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Toxocariasis is an illness of humans caused by larvae (immature worms) of either the dog roundworm (''Toxocara canis''), the cat roundworm (''Toxocara cati'') or the fox (''Toxocara canis''). Toxocariasis is often called visceral larva migrans (VLM). Depending on geographic location, degree of eosinophilia, eye and/or pulmonary signs the terms ocular larva migrans (OLM), Weingarten's disease, Frimodt-Møller's syndrome, and eosinophilic pseudoleukemia〔Marty, Aileen. Toxocariasis Chapter 27, pages 411- 421 ''in'' Meyers WM, Neafie RC, Marty AM, Wear DJ. (Eds) Pathology of Infectious Diseases Volume I: Helminthiases. Armed Forces Institute of Pathology, Washington DC. 2000;http://www.afip.org/cgi-bin/description.cgi?item=FS28〕 are applied to toxocariasis. Other terms sometimes or rarely used include nematode ophthalmitis, toxocaral disease, toxocarose, and covert toxocariasis.〔 This zoonotic, helminthic infection is a major cause of blindness and may provoke rheumatic, neurologic, or asthmatic symptoms. Humans normally become infected by ingestion of embryonated eggs (each containing a fully developed larva, L2) from contaminated sources (soil, fresh or unwashed vegetables, or improperly cooked paratenic hosts).〔 ''Toxocara canis'' and ''Toxocara cati'' are perhaps the most ubiquitous gastrointestinal worms (helminths) of domestic dogs and cats and foxes. There are many 'accidental' or paratenic hosts including humans, birds, pigs, rodents, goats, monkeys, and rabbits.〔 In paratenic hosts the larvae never mature and remain at the L2 stage.〔Markell, Edward K. and Marietta Voge. Markell and Voge’s Medical Parasitology. 9th ed. St. Louis: Saunders Elsevier, 2006〕 There are three main syndromes: ''visceral larva migrans'' (VLM), which encompasses diseases associated with major organs; ''covert toxocariasis'', which is a milder version of VLM; and ''ocular larva migrans'' (OLM), in which pathological effects on the host are restricted to the eye and the optic nerve. ==Signs and symptoms== Physiological reactions to ''Toxocara'' infection depend on the host’s immune response and the parasitic load. Most cases of ''Toxocara'' infection are asymptomatic, especially in adults.〔〔Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, Division of Parasitic diseases. "Fact Sheet: Toxocariasis." 5 Nov. 2007. 19 Jan. 2009. Covert toxocariasis is the least serious of the three syndromes and is believed to be due to chronic exposure. Signs and symptoms of covert toxocariasis are coughing, fever, abdominal pain, headaches, and changes in behavior and ability to sleep.〔〔 Upon medical examination, wheezing, hepatomegaly, and lymphadenitis are often noted.〔 High parasitic loads or repeated infection can lead to visceral larva migrans (VLM).〔 VLM is primarily diagnosed in young children, because they are more prone to exposure and ingestion of infective eggs.〔 ''Toxocara'' infection commonly resolves itself within weeks, but chronic eosinophilia may result.〔 In VLM, larvae migration incites inflammation of internal organs and sometimes the central nervous system.〔〔 Symptoms depend on the organ(s) affected.〔 Patients can present with pallor, fatigue, weight loss, anorexia, fever, headache, rash, cough, asthma, chest tightness, increased irritability, abdominal pain, nausea, and vomiting.〔〔 Sometimes the subcutaneous migration tracks of the larvae can be seen.〔 Patients are commonly diagnosed with pneumonia, bronchospasms, chronic pulmonary inflammation, hypereosinophilia, hepatomegaly, hypergammaglobulinaemia (IgM, IgG, and IgE classes), leucocytosis, and elevated anti-A and –B isohaemagglutinins.〔〔〔〔 Severe cases have occurred in people who are hypersensitive to allergens; in rare cases, epilepsy, inflammation of the heart, pleural effusion, respiratory failure, and death have resulted from VLM.〔〔 Ocular larva migrans (OLM) is rare compared with VLM.〔〔The Merck Veterinary Manual. “Roundworm.” 2008. 26 Jan. 2009 A case study published in 2008 supported the hypothesis that eosinophilic cellulitis may also be caused by infection with ''Toxocara''. In this study, the adult patient presented with eosinophilic cellulitis, hepatosplenomegaly, anemia, and a positive ELISA for ''T. cani''s.〔Bassukas, Ioannis D., Georgios Gaitanis, Aikaterini Zioga, Christina Boboyianni, and Christina Stergiopoulou. Febrile “migrating” eosinophilic cellulitis with hepatosplenomegaly: adult Toxocariasis – a case report. Cases Journal 2008, 1:356〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「toxocariasis」の詳細全文を読む スポンサード リンク
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