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 Table of Contents  
Year : 2022  |  Volume : 24  |  Issue : 1  |  Page : 44-47

An unusual guest in an unusual location of the brain of a rural tribal man

1 Department of Microbiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
2 Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
3 Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
4 Department of Pathology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
5 Department of Medical Parasitology, Post Graduate Institute for Medical Education and Research, Chandigarh, India

Date of Submission10-May-2022
Date of Acceptance10-Jun-2022
Date of Web Publication11-Jul-2022

Correspondence Address:
Kavita Raja
Department of Microbiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Thiruvananthapuram - 695 011, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jacm.jacm_9_22

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We report a rare occurrence of central nervous system hydatid disease involving the occipital lobe caused by Echinococcus multilocularis in an immunocompetent rural tribal man. A 40-year-old man presented with gradual onset of headache for 6-month duration with associated seizures and giddiness. Neurological examination revealed cerebellar signs with visual field defect. Magnetic resonance imaging revealed a multilobulated cystic lesion with membranous septations and peri-lesional oedema involving the left occipital lobe. Wet mount examination of the aspirated cystic fluid showed multiple daughter cysts and hooklets with histopathological examination showing features suggestive of hydatid disease. The identification of the causative organism was confirmed as E. multilocularis by conventional polymerase chain reaction. The patient's condition improved during the post-operative period and was discharged 2 days later, on oral albendazole for 3 months. At 2 years follow-up, the patient neurological symptoms have recovered with minimal visual field defect.

Keywords: Brain, Echinococcus multilocularis, hydatid disease, occipital lobe

How to cite this article:
Ponnambath DK, Kaviyil JE, Raja K, Kesavapisharady K, Thomas B, Narasimhaiah D, Sehgal R, Kaur U. An unusual guest in an unusual location of the brain of a rural tribal man. J Acad Clin Microbiol 2022;24:44-7

How to cite this URL:
Ponnambath DK, Kaviyil JE, Raja K, Kesavapisharady K, Thomas B, Narasimhaiah D, Sehgal R, Kaur U. An unusual guest in an unusual location of the brain of a rural tribal man. J Acad Clin Microbiol [serial online] 2022 [cited 2023 Nov 30];24:44-7. Available from: https://www.jacmjournal.org/text.asp?2022/24/1/44/350324

  Introduction Top

Echinococcosis or hydatid disease is a zoonotic disease caused by the cestode helminth parasite Echinococcus spp. which is widely distributed globally and is also endemic in India. Humans, being the accidental intermediate host acquire infection by ingestion of food/water contaminated with Echinococcus eggs excreted by the canine definitive hosts. Although the liver is the most common site of infection, extrahepatic lesions have also been described in the literature.[1] In this report, we describe a rare occurrence of intracranial alveolar hydatid disease caused by Echinococcus multilocularis, involving the occipital lobe of a rural tribal man from Tamil Nadu.

  Case Report Top

A 40-year-old chronic smoker and alcoholic labour worker from Udumalaipettai, Tirupur district of Tamilnadu, was referred with gradual onset of headache for 6-month duration which was initially bifrontal, later progressing to holocranial. The frequency of the headache was initially intermittent in nature, which later became continuous with increasing severity over the past 6 months. There were associated two episodes of seizures; the first episode was 4 months before the presentation with semiology of tonic posturing with uprolling of eyes and deviation of mouth lasting for 2 min. The seizure was not preceded by aura. There was the postictal loss of consciousness lasting for 5 min. The second episode of seizure occurred 3 days before admission, with similar pre- and postictal semiology. There was also associated giddiness for the past 6 months which was initially mild but became severe with difficulty in walking with swaying more towards the right side, since the second episode of seizure. There was no associated history of fever, nausea, vomiting, loose stools, abdominal pain, neck stiffness, weakness, sensory or autonomic nervous system disturbances or features of cranial nerve palsies. There was also no history or features suggestive of cardiovascular, haematological or immunosuppressive disorders (tested retroviral negative). The patient did not have any comorbid conditions such as diabetes, hypertension or known liver or renal diseases. There was no history of pulmonary tuberculosis or history of contact with patients with tuberculosis.

Laboratory analysis revealed mild normocytic normochromic anaemia (Hb –11.4 g/dl), normal total and differential leucocyte count (5100 cells/mm3, polymorphs –63% and lymphocytes –34%) and normal erythrocyte sedimentation rate (05 mm/h). The liver enzymes and electrolyte levels were within the normal reference range. The general examination revealed no abnormalities. Neurological examination revealed positive Romberg's sign, bilateral lateral gaze nystagmus, dysdiadochokinesia and past pointing with mild swaying while walking and slurring of speech. Visual field examination of the left eye revealed minimal nasal field defect and the right eye showed minimal temporal field defect. Ultrasonogram of the abdomen showed no abnormal findings.

Magnetic resonance imaging revealed a 3.2 × 3.1 × 2.8 (AP × Tr × CC) cm, well-defined multilobulated cystic lesion predominantly involving the subcortical white matter of the left occipital lobe. It had a small outpouching extending into the occipital cortex. The lesion was hypointense on T1W1, while hyperintense in T2W1 and mildly hyperintense on Fluid attenuated inversion recovery (FLAIR). A well-defined hypointense rim was noted around the lesion. Multiple hypointense membrane-like septations with few susceptibility artifacts were observed within the cystic lesion. The contents within the lesion showed no restriction of diffusion while some restriction was noted within the wall of the lesion. Post-contrast, neither the septations within the lesion nor the contents showed enhancement. Peri-lesional oedema with mass effect on the occipital horn of the left ventricle was observed [Figure 1]. MR spectroscopy showed a lipid peak within the lesion. Other areas of the brain parenchyma, sinuses, sella, intracranial arteries and venous sinuses were normal.
Figure 1: A left temporo-occipital cystic lesion on T1-weighted MRI (a) showing thin wall enhancement including the daughter cyst, on the gadolinium-enhanced scan (b). T2-weighted image shows cyst and the daughter cyst with internal membranes (c) with significant peri-lesional oedema well demonstrated on axial FLAIR sequence (d)

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The patient underwent left parieto-occipital craniotomy with complete dissection-excision of the cystic lesion under neuronavigation and intraoperative ultrasonogram guidance [Figure 2]. The cystic lesion with aspirate fluid was sent for microbiological culture and histopathological examination (HPE). Gram staining and Ziehl–Neelsen staining of the aspirate fluid showed daughter cysts with rows of hooklets in their scolex. Multiple individual hooklets were also observed in the aspirated fluid [Figure 3]. Bacteriological culture on blood, chocolate, MacConkey and Lowenstein–Jensen medium showed no growth. Cartridge-Based Nucleic Acid Amplification Test (CBNAAT) performed in the aspirated fluid for detecting Mycobacterium tuberculosis complex was also tested negative. The resected cystic lesion was sent to histopathology. On macroscopic examination, the cyst measured 4 cm × 4 cm × 3.5 cm with yellow and flaky cyst content. The cyst wall was white and membranous and was surrounded by a thick pericyst. On microscopic examination, the cyst comprised an acellular eosinophilic thick laminated layer (periodic acid–Schiff-positive) with prominent striations and an inner degenerated germinal layer. There were protoscolices in varying stages of degeneration, some with birefringent hooklets [Figure 4]a. The pericyst surrounding the cyst was thick, composed of fibrocollagenous tissue with palisading histiocytes, multinucleate giant cells, moderate infiltrates of lymphocytes, plasma cells and few eosinophils [Figure 4]b. The adjacent cerebral cortex was oedematous with reactive astrocytes and cerebritis. Based on these histological features, a diagnosis of hydatid cyst (echinococcosis) was rendered.
Figure 2: Image of the dissected intracerebral hydatid cyst removed by complete excision of the cystic lesion under neuronavigation and intraoperative ultrasonogram guidance showing white and membranous cyst wall (arrow) surrounded by fibrous pericyst

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Figure 3: Ziehl–Neelsen staining (×400) of aspirated hydatid cyst fluid showing protoscolex of the daughter cysts with a row of rostellar hooklets (a) and free hooklets released in the hydatid cyst (b)

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Figure 4: Laminated layer of the hydatid cyst with a scolex (a) and fibrous pericyst with chronic inflammatory cells (b) enclosing the cyst (arrow) (haematoxylin and eosin, original magnification = scale bar)

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The HPE revealed the following findings [Figure 4]. The identification of the causative organism was confirmed as E. multilocularis by the detection of E. multilocularis DNA by polymerase chain reaction (PCR) (Georges et al.; 2004).[2] DNA extraction was performed using the QIAamp DNA Mini kit (QIAGEN, Valencia, CA). E. multilocularis DNA was detected by a modified PCR described by Dinkel et al. and Stieger et al., with the primer pair EM-H15 (5'-CCATATTACAAC AATATTCCTATC-3') and EM-H17 (5'-GTGAGT GATTCTTGTTAGGGGAAG-3').[3],[4] A 200-bp product from the E. multilocularis 12S rRNA gene was amplified. PCR amplification was performed within a 50-μl reaction volume using a HotStart Taq DNA polymerase (HotStar Taq; QIAGEN SA). The reaction mixture consisted of 10 μl of DNA template, 5 μl of ×10 HotStarTaq PCR buffer (including 1.5 mM [final concentration] MgCl2), 5 μl of dATP, dTTP, dGTP and dCTP (each at 200 μM [final concentration]), 1 μl of each primer (1 μM [final concentration]) and 0.25 μl of HotStarTaq DNA polymerase (1.25 U [final amount]). The thermal cycling conditions were as follows: 95°C for 15 min, 40 cycles at 95°C for 30 s, 55°C for 30 s and 72°C for 30 s and a final extension at 72°C for 5 min. Amplicons were detected after electrophoresis on a 2% agarose gel by staining the gel with ethidium bromide.

The patient's condition improved in the post-operative period and was discharged 2 days later on oral albendazole 400 mg once daily dose for 3 months. Steroids were not used in the post-operative medical management regimen. At a 2-year follow-up, the patient neurological symptoms have recovered with minimal visual field defect.

  Discussion Top

Hydatid disease is caused by the larval form of the cestode parasite, Echinococcus spp. There are four species of Echinococcus known: Echinococcus granulosus, E. multilocularis, Echinococcus vogeli and Echinococcus oligarthus. Cystic echinococcosis is caused by E. granulosus while alveolar echinococcosis is caused by E. multilocularis. Two forms of neotropical echinococcosis are caused by E. vogeli (polycystic) and E. oligarthus (unicystic). Cystic echinococcosis is distributed globally while it is reported endemic in the Middle East, North Africa, India, Central Asia, Australia and South America. Alveolar echinococcosis is mostly reported in the northern hemisphere (colder climates), i.e., China, the Russian Federation and countries in continental Europe and North America.[5] Canines (dogs, foxes and wolves) act as the definitive hosts while sheep and goats act as the intermediate hosts. The eggs laid in the soil by the definitive hosts can remain viable for months since they resist desiccation. Humans are accidental intermediate hosts and get infected by the consumption of food contaminated with these viable eggs. This leads to the transmission of infection to humans even to those who have no direct contact with the animals acting as definitive hosts.[1] The patient's occupation as an agricultural field labourer who was also involved in rearing goats has been deciphered as the risk factors leading to contact and consumption of contaminated food or water with Echinococcus eggs. The patient did not have dogs as pet while history revealed the widespread distribution of dogs and foxes in the tribal area where he resides.

Hydatid cysts tend to occur commonly in the liver (50%–70%), followed by the lungs (20%–30%) and in other organs (<10%) such as bones, brain and heart. Approximately, 1%–3% of hydatid disease occurs in the brain (primary cerebral echinococcosis). The intracranial lesion usually occurs following dissemination of the infection from the primary site in the liver or lung. In our patient, no extracranial infection site was documented. Isolated cerebral alveolar echinococcosis without other organ involvement has been reported in the literature.[6],[7],[8],[9] The rate of growth of these intracranial lesions has been described to be at 1 cm/year, but can increase to a rate of 5–10 cm/year in certain cases.[9] Intracranial lesions are reported to involve mostly the supratentorial region, particularly the parietal and temporal lobes in cystic echinococcosis. In a recent large retrospective cohort analysis of intracranial alveolar echinococcosis reported from rural China, most patients were males (62%) with coexisting liver lesions.[10] The most common complaints reported in this cohort were headache (81%), dizziness (52.4%), seizures (19%) and visual disturbances (14.3%). Our patient also presented with all these clinical features at presentation. Multiple cerebral lesions were reported in 57.1% of cases most commonly involving the parietal (71.5%) and occipital lobes (61.7%) in this cohort.

In contrast to the less common involvement of the occipital lobe in intracranial cystic echinococcosis, the lobe was commonly found to be involved in intracranial alveolar echinococcosis. The differentiating features between cystic and alveolar echinococcosis include relatively thin outer laminar membrane and pericyst. Fibrous tissue and calcification around the cysts and cysts being embedded in a hard, dense stroma for E. multilocularis; While E. granulosus cysts have thick-walled chambers which are not usually demarcated at its outer margin by a fibrous capsule and the cyst is filled with fluid and is free of the host material (Kantarci et al., 2012).[11] High mortality rate (47.6%) was observed in this cohort during the follow-up period for a mean duration of 21.7 ± 11.9 (3–46) months. Due to high mortality and post-operative recurrence rates, periodic follow-up and long duration (months to years) of oral albendazole treatment are recommended. In spite of the availability of advanced diagnostic and therapeutic modalities, lack of access to healthcare, poor compliance to oral medications and loss to follow-up has been reported to contribute to their poor outcome.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Bennett JE, Dolin R, Blaser MJ, editors. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020.  Back to cited text no. 1
Georges S, Villard O, Filisetti D, Mathis A, Marcellin L, Hansmann Y, et al. Usefulness of PCR analysis for diagnosis of alveolar echinococcosis with unusual localizations: Two case studies. J Clin Microbiol 2004;42:5954-6.  Back to cited text no. 2
Dinkel A, von Nickisch-Rosenegk M, Bilger B, Merli M, Lucius R, Romig T. Detection of Echinococcus multilocularis in the definitive host: Coprodiagnosis by PCR as an alternative to necropsy. J Clin Microbiol 1998;36:1871-6.  Back to cited text no. 3
Stieger C, Hegglin D, Schwarzenbach G, Mathis A, Deplazes P. Spatial and temporal aspects of urban transmission of Echinococcus multilocularis. Parasitology 2002;124:631-40.  Back to cited text no. 4
WHO. World Health Organisation (WHO) Fact Sheet on Echinococcosis; 2021. Available from: https://www.who.int/news-room/fact-sheets/detail/echinococcosis. [Last accessed on 2022 Apr 04].  Back to cited text no. 5
Baldolli A, Bonhomme J, Yera H, Grenouillet F, Chapon F, Barbier C, et al. Isolated cerebral alveolar echinococcosis. Open Forum Infect Dis 2019;6:ofy349.  Back to cited text no. 6
Reuss AM, Wulf MA, Oertel MF, Bozinov O, Henzi A, Kaelin MB, et al. An immunocompetent farmer with isolated cerebral alveolar echinococcosis: Illustrative case. J Neurosurg Case Lessons 2021;1:CASE2187. Available from: https://thejns.org/view/journals/j-neurosurg-case-lessons/1/22/article-CASE2187.xml. [Last accessed on 2022 Apr 07].  Back to cited text no. 7
Du G, Li Y, Wu P, Wang X, Su R, Fan Y, et al. Diagnosis, treatment, and misdiagnosis analysis of 28 cases of central nervous system echinococcosis. Chin Neurosurg J 2021;7:30.  Back to cited text no. 8
Kemaloğlu S, Ozkan U, Bükte Y, Acar M, Ceviz A. Growth rate of cerebral hydatid cyst, with a review of the literature. Childs Nerv Syst 2001;17:743-5.  Back to cited text no. 9
Li S, Chen J, He Y, Deng Y, Chen J, Fang W, et al. Clinical features, radiological characteristics, and outcomes of patients with intracranial alveolar echinococcosis: A case series from Tibetan areas of Sichuan Province, China. Front Neurol 2020;11:537565.  Back to cited text no. 10
Kantarci M, Bayraktutan U, Karabulut N, Aydinli B, Ogul H, Yuce I, et al. Alveolar echinococcosis: Spectrum of findings at cross-sectional imaging. Radiographics 2012;32:2053-70.  Back to cited text no. 11


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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