-Cutaneous Larva Migrans (CLM) 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 (dog roundworm) and less frequently of T. cati (cat roundworm), two nematode parasites of animals. Larva Migrans

2 Toxocara canis

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4 Toxocara cati egg

5 Toxocara cati

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10 Clinical Features Many human infections are asymptomatic, with only eosinophilia and positive serology. Many human infections are asymptomatic, with only eosinophilia and positive serology. The two main clinical presentations of toxocariasis are visceral larva migrans (VLM) and ocular larva migrans (OLM). The two main clinical presentations of toxocariasis are visceral larva migrans (VLM) and ocular larva migrans (OLM). In VLM, which occurs mostly in preschool children, the larvae invade multiple tissues (liver, heart, lungs, brain, muscle) and cause various symptoms including fever, anorexia, weight loss, cough, wheezing, rashes, hepatosplenomegaly, and hypereosinophilia. Death can occur rarely, by severe cardiac, pulmonary or neurologic involvement. In VLM, which occurs mostly in preschool children, the larvae invade multiple tissues (liver, heart, lungs, brain, muscle) and cause various symptoms including fever, anorexia, weight loss, cough, wheezing, rashes, hepatosplenomegaly, and hypereosinophilia. Death can occur rarely, by severe cardiac, pulmonary or neurologic involvement. In OLM, the larvae produce various ophthalmologic lesions, which in some cases have been misdiagnosed as retinoblastoma, resulting in surgical enucleation. In OLM, the larvae produce various ophthalmologic lesions, which in some cases have been misdiagnosed as retinoblastoma, resulting in surgical enucleation. OLM often occurs in older children or young adults, with only rare eosinophilia or visceral manifestations. OLM often occurs in older children or young adults, with only rare eosinophilia or visceral manifestations.

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12 OLM

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14 Pulmonary granuloma

15 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 stool examination would not detect any Toxocara eggs. 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 stool examination would not detect any Toxocara eggs. However, the presence of Ascaris and Trichuris eggs in feces, indicating fecal exposure, increases the probability of Toxocara in the tissues. However, the presence of Ascaris and Trichuris eggs in feces, indicating fecal exposure, increases the probability of Toxocara in the tissues. For both VLM and OLM, a presumptive diagnosis rests on clinical signs, history of exposure to puppies, laboratory findings (including eosinophilia), and the detection of antibodies to Toxocara. For both VLM and OLM, a presumptive diagnosis rests on clinical signs, history of exposure to puppies, laboratory findings (including eosinophilia), and the detection of antibodies to Toxocara.

16 Eggs of Toxocara canis. These eggs are passed in dog feces, especially puppies' feces.

17 Antibody Detection The currently recommended serologic test for toxocariasis is enzyme immunoassay (EIA) with larval stage antigens extracted from embryonated eggs or released in vitro by cultured infective larvae. The currently recommended serologic test for toxocariasis is enzyme immunoassay (EIA) with larval stage antigens extracted from embryonated eggs or released in vitro by cultured infective larvae. The latter, Toxocara excretory-secretory (TES) antigens, are preferable to larval extracts because they are convenient to produce and because an absorption- purification step is not required for obtaining maximum specificity. The latter, Toxocara excretory-secretory (TES) antigens, are preferable to larval extracts because they are convenient to produce and because an absorption- purification step is not required for obtaining maximum specificity.

18 Treatment VLM is treated with antiparasitic drugs, usually in combination with antiinflammatory medications. VLM is treated with antiparasitic drugs, usually in combination with antiinflammatory medications. The antiparasitic drug recommended in The Medical Letter is albendazole*, with mebendazole* as an alternative. The antiparasitic drug recommended in The Medical Letter is albendazole*, with mebendazole* as an alternative.

19 Causal Agents: Trichinellosis (trichinosis) is caused by nematodes (roundworms) of the genus Trichinella. Causal Agents: Trichinellosis (trichinosis) is caused by nematodes (roundworms) of the genus Trichinella. In addition to the classical agent T. spiralis (found worldwide in many carnivorous and omnivorous animals), several other species of Trichinella are now recognized. In addition to the classical agent T. spiralis (found worldwide in many carnivorous and omnivorous animals), several other species of Trichinella are now recognized.

20 Trichinella spp. 1- T. pseudospiralis (mammals and birds) worldwide), 1- T. pseudospiralis (mammals and birds) worldwide), 2- T. nativa (Arctic bears) 2- T. nativa (Arctic bears) 3- T. nelsoni (African predators and scavengers) 3- T. nelsoni (African predators and scavengers) 4- T. britovi )carnivores of Europe and western Asia). 4- T. britovi )carnivores of Europe and western Asia).

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22 Trichinella-adult

23 Trichinella nativa

24 Life cycle

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26 Geographic Distribution Worldwide. Most common in parts of Europe and the United States.

27 Clinical Features Light infections may be asymptomatic. Light infections may be asymptomatic. Intestinal invasion can be accompanied by gastrointestinal symptoms (diarrhea, abdominal pain, vomiting). Intestinal invasion can be accompanied by gastrointestinal symptoms (diarrhea, abdominal pain, vomiting). Larval migration into muscle tissues (one week after infection) can cause periorbital and facial edema, conjunctivitis, fever, myalgias, splinter hemorrhages, rashes, and blood eosinophilia. Larval migration into muscle tissues (one week after infection) can cause periorbital and facial edema, conjunctivitis, fever, myalgias, splinter hemorrhages, rashes, and blood eosinophilia. Occasional life-threatening manifestations include myocarditis, central nervous system involvement, and pneumonitis. Occasional life-threatening manifestations include myocarditis, central nervous system involvement, and pneumonitis. Larval encystment in the muscles causes myalgia and weakness, followed by subsidence of symptoms. Larval encystment in the muscles causes myalgia and weakness, followed by subsidence of symptoms.

28 Splinter hemorrhages 2 Swollen eyes

29 A, B: Encysted larvae of Trichinella in pressed muscle tissue sample. The coiled larvae can be seen inside the cysts BA

30 Trichinella spiralis encysted larva

31 C, D: Larvae of Trichinella, freed from their cysts, typically coiled; length: 0.8 to 1 mm. C, D: Larvae of Trichinella, freed from their cysts, typically coiled; length: 0.8 to 1 mm. DC

32 Laboratory Diagnosis The suspicion of trichinellosis (trichinosis), based on clinical symptoms and eosinophilia, can be confirmed by specific diagnostic tests, including antibody detection, muscle biopsy, and microscopy. The suspicion of trichinellosis (trichinosis), based on clinical symptoms and eosinophilia, can be confirmed by specific diagnostic tests, including antibody detection, muscle biopsy, and microscopy.

33 Antibody Detection Immunodiagnostic tests currently available in the U.S. include enzyme immunoassays (EIA). Immunodiagnostic tests currently available in the U.S. include enzyme immunoassays (EIA). Antigen preparations may be crude antigens prepared from homogenates of Trichinella spiralis muscle larvae or excretory-secretory (ES) products produced by cultured larvae.


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