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Eosinophilic meningitis is caused by various parasites, a representive of which is Angiostrongylus cantonensis. The disease has also occasionally been reported in visceral larva migrans due to Toxocara canis, although the parenchymatous involvement of the CNS is extremely rare in T canis visceral larva migrans.1 Recently an outbreak of visceral larva migrans due to Ascaris suum infection has been reported in Kyushu, Japan, where chemical fertiliser has been replaced in part with pig manure.2 We report a case of myelopathy probably due to A suum infection.
A 22 year old man, living in the Tokyo metropolitan area, noticed that his right hand was swollen and warm in mid-August, 1999. The oedema subsided spontaneously within a week. In early October, he felt thermanaesthesia in his right leg while he was taking a shower. Because he had sometimes felt numbness in one or both axillas from the beginning of November, he was admitted to a hospital on 7 December 1999. Physical examination on admission showed hypalgesia and thermanaesthesia below the Th9 level on the right and a positive Lhermitte's sign. Peripheral blood eosinophil count was raised at 610/μl (10.5% leucocytes). Serum IgE concentration was 155 IU/ml (normal <240 IU/ml). Thoracic MRI disclosed an isolated high signal intensity lesion at the Th1 spine level on T2 weighted images. His symptoms improved gradually without any treatment. He was transferred to our hospital for diagnostic evaluation on 31 January 2000. He had a habit of eating raw beef liver and chicken liver. He had been to Fukuoka City, which is located at the northern part of Kyushu island, and ate raw beef liver in early August, 1999.
Physical examination on 31 January was normal except for the positive Lhermitte's sign. The peripheral blood eosinophil counts remained increased at 470/μl (7.0% leukocytes). Serum IgE, IgM, IgG, IgA, glutamic oxaloacetic transminase, and glutamic pyruvic transminase were normal. Antinuclear antibody, anti-ds-DNA antibody, c-ANCA, p-ANCA, and all other autoantibodies tested for were negative. Radioallergosorbent tests for Dermatophagoides pteronyssinus andDermatophagoides farinae were positive. Chest radiography and CT of the liver were normal.
His CSF showed 10 cells/μl, 10% of which were eosinophils, a protein concentration of 65 mg/dl, normal glucose concentration, and a normal IgG index. Oligoclonal IgG bands were negative. Spinal cord MRI showed a high signal intensity lesion at the Th1 spine level on T2 weighted images, which was enhanced by gadolinium-DTPA (figure). Brain MRI, somatosensory evoked potentials, motor evoked potentials, visual evoked potentials, and peripheral nerve conduction studies were all normal. On multiple dot ELISA for 12 parasite antigens, A suum, T canis, Dirofilaria immitis, Anisakis simplex, Gnathostoma doloresi, Strongyloides ratti, Paragonimus westermanii, Paragonimus miyazakii, Fasciola hepatica, Clonorchis sinensis, Spirometra erinaceiand Cysticercus cellulosae, both serum and CSF bound strongly to A suum and weakly to T canis but not to the others. On Ouchterlony's double diffusion test in agarose gel, the patient's serum but not CSF formed a sharp precipitin band againstA suum antigen, but not against eitherT canis orAngiostrongylus cantonensis antigens. Parasite eggs were not found in repeated stool examinations.
The diagnosis of A suum infection was made, and albendazole (600 mg/day) was given for 2 weeks with a 1 week interval. Thereafter, Lhermitte's sign as well as the MRI lesion were almost resolved (figure). His CSF after therapy showed normal cell counts (0/μl) and a normal protein concentration (41 mg/dl).
This is the first case report of myelopathy caused by visceral larva migrans probably due to A suum. The presence of a specific antibody against A suum in CSF as well as in serum, together with the presence of eosinophils in CSF, suggest that the spinal cord lesion is attributable to the presence of parasite larvae in the lesion. The resolution of the lesion after albendazole treatment strongly supports this hypothesis.
Among A suum visceral larva migrans cases, only one probable case of encephalopathy in which multiple enhanced lesions on brain MRI were markedly attenuated by corticosteroids has been reported.3 In that case, an immunoallergic mechanism was suggested for the CNS involvement. In our patient, albendazole, which efficiently passes through the blood-brain barrier, showed beneficial effects clinically as well as on MRI. Ascarid larvae have been reported to survive longer in the parenchymatous tissue and secrete antigens that cause allergic reactions in hosts.4Albendazole was therefore considered to have directly killed the larvae and effectively suppressed the host's immunoallergic reactions in the present patient.
Visceral larva migrans due to ascarid parasites is characterised by hepatopulmonary lesions associated with marked eosinophilia,2 which was also true for the previously reported patient with encephalopathy due to A suum visceral larva migrans.3 The present patient had neither pulmonary nor hepatic lesions, although he had had a transient hand oedema before the onset of neurological symptoms. Variations in clinical manifestations of visceral larva migrans may, at least in part, be attributed to the degree of infection. Even in a low grade infection without detectable hepatopulmonary lesions, ascarid larvae can migrate to an unexpected site to cause unusual clinical manifestations.
In areas where it is endemic, such as Kyushu, Japan, infection withA suum occurs primarily from ingesting vegetables contaminated with pig manure containing parasite eggs.2 3 In addition, some patients were assumed to be infected by eating raw beef or chicken liver contaminated withA suum larvae (Nawa Y, unpublished data). Infection of cattle with A suum has been reported when they were kept in the same field.5 Our patient developed myelopathy after ingesting raw beef liver, although he had never lived in the endemic areas. Because food borne parasitic zoonoses can be transported to areas distant from where they are endemic, neurologists should take a careful history of eating habits when eosinophilia that suggests visceral larva migrans is present in patients with neurological symptoms.
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