CASE REPORT

Neurocysticercosis without Detectable Specific AntibodyYoshinobu Ohsaki, Akihiko Matsumoto* , Kenji Miyamoto* * ,

Nobuo Kondoh***, Kunioki Araki****, Akira Ito** and Kenjiro Kikuchi

A 19-year-old girl who had lived in India for five years until 1992 was admitted to HokutoHospital after general seizures which lasted for fifteen minutes. Cerebral magnetic resonanceimaging (MRI) showed a ring-enhanced lesion of 6 mmin diameter in the right parietal lobe. Sheunderwent surgical resection after diagnosis of the brain tumor. Histopathological examinationsrevealed that the resected tumor was a cysticercus of Taenia solium (T. solium), and we concludedthat her seizures were caused by neurocysticercosis. Serological examinations by enzyme-linkedimmunosorbent assay (ELISA) and immunoblots to detect specific antibody against the glyco-proteins of T. solium showedno detectable antibody response. The patient is under carefulobservation in our out-patient clinic with no medication.(Internal Medicine 38: 67-70, 1999)

Key words: parasite, magnetic resonance imaging (MRI), cerebral cysticercosis, Cysticercuscellulosae, Taenia solium, serodiagnosis

Introduction

Neurocysticercosis (NCC) is caused by infection with thelarval stage of the pork tapeworm, Taenia solium (T. solium),which has been recognized as a major cause of parasitic diseaseof the central nervous system not only in developing countrieswhere the infection is endemic, but also even in developedcountries (1-4). With the development of new techniques ofneurological imaging and sensitive and specific serodiagnosis,cysticercosis has been found to be more commonthan previ-ously estimated (2, 3, 5-7).T. solium completes its life cycle both in swine and humans.The adult tapewormmatures exclusively in the intestine of thehuman who has eaten under-cooked pork contaminated withthe larval stage, cysticerci. Eggs which are released from

humans, the wormcarriers, are ready to infect both swine andhumans and thus, cysticercosis is communicable from humantohuman(.2-4). Therefore, wormcarriers can be the source of newcysticercosis in non-endemic areas into which they move, ashas beert reported of New York (1).

NCC is not endemic in Japan, therefore, most Japaneseclinicians are not familiar with such a parasitic disease and tendto consider it to be a tumor. Almost all NCCcases reported inJapan, either Japanese or foreigners, have been exposed to thepossible intake of eggs in the endemic countries. Increases in

numbers of immigrants, refugees and tourists means that carri-ers of T. solium are spreading in Japan and worldwide (1, 3, 4).In this case report, we describe a NCCcase of Japaneseyoung womanwho was found to have a ring-enhanced lesion bymagnetic resonance imaging (MRI) without any detectableantibody against glycoproteins of T. solium in the serum.

Case ReportA 19-year-old Japanese womanwas transferred from theObihiro Municipal Hospital to the Department of Neurosur-gery, Hokuto Hospital on August 7, 1997, because of general-ized seizures on August 3. She had lived with her family in Indiafor five years from 1987 until 1992. She had received a partialskin resection to removea cystic lesion smaller than 1 cmindiameter in 1994, three years before the onset of seizures.

However,no pathological examination of the skin lesion wasperformed. The generalized seizures began without any preced-ing neurological abnormalities and the convulsion lasted for15 minutes. Until the onset of seizures, she had not ex-

perienced any abnormal signs of the central nervous system.Cerebral MRIscans showed a ring-enhanced lesion of 6 mmindiameter in the right parietal lobe (Fig. 1A, B). There were nosigns of brain edemaor mass effect in the MRIscanning.Physical examinations revealed no abnormal findings in the

From the First Department of Medicine, **the Department of Parasitology, Asahikawa Medical College, Asahikawa, *the Department of Neurosurgery, HokutoHospital, Obihiro, ***Laboratory for Surgical Pathology, Sapporo and ****Institute of Public Health, Tokyo

Received for publication April 13, 1998; Accepted for publication October 26, 1998Reprint requests should be addressed to Dr. Yoshinobu Ohsaki, the First Department of Medicine, Asahikawa Medical College, 4-5-3 Nishikagura, Asahikawa

078-8510

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Figure 1. Tl-weighted gadolinium enhanced magnetic resonance image scanning of the brain. A solitary ring-enhancedcystic lesion of6 mmin diameter is seen on the film. Brain edema is not apparent, a: frontal view, b: coronal view (TR: 360, TE:9/Fr).

neck, chest or abdomen. There were no lesions under the skin.Breathing and heart sounds were normal. Neurological exami-nations revealed no abnormal findings including neck stiffness.Results of hematological, biochemical and serological exami-nations are listed in Table 1. Chest and abdominal scanningrevealed no abnormality.The patient received a right parietal craniotomy to removethe lesion under the diagnosis of brain tumor on August 14,1997. Histopathological examinations of the resected lesion

revealed a cysticercus, the larval stage of T. solium (Fig. 2A, B).Stool examinations after the operation showedno evidence ofon-going infection with adult tapeworm, T. solium. Serologicalexaminations by enzyme-linked immunosorbent assay (ELISA)and immunoblots to detect specific antibody against the specificantigens of this parasite failed to detect any specific antibody inher serum (figures not shown). She is under careful observationat the Asahikawa Medical College Hospital Out-patient clinicwithout any medication because no antibody has been detected.

Table 1. Laboratory DataWh i t e b lo o d c e ll s 4, 8 00 / u l A l a n i n e a m i n o t r a n s f e r a s e 1 0 I U / /

n e u tro p h ils 4 5 % A s p a r t a t e a m i n o t r a n s f e r a s e 9 I U / /e o s in o p h ils 4 % L a c t a t e d e h y d r o g e n a s e 2 6 0 I U / /b a s o p h ils 1 % y - g l u t a m y l t r a n s f e r a s e 8 I U / /m o n o c y te s 4 % A l k a l i n e p h o s p h a t a s e 7 0 I U / /ly m p h o c y te s 4 6 % C r e a t i n e k i n a s e 6 0 I U / /

Re d b l oo d c e ll s 5 3 2 x l O 4/u l T o t a l c h o l e s t e r o l 1 2 9 m g / d lP la te le ts 20.9 x 1 04/ ul T r i g l y c e r i d e 8 1 m g / d l

B l o o d u r e a n i t r o g e n 1 1 . 8 m g / d lT o ta l p r o te in 5 .7 g/d l C r e a t i n i n e 0 . 7 m g / d l

a lb u m in 6 8 . 7 % U r i c a c i d 1 . 8 m g / d lo ci -g lo b u lin 2 . 9 % N a 1 4 0 m E q / /O C2-g lo b u lin 8 . 3 % C 1 1 0 3 m E q / /B -g lo b u lin 9 . 1 % K 4 . 3 m E q / /y -g lo b u lin l l.0 % F e 8 6 m g / d l

To ta l bi li ru bin 0 .4 m g/ d l A m y l a s e 8 8 J U / lC h o lin e ste ra se 3, 63 6 I U/ 1 C r o s s - r e a c t i n g p r o t e i n < 0 . 4 m g / d l

68 Internal Medicine Vol. 38, No. 1 (January 1999)

A Case of Neurocysticercosis

Figure 2. Pathological findings of the cyst. A scolex withspinal canal is found in the wall of the cyst. A: Three suckers andbooklets are seen (arrows, HEstain, x50). B: Calcareous corpus-cles are seen in a portion of the neck (HE stain, x200).

Discussion

NCCis the most common,serious and life-threateningdisease due to T. solium infection (3). In 33 reported cysticer-cosis cases from 1983 until 1992 in Japan, 31 cases were NCC,and 24 had had experience of visiting or staying in endemicregions of T. solium infection (8). Endemic regions includealmost all Latin America, Southeast Asia, South Africa andother African countries (4, 9). Wormcarriers of adult T. soliumgenerally do not have serious health problems, however, cys-ticercosis can develop due to the released eggs. Althoughautoinfection is one cause of cysticercosis, it appears to havebeen overstressed (10). In the present case, fecal examinationrevealed no evidence of infection of adult wormsin the intes-tine. Based on her personal history, we speculated that she hadaccidentally ingested eggs ofT. solium during her five-year stayin India.Epilepsy is the most frequent sign of NCC(1 1). However,other types ofcysticercosis such as subcutaneouscysticercosis,although not ocular cysticercosis, are generally asymptomatic.In the present case, although a pathological examination hadnot been carried out, a partial resection of a cystic lesion from

the skin had been done three years before the parietal crani-otomy. The most frequent form of NCCis parenchymal cys-ticercosis, which is found as brain granulomas or calcifications(12). MRI and computed tomography (CT) scanning are usefulprocedures in the diagnosis of NCC.MRIfeatures of solitarycerebral cysticercus granulomas vary considerably ( 1 2). Cysticlesions, ring-enhanced lesion, parenchymal brain calcifica-

tions, hydrocephalus and abnormal enhancement of the lep-tomeninges are representative signs of NCCby CTand MRIscanning (6).

Recent advances in serodiagnosis reveal that most cases ofNCC,including those with a single cyst, are antibody positiveagainst the specific antigens (5, 7). However, the sensitive andspecific serodiagnosis for NCCcarried out at both Institute ofPublic Health and Asahikawa Medical College showed noantibody response in the present case. In the former, ELISA wasperformed, while in the latter immunoblots using glycoproteinsprepared at Asahikawa Medical College and at the Centers forDisease Control and Prevention in Atlanta, Georgia were used(5, 7, 13). The enzyme-linked immunoelectrotransfer blot as-say is nearly 100% sensitive for patients with either multipleactive parenchymal cysts or extraparenchymal neurocysti-cercosis. However, the sensitivity is lower for patients witheither single parenchymal cysts or calcifications alone (3).

Therefore, our results suggested that the patient had only onecyst in the brain. However, this is difficult to confirm as the skincyst had not been examined.Surgical resection is not always necessary in cases of NCC(14); praziquantel and albendazole are highly effective for itstreatment. Delivery of anti-cysticercosis drugs improved sei-zures in the patients with inflammatory parenchymal NCC( 1 1 ).NCCis classified into active and inactive types. A parenchymalcyst without calcification was considered to be an active NCCin which deliveries of anti-cysticercosis drugs have been rec-ommended.Further, the active NCCis classified a non-inflam-matory or acute inflammatory cyst according to findings ofcerebrospinal fluid. In the acute inflammatory case, ring en-hancement and edema are seen on CT scanning (15) and in suchcases anti-cysticercosis drugs are necessary for treatment. Ifboth neurological imaging and serological testing show clearevidence of NCCin patients with a personal history whichsuggests NCCinfection, chemotherapy is first recommend.In the present case, the patient did not receive any medica-tion after the surgery because she had the single brain cystwithout edema resected, and showed no antibody responsesagainst highly sensitive and specific antigens. However, she isstill under careful observation and visits our out-patient clinic.For the follow-up period of our patient it is not necessary toexceed five years, because natural history study findings sug-gest that most NCClesions are resolved within a period ofa fewyears, even in the absence of antiparasitic therapy (3).

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